Caster Adjustment
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Advanced
Joined: Feb 2014
Posts: 97
Likes: 16
From: Green Bay Wi.
Caster Adjustment
I would like to add more positive caster to the ailnment on my 73 after installing a borgeson box, from what I have read I need to add shims to the rear of the a-arm. My question is how much amount of shim gives you how much more degree of caster? My last ailnment showed I had 2.8 on passenger side and 3.0 on drivers side.
Thanks, John
Thanks, John
Burning Brakes
Joined: May 2014
Posts: 884
Likes: 128
From: Rhine Georgia
You may need new upper control arms to get the amount your looking for. 2.8/3.0 is not far off from the 3-5 borgeson recommends so your close. A product like CTA-31A from Global West would do what you need. From what I've read borgeson units like as much caster as you can get without hurting other specs.
I installed the Borgeson and got my caster close. But because my front end is lowered I could only get 2ish pos caster. Car drives bad on uneven roads. I have a set of the CTA-31As waiting to be installed soon as car gets home from paint.
I installed the Borgeson and got my caster close. But because my front end is lowered I could only get 2ish pos caster. Car drives bad on uneven roads. I have a set of the CTA-31As waiting to be installed soon as car gets home from paint.
Last edited by Bloodzone; Apr 15, 2017 at 12:00 PM.
Melting Slicks
Joined: Jun 2011
Posts: 3,116
Likes: 598
I would like to add more positive caster to the ailnment on my 73 after installing a borgeson box, from what I have read I need to add shims to the rear of the a-arm. My question is how much amount of shim gives you how much more degree of caster? My last ailnment showed I had 2.8 on passenger side and 3.0 on drivers side.
Thanks, John
Thanks, John
If you want better straight line tracking toe / camber adjustments make a bigger difference, and most important is left side vs right side should be equal. and the Trust angle rear vs front needs to be in the range of 0.01 - .03 degrees.
If the thrust angle is off the car will not drive straight. The rear will try to come around the front during acceleration.
Thread Starter
Advanced
Joined: Feb 2014
Posts: 97
Likes: 16
From: Green Bay Wi.
You may need new upper control arms to get the amount your looking for. 2.8/3.0 is not far off from the 3-5 borgeson recommends so your close. A product like CTA-31A from Global West would do what you need. From what I've read borgeson units like as much caster as you can get without hurting other specs.
I installed the Borgeson and got my caster close. But because my front end is lowered I could only get 2ish pos caster. Car drives bad on uneven roads. I have a set of the CTA-31As waiting to be installed soon as car gets home from paint.
I installed the Borgeson and got my caster close. But because my front end is lowered I could only get 2ish pos caster. Car drives bad on uneven roads. I have a set of the CTA-31As waiting to be installed soon as car gets home from paint.
Melting Slicks
Joined: May 2005
Posts: 2,486
Likes: 71
From: Elkhart Lake, Wisconsin
I slotted my upper control arms.
Here is an old thread.
https://www.corvetteforum.com/forums...trol-arms.html
Here is an old thread.
https://www.corvetteforum.com/forums...trol-arms.html
Burning Brakes
Joined: May 2014
Posts: 884
Likes: 128
From: Rhine Georgia
I think the issue is the Borgeson units need more caster for some reason. I was happy with below 3 pos caster with my factory PS. When it failed and I upgraded to Borgeson They recommened as much as 5.
Thread Starter
Advanced
Joined: Feb 2014
Posts: 97
Likes: 16
From: Green Bay Wi.
What is wrong with the current settings. Increase caster beyond 3 degrees is not noticeable driving on the street. You need to hit high MPH to feel a difference.
If you want better straight line tracking toe / camber adjustments make a bigger difference, and most important is left side vs right side should be equal. and the Trust angle rear vs front needs to be in the range of 0.01 - .03 degrees.
If the thrust angle is off the car will not drive straight. The rear will try to come around the front during acceleration.
If you want better straight line tracking toe / camber adjustments make a bigger difference, and most important is left side vs right side should be equal. and the Trust angle rear vs front needs to be in the range of 0.01 - .03 degrees.
If the thrust angle is off the car will not drive straight. The rear will try to come around the front during acceleration.
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
The best way to increase caster without affecting camber and toe very much is to remove a shim from the front and add it to the rear and do the same on both sides.
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As you play with caster, your camber will begin to move also.
I added VB upper arms to get some more range. I was able to get near 6* in it. Drives great. Wasn't bad before at 2.5* even at 150+ MPH...but especially since I've been doing some higher speed events lately...it does very well.
