Mike's Cabrio Build

[Mike]

Re: Mike's Cabrio Build

This will be a lengthy one, and is probably the most satisfying part of my build for me:

The Dash: Part 1

Like so many builders I guess the choice of dash layout and style causes as much thought provoking as the final colour of your car!

I had some basic ideas of what I wanted. It would be a wooden dash, and I liked the old Triumph Vitesse gauges with the V - bezels. I also felt that the straight line across the bottom of the standard Cabrio dash was at odds with all the curves in the Cabrio.

After trying 33 different layouts (literally) I found I was gravitating to this layout:



I had seen Simon Gregory make use of the centre vent from his 5 series BMW donor and connect it to the Sierra's centre outlet. The BMW vent ios a little ddeper than the depth of the Cabrio's lower section but can be squeezed in.

However, this left the long straight edge across the bottom of the main dash which I preferred no to see.





I preferred the look of lowering the central section. But this would mean making a special housing for the vent..................but it had to be done!

Whilst I was experimenting with dash layouts, I did manage to make myself much improved upper dash.

Obviously IVA requirements for large radiuses were important, and the looks and feel matter too.

Firstly I welded on ally end plates to the standard dash as this produces a much neater finish when it is leathered up.



I also added side window vent holes, for vents found in an early Audi A4.
I found a soft rubber profile at Woolies which within its overall profile had a perfect D section to fit the front face of the top of my dash. So I cut the surplus off, to leave just a D, and glued it on.

I then glued a dense foam sheet to the ally dash.



I then had it covered in black leather:



In order to include the % series vent, and change the lower dash line I needed to make an ally box to support it. This grew and grew until I had created a complete centre console!
Again I have made this curve both in the front face, and the sides.



IVA is always at the back of my mind as I come up with variations and improvements, but one problem I had was I wanted the V bezels on my guages, yet I know they will fail IVA. I could have recessed them into my dash, but that's not what I wanted, so I have come up with a cunning plan.............



I have made an additional gash dash centre section out of 6mm ply which I will position over the main dials
so that they will effectively be flush with the front of this dash section. It will become clearer later....



This is the main dash - it looks fabulous - its so shiny it is difficult to take a good photo due to all the reflections!
Obviously this will fail IVA, so you can see why I've had to fit the additional gash dash...........

[Mike]

Re: Mike's Cabrio Build

The Dash : Part 2

The dash has taken me a couple of years to develop to the final article, so you are seeing a much speeded up process here.

One of the build problems with the centre console was how to make the edges of the centre vent IVA proof. I wanted compound curves which can not be rolled - in one plane yes, but two definitely not. I had a go with MDF, as this can be crafted, but mixing ally and MDF didn't work too well.

In the end, like so many good ideas, the solution was simple.



I made the side section out of a sheet of ally, which meant I could have an outer curve in the width, and one around the vent itself, but this would only have the thickness of the ally. The solution was to stretch some medium density foam layers over the curved edge until I had built up a much thicker edge.



This has 4 layers of foam to give a very tactile curved face.
Whilst the side of the console now looks like this.



This is almost the final layout of my console: some of the switches will have to be swapped out for the IVA:



Its starting to come together:though the simplicity belies the effort that has gone into it.
Some of the switch gear is recognisable Sierra kit. The electric window switches are Granada: the heater vent control and hazard warning lights are old BMW 5 series: and the heater switch is a work of art!

The outer bezel is from a modern 5 Series light switch, the switch mechanism is the Sierra's heater switch, but the knob is from a Granada, and the fan logo on the knob is taken from Metro!

This switch has then been repeated to make a new light switch to the right of the dash. This will replace the Sierra's column light switch after IVA, as it will allow the steering column to press forward further into the dash - but more of that later.



I even had to adapt one of the warning lights. These high quality aero warning lights are in polished aluminium - the problem is the range is very limited - there are only 5 above, for 6 holes. I had to buy one of their black range, and scratch the black paint off, and then [polish the aluminium behind to match my others. In the end I stuck it in an electric drill and polished it that way: worked a treat!



This shows the centre gash dash covering the bezel sharp edges.




Whilst I had been trial fitting the dash into the Cabrio I was very aware that the dash had no strength to it. I have chosen a push start button, but when I press it, the centre of the dash moves back rather than the button going in!

It required some triangulation to make it stronger, so I have welded some buttresses on the back to make it stiffer. Also I have attached it to the centre console which in turn will be attached to the transmission tunnel, and the whole arrangement becomes quite rigid.




I have added 4 buttresses - either side of the steering column, and either side of the centre console.
The switch on the left is a modern BMW 5 series which has the bezel I like, but this switch is designed for modern computer controlled instruments - I'll convert the back of this tto use another heater control, with the different fan settings being used for side and main lights, plus fogs.



