Advice for Sierra based roadster

[b_caswell]

As the last post on the YKC thread was two and a half years ago I have posted here as most read this.

A member has contacted me for advice
I have a Sierra based YKC roadster.
I did not build it but I do have the build manual on file. However it's not very comprehensive. I think there are many technical articles on the forum but I find the forum difficult to navigate. Can you aid me?
My biggest issue is the suspension. It was YKC designed I understand. How should it be set up?. Is there any documentation or technical data.

The build manual info posted further down the forum doesn't really help so someone YKC savvy would be appreciated.

[stevejgreen]

Re: Advice for Sierra based roadster

It would be useful if gentlemen requiring advice, posted his own question, rather than through a third party.

Has he for example read the archived YKC documents available in the members only section?

I have complimentary docs stored on keepandshare, but I cannot pass the location on to him, so rather a waste of time.

His loss, as there is nothing I can do to help.

[milliemarlin]

Re: Advice for Sierra based roadster

I agree with Steve. Our best advice is that he or she joins the club. It will give them access to a large amount of technical data and the pooled knowledge of hundreds of members. It really is not that much and could save them many times the subscription in time, effort and parts.

That information should be of benefit to other YKC members too. They are all most welcome.
Paul

PS: If the best advice, joining the club, was given with a sample of great advice copied from here that would be a great advert for us.

[b_caswell]

Re: Advice for Sierra based roadster

Read my first post!!!! the guy is a member the notifications only work with members and he says hestruggles to navigate the forum and technical pages but there aynt much info there any way. Constructive guidance is what he needs. Im only trying help !!!!!!!!!!

[milliemarlin]

Re: Advice for Sierra based roadster

Read my first post!!!! the guy is a member the notifications only work with members and he says hestruggles to navigate the forum and technical pages but there aynt much info there any way. Constructive guidance is what he needs. Im only trying help for FFFF sakes!!!!!!!!!!

Sorry Ben I misunderstood.

I’ll get my coat!
Paul

[chrislibby]

Re: Advice for Sierra based roadster

Thank you Ben. As you say I am a paid up member. Rather surprised at the response from the other two.

[chrislibby]

Re: Advice for Sierra based roadster

Excuse me but I am a member of the club.
If you have archived material I would be grateful to have some access to it. As I said in my first post, I have difficulty navigating the forum. I am a mechanic not a computer person.
Chris

[mocad2016]

Re: Advice for Sierra based roadster

Hi Chris,
When I first read Ben's post I thought that he was copying a post from another website. In an effort to redeem my faux pas:

I have experience of setting up Cabrio and Sportster both of which are Sierra based suspension. Both are very different. The Cabrio has little adjustment the Sportster has lots.

Do you need general advice on basic procedures to set things up or dimensions, toe in, camber, etc..?
Paul

[chrislibby]

Re: Advice for Sierra based roadster

Thanks for that.
My car seems to handle and drive fine, but it's ten years old and I wonder if it's set up ok. I seem to have excessive camber on the front end. The suspension seems very hard on the front and soft on the rear. I could do with studying how things should have been set up and then deciding if mine needs adjusting.
Is there any special tool for winding up those little adjustable dampers?

My car is a Roadster not a cabrio

[greyV8pete]

Re: Advice for Sierra based roadster

If they are GAZ coil overs you need a C-spanner. There are two diameters. Merlin Motorsport sell them.

On the GAZ ones there I’d a small grub screw locking screw in the side of the adjuster ring. Make sure you undo it a couple of turns before adjustment and of course don’t forget to tighten it afterwards. Also clean the threads with a stiff brush and oil them before adjusting. Jack the chassis too to uncompress the springs as much as possible. The adjusters will probably still be quite stiff to turn.

Start with the shocks adjusters fully off / soft and then do up one click at a time until the “bounce” of the car is just eliminated. Many owners have them set far too hard. Some people just fit non adjustable O/E dampers which may be ok but are designed for much heavier production cars, so unlikely to be correct for a lighter Marlin. Peter.

[danny_nelson]

Re: Advice for Sierra based roadster

We have a member located in Walsall (Midlands) with a Julietta. Somewhere on this site he shared his experience with a problem ref mounting of rear shockabsorbers on his car. YKC supplied AVO for their Sierra based models, because they can be rebuilt. In my experience the mini strut used on the front end tends to be on the stiff side. It is very short. I can think of several members with very hands on knowledge of Sierra based YKC models and I am sure one of them will come along with good advice for you.

