Pinion Angle Help - Team Camaro Tech
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post #1 of 18 (permalink) Old Nov 3rd, 19, 02:57 PM Thread Starter
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Pinion Angle Help

Car is a 1969 with a 12 bolt rear. I know nothing on the history of the car or the 12 bolt thats in it. I am doing a Resto Mod, TKO600 with a LS3. Got the Engine and Trans put in last night and started looking at the drive line angles. The pinion angle has about 10 degrees of drop. I know this is way to much but I dont know why or what to do about it. Springs are 1.5 drops from Hotchkis. Springs are multiLeaf but the perches are monos. Is there a way to check and see if the perches have been welded on wrong? Any help is appreciated.
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post #2 of 18 (permalink) Old Nov 3rd, 19, 07:24 PM
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Al
 
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Re: Pinion Angle Help

The perches should be welded at 6* to the pinion. This link will help explain.
The pinion angle needs to be checking with the suspension loaded at ride height.
https://www.camaros.net/forums/27-tr...-question.html

Al

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post #3 of 18 (permalink) Old Nov 4th, 19, 05:14 AM Thread Starter
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Re: Pinion Angle Help

Thank you! At least I have a starting point to check.
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post #4 of 18 (permalink) Old Nov 7th, 19, 06:29 PM Thread Starter
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Re: Pinion Angle Help

I think I found the issue. Below are my results. The yellow one is the one from the post referenced above. Looks like they are welded wrong. Thoughts?
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post #5 of 18 (permalink) Old Nov 7th, 19, 07:00 PM
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Al
 
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Re: Pinion Angle Help

Greg, If your pinion is sitting at 0* then yes it appears the perch is off 10*. Yikes that's a lot.
The perches don't mount straight. I believe they are to be angled inward 2* each. Narrower
towards the front of the car. You'll have to do some searching to be sure. I've seen measurements
here somewhere. Do you see evidence the perches were moved? Are you sure the rear end is
from a 1st gen?

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post #6 of 18 (permalink) Old Nov 7th, 19, 07:14 PM Thread Starter
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Re: Pinion Angle Help

I looked up the numbers, it seems to be a 1st gen 12 bolt. The welds on the perches look a little cobbled up, so I am guessing that at some point they have been off. I had the pinion at 0. This would explain why my angle is off 10*. At least this gives me a chance to get the multileaf perches and weld them on. I assume I need to swap shock plates as well. I really appreciate the help on this. Been driving my nuts for the past week.
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post #7 of 18 (permalink) Old Nov 7th, 19, 08:01 PM
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Al
 
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Re: Pinion Angle Help

Greg, This post at CRG should help you. Reply #21 has a few pics. Unfortunately Photo Bucket
has trashed the other pics. If you're not a member at CRG you can join for free. You may have
to be a member to see the pics in reply #21.
factory 1969 12 bolt pinion angle

Al

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post #8 of 18 (permalink) Old Nov 7th, 19, 08:15 PM
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Al
 
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Re: Pinion Angle Help

Better pics here.
Alignment to Weld Spring Perches

Al

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post #9 of 18 (permalink) Old Nov 8th, 19, 04:42 AM Thread Starter
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Re: Pinion Angle Help

Those pictures really help. Do I need to disassemble the gears and bearing before I have the new ones welded on? I just rebuilt it and I'm not looking forward to that Also, do I need shock plates to match the Multileaf perch?
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post #10 of 18 (permalink) Old Nov 8th, 19, 09:37 AM
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Al
 
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Re: Pinion Angle Help

Greg, I would drain it and pull the axles. Shouldn't need to remove the carrier/gears.
Just cover them for protection. After you're done welding you can pull a rag through
the tubes to wipe any interior residue created from welding. I would use multi shock
plates. I believe Detroit Spring (DSE) is the recommended supplier for shock plates.

Al

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post #11 of 18 (permalink) Old Nov 8th, 19, 11:05 AM Thread Starter
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Re: Pinion Angle Help

Thanks Al. I ordered new perches and the DSE plates this morning. Appreciate all the help on this.
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post #12 of 18 (permalink) Old Nov 10th, 19, 03:56 PM
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Re: Pinion Angle Help

If you weld on the perches at a factory setting, you will have a good pinion angle if you use stock springs at stock ride height. If you then add Hotchkis lowering springs, the pinion angle will change and you may have to shim the axle to correct it. I would install the axle with perches and hold it together with the U bolts. Put the car on it's wheels and rotate pinion to the desired angle, tack weld the perches then remove and finish weld them.
I like to weld a brace front and rear as shown on this photo. It supports the perches better.
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67 RS 327 original owner. 1965 Lola T-70
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post #13 of 18 (permalink) Old Nov 10th, 19, 06:07 PM Thread Starter
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Re: Pinion Angle Help

Thanks for the idea, thats what I have been doing today. Have everything in place and ready to tack them in. One thing that is troubling me is the old perches measured 10" from perch to the inside of the tube where it goes into the axle. I have everything in place and Im getting around 9 7/8 on each side. Think this is an issue?
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post #14 of 18 (permalink) Old Nov 10th, 19, 06:50 PM
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Re: Pinion Angle Help

There is a little bit of room on the front leaf mounting bracket to the unibody, those three bolts. The inboard one is the main locator. The other two holes in the bracket are oversize. I have seen variances in the amount the front bushing is pressed into the leaf eye. Had some leaf springs that fit better when swapped side for side.
I think 1/8 wont be a problem.
By the way, if horsepower is above stock, I delete the rubber leaf pads & add a steel shim if needed. I think it reduces the chance of wheel hop. I watched a Camaro on the