This is a better shot of one of the stiffening buttresses.

The centre console leathered up.



And all together:




I have still to add the Triumph Vitesse glove box lock that I have final sourced.

The finishing touches for me are the two stainless strip above and below the vent. These were surplus pieces of the U profile I used to make the grille frame. I just have to find a way to close off their ends on the left as they are sharp. (the ones on the right can not be reached by a ball of 165mm diameter as set out in the IVA Method of Inspection!

[Mike]

Re: Mike's Cabrio Build

Whilst I'm posting the dash, there are a couple of shots which explain why I have made new light and hazard warning switches:

If you look carefully below, the light switch and hazard warning switches have both been removed. The position of the steering wheel in this shot shows where it has to be if these switches were still fitted to allow hand/finger access to them.



Below the position of the steering wheel is no longer sconstrained by either the light switch or the indicator stalk, but is limited by finger space behind the wheel itself.

Post IVA, this is what I plan to do to give myself a little more arm room, by pushing the wheel away from the seat as far as is reasonable.

[Mike]

Re: Mike's Cabrio Build

External Body Work: Part 1

Marlin tell you that the body work alignment starts from the nose cone and works back.
Whilst this is I guess true, it seems to me the quality of a Cabrio's bodywork can be seen around the interface of the 5 panels which meet together at one point:

Screen capping
A post cover
Door
Bonnet side panel
Bonnet top

With a lot of my modifications, I have often come back to them to make further improvements.
Initially I wanted to eliminate the gap between the screen capping cover and the A post cover below it, so when I trimmed the lower part of the capping I have re shaped the lower line to match the A post cover. I then found I had to maintain the parallel lines with the door line, and the bonnet top. I think the 'final' result is pretty good, but the top of the door edging is letting the panel gap down - more later!



This worked very well, but the design of the A post cover, being a thin sheet of aluminium, double folded, and screwed to the chassis in a single plane, means it will not stay perfectly aligned with my capping cover: and because the two surfaces now touch, even the slightest mis-alignment stands out. i left this problem for over 18 months until I worked out a solution.
This week I returned to this problem, as one of only a few external modifications I want to complete before my IVA test, as I have worked out how I can hold these two together.

I have now welded a plate into the back of the A post cover to create a slot when viewed from the top.

IMG_3607.jpg

I then cut a section of aluminium exactly the same width as this slot, and bolted it to the inside of the capping cover to act as a splice plate between the capping cover, and the A plate cover.

IMG_3595.jpg

This will then slide down and slot into the A post cover, holding it rigidly in place.

IMG_3600.jpg

Now, the arrangement seen first will be repeatable when its reassembled later.


The top of the passenger door did not line up well with the screen capping cover, and I concluded the two angles were just not the same, and were never going to line up, no matter what I did.



The top of the door angles in to the cabin more acutely than the screen capping - so, you've guessed - I set about modifying the door.



I cut the top of the outer door skin welds away to allow the top part of the door to be eased out. The gap above shows how much the door needed easing at the top.
(Note the front face of the top of the door has a full width section, whereas when it gets down to the hinge, there is only a thin rolled edge......more later)



This photo does not do the change justice - the door is now flush with the capping cover along its complete length.

Finally to improve the shut line, (and the shadow which falls behind it) I have added a plate along the thin rolled edge to continue the full width of the door above. This has improved the quality of the shut line, as seen below.



Once this had all been reassembled I then became aware of another issue with the A post/door sill.
Many owners have told me to lower my wings to make sure the doors ope fully without scraping on the wings: this is good advice. however, it lead to this problem:



The sill does not run the length of the A post cover. If the wing is set higher, then the wing piping covers this up, but when set 10-15mm lower it shows. So again I decided to make myself some longer, stainless sills.
This also coincided with an improvement I wanted to make regarding the door sill and the rear tub.



Marlin are a commercial organisation, and have a limited time to make and fit each panel, so they make things easy for themselves, but this compromises quality at times.
The rear of the sill is cut away at the top as it nears the rear arch of the chassis. This leaves a gap between the rear tub and the door sill. I decided that if I was going to make a new one, I could improve this panel line finish.

[Mike]

Re: Mike's Cabrio Build

External Body Work : Part 2

This shows the new extended sill lining up with the front of the A pillar, and the rear where I have allowed the top edge to return in towards the tub, closing the gap between the sill and the rear tub.



( For the very sharp eyed, and those that know it, the rear tub twists back in towards the chassis as it it kicks up over the back wheel), so does not quite line up with my new sill.

