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Author: Subject: suspension experts comments please
givemethebighammer

posted on 3/5/05 at 04:31 PM Reply With Quote
suspension experts comments please

After having my tiger cat on the laser alignment equipment on the local garage it was evident that the rear end of the car was quick badly misaligned (uses the entire sierra rear end).

Figures from garage session

Rear: left
camber: -2 degrees 14 minutes
toe 5.8mm toe in

Rear: right
camber: -2 degrees 50 minutes
toe 0.4mm toe in

I have obtained a decambering kit from the Ford performance people "BAT" in the USA (basically a bag of 1.5mm shims).

I have calculated that by fitting these shims into various positions between the hub carrier and the back plate the following results are possible:

rear left:
camber: 0 degrees 39 minutes negative
toe: 0.296mm toe in

rear right:
camber: 1 degrees 15 minutes negative
toe 0.4mm toe in

the question is are the differences from one side of the car great enough to affect the handling ?. I think the new toe setting have a small enough difference to ignore, but the 36 minutes difference (just over half a degree) on the camber I'm not so sure about.

thanks

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JoelP

posted on 3/5/05 at 06:18 PM Reply With Quote
excessive camber is a fact you have to live with when using a full sierra back end. you can correct it with shims apparently though. i sorted mine slightly (as in, by eye, not measured) by raising the diff, hence changing the angle of the subframe and pointing the wheels out a bit.

edit: i promise to read the post in full in future...

is it not possible to mix and match the shims to end up with even camber?

[Edited on 3/5/05 by JoelP]






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givemethebighammer

posted on 3/5/05 at 07:16 PM Reply With Quote
thanks Joel,

but all the shims in the kit are the same thickness so I can only adjust in equal increments. Basically to get even camber I need to either use a thinner shim on the left side to achieve the 1 degree camber or add another shim to the right side to get the half degree of camber on both sides. After some reading I had hoped to get about 1 degree of negative camber on both sides at the back end to improve the road holding. What the difference between half a degree and one degree would be I'm not sure ?

Anyone know where to buy more shims, the ones I have look like the ones you get under the bolts on the sierra diff (square / rectangle with u shaped cut out).

For the half degree option I need either some shims 1.93mm thick or some 0.43mm thick to add to the existing 1.5mm ones.

all calculations based on tables here:

http://merkurencyclopedia.com/Suspension/rear_align.html

from this site

http://merkurencyclopedia.com/index.html

maybe useful for other stuff as well


[Edited on 3/5/05 by givemethebighammer]

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rusty nuts

posted on 3/5/05 at 07:22 PM Reply With Quote
Don't know if you can still get it ,but I used to have a tin of Shim Stock. It was just lengths of various thickness steel sheet that had to be cut to size/shape . May be worth checking your local engineering supplies. H.T.H
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givemethebighammer

posted on 3/5/05 at 08:13 PM Reply With Quote
thanks Rusty I may be on the right track

http://www.rs-components.co.uk/electronic-components-uk/92578-RS-Components-Shim-Stock--Mechanical-Engineering-Materials-Shim-Stock.html

stainless:

http://rswww.com/cgi-bin/bv/browse/Module.jsp?BV_SessionID=@@@@0609505621.1115150796@@@@&BV_EngineID=ccckaddehjgmheicefeceefdffhdglj.0&cacheID =uknetscape&3292603596=3292603596&catoid=-447716011

and steel:

http://rswww.com/cgi-bin/bv/browse/Module.jsp?BV_SessionID=@@@@0609505621.1115150796@@@@&BV_EngineID=ccckaddehjgmheicefeceefdffhdglj.0&cacheID =uknetscape&3292603596=3292603596&catoid=-102591511

question is do they have minimum order etc.

off to find out........

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britishtrident

posted on 3/5/05 at 09:23 PM Reply With Quote
Regarding toe-in have seen a lot worse on this layout of suspension.

Based on experience racing Imps and Davrians which used a semi-traillng arm setup at the rear which had similar pivot axis angle to the Sierra I would sugest you need a fair bit of toe-in say 1.5 mm per wheel because on both bump and droop semi-trailing arms move towards toe-out if the outside wheel on a corner actually moves into toe-out it will give very evil handling.

Shims are an obvious way of correcting asymmetric toe-in but before fitting them I would look at the alignment of the subframe -- can the left side be moved back and the right forward a few mm ?


Normally would set the ride height take all measurements on a car like a 7 with the driver onboard --- In a very light car static roll due to the offset weight of the driver has a big direct effect on the left to right difference camber angle.

[Edited on 3/5/05 by britishtrident]

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NS Dev

posted on 4/5/05 at 07:33 AM Reply With Quote
Get it as good as you can but the figures you mention will not cause major problems at all.

No RS components don't have a min order (other than the minimum supply multiple shown by each item) and they deliver free next day. They are very good indeed, just expensive! Very convenient though and I guess you pay for convenience.

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