Sierras 3 Inboard Suspension

[Snapperpaul]

Car is running after the dragging clutch debacle and with a week tp go before taxing it, thought I would setup the suspension after fitting tie bars and Gaz shocks.

Reading DES Hammills suspension book, all very informative and good diagrams of what to look for etc.

But the S3 front upper wishbone points down and most othe 7's point up, DES reckons up.

With the mushroom insert fully in it's down, there may be some adjustment available on the springs and by moving the mushrooms up ( my wing brackets will need modifying) have any S3 owners moved the top wishbone up or are they all left where they fell?

[Peter Bell]

Mine S1 pretty similar I have moved up as far as I dare, in theory helps to reduce camber change on bump, not sure if it is noticeable. I think GBS now do long mushrooms for the 2b modified wishbones. Problem is as you move the ball joint end up you need a shorter shocker on the inboard end

[Guest mower man]

I've pondered over this for some while mainly because of a lack of droop travel /bumpsteer and camber change. I dont think you will need shorter shocks and will be able to run less pre load on the springs for the same ride height I believe lifting the rack to give the steering rods from the rack a better angle will also help with bumpsteer, waiting to heer from others---- mower man

[Snapperpaul]

My steering rods are near ideal according to the book, bottom track control arm looks good.

Camber close but will be set this weekend as will toe.

It's just the drop from wishbone mounting on the chassis to the mushroom.

There is room to raise it up as long as I fix it the the hub carrier and fix the wing stays which right now are clamped by the mushroom.

There is some interesting points on Akerman angles, I won't stress over this but may measure so I am aware.

Setting up ride height with reference to bottom ball joints looks simple so I will follow the book and report.

One of the drivers of setting up the suspension was the awful understeer, better since the tie bar mod but still evident.

[Guest old_timbo]

I wonder if the same problem exisits as with the Wishbone 2Bs? If you jack up the front of the car so the suspension droops, how does the camber change? It should build +ve camber i.e. the top of the wheeel should move outwards. It does the oppposite on the 2B and causes understeer. Hence the need to extend the dummy strut upwards to make the top wishbone slope upwards from the inboard end.

[Peter Bell]

A long time ago I made a drawing of the front suspension on my car, and with the lower arm horizontal, 1" bump movement results in nearly 1° +ve camber change. If you could raise the upper ball joint 35mm it reduces this camber change by about two thirds.

This of course does not take into account of body roll where 1° of roll will impart slightly more than that to the wheel and the fact that as soon as the steering wheel is turned all this geometry goes to pot anyway.

[Snapperpaul]

Have just spent a very frustrating few hours in the barn trying to setup the suspension using wood, string, lasers and a netal tape measure.

Managed to get the ride height sorted, didn't manage the toe to any great degree but did use the lasers to level the bottom TCA then had a look at the top wishbone, not as bad as I thought, practically level as it is, perhaps a 1" lift is all it will need.

 

http://i750.photobucket.com/albums/xx141/snapperpaul/00731eb2.jpg

http://i750.photobucket.com/albums/xx141/snapperpaul/0b31fe47.jpg

[Guest The Modfather]

The mushrooms on mine are fully down which mean the top wishbones point downwards. I have noticed that my steering arms point upwards but the lower TCA seems pretty horizontal. I still haven't driven it yet, so will report just how good the tie-bars really are and whether I need to mess about with the rest of the suspension.

 

Daz

[Snapperpaul]

You can see from my photos, the wishbones point down but the horizontal line drawn by the laser transects the pivot bolt and the centre of the ball joint, which is what needs to be measured, just an inch up at the ball joint will be enough.

[Guest mower man]

Looking ar your results Paul I think you may have something usefull to try I've got some front end work to do soon and fortunatly have full wings so it's adjust and try if I don't like it adjust back nobig probs will keep atrack on your progress bye for now mick [mower man]