Recently, whilst I had to remove the rear tub to finalise my rear bumpers ( more later) I decided to return to this issue. I had forgotten, but when the rear arch is offered to the rear tub, there is a 12mm gap in the front lower corner, as the arch is held away by the chassis. This gap is closed by bolting the tweo surfaces together and forcing the tub to twist and flex out to meet the arch. I decided having the GRP constantly in tension was likely to lead to pain problem in the future, with probable crazing breaking through.


I had to add around 6-8mm to the back edge of the rear tub arch as it swept up over the wheel.




Similarly I've built up the inside edge of the rear wing, so that when the arch and tub are mated there is little or no gap between them.





The wing piping now fits along this section more neatly, as it is not trying to hide the distortion.

Whilst I was in GRP improvement mode, I also had a go at the boot lid.



The edges of the boot fall away much too quickly, and required building up around 5mm in places.



This also allowed me to improve the parallel lines all the way around the boot lid.



And remember The Hump? ( back in Post 31?)
Well, a bit like Jaws it just kept coming back!
18 months after warming it all up, and making what I thought was a good job, it slowly re-emerged: Not as pronounced as before, but definitely there nonetheless - despite the weight of my spare wheel sitting on it for a further 18 months!

My second major assault on it was to repeat the warming process, but this time I would glass triangulating webs out to the corners to stop them easing back.



This worked reasonably well, but this time I let the show down, by placing the longest, and therefore strongest web, right where the latching mechanism is fitted. As soon as I removed it, the corners eased back a little, a the hump returned once more.

Third and Final Effort?
The hump was now really no more than me being pernickety, .....but the lid still did not fit the rear tub very well. This was another of those jobs that I returned to again after another 12 months.
This final effort involved a couple of other processes which I'll return to later, but finally I decided that if I couldn't get rid of the hump, I'd match it in the rear tub top rail! It only required 1-2mm in the very centre, but now the boot lid follows the line of the rear tub, or in the centre, the rear tub follows the line of the boot lid!




This time I am very confident it will remain as required!


As I am bringing you pretty much up todate with this part of the build, I have been trying to resolve all the external little niggles that have remained open. Part of this exercise was to make the acceptable fitting of the rear tub and boot lid a repeatable exercise.
I guess most Cabrio builders know of the problem of re-fitting the rear tub and boot lid back together, only to find the shut lines that you worked so hard at the first time around to achieve, just seem to have disappeared since you took it apart!

For me the solution came in three areas.
Firstly, by filling in the rrear wheel arch areas, I was no longer stressing the rear tub to make it fit - and of course this meant that which ever bolt was tightened first tended to pull the tub in that direction. Now as the tub is stress free it location at the outset is more predictable (all things are relative with a kit car!).
Secondly I made two brackets that supported the rear tub under the drip rails at the back. This was a big step forward, as this finally gave me a fixed position for the back of the tub in 3 dimension space.



The little stainless bracket projecting up from the boot hinge fixing bolt allowed me to set the height of the rear tub at the back. previously this point could flex by I guess as much as 20mm depending on how I fixed the sides of the rear to to the chassis. If I pinched them in the rear of the tub would rise, and vice a versa.

As a little digression at this point, the whole reason for the tub coming off at this late stage was that I wanted to finalise my bumpers, but had not fitted a set screw to stop the bumper tube rotating. With the rear tub fitted I found rather annoyingly that I could not get a drill in position to make it happen, so I had to remove all the rear lighting, the rear wings, the boot lid, and finally the rear tub just to drill two little set screws! In the end I drilled two in each tube, top and bottom, to hold the tube in exactly the position I wanted.

When you think your car is almost complete, this is not the sight you want to see on your garage floor...........

[Mike]

Re: Mike's Cabrio Build

External Bodywork Part 3

There are so many little things that make building a kit an uncertain affair.
Take the bumpers:

When I fitted the bumper tubes as per the manual instructions, they were horribly loose. The Id of the chassis tubes was greater than the OD of the bumper tubes. I'm not sure if this is deliberate, but it all formed part of my problem of locating the rear tub in the same place each time I fitted it. If the bumper tubes were not repeatable it just added to the whole damn issue.

The solution here was to cut some strips of thin metal from an old fashioned biscuit tin. This is very thin, but just the right thickness to make circular shim to fit between the chassis and the bumper tube.



I had to do the same at the front as well.


One of the unintended consequences of finally fixing the rear tub, and the bumper tubes was that it showed up the overly large holes I had created for the bumper tubes in the rear tub.



I should not be, but I am slightly embarrassed by the size of these holes. So, whilst in GRP mode, I decide to fill these in. I wrapped a sheet of car around the bumper tubes, and then body fillered the gap. It made a god tight in-fill. I reasoned that I could now repeat the fitting of my tub, and the bumpers so a tight fit would be OK.