JIM
I added VB upper arms to get some more range. I was able to get near 6* in it. Drives great. Wasn't bad before at 2.5* even at 150+ MPH...but especially since I've been doing some higher speed events lately...it does very well.
JIM
Racer
Joined: Jan 2015
Posts: 314
Likes: 50
From: Woodbury NJ
+1 for slotting the cross shafts on the upper control arms. I did mine last year along with the Borgeson box, 550 springs cut a 1/4 coil, all new poly bushings and new balljoints & tie rods. I referenced that same thread posted above for slotting cross shafts. here's the rub in my situation. At the alignment shop, i was able to get 5 degrees caster on one side, but only 3.1 on the other side. So we set the alignment at 3.1* on both sides. I love how it handles. (15" rims, 245-50/r15s).
I'm curious as to why i have different max castor or each side. The frame is 1/4 out on driver side, but that is within tolerances. It might be a bent control arm, but I'll figure that out later.
I'm curious as to why i have different max castor or each side. The frame is 1/4 out on driver side, but that is within tolerances. It might be a bent control arm, but I'll figure that out later.
Last edited by Cool bean; Apr 16, 2017 at 07:35 AM.
Melting Slicks
Joined: Jun 2011
Posts: 3,116
Likes: 598
But.The difference between 3 degrees and 5 degrees on the street you will never tell the difference in a blind test. I hear this all the time.
Example set the caster to 3 degrees, then take it for a drive. Next change it to 5 degrees ( tell the driver and actually don't change anything) the driver will most likely claim it is day and night change.
The human mind is a strange thing, it likes to think the effort we put into something is not a waste of time, and therefor believes a drastic improvement is perceived.
427Hotrod is an example of someone that needs to look at caster @ speeds like 155+ 200 MPH.
If you want your car to drive straight and handle great on the street, start with.
#1 Thrust angle (Rear axle vs front axle)
#2 Toe / caster / caster equal on both sides.
Alignment shops use within-specs which could give you an imbalance left vs right side. It is important you always get the printout and check how much they care about how your car will drive.
This is the biggest reason why I DIY my alignments, but also because I change the alignment from street to track days so often.
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I agree with the "within specs" comment. Alignment shops are notorious for telling people that...yet when it's done it still drives poorly. You should be able to let go of the wheel and it should track straight. If it doesn't drive right...you're not done.
A little goes a long way with alignment. It can be within tolerance range, but still not be correct.
I am at the extreme of what most folks do for high speed work...and if I was doing track days...it would be a completely different alignment. Mine drove fine at 2.5* caster....but drives even better with the added amount. Added more feel to the steering...slightly heavier.
Toe-out...even the slightest amount on a street driver is bad. Track use is another thing....but lots of shimmy's and wandering are caused by toe out on the front or rear.
I do my alignments at home also. Easy to do and I know it's right.
JIM
A little goes a long way with alignment. It can be within tolerance range, but still not be correct.
I am at the extreme of what most folks do for high speed work...and if I was doing track days...it would be a completely different alignment. Mine drove fine at 2.5* caster....but drives even better with the added amount. Added more feel to the steering...slightly heavier.
Toe-out...even the slightest amount on a street driver is bad. Track use is another thing....but lots of shimmy's and wandering are caused by toe out on the front or rear.
I do my alignments at home also. Easy to do and I know it's right.
JIM
Racer
Joined: Dec 2010
Posts: 251
Likes: 36
From: Jefferson Ohio
What is wrong with the current settings. Increase caster beyond 3 degrees is not noticeable driving on the street. You need to hit high MPH to feel a difference.
If you want better straight line tracking toe / camber adjustments make a bigger difference, and most important is left side vs right side should be equal. and the Trust angle rear vs front needs to be in the range of 0.01 - .03 degrees.
If the thrust angle is off the car will not drive straight. The rear will try to come around the front during acceleration.
If you want better straight line tracking toe / camber adjustments make a bigger difference, and most important is left side vs right side should be equal. and the Trust angle rear vs front needs to be in the range of 0.01 - .03 degrees.
If the thrust angle is off the car will not drive straight. The rear will try to come around the front during acceleration.
Thanks,
Jim
Melting Slicks
Joined: Jun 2011
Posts: 3,116
Likes: 598
But basics is the difference where the rear wheels point vs where the front wheels point.
https://www.tirerack.com/tires/tiret...e.jsp?techid=4
Race Director
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From: Corsicana, Tx
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You really have to watch the rear toe. When folks are moving shims to set each side, they sometimes take the easy way out and do more on one side than the other. Each has to be set correctly to end up with total toe. Same can happen on the front, but you notice it with a crooked steering wheel.
JIM
JIM