[milliemarlin]

Re: Advice for Sierra based roadster

I am not familiar with the YKC Roadster set up so can’t make any specific recommendations. The Sportster has upper wishbones that are fully adjustable. The Cabrio has fixed welded arms although slight adjustment can be made by shimming out the pivot brackets. I guess the Roadster suspension is similar the Cabrio. If all three are based on the Sierra so the set up should be similar. Judging from Danny’s post by Sierra based you might be referring to the engine and gearbox but not the suspension. In which case, this post is even less useful.

Danny could be referring to this thread:

http://www.marlinownersclub.com/forum/showthread.php?7157-YKC-Rear-Suspension&highlight=Julietta

To check the set up on both my cars I use axle stands adjusted to be close to hub height. These are used to support two parallel strings approximately 1.7m apart. These are placed on either side of the car and adjusted to be as close as practice to equally distant from all four wheels. Of greatest importance is that they are parallel. Measure the parallelism first and last. If practical check the rims for run out. If necessary put a low or high point at the bottom or top.

A fuller description can be found here:

https://ralphhosier.wordpress.com/2010/12/28/setting-suspension-geometry-using-string/

A more sophisticated set up is shown here:

http://suspensionsecrets.co.uk/how-to-align-your-car/?i=1

I measure from the front and rear of the rim to the string on all four wheels to see if the wheels have toe in or out. The rears should be parallel the fronts should be (from the Haynes manual):

Production toe-setting:
Saloon, Hatchback and Estate models: 2.0 mm ± 1.0 mm toe-in

It is my understanding that the front wheels are angled in slightly so that in normal running the forces on them cause them to be parallel. The Sierra suspension has a number of rubber bushes that will flex under driving conditions.

I made up a small plum line jig to measure camber. On both my cars camber varies as the suspension rises. When lifted off the ground the wheels are out at the top (positive camber). When fully compressed the wheels are in at the top (negative camber). This improves handling when cornering by increasing negative camber on the outside wheel as the body rolls into the corner, helping to keep the tyre’s tread in contact with the road. When the suspension is at rest the wheels should be about vertical. You mention excessive camber and I wonder if this might be because the ride height is out.

People seem to run quite happily with wildly differing ride heights. As a rule of thumb Sierra based cars should have tie rods that are parallel to the ground. This presumes the steering rack is in about the right position.

At the rear ride height seems to affect toe in. The trailing arms are not perpendicular to the cars axis. For a long time I lived with rear wheel that were toed out. Raising the suspension by about 25 mm made them more parallel. Ride height must also change rear camber but I have not measured it. This small change made a big difference to rear tyre wear.

Caster angle is really difficult to measure on the Sierra as the top and bottom “kingpins” are on different centrelines (in four planes). This causes the geometry to change as the car is steered. They are actually ball joints which can’t be accessed. The best I can do is to measure from a fixed point on the car to the countersunk hole in the top and bottom ball joint mountings. I have measured from a pin set in the centre hole in the rear wheel hubs to swivel joint. It is easier to measure from a fixed point nearer the front of the car such as the anti-roll bar mounting. The absolute measurement is not important but the comparison top to bottom, side to side is. The lower swivel should be in front of the top. I drove for about 12 years with one side 20mm further forward at the bottom on the nearside due to a bent anti-roll bar. It didn’t really make much difference to my conservative handling requirements. There are machines with computer guidance that can measure caster and every other angle but I’m not likely to buy one.

The caster angle at each steering lock should also be similar. Again the geometry is such that the outside wheel will have a greater caster. Again the important thing is that both sides are about the same.

I’ve heard it said that Lewis Hamilton is such a good driver because he can feel how the car is set up for different tracks and make minor adjustments to his steering geometry, suspension, brakes and aerodynamics. If you are thinking of driving on the edge in that way you need way more sophisticated help than I can give.

In my opinion the best indicator of suspension set up is tyre wear. Uneven tyre wear certainly indicates bad tracking.

Hope this helps. If you can a photo of the Sierra based Roadster suspension would be a big help to me.
Paul

PS: I have been told in no uncertain terms by a couple of members that you need lasers to set up suspension accurately. I am unconvinced. Shine a laser down a piece of string in still air and it will cast an even shadow on the floor. Measurements to within 0.5mm should be satisfactory.

PPS: I am sure others have more to contribute.

[danny_nelson]

Re: Advice for Sierra based roadster

The top suspension on the Sierra based YKC Has a mini macpherson strut located in the Sierra upright the bottom has the Ford track control arm which is located with a tie rod made up from the outer ends of the anti roll bar and reversed from one side to the other and tied forward. (Marlin used the mini strut on several Cabrio models) However the back end is a 5link dedion tube set up which is a delight. Paul give me a call or email please I would like to pass on some important information about Cabrio front set up.

[keith_h]

Re: Advice for Sierra based roadster

Treat yiurself to a Sierra Haynes manual