No - not a good idea!

As I rub it down, a section of my new filler dropped out - which made me think that the rest would get vibrated out in the future. What I needed was a large rubber grommet.

I searched through my tin of Sierra rubber grommets, and found one perfect plug. It was the blanking plug from the front fire wall on the near side, used to close the hole used for Left hand drive steering columns. All I had to do was cut a hole the size of my bumper tubes out of the centre and it would make a lovely neat grommet capable of taking any amount of vibration.



Of course I didn'y have two of these, so I had to go down to my local breakers and find another (that's how I know where it came from! _) It has been 7 years since I stripped my Sierra down, and my memory is not that good!).

But I am really pleased how it has turned an embarrassment into a neat solution.


Whilst on the subject of the rear tub, I am currently completing the boot in 'real time'



I have changed my tank straps for wider thicker stainless steel ones: and raised the tank until it is almost flush with the top of the chassis rails, to maximise the ground clearance for the twin exhausts.

I then fitted a sheet of polyurethane over the top of this in place of plywood, reasoning that it is totally impervious or will be when I seal it all after the IVA test.









To finish off the bodywork, I am going to round up a few single item under 'miscellaneous'

IVA Number Plate Aperture
The IVA test states that there must be a space 520mm wide x 120mm deep for a number plate.
Unfortunately, if you fit two standard number plate lights either side of the boot lid, positioned as wide as the boot lid accommodates, the space between will fail the IVA by around 10mm!
I' have had to file the fixing holes out, and slide the lights out 5mm each side so that the bases are overlapping the shut line. The IVA method for testing is to use a 520mm number plate to see if if it will sit on the allocate space - mine does now - just!



These will mysteriously migrate back again after the test!


This annoyed me:



It just strikes me that Marlin cut my inner wings too short - the hole is so big the piping gets no where near close to hiding it. So, i decide to fill it in - it took sveral hours to make these:



- then remove the wings, separate the inner from outer wings, then weld the 50mm extensions on, and then put it all back together.

This is what it looks like now.......................



.......and before you rush to tell me that water gathers in the inner wings, I have shaped my infill to run water off at the rear.

[Mike]

Re: Mike's Cabrio Build

My daughter is running in the London marathon next weekend - I feel like this diary is my marathon, and I think I may cross the line with my daughter by next Sunday.

External Brightwork & Lights

Rear lights
You may recall I widened my rear light pods so that I could fit Volvo P180 rear light clusters:



This has worked out OK, but the escutcheons supplied by marlin mean that their rear lights look just as good, and at a fraction of my overall cost. I wouldn't do it again.

Front Side Lights

I removed the Marlin GRP bleb, so that I could fit separate side lights - these are the third pair I have fitted, and will remain now.



Front Light Bar

A nice touch withnthe wiring for the front headlights is to take the wiring into the stainless headlamp bar, and out through the end. grommets seal it off nicely..............



..............so that the wiring can not even be seen when they are fully mounted - neat!



The head light is wired up and switched on.

Incidentally, I have made jigs for the Berlinetta and Roadster, so that stainless headlamp bars are now available for both these models to MOC members at only £50 each including P&P.



These are the side repeaters I have fitted in to the front wings. When I came to test them they did not work, yet when I tested them off the car they did. I'm no electrician, but eventually worked out that LED lights only work with the power going through them in one direction (unlike ordinary bulbs where it makes no difference.

Wing Mirrors


Trying to maintain the theme of no straight lines, I have gone for bent stemmed supports. These are spring loaded so should be IVA compatible - as long as the size of the mirror is accepted - it is right on the limit as far as I can tell. I have already added not covers to avoid any sharp edge issue.



The stems are spring loaded, and although I measured the space available, it was nice to see them fit.




A guy came on to the Madabout Kitcars site, advertising wheel centre logo badges. I had some marlin ones made, and they are really good. Contact details are available if anyopne likes therm, or wants something of their own.


Whilst searching the local breakers yard, I came across these door conduits in a Modeo, and thought they would be easy to incorporate in to my doors.





There is a plug-in screw between the door and the chassis, to make removal of a door easier, and it keeps the door electrics dry.

[Mike]

Re: Mike's Cabrio Build

There have been over 1,000 visits to this diary - not bad I thought in two weeks. But then it struck me that there have been around 50 posts, so there may only be 20 people watching it!
Edit: It appears there have been 47 members viewing this, but there are no records for how many non members.

Oh well - its here for posterity!

There are a few items that do not seem to have fitted in with anything else:

Windscreen

The IVA requirements have been asking for E marked windscreens for several years but then making dispensation to allow BS screens. Currently the last dispensation is set to end later this month (April 2013).

