Board logo

Indy suspension measurement readings - discuss!
matt_claydon - 17/8/04 at 11:21 AM

Had my sus. geometry checked today, here are the readings:

Front:

Caster:
Left: 3.92
Right: 5.42

Camber:
Left: -0.18
Right: 0.09

Toe: 0

Rear:

Camber:
Left: -0.16
Right: 0.23

Toe:
Left: -0.25
Right: 0.95


Particularly worrying is the rear toe of nearly a degree, since it is non-adjustable. What's my best option? I thought of drilling out the holes in the wishbone mounts so that the crush tubes can be moved in/out, but worry that they would not stay where they were clamped anyway.

Also a bit odd is the caster not being equal, as both mushroom inserts are at exactly the 12 o'clock position.

Cheers,
Matt.



[Edited on 17/8/04 by matt_claydon]


garage19 - 17/8/04 at 11:33 AM

I think you will find that rose jointed wishbones will be the only answer.

DC


nick205 - 17/8/04 at 11:46 AM

Hi Matt,

Sounds like you're getting good use out of the car!

How does the car drive and handle and how is the tyre wear?

Let me know if you're back down this way over the summer as I would still be up for a ride in the car

Cheers

Nick


Surrey Dave - 17/8/04 at 12:50 PM

Matt - Where did you get your suspension checked?


James - 17/8/04 at 01:03 PM

quote:
Originally posted by matt_claydon

Particularly worrying is the rear toe of nearly a degree, since it is non-adjustable. What's my best option? I thought of drilling out the holes in the wishbone mounts so that the crush tubes can be moved in/out, but worry that they would not stay where they were clamped anyway.

[Edited on 17/8/04 by matt_claydon]


What about fitting washers on the bolts in between the hub carrier and the rear upright?
This would alter the toe-in.

To alter the rear castor: is there enough space between the crush tube and the bracket to fit a washer? You could move the lower wishbone forwards by a washers thickness and the upper back a washer to increase the castor...

...maybe...

Hope that fantastic bodge idea helps,

James

P.S. Have a look at Viper's archive for his wishbones. Have built-in castor adjustment. Maybe a possible mod for your car?


Mk-Ninja - 17/8/04 at 01:24 PM

Think you will find a washer is too thick, all you need is some shims.


matt_claydon - 17/8/04 at 01:28 PM

quote:
Originally posted by James

What about fitting washers on the bolts in between the hub carrier and the rear upright?
This would alter the toe-in.

To alter the rear castor: is there enough space between the crush tube and the bracket to fit a washer? You could move the lower wishbone forwards by a washers thickness and the upper back a washer to increase the castor...



Good idea for the rear toe, all I need to do is a bit of trig to work out the thickness of washers required to bring the right wheel equal to the left.

Your second bit of advice is also good, although perhaps slightly irrelevant since I didn't give figures for rear caster!

The front caster is adjustable, and I could reduce the amount on the right to equal the left, but this would affect the camber and toe which are both fine now! Since the car does not pull either way, I am tempted to ignore the caster discrepancy for now anyway.

Cheers,
Matt (off to get his calculator and some washers!)


theconrodkid - 17/8/04 at 01:52 PM

mat,take your average road car and get it checked,youl be suprised how far out of square they are,i wouldnt worry too much bout it


matt_claydon - 17/8/04 at 02:03 PM

The distance between the front and rear hub mounting bolts is about 90mm, which my calculations show would require 0.4mm of shims/washers under the rear bolts to remove the -0.25 degree toe out, and 1.5mm of shims under the front bolts to remove the 0.95 degree toe in.

Anyone care to check that I've worked this out right? Seems like quite a large amount of shimming and I'm a bit worried about the hubs being mounted to the carriers with only point contact.

If I go the locost route and just use washers, would it be better to end up with slight toe-in or toe-out, assuming I can't get washers of exactly the right thickness?

Cheers,
Matt.


matt_claydon - 17/8/04 at 02:04 PM

Good point Conrod, although I would like to have it close to being right, then I can stop blaming the car and work on my driving


MikeRJ - 18/8/04 at 01:38 PM

quote:
Originally posted by matt_claydon
I thought of drilling out the holes in the wishbone mounts so that the crush tubes can be moved in/out, but worry that they would not stay where they were clamped anyway.


Way to do this is to slot the holes in the wishbone brackets and then weld a washer in the correct place.


SteveO - 22/8/04 at 09:20 AM

i had a bit done as well on the front 'cause the bump steer was bad.

my rears were bad
camber:
left -1.41 degrees right :-1.14 degrees

toe.
left: 0.36 right: 0.14

But more important was the loose knuckles on the front rack thats covered by the rubber gaitors. didn't know they were- loose dangerous stuff .
so guys check all nuts around the front suspension and rack.

But the drive now is soo much better without having done the cornering yet.

Steve


bob - 22/8/04 at 09:45 PM

I mentioned a couple of years back about shimming the rear hubs to level the car up,i didnt bother in the end after trying to work out the measurments.

If you havnt got a boot box on the indy like me have a go at this.......put the handbrake on and grab the roll bar from the rear,give it a good shove back and forth while having a look at the wishbone to hub joints.
It all moves around that much you wont bother worrying anymore