DRL152K Marina based roadster rebuild

[J_Hammond]

Re: DRL152K Marina based roadster rebuild

I have made some good progress on replacing the front bulkhead. The original was rather tired and had a scary crack from pressure from the pedal box.
cracked by Robin Martin, on Flickr
I have made the replacement in steel, the same as the rear bulkhead. Proved to be quite tricky getting it right particularly at the bottom arround the chassis members. I have a couple of closing plates to still to fit there.
The pedal box is also trial fitted. I have made a L & H shaped reinforcement from 25mm angle to help spread the load. The clutch pedal needs a little adjustment using the blowtorch and hammer it seems.
The observant might notice there are 2 rows of fixings at the top rear of the bulkhead. The original design used the same fixings both to fix the scuttle (dashboard) moulding and secure the bulkhead to a chassis crossmember. I decided to make those seperate thereby improving the strength. I know the fixings are stainless, generally frowned upon for anything structural, but there are enough of them to well distribute any loads. On the final assembly I will also bond the bulkhead using a Sikaflex adhesive - same as I did on the Pembleton.
front_bulkhead1 by Robin Martin, on Flickr
front_bulkhead2 by Robin Martin, on Flickr

Next job: overhaul the steering rack and decide on the position for the steering column. I want it under, rather than through, the dash as in the original design. The orginal Marina steering column is pretty shot so I am thinking of using one from a Triumph Spitfire for which you can still get things like bushes.

Cheers for now, Robin

Donkey's years ago my pedal box mounting gave way as I was driving home, fortunately very close to home so I could coast it onto the driveway, and use the handbrake.
I wrote about this in Pitstop and also to the main Kit Car magazines of the time, this would be in 1989. This was taken seriously and Marlin produced a so called "strengthening piece" which could only be fitted by dismantling the offside of the engine compartment. So I cut bits off it and used these plus threaded bar to mount it to the rear wengine mount, unused with a 1.8 engine. A long piece of bar but it made it rock solid.
At the time Pitstop publuished other builders' solutions but it deffo was/is a serious weak point. So well done for spotting it and hopefully fixing it!

[dcunn]

Going well Robin.

[martinclan56]

After a considerable ammount of fettling I finally have an acceptable radiator surround.
It was orginally fitted very badly and I struggled to get a better fit until I finally discovered the whole moulding is on the sqiff! Once I had worked that out I managed to get a reasonable fit although still not 100% square at least it looks OK to the eye. In the process I filled many holes and extended the sides down so they touch the chassis rails. Needed as I will be using cycle wings so this part will be visible. I also did a bit of re-inforcing arround the edges and filled in the gap that is normally visible between the front horizontal edge and the bumper. (Later cars have a neater wrap arround bit that fitted arround the bumper and provides somewhere to mount the number plate.)

ra

[martinclan56]

I have been making slow progress once again. This getting old certainly slows things down a bit. Plus the more than occaisional holiday...

The chassis is finally all cleaned and primered. I am going to coach paint the bodywork so I thought I would practice on the chassis. This means a further coat of primer, 2 x undercoat and 2 x topcoat. Could take some time, especially as I am going to do it in two halves - first the front as far as the windscreen and then the rear. There is a convinient weld in the chassis at this point to which I can paint up to. I have also painted the front and rear bulkheads. I remade these from zintec some time ago and, although rust resistant, are not rust proof.

chassis_in_primer by Robin Martin, on Flickr

The plan was always to convert the car to cycle wings but I have seen a few Marlins where this has been done but where the rear wings were retained. So I have dug them out of the weeds and given them a clean. Before and after picture.

rear_wings_clean by Robin Martin, on Flickr

One of them though has a real bodge with part of it being ground away. I assume this was to aid fitting - who knows. Anyway, I don't like bodges so I have started to repair this.

rear_wing_bodge by Robin Martin, on Flickr

While the fibreglass is out, and my hands itching, I am also modifying the radiator surround, no pictures yet though...