There is a relevance to this story, because of this:



Whilst working on my screen capping I pressed a little too hard and a small crack appeared. It was then just a matter of time before it spread.

My search for a replacement with an E mark finally came to an end when Autoglass cut me one from a flat Landrover screen with the E mark in the corner:



The radiused corners at the bottom are because this was the only shape available that would include the E mark.
The stupid thing is that, after the IVA, it is legal to fit a BS marked screen which is much easier to get hold of.



And Now for Something Completely Different....................

Whilst holidaying in Devon and walking along the coast, I spotted a car show at Branscombe - and so had to go and have a look! It was very good - and as a real bonus I came across Gerry Haines' Cabrio.
You may recall, very early in my diary I said I would have chosen the Sportster's front suspension in preference to the standard Cabrio set up. Well here it is! Gerry was of a similar mind, so asked Marlin to make him a Cabrio with the Sportsters suspension. They declined - he walked away - they agreed !
Why didn't I think of that? - just ask for what you want?!

This car does seem to divide opinion though. The Sportster guys don't think much to it, because it is a Cabrio, yet Cabrio owners see it more as a Sportster!

Personally, I love it.

Not just the suspension, but the cycle wings......and the V8 exhausts make it just perfect.



Whilst working on my Cabrio many of you will be aware that I found a Dual 7" servo upgrade that caught the imagination of over 50 of our members who went on to buy a kit - I'll devote a thread to this separately, but what that exercise did allow me, was to talk to many owners with interesting engines, and I'll share a few here, as anyone upgrading a Cabrio in the future might like to consider them.

A BMW M20 with 6 separate throttle boddies!



A Nissan ZX280 makes for a very nice period look under the bonnet: this has been fitted with a pair of 2" Jaguar carbs.





This one is particularly interesting to me as it is a BMW 6 cylinder 2.5 litre, but because it is the later M52 engine, the inlet manifold is different, and did not require carving up like mine. So if my inlet proves not to be unreliable, I know there is a solution available.
Anyone considering the BMW upgrade in a Cabrio might like to consider.





And finally, if you want to go mad, how about 320BHP under the bonnet?

An M3 EVO 3.2 litre..............





...............and one special engine..............



Whilst working on my car last year, I heard a strange rumbling coming up the road, and wondered what it was............

and then this parked across the drive.

Not every day a school teacher - female at that - comes to see you with her boy friend on the back of a 3/4HP traction engine!



It must have been that one sunny day we had for summer last year!!!!!!!!!

[Mike]

Re: Mike's Cabrio Build

Looking back on my build there have not been too many failures. Maybe its because I eventually go back and improve them years later! There is one little project that worked, but I'm not prepared to maintian long term - my Spare Wheel Bracket.

Years ago my roadster has a flat plate, which bolted to the boot lid, welded to a section of square box section, with a second flat plate with 4 wheel bolts.This seems a reasonable way to go, so I developed the idea.

Obviously the Sierra disc has a flat centre with 4 holes at the appropriate centres: I thought I could chop three centres out to make three flat plates. Two could sandwich the boot lid to make it more rigid, and then a round tube between these and the top disc would make for a good overall bracket.

For the squeamish, look away now!

Take the rustiest disc in the scrap yard - cost £1, and blow the centre out using oxy-acetylene!



Its brutal, but very quick!

When its cooled down you then ask yourself, "How can I possibly make this look neat?!"



An angle grinder soon takes away the worst of the molten mess........



Then turning it in a lathe finally cleans up the perimeter, and a quick rub on the face with an emery cloth as it spinning, polishes the face to give this: an amazing transformation in just 2 hours.



I used the standard Sierra wheel bolts, that I had removed when I fitted my new wheels, to clamp the first two discs either side of my boot lid.

Next I welded a steel tube between discs 2 & 3 to act as the spacer. However, I did have reservations about this, as the discs are made from a very grainy steel, (they are designed to wear along with the pads these days now that asbestos pads are no longer used), and I did have concerns that the weld may not work. it was not a success. Although it looked neat, a slight tap was all that was required to break the complete circle of weld. I have found it is impossible to weld cast steel to leave it with any strength.

Plan B
I fitted a second nut to the top of the wheel studs clamping the two discs to the boot lid, but only screwed it half on. I then cut the threaded sections from 4 more studs and screwed these into the half of the nut thread showing, and welded them on. This gave me 4 extended wheel studs to which I could bolt the spare wheel.

It works, but is so heavy it is ridiculous! I have a plan to repeat the excercise, but substituting aluminium plate to make the discs, but this can wait as its only aesthetic/weight saving.

