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Author: Subject: Car wondering/edging handling HELP
Davidthomas

posted on 20/1/14 at 09:51 PM Reply With Quote
Car wondering/edging handling HELP

I wrote a post yesterday about my car wondering/feeling unstable at 40+mph. Some people wanted to know what caster/camber setting I had so here you go..



Do this look ok??

[Edited on 20/1/14 by Davidthomas]

[Edited on 20/1/14 by Davidthomas]

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JAG

posted on 20/1/14 at 09:56 PM Reply With Quote
OK - so in my experience a little toe-in at the front will make the car more stable in a straight line





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unijacko67

posted on 21/1/14 at 01:07 AM Reply With Quote
I'm not qualified to help, but where did you go to get that done and how much, wouldn't mind having a session.





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Acc8braman

posted on 21/1/14 at 05:32 AM Reply With Quote
Kwik fit now have the equipment to show this info
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Ivan

posted on 21/1/14 at 06:40 AM Reply With Quote
Assuming that +ve toe at the rear indicates toe out I would guess that the answer to your problem is to set up a little -ve toe at the rear.

Any toe out at the rear will cause instability and is a genuinely bad thing.

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Davidthomas

posted on 21/1/14 at 07:03 AM Reply With Quote
Ok cheers

Is there any thing I can try regarding damping settings. I have avo adjustable shocks. Should the rears be softer than the front? Or the other way round??

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steve m

posted on 21/1/14 at 07:14 AM Reply With Quote
Have you tried different tyre pressures yet, as that would be the first thing to do, as per your other thread

Steve





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40inches

posted on 21/1/14 at 08:32 AM Reply With Quote
quote:
Originally posted by steve m
Have you tried different tyre pressures yet, as that would be the first thing to do, as per your other thread

Steve


Exactly, Geo isn't at all bad, but tyre pressures should be around 16psi all round, not 30psi rear 20psi front. Must be like driving on ice!
This question was answered in this thread http://www.locostbuilders.co.uk/viewthread.php?tid=188234
Have you lowered the pressures to 16psi yet?

[Edited on 21-1-14 by 40inches]






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britishtrident

posted on 21/1/14 at 08:46 AM Reply With Quote
Toe-in is essential to stabilise the car Toe-in at the front stops the steering being hyper sensitive to inputs around the straight ahead position and prevents the steering diving off line in response to unevenness in the road surface. At the rear toe-in reduces the tendency for the rear to go into snap oversteer on entry to a corner. Toe-out at the rear is to be avoided at all costs.

At the front about 0.1 to 0.2 degrees across both wheels is about right, at the rear try 0.15 to 0.25 degrees should work.
Toe should should always beset with the car loaded with the drivers weight.

Because of the low weight compared to a tintop the dampers should be set at a soft setting.





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renetom

posted on 21/1/14 at 09:09 AM Reply With Quote
wandering

Have you checked for bump steer ?.
Tyre pressures
Rear toe in
soften the shocks
all that's been already mentioned .
Good luck

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Not Anumber

posted on 21/1/14 at 10:52 AM Reply With Quote
A small amount out here and there combined with the wrong tyre pressures can really affect the way these cars handle and feel on the road.

To be frank I didnt enjoy driving mine very much on the open road until:

The tyre pressures were reduced from around 30psi (tyre fitters!) to 16 psi
The fixed upper front wishbones were replaced with adjustables (steering self centring)
Indy Bird (knowledeable forum member) kindly set the suspension heights, damper rates, tracking, camber and caster.

Once these things were right it also dramatically reduced the amount of bump steer that previously been evident.

This work made a huge difference to the cornering and overall driveability of the car without spending very much at all.






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pewe

posted on 21/1/14 at 11:50 AM Reply With Quote
Regarding shock settings - all things being equal the fronts should be set firmer than the rears.
On my other (hairdressers) car the MeisterR's are set two clicks firmer on the front but it may need more given the weight distribution on a Se7en type car.
It was very noticeable that the car was washboarding at higher speeds when the adjustment was nearing equal.
Another consideration is whether the oil and valving in the dampers is set for a Se7en type car especially if it's live axle.
Matt at Procomp (on here) can dyno test coil-overs and advise the best set up.
HTH.
Cheers, Pewe10

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rodgling

posted on 21/1/14 at 12:30 PM Reply With Quote
Disagree about toe-in being needed at the front, I have zero-toe at the front and I'm very happy with how that feels. Personal preference I think, probably depends a bit on the car and how you use it too.

Toe-in at the back... I used to (unintentionally) have some toe out at the back. Going sideways around roundabouts was easy and fun but apart from that I would not recommend this, as everyone else says, toe-in at the back is essential.

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Davidthomas

posted on 2/2/14 at 04:38 PM Reply With Quote
Iv changed the tyre pressure to 16psi all round. Had a run out in it and it does feel better but still not fully planted.

I noticed that my rear shock were set pretty firm so iv put them to the softest setting but haven't got round to taking it out again.

I'm changing my wheels from 15" to 13" in the next month or so. I'll be fitting some yokohama A048s

Il see how it feels then.

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unijacko67

posted on 2/2/14 at 05:01 PM Reply With Quote
The only time my car has been very unstable and I mean hard to even keep in one lane of the motorway, at speed I may ad, was when checked it had excessive toe out (arround 6mm). I have found it to be good set at zero and also stable under braking. I had forgot to re-track the car after setting the caster and camber (reason for it being so far out).





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ashg

posted on 2/2/14 at 05:46 PM Reply With Quote
its got to be the rear toe out causing the problem it needs to be -0.2 not +0.2 that means your nearly half a degree out on each wheel at the back, that's going to have a big effect on the stability of the car.

I would be aiming to start with this

front
camber -1deg

toe anywhere between 0 and -0.5 deg (i run mine -0.2)

caster wants to be somewhere between +6 and +10 (if you want well weighted and good self centring on the steering) may be tricky to sort if you dont have adjustable upper front wishbones

rear

camber -1deg to -1.2deg

toe somewhere around -0.2deg ( may be tricky to sort if you have no toe adjustment on the rear as it will either need shimming or new adjustable wishbones)

tyre pressures around 15-16psi

rear ride height 15-20mm higher than the front with you in it.


if you fancy learning how to make a string computer you can play about with the settings yourself, you already know what the base settings are so you can easily make adjustments to one thing at a time then go out for a drive and see how the car feels, you will very quickly learn what adjustment does what.





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