Suspension Front caster set up Problems

[StuartW]

I am Planning some more track days and so wanted to make the Supra feel more planted.

 

Had the Geometry set up on the T67 Today, Very interesting!

 

The car was way out to start with, Some of this may be down to my even adjustments of the rear Camber for drag racing.

 

The car felt like it was on ice, Whenever you went over a bump the rear would skip left or right and i had just got used to it:blink: for the past 4000 spirited miles!!

 

I Used the Lance W Set up proclaimed by many on these forums as being a good "Baseline" set up.

 

 

The problem we had is the front Caster adjustment, Not enough travel on the adjusting cams to get the right setting of +5.0 degrees

 

Has anyone else come across the same problem

 

I could get over it by purchasing adjustable top mounts and compensating for the adjustments with that..BUT it doesn't seem right.

 

is the car bent? has it been in an accident i did not know about?, Was a Import with a clear HP i have owned for 6 years from Japan import.

 

Even with the Caster as it is the Supra is ABSOLUTELY transformed in drive ability

 

Real night and day difference.

 

Hope someone has had the same issue before and resolved it by replacing a bush or something!!

 

Running Toyo R888's on 18's for track and Eagle F1's for road use.

 

 

This took the mechanic 1hour 15mins to do with me standing beside him, He was sweating with the pace, i was charged £129.63 I have no idea if that is fair or not?

Edited July 30, 2010 by StuartW (see edit history)

[Kirk]

How the hell did you manage to end up with worse caster on the right wheel than the left?

 

I use john bean aligners myself at work but i just dont understand why you have adjusted it so much out of spec. I know your going for the lance setup but why have one so far out compared to the other?

 

£129 isnt to bad, we charge around £100 for a custom setup and £45 for a standard set.

 

Looking at the print out sheet there doesnt seem to be anything suspect as your SAI is bang on and included angles are not miles apart. Anything over a degree out then id be a little suspicious.

Edited July 30, 2010 by Kirk (see edit history)

[StuartW]

How the hell did you manage to end up with worse caster on the right wheel than the left?

 

I use john bean aligners myself at work but i just dont understand why you have adjusted it so much out of spec. I know your going for the lance setup but why have one so far out compared to the other?

 

£129 isnt to bad, we charge around £100 for a custom setup and £45 for a standard set.

 

Looking at the print out sheet there doesnt seem to be anything suspect as your SAI is bang on and included angles are not miles apart. Anything over a degree out then id be a little suspicious.

 

Thanks for reply, I am glad it doesn't seem to be bent.

Could it be a worn or soggy bush? it passed its MOT last week but i know that means nothing. I do have spare Wishbones i could fit but its a bit of a BIG shot in the dark

[Homer]

I tried the Lance settings a few years back but really didn't like it, the car didn't feel like it tracked correctly and was a little twitchy. I had a garage do a custom setup which felt much more settled.

 

Anyway, kind of off your original subject. Not sure how the castor ended up so wrong but can only imagine it's a bent arm/hub or worn bush. Very tricky to locate though

[Kirk]

If anything id swap both front upper an lower and try again but i dont understand how the caster went from good to so bad? I know you were aiming for 5.0 degrees but could of atleast wound it back.

 

If there was anything bent it would show up on your included angle as thats the measurement you use to diagnose bent suspension but as i said originaly there isnt a huge difference between the two so its nigh impossible to tell.

[Chris Wilson]

Adjustable top mounts won't change the caster, camber or toe in any way whatsoever. Caster and camber adjustment are intrinsically linked on the stock MKIV front suspension, and often compromises will have to me made when looking for maximum attainable values.

[StuartW]

so the big Q is do i take it back for them to check again, or take it to someone else (Who locally in Devon?) or start replacing parts

 

The fitter did say "you are welcome to bring it back after driving a few miles" and then he vanished like a genie

 

At the desk the guy said "when you bring it back it wont cost you as much"

 

I will mention the Intrinsically linked part too.

 

Are there any down loadable instructions i could print to show the guy?

[Chris Wilson]

If it doesn't pull, or have noticeably different steering effort in fast left and right hand bends I'd just forget all about it and throw the sheet away. Caster is one of the less critical geo angles.

[StuartW]

If it doesn't pull, or have noticeably different steering effort in fast left and right hand bends I'd just forget all about it and throw the sheet away. Caster is one of the less critical geo angles.

 

Thank you for that Chris, She drives perfectly to me ....Track day away