[Mike]

Re: Mike's Cabrio Build


Electric Windows & Door Cards

My electric windows were fitted as per the Marlin manual - there is something I have not altered!

The instructions are reasonably good, but I did struggle to get my windows to run up and down smoothly. There were two major factors for this: ensuring the fron and rear aluminium channels were parallel, and using the correct rubber inserts originally I used some new channels from Woolies, but the motor really struggled to push the windows up. I then changed the channel to the standard Sierra rubber channel, and it works quite nicely now.



Window Up..........

The window in its up position, but without a top limit stop fitted yet. The fixing of the screen in the winder U-clamp is only temporary but neoprene is a good material to use as it has the right firmness to compress in yet grip the glass.

Window Down........



Window Down........

Though it proved more difficult than I expected.......................
Making the door pillar parallel with the windscreen surround meant adjusting the angle of the pillar at the front, and therefore I had to do the same at the rear. Then trying to get the screen to stay in the steel winder U channel while I tested it was not easy (I did not want another broken piece of glass!) as it has to be forced in.
However, it now goes up and down,........ up and down......up/down.......up/down.......up....
....down..... its great when something finally works!!



Oh I Lie!...........



The Sierra door has scope for significantly more window movement, so it is necessary to limit the lower stop, otherwise the motor hits the bottom of the door, and causes all kind of horrible flexing in the door panel. I chose to weld in a dummy stop bar, so that I could use the standard plastic stop.

Incidentally I found there are two different sizes of plastic stop Green & White - useful if you need to slightly alter the top or lower stop position of your glass.

Door Cards

marlin supplied the door cards with a strange angled recess to accommodate the electric motor, and door handle pull mechanism. I didn't like the treatment of the angle at the front, and I wanted to fit the Granada's internal pull handle.
So, I changed the shape of the handle hole to accommodate the handle pull, and I cut and re-welded the arm rest recess to give a continuous recess, whic I felt could be leathered up more successfully.



Although not clear in this photo, I used the opportunity to extend the lower recess plate out into the car by 30mm. This is the base to later screw on an arm rest. I have not made this yet, as the final position,size, length, depth etc can only be determined by driving the car some distance.

[Mike]

Re: Mike's Cabrio Build

Upgrades

Rear Diff Support

My whole car is one continuous upgrade. I have benefited enormously from building the last Cabrio to be tested and registered on the road, as I have been able to build in so many ideas taken from other Cabrio builds.

One of the issues I became aware of during my build was the weakness of the Sierra's rear diff support, especially as I have 200BHP, and plenty of torque on tap. Sierra owners on the Passion Ford site,and others complain that the diff mount does not control diff movement adequately. This is a particular concern to me, because I have reduced the width and height of my transmission tunnel, so can not cope with too much movement, otherwise I'll have it rattling round like a bobsleigh on the Cresta run!




This is the standard D mount I originally fitted.

When I finally started my engine up I asked my wife to sit in the car and go through the gears gently, while I watched from beneath the car.

I was horrified by the amount of movement I saw in the diff. Without the wheels on the ground, and letting the clutch out gently it significantly rotated on the axle axis, and promptly caught the underside of the tunnel. Whilst this was always a concern, I had no expectation it would happen without any load on the wheels! Clearly I had to do something.

Whislt researching this on the internet I came across a solution the Cosworth boys, and track day racers use: a much more rigid billet aluminium poly bush mount.

Also during my build I came upon a kindred spirit in the name of Mark Scott in Livingston.
Mark had built his Cabrio back in the heyday of the 90s and used it for several years before laying it up in his garage. Like so many of us, he later returned to it, and decided on a total rebuild,including an engine upgrade from its original Ford unit, to the same BMW M50TUB25 that I had chosen. As he is only the third builder to take this on (Chris Cunliffe is the only other builder I am aware of to have used the M50 engine in a cabrio) there was obviously an immediate shared mutual interest. This is the benefit of the MOC Forum - it connects members from all over the UK.

Mark had taken on board the rear diff issue, and had already bought the billet aluminium poly bush replacement mount, but not fitted it yet. he very kindly let me borrow his to test in my Cabrio:



It is much neater than the old Ford D mount, and the design means it is much more rigid, emphasised by the use of an enclosed poly bush compared to the voided Ford rubber mount.

This improved my diff mount enormously.

However, during my research I found Ford had developed a new mount for the last Granada/Scoprio/Ultimate: The 'Koala' mount:



This looked really interesting, as the two mounts set wide apart would almost eliminate any significant movement, either around the axle, or prop-shaft axis. Also having two rubber mounts it would absorb vibration better than the single poly bush.
The only drawback was that Ford had moved on their 71/2" casings for their diffs, so If I wanted to go down this route I would have to change my diff, and as i had spent 2 years looking for a 3.38 diff, and found a good one, I was not prepared to do that.

