upper control are shaft

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Nov 3, 2003 | 03:01 PM

Phil's79

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Heel & Toe

Joined: Sep 2000

Posts: 20

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From: lebanon,tn,37090

upper control are shaft

It has taken me three years to get to the point of putting my 79 back together and it sure feels good. No more rust, grease or dirt. Started frame assembly this weekend and installed new bushing on control arms. When installing upper control arms on frame noticed that I did not note the position and pictures were not clear enough to make out how the shaft should be installed. My shafts and I presume all of them are "offset". On disassmbley both sides had about 1/2 to 3/4 inch of alignment shims. Which way should they be installed? Where the offset is in or out? That is to say where the upper control arm assembly is closer to or farther away from the frame? Hope that makes sense and my thanks to everyone on this forum. It is tremendously helpful.

Nov 3, 2003 | 03:18 PM

CHEESERAL

Racer

Joined: Feb 1999

Posts: 369

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From: Garner NC

Re: upper control are shaft (Phil's79)

My originals were not off set, but I bought the off set ones from vette brakes. I installed mine (and I think this is correct) so that it acts like there is already a shim installed (or so that the assembley is further away from the frame.) I hope that makes since.

Good luck!

Nov 3, 2003 | 05:46 PM

Tom454

Le Mans Master

Joined: Apr 1999

Posts: 6,134

Likes: 46

From: Raleigh North Carolina

Re: upper control are shaft (CHEESERAL)

The shims are inserted/removed to set caster & camber.

Inserting/removing any shims affects camber.

If you do it equally at both ends, it affects only camber.
If unequally, it affects caster as well as camber because the upper ball joint will react in an arc, not a straight line..

The number of shims will vary greatly from car to car.

I don't know if you can say in general:

"there are more shims in the front than in the back." (or the other way around)

My 66 and 70 are all over the map.

Nov 3, 2003 | 06:05 PM

75 BBC Stingray

Racer

Joined: Oct 2002

Posts: 328

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From: Marlborough MA

Re: upper control are shaft (Phil's79)

Funny, I was looking at this and wondering the same the other day. I bought the Performance Plus system fro VBP, and the upper A-arms come with offset shafts. My thought would be that the shaft should be installed so that the pivot point of the A-arm is offset to the inside of the vehicle. In other words, the offset of the cross-shaft replaces some of the shims that would ordinarily be used. That being said, when you look at the VBP website, as well as this article from VETTE magazine, you would see that they show the opposite install.
Magazine Article
http://www.vetteweb.com/tech/vet_0309_arms/

Closeup of arm install
http://www.vetteweb.com/tech/vet_0309_arms_14_z.jpg

I am planning on calling VBP in the coming weeks to ask just this...

[Modified by 75 BBC Stingray, 6:07 PM 11/3/2003]

Nov 3, 2003 | 06:09 PM

75 BBC Stingray

Racer

Joined: Oct 2002

Posts: 328

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From: Marlborough MA

Re: upper control are shaft (Tom454)

Tom,

I think the question was regarding the offset in place in the forged cross-shaft, independent of the shims...

Nov 3, 2003 | 07:43 PM

Phil's79

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Heel & Toe

Joined: Sep 2000

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From: lebanon,tn,37090

Re: upper control arm shaft (Phil's79)

Seems everyone understands. Depending on which way you turn the shaft, offset in or offset out, will determine the number of shims needed for proper alignment. I was under the impression that they came this way from the factory. I am pretty sure mine has GM part numbers stamped on them. Maybe this was just in the later C3 models. So if that is right, how did it come from the factory, offset in or offset out. Thanks for everyones help so far.

Nov 3, 2003 | 09:35 PM

75 BBC Stingray

Racer

Joined: Oct 2002

Posts: 328

Likes: 0

From: Marlborough MA

Re: upper control arm shaft (Phil's79)

I'm pretty sure mine were not offset, and looking at one of the photos from the article I mentioned also shows a non-offset arm.

http://www.vetteweb.com/tech/vet_0309_arms_08_z.jpg

http://www.vetteweb.com/tech/vet_0309_arms_11_z.jpg

Of course my car is a '75, so I can not comment on what came in later years... Good luck.