[martinclan56]

Front suspension rebuild has moved on to fitting the hubs. At this stage I was feeling fairly smug with the bargain triumph wire wheel adapters I had bought from Ebay as a trial fit seemed to be good.
However when I came to fit them properly I found they didn't (fit). The hub casting, where the grease cap fitted, fouled the inside of the adapter. "Easily" fixed by some heavy duty filing. I then found that the wheel studs have a large shoulder on them, great for centering the wire wheel adapter, but unfortunately preventing the nuts securing the adapter to be screwed fully home. Hmmm. after some head scratching I made a thin, 1mm, spacer which did the trick. now everthing fits OK :-).
So the front suspension is pretty much complete and I would have a rolling chassis - if my wheels had any tyres on them,
Some pictures....
hub_before by Robin Martin, on Flickr

hub_and_spacer by Robin Martin, on Flickr

front_suspension1 by Robin Martin, on Flickr

[martinclan56]

I have made some new adjustable tie bars following what has been done in the past by other Marlin owners. They comprise the front part of the old tie bar, a turnbuckle and some rose joints. The idea is not so much to make the suspension adjustable but to be able to dial out any inaccuracies in the chassis geometry. From what I have read this is not uncommon. I am going to remake the U shaped chassis brackets as I don't think my first attempt looks substantial enough.

tie_bar1 by Robin Martin, on Flickr
tie_bar2 by Robin Martin, on Flickr

Cutting the 1/2" UNF thread on the tie bar proved tricky. Ideally a lathe should be used for larger external threads but I don't have one. I do however have a decent pillar drill - so I used this to drill a perpendicular 1/2" hole through some substantial box section. I then attached this to the die holder positioning it with a 1/2" UNF bolt. The hole through the box section acts as a guide resulting in a perfect thread on the item to be threaded.

modified_die_holder by Robin Martin, on Flickr
die_holder_use by Robin Martin, on Flickr

I should say the guide wasn't my idea. I found the basics on t'internet after a failed attempt at cutting a thread.

[martinclan56]

Doing a bit more on preparation.

First the front hubs. The good news was they still had the original Timken bearings - or so I thought.... However when I looked at one of them it was totaly trashed inside. It looks like a bearing had broken up at some time judging by the damage. Even the step which locates the bearing outer race was destroyed. Someone had done a quick fix and popped in a new bearing but that's not really an acceptable solution so I am looking for a replacement.
damaged hub by Robin Martin, on Flickr

And the brake calipers. They are almost the same as those used on the Triumph Spitfire (Girling type 14) so there are plenty of replacements available. But, after experience with buying bits for the engine I am a bit suspicious of some of the stuff that is available. So I thought I would have a go at stripping them - keeping in mind they are at least 50 years old and haven't seen any use for at least the last 30!
Following a good tip I cut the end off an old flexi brake pipe, screwed the uncut end into the caliper and used my compressor to blow down the other. This allowed me to have the caliper safely in a bucket at arms length just in case any of the pistons came flying out!
Three of the four came out "easily" but the last one wouldn't budge.
Now I followed another good tip! I put back the piston in the caliper with the stuck one but in an almost out position. I then filled the caliper with water (yes really) with the bleed nipple screwed up and then a spare bleed nipple where the brake line should go. I used a couple of clamps to push back the "good" piston and Hey Presto the water pressure was sufficient to get the stuck piston moving! Amazing!
Finally I split the calipers. You are not supposed to do this but I couldn't see any other way of properly inspecting and cleaning the bores. There is only a single O ring to worry about and this comes with the refurb kit you can get from Bigg Red. And, suprise suprise, everything looks good even though there was rusty crud in most of them!

stripped calipers by Robin Martin, on Flickr

[martinclan56]

After several months of DIY I finally have some time to spend on the Marlin. I really should be completing the resto of the chassis but I fancied something a bit more interesting so decided to trial fit the front suspension. The Marina uses an odd setup for the front suspension using torsion bars and trunions, based on that used by the Morris Minor but, unfortunately, having no common parts. Parts are as rare as hens teeth....