Another solution was required - I would make my own!
If I made a T bar with two rubber bush mounts on the ends, and attached it to the standard Sierra diffit would replicate the Koala set up, but make use of my standard 7" diff.
I put the idea up on Madabout Kitcars, and received this excellent sketch back from Jason Cundall (more of him later too.....):



I measured the space available between my diff and the fuel tank, and decided that something like this would be possible. A bit more internet research found me a guy selling a scrap Koala diff only 15 miles away. So I used the aluminium casings for the rubber mounts, and welded them to a 20mm thick T bar, and then made a support bracket from stainless steel:



The support bracket picks up on the standard Cabrio diff support plate, and the T bar is bolted to the standard Sierra diff rear mounting bolts. So it is a direct swap for the Sierra D mount.

I've fitted two new rubber bushes, so am hoping for not only limited diff movement, but reduced vibration back into the chassis.
Only time will tell...........

[Mike]

Re: Mike's Cabrio Build

First Drive

I am nothing if not persistent. Six years after I received my kit, I was able to start my engine. the next day I was able to lower my Cabrio off its support stands, and take it for a drive:



First Drive!

Bambi is now stood on all four wheels for the first time! It had been on stands since Day 1. First impressions are:
1. Wow!
2. What a gorgeous sound - it may be a bit too quiet!
3. Exhaust fumes may be a problem - but wait until boot lid is fitted.............
4. Smells as though it is running very rich - why? ( I found a very tiny fuel leak later)
5. The brakes are soft - the servo is great
6. The brakes need to bed in as they are rusty on the surface through never being used
7. Stay with the 22mm Master Cylinder - the pedal travel is more on the road than in the garage stationary.
8 The castor camber and Toe in all need looking at.
9. The ride height needs adjusting
10. The diff movement seems ok on gentle starts.
11. Engine paint smells horrible when it gets hot !
12 I' really pleased with my new wheels which I deliberated over for the entire length of my build!



The front and rear suspension all require setting up properly. This has not been possible while my car has been stood on mobile stands.

[Mike]

Re: Mike's Cabrio Build

A former manager and friend of mine died very recently: at his funeral his service card were printed the words:

"I shall pass through this world once.
Any good, therefore, that I can do,
or any kindness that I can show to any human being,
Let me do it now.
Let me not defer, or neglect it,
For I shall not pass this way again"

I still find them incredibly moving: He was a truly inspirational man.

Servo Upgrade

The servo upgrade I carried out on my Cabrio, and have been able to help over 50 MOC members to share has been my good deed and kindness to the club ................. an attempt to give back something for the pleasure I have gained over the past 25 years.
Hopefully this diary will have given others pleasure too, and who knows, it may even help the odd member in the future.




If you look back through the Forum threads, brake issues appear regularly. Many members have not been happy with their brakes. Some have fitted new pads, shoes, bigger front discs, even swapped rear drums for discs, yet still they have not found their Nirvana...........some have spent a lot of moneytoo!

When I drove Chris Cunliffe's Cabrio I remember finding myself on a roundabout, rather than pulling up before it. As Patrick Short put it so eloquently, many of us are used to modern tin tops "with servos bigger than their engines" - they require very little effort to stand them on their nose when stopping urgently.

A little background.
In order to fit certain engines, Marlin developed their own pedal box to replace the Sierra unit in the Cabrio, and this was carried into the Sportster. This allowed more engine space, but meant the original 8" Sierra servo (or bigger BMW servo) could not be used: Marlin recommended the 7" Metro as an alternative. The problem is whilst it offers some assistance, it does not match that of the original Sierra's servo larger diaphragm, and as a result is mechanically inadequate for disc brakes.

When Jason Cundall floated an advert of a Dual 7" servo on the Madabout Kitcars site, it struck a chord with me. It was the same diameter as the Metro servo, but offered more assistance.

A bit of research suggested it would fit in my Cabrio, so I made a Leap of Faith and bought one - it arrived the next morning!



It was the same diameter as the Metro, but deeper front to back. However this was offset by the front chamber having a smaller diameter. The four studs at the back were only 5mm less than the Metros, so could be made to fit easily.
The master cylinder studs were in a different position, so I had to make a new adaptor plate. I also wanted to fit the Sierra Master cylinder.
I had three reasons:
With a standard Sierra master cylinder, and a servo which offered the same boost as the Sierra's servo, I would have a standard Cosworth Sierra brake set up - all the items would be balanced as originally designed by Ford.
Secondly it has three ports for split braking on the front axle.
Thirdly, I could fit it vertically, and use the standard Sierra reservoir to reed the master cylinder.


