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Author Topic: Chassis Geoometry 101.........  (Read 4685 times)
Lee.C
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« on: October 01, 2009, 12:47:45 pm »

Well guys as a few of you will know I am working on a nice little project at the moment for a customer:
http://cal-look.no/lounge/index.php/topic,7573.0.html

The Chassis is a late type balljoint front end with CB dropped spindles and a 2" narrowed/adjustable beam with IRS rear end, There is also a "bolt in" type Rear truss bar (shock towers/frame horns) which is also fully adjustable,

Now I have a FULL rolling pan so my question is:

How do I set up ALL the chassis geoometry  Huh ie Tracking, Camber, caster, rear axle/A arm alinement Huh

One thing I was really surprised about was the amount of movement/deflection when adjusting the rear truss bar  Shocked
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roland
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« Reply #1 on: October 01, 2009, 14:29:45 pm »

I don't think you can do that if you don't have a full weight car at the correct ride height...
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G77
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« Reply #2 on: October 01, 2009, 21:48:25 pm »

Hey it lee here (signed in on a friends pc)

I was thinking the same thing but I was hoping to get some info on the adjustment/pre-load on the rear truss bar  Undecided

You can get ALOT of movement in the shock towers and framehorns when adjusting the 3 bars,

I was also hoping to get some info adjustment/alinement process of the springplates/A arms Undecided

Any input would be great guys  Smiley
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Lee.C
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« Reply #3 on: October 03, 2009, 14:28:27 pm »

Any thoughts guys Undecided
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Bruce
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« Reply #4 on: October 03, 2009, 17:21:18 pm »

I was thinking the same thing but I was hoping to get some info on the adjustment/pre-load on the rear truss bar 
You don't need to pre-load anything.  Doing so accomplishes nothing.
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Lee.C
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« Reply #5 on: October 03, 2009, 20:10:32 pm »

Ok thanks Bruce BUT still not much "info" on adjustment/settings, Maybe some of the Racers can help Undecided
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WhiteTrash
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« Reply #6 on: October 06, 2009, 13:45:15 pm »

Lee,

I've set up my rear torsionbars with an angle finder and a workshop manual.
There are specific angles the spring plates were set from factory depending on year and model. The differents between inner and outer splines on all torsion bars are 8 degree 10' to 9 degrees so you can change he angles in increments of 50' (60' = 1 Degree)
After i put the IRS in mine i started at stock pre 74 model IRS measurements as i'm using all parts from the donor, but as its lighter I took 1 degree 30' off the original 20 degree something for starters which was to high and ended up on 16 degree 30' or something on Passenger side and 17 degrees on drivers side to compensate for my weight. I think the car sits just right.
Both big washers on the 17mm IRS arm Allenbolt are fitted towards the outside of the car, the rest i just eyed up and it still runs nice and straight even after the 1/4 mile at 107mph at Shakeys run off area.
I never touched the front camber since i had it and set the toe slightly in as per original, but you can't really do it until you got all weight in.
I will just get it 4 wheel aligned in the winter but only to see if it's even. If it ain't broke, don't fix it.

Oh the other thing, put a new steeringbox on, for the £65.00 they cost it's not worth fucking around with even slightly sloppy steering which won't help setting up

Frank
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Lids
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« Reply #7 on: October 07, 2009, 18:12:50 pm »

i always thought that as a drag car digs in at the back you need to compensate for the loss of front camber.  So i was advised to set the front camber with the car rasied so that the wheels are vertical in this position.  Not useful for general driving but should help keep the car straight ion the track.
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Lee.C
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« Reply #8 on: October 08, 2009, 11:36:07 am »

hmmmm all very interesting - keep the info coming guys  Smiley
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WhiteTrash
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« Reply #9 on: October 09, 2009, 15:08:16 pm »

i always thought that as a drag car digs in at the back you need to compensate for the loss of front camber.  So i was advised to set the front camber with the car rasied so that the wheels are vertical in this position.  Not useful for general driving but should help keep the car straight ion the track.

The front only lifts at launch. If it lifts during the run you got aerodynamic issues with keeping the car on the track.
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Lids
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« Reply #10 on: October 09, 2009, 20:04:18 pm »

i always thought that as a drag car digs in at the back you need to compensate for the loss of front camber.  So i was advised to set the front camber with the car rasied so that the wheels are vertical in this position.  Not useful for general driving but should help keep the car straight ion the track.

Mine don't lift at all, it doesn't move Smiley

The front only lifts at launch. If it lifts during the run you got aerodynamic issues with keeping the car on the track.
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Lee.C
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« Reply #11 on: October 09, 2009, 20:18:28 pm »

I think i'm gonna listen to the guys with DRIVING cars  Wink

Lets have more info guys  Smiley
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jick
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« Reply #12 on: October 09, 2009, 20:21:30 pm »

I think i'm gonna listen to the guys with DRIVING cars  Wink

Lets have more info guys  Smiley

 Cheesy Cheesy Cheesy
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Lids
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« Reply #13 on: October 09, 2009, 20:31:52 pm »

read this: http://www.aircooled.net/gnrlsite/resource/articles/dragsetup.htm

and this: http://www.aircooled.net/gnrlsite/resource/articles/handling.htm
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Lee.C
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« Reply #14 on: October 09, 2009, 21:25:31 pm »

Thanks dude but it not really for "Drag racing" it for a street car - balljoint front (with dropped spindles)IRS rear,

Some usefull info though  Smiley
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