The standard problem with the upright is lack of maintenance causes the lower thread on the upright to deteriorate. Ultimately the trunion can part company with the upright. Mine were no exception.

upright rusted thread 2 by Robin Martin, on Flickr

I was able to track down, thanks to the Marina Owners Club, some new old stock of "Walford Trunions" which were a period fix for the problem. Basically a new threaded sleeve is screwed on to the old damaged thread and a new oversize trunion fits to that.

original and walford trunion by Robin Martin, on Flickr

You are supposed to fit the new threaded sleeve using the supplied threadlock but that was a bit suspect being 30+ years old so instead I bonded it using an industrial Araldite. Jobs a good-un. I should say that it is also tightened up to 100 Lb/ft as well!

inner component of walford trunion by Robin Martin, on Flickr

walford trunion fitted by Robin Martin, on Flickr

Finally I fitted all the bits up to the car. The Marina uses a lever arm damper but on the Marlin this is replaced by a Mini upper suspension arm and a conventional damper (not fitted yet)

front suspension trial fit by Robin Martin, on Flickr

The critical point is that the torsion bar should pass through a hole, on the chassis where it is finally fixed, without any lateral or vertical tension. This is also the rubbish part about Marina front suspension as it makes it pretty much impossible to play with the castor or camber. Anyway after a bit of fettling it's a great fit.

torsion bar position by Robin Martin, on Flickr

Now that I am happy it fits, and I am not missing any major bits, I can take it all off again and complete the cleaning up of the chassis!

Cheers, Robin

[andyf]

I would consider using grease. I've swapped mine to grease and it seems to be doing fine

[martinclan56]

Not a great deal has been happening on the Marlin front due to other, house related, activities. However those are nearly at an end so have been able to go to the man (Marlin) shed for short periods.
One of the weak spots on the Marina based Marlin is the steering rack. It has an internal bush at one end of the rack which inevitably wears out. It is a real pain to replace as:
A. The only replacements available are a polybush that is made in Australia
B. You have to drill out the peans on the inner rack ball joints to gain access.
Anyway I did that succesfully but now the rack is incontinent leaking oil from the pinion housing. Grrrr. And yes I did say oil, the Marina rack is oil filled rather than the more usual grease. Weird. I suppose it seemed like a good idea at the time.

To cut a long story short an (apparently) new old stock rack turned up on Ebay. Rare as hens teath and then some. I duly bought it and it's a good'un. The only slightly funny thing is the seller obviously didn't realise it was oil filled and the corrogated packing it arrived in was soggy to say the least!
Here it is after a bit of a clean up. Even the gaiters are in good nick. I half expected them to be perished in view of the fact it must be at least 40 years old! And the alluminium bits are all shiny as they were covered in some sort of wax for protection.

nos steering rack by Robin Martin, on Flickr

[phild]

This is coming along well and I like the changes and mods you have been doing to update it.

Cheers Phild

[HairyDave]

Re: DRL152K Marina based roadster rebuild

Very smart! When you mentioned bonnet bulges my 1800TC has L-R mountings and my carbs clear the bonnet but without going out to look I think the black spacers are narrower on mine and the front carb has a thin pancake filter. But mine is a Roadster.

[David]

Re: DRL152K Marina based roadster rebuild

That’s a nice looking donk.

[martinclan56]

Re: DRL152K Marina based roadster rebuild

Engine build now complete. Been a bit delayed with problems caused by poor quality parts. As the MGB is so popular you wouldn't think it would be a problem but there is pretty much nothing available from the "normal" aftermarket and everything seems to come from China. Having said that some of it is very good, but some of it absolute rubbish...
I have fitted a fancy rocker cover as the original was a bit bent, but in fact it is not a great fit so may go back to the original. And a new distributor which has an advance curve (allegedly) tweaked for stage 2. Was rather cheap though, although it looks made well enough, but it will be another 12 months or so before I can verify its operation. In the meantime I will have a go a stripping and rebuilding the original.
Some pictures.
engine10 by Robin Martin, on Flickr
engine11 by Robin Martin, on Flickr
The observant may notice the non-standard engine mounting rubbers. The original Marina ones are like rocking horse poo and so I have used Land Rover ones as suggested by the original Marlin build manual. These have the added advantage of lowering the engine slightly which I hope will give enough clearance for the fron carb to fit under the bonnet. The original bonnet had a couple of unslightly bulges.

[David]

Re: DRL152K Marina based roadster rebuild

Thanks Robin.