I turned up an adaptor on a lathe, and trial fitted the servo. It was a doddle. I was lucky that my hard brake pipes had enough slack in them to allow the master cylinder to move forward without alteration.



My only problem was that I did not have my Cabrio on the road, so could not test it. re-enter Jason Cundall. Jason had recently registered his Sportster and was road legal. Luckily he had received a master cylinder from marlin which proved to be a Sierra copy, so he was able to fit the Dual servo very easily.
The test was a big success.
There were around 20 Marlin owners/builders watching the Madabout thread as we developed this project, and several suggested they would like an upgrade kit. Very quickly I had orders for 20 kits, including the servo, laser cut adaptor plate, and a screw on clasp to connect to the brake pedal.




Word soon spread of the improvement this offered to Cabrio owners with big V8 engines, and Sportster owners with modern slanted BMW engines, which all had the under strength Metro servo.

One owner even carried out his own Top Gear style test. Andrew Curtis has a BMW Sportster, and lives on a farm backing on to a disused airfield. He took his Sportster along the old runway, and braked from 70mph at a fixed marker. He then fitted the Dual servo, and repeated the exercise. The difference was amazing.

The average braking distance over 4 runs was 210 feet with the Metro servo: the Dual servo stopped in just 103 feet, with much less effort, and very progressive braking.

Later he tried an all out emergency: with tyres beginning to lock up, it stopped in just 85 feet.
A quite remarkable improvement, and a massive advance in safety.

I published an article in Pitstop, and, via the Membership secretary, forwarded an email to all the V8 and Sportster owners on the MOC membership list, and very quickly had orders for over 30 more kits.

Everyone who has fitted a Dual servo in place of the Metro unit has been truly delighted. They have a car that is now safe to drive in modern traffic.
If you have a Metro servo and haven't made the change, there are 50 members who will thoroughly recommend it.

The new Dual servo looks like it was designed to fit in the tapering Marlin bonnet. if you look back at my original treatment of the servo fitting, I had removed a section from the bonnet side panel return around the servo - it was crude, and I was not impressed. The new servo looked so neat, I felt obliged to improve the side panel. So, I welded a new piece back in, which improved it strength, and improved the aesthetic greatly.



Tailor-made!
I've fitted a thin piece of neoprene to the inside of the panel to prevent it vibrating on the servo.

[Mike]

Re: Mike's Cabrio Build

And finally............

One upgrade too many. Power Steering

We live in a pampered and cosseted age. Modern cars are fitted with so many driver aids to make them easier to drive - power steering is a prime example.

Lee Hunter developed a power steering conversion fro his cabrio, and posted it to the MOC Forum. I like the idea, and have copied the general arrangement. however, I have decided not to fit it prior to the IVA test for two reasons. Firstly I am advised it reduces self centering which is a requirement of the IVA, and secondly, it is just something else they could pick up on and find issues with.

I have developed my kit ready for fitting, and will certainly try it after I gaet my cabrio legally registered and on the road.

The conversion starts with a Corsa C EPAS fixed power steering column which can be picked up on ebay for around £50:



Careful stripping down reveals the central motor unit, and the upper splined shaft:



There are a number of ways to go about this, but I want mine to be totally interchangeable with my Sierra steering column, in case I do not like it, and that the Corsa's central motor section remains totally standard, allowing a replacement to be fitted if there is ever a fault.



The Corsa steering system has a lower link with a spliced clamp which connects to central motor unit. I cut the Corsa's lower link from the clap, and will weld a Sierra lower sliding column back on:



With the upper column removed, the Corsa's input shaft looks like this:



The upper Sierra shaft has to be cut off just below the collar and spring which locate it in the Sierra's upper outer column housing.



Quite by chance it will fit over the Corsa's input shaft - even the collar inside the housing.



and the final arrangement looks like this, with the Corsa motor effectively spliced in to the centre of a standard Sierra column:



I had one issue to deal with to make it fit in the space of my footwell: routed through the original steering column bulkhead hole the clapm bolt on the lower fixing just caught the brake pedal. I have therefore moved my bulklhead steering column bearing over by 10mm to clear this, and fitted a covering plate ove the extended hole.



All that is required is to change the columns over, ( slightly easier said than done, as I want to retain the adjustable column, requiring the motor mounting to be adjustable too) and then provide a power source, and a special actuator for the electronic controls which can be sourced for around £15.

This can all be done post IVA.

[cameronfurnival]

Re: Mike's Cabrio Build

Well done Mike - a fabulous diary! Now you just have to keep updating it as you do those last little jobs! When's IVA booked?