6066 (1960-1966) GMC Truck Club

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-   -   Positive camber... just remove the shims? (https://6066gmcclub.com/showthread.php?t=51080)

biscaynebirdie March 6th, 2021 03:53 AM

Positive camber... just remove the shims?
 
It seems that after installing disc brakes on the front of my 1965 1000, I have some positive camber. After only about 10,000 miles, I have destroyed the outside of my 255/60R15 BF Goodrich Radial TAs.

Im bringing the truck into Les Schwab on Monday for new tires (255/70R15 Cooper Cobra Radial GTs), and am curious if they will be able to fix the positive camber without needing any new parts. Will it be as simple as removing the original shims? Im going to replace the tie rods tomorrow morning (might as well do it now... most of the boots are cracked/missing).

Thoughts?

FetchMeAPepsi March 6th, 2021 06:31 AM

Re: Positive camber... just remove the shims?
 
Depends on where the shims are and what you did to set it up. Got any pics? Details?

biscaynebirdie March 6th, 2021 08:21 AM

Re: Positive camber... just remove the shims?
 
2 Attachment(s)
The only things we changed on the front end was the new spindles for the disc brakes and the rims. We replaced the upper and lower ball joints for safety's sake. Nothing else has been messed with other than replacing the shock absorbers. Control arms, shim placement, steering box, and coil springs are all original. The first photo is the driver side (you can clearly see the steering shaft) and the second is the passenger side.

James March 6th, 2021 09:25 PM

Re: Positive camber... just remove the shims?
 
Changing the spindle is enough to require a front end alignment. Worn parts: the old spindle might had a slight bend in them from years of driving, worn ball joints, or toe in too much. Plus manufacture tolerance can play a role in it. In my opinion any time I do front end work I perform a alignment check. Money ahead in my book. Whoever perform the alignment will be changing/adjusting the shims to get the caster and camber correct. And with our trucks the frame angle is taken into account (ref. the manual).

One thing to note if you have manual steering. Make sure your caster is close to zero on the positive side. This will make steering easier when drive slowly.

Sonic65 March 7th, 2021 06:13 PM

Re: Positive camber... just remove the shims?
 
Quote:

Originally Posted by biscaynebirdie (Post 73847)
The only things we changed on the front end was the new spindles for the disc brakes and the rims. We replaced the upper and lower ball joints for safety's sake. Nothing else has been messed with other than replacing the shock absorbers. Control arms, shim placement, steering box, and coil springs are all original. The first photo is the driver side (you can clearly see the steering shaft) and the second is the passenger side.

The offser of the new rims could be enough to add stress to the existing parts and cause wear on the tires.

James March 7th, 2021 09:22 PM

Re: Positive camber... just remove the shims?
 
Take a tape measure and measure the toe on the front and back of the front tires. Should be toe in approx 1/8" (front of tire closer together than the back of the tire), this allow the wheels to roll down the road straight. Too much toe in could cause excessive wear on the outside edge of the tires. Too much toe out can cause excessive wear on the inside edge of the tires. Also wider rim/tire will make this wear more noticeable.

biscaynebirdie March 10th, 2021 07:01 PM

Re: Positive camber... just remove the shims?
 
2 Attachment(s)
Well, got the truck back from the shop. I could instantly feel the difference in ride, as well as ease of turning. It feels like it rolls much more smoothly. They removed most of the original shims as well as added some new ones.

Unfortunately someone made a mistake and accidentally ordered two 225/70R15s for the front instead of 255/70R15s all around, so I'll be bringing it back into the shop on Friday to swap them out. I didn't even realize it until I was looking at the truck from a distance, noticed something looked off, and checked the numbers. I know a lot of people like the staggered look, but I'm not the biggest fan.

My biggest concern is this... If they did the alignment with these smaller tires up front, should they recheck the alignment once they put the 255s up front or does it not matter?

Here's the before and after alignment adjustments, as well as a photo of how it looks (for now):

James March 10th, 2021 11:32 PM

Re: Positive camber... just remove the shims?
 
Yes it will affect the alignment. It will increase the Caster, making it harder to steer with manual steering (power steering not so much). With that much camber and over an inch of toe-in no wonder your tires got ate up.

In fact with that much caster with manual steering it would still be hard to turn the wheel. In my 64 maintenance manual it stated I needed to set it to approx .5 and I have manual steering. Before I adjusted it it had over 3 and extremely hard to steer.

biscaynebirdie March 11th, 2021 12:01 AM

Re: Positive camber... just remove the shims?
 
Quote:

Originally Posted by James (Post 73877)
Yes it will affect the alignment. It will increase the Caster, making it harder to steer with manual steering (power steering not so much). With that much camber and over an inch of toe-in no wonder your tires got ate up.

In fact with that much caster with manual steering it would still be hard to turn the wheel. In my 64 maintenance manual it stated I needed to set it to approx .5 and I have manual steering. Before I adjusted it it had over 3 and extremely hard to steer.

Well shoot... Should I say something to the tech about it Friday morning? I can't really afford to pay another $90 for alignment at the moment.

The 1964 GMC manual calls for .5 caster? The 1963 Chevrolet Truck Shop Manual (if I am reading the chart correctly) calls for 2 caster at 0 camber, so it seems like the tech got pretty close to spec. I have a scan of the chart on my computer, but I'm not sure if I should share it here for copyright infringement reasons.

James March 11th, 2021 02:26 AM

Re: Positive camber... just remove the shims?
 
Quote:

Originally Posted by biscaynebirdie (Post 73878)
I have a scan of the chart on my computer, but I'm not sure if I should share it here for copyright infringement reasons.

I don't know the copyright laws, but I been lead to believe if it been over 20 years since the last copyright date in the document then it can freely be copy. Maybe someone else that know more can chime in for clarification.

My caster is what is measured at the wheel without taking into account the ride height or frame angle. Your manual should show you a formula on getting the corrected caster angle. My frame angle is 2.5. So my corrected caster is 3. Also the manual talk about ride height of the front suspension, this give me the range for my caster setting. Both measurements is used to determine corrected caster for different load on the truck. Even my 79 Chevy pickup 1/2 ton maintenance manual make reference to frame angle for setting the caster.

Hope this help.


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