Litton Corse build with 2.0l Lancia 8v TC

[hollytree]

Hello Paul,

As John says it is extra caster you require for the self centering on the steering. If you have already set the bump steer with the caster as it is set now then you could disconnect the swing bolt where it attaches to the TCA and wind it in say 3 full turns, the thread is a 2mm pitch & every 2 full turns will add approx 1 degree of caster so this would increase the caster to approx 6 degrees. This way after the test you can wind the swing bolt back to where you are now safe in the knowledge that you don't need to reset the bumpsteer. Quite often a new ball joint has a reasonable amount of stiction which can hinderthe self centering, once the ball joint loses its "newness" then things will free up, not helpful for IVA but something I have witnessed in the past which could be worth mentioning to the examiner on the retest.
If you have 1 degree of toe in then this could possibly affect the self centering too, 10minutes is a better starting point for the front axle.
With regards to the rear settings, the set up John has posted is very agressive on the rear (the front is fine), the rear toe is marginally more than I would start with & the rear camber is way more than I would look for on a road car.

Good luck with the retest!

Corse I
I got some front damper mount plates made to drop the top mount by 1" as the front trailing arm was only about 1/4" from the chassis rail and on bump was hitting it. If I jacked the spring collars then I had no droop. Now I have about 2" bumps and 1'1/2" droop and it feels good.
I have just had it set on one of those new fangled laser jigs.
I have got all the settings pretty close to those in the Corse I build manual, however:-

I started with caster FL 2"35' FR 3"31'
To increase these towards the Corse I suggestion of 3"-5" the trailing arms had to be wound out to lengthen them and now both L&R are 4"30' BUT the lower rear wishbone arms are now very much to the rear of the little tunnel they sit in just in front of the bulkhead.

Lengthening the trailing arms to increase caster does not tie up with what Craig says above when he says "wind it in", which implies shortening the trailing arm.

Am I doing something wrong?
Am I missing something?

[Strat Fan]

Corse I
I got some front damper mount plates made to drop the top mount by 1" as the front trailing arm was only about 1/4" from the chassis rail and on bump was hitting it. If I jacked the spring collars then I had no droop. Now I have about 2" bumps and 1'1/2" droop and it feels good.
I have just had it set on one of those new fangled laser jigs.
I have got all the settings pretty close to those in the Corse I build manual, however:-

I started with caster FL 2"35' FR 3"31'
To increase these towards the Corse I suggestion of 3"-5" the trailing arms had to be wound out to lengthen them and now both L&R are 4"30' BUT the lower rear wishbone arms are now very much to the rear of the little tunnel they sit in just in front of the bulkhead.

Lengthening the trailing arms to increase caster does not tie up with what Craig says above when he says "wind it in", which implies shortening the trailing arm.

Am I doing something wrong?
Am I missing something?

Extending the front trailing links reduces the castor unless your upright was already leaning forwards (negative castor) rather than backwards (positive castor).
From what you describe then it sounds like your Track Control Arm is leaning back too far and that the top ball joint is actually farther forwards than the lower ball joint?
The image below was pulled from the www for the image but some of the text is relevant as well, just disregard the bit about power steering.

[hollytree]

Craig
Thanks
That is what is "visually" looks like, but how can that happen?
There is no adjustment in the top ball joint position.
If I had to lengthen the trailing arm to increase caster, should the machine be recording it a Negative caster?

PS when do you want me to drive down

[hollytree]

I have just gone and wound the trailing arms in so the bottom wishbone arms are now towards the front of the tunnel.
Looking down on the top ball joint the bottom joint is now in front - positive caster.
Amazing how only a couple of inches of adjustment makes such a difference.
More annoyed the machine did not pick up Negative!

[hollytree]

I have just gone and wound the trailing arms in so the bottom wishbone arms are now towards the front of the tunnel.
Looking down on the top ball joint the bottom joint is now in front - positive caster.
Amazing how only a couple of inches of adjustment makes such a difference.
More annoyed the machine did not pick up Negative!

Well that all worked out well.
Just been up and down the dual carriageway at 90kph (I think my gauges are KPH ahem!)
All feels good.
I must have been on negative camber. I will have a word with the man on the fancy machine tomorrow

[Darkspeed]

Corky had a bit of fun with Caster IIRC

[hollytree]

Andrew
Thanks
That was the photo on the right I was looking for to describe the tunnel

[Strat Fan]

Corky had a bit of fun with Caster IIRC

From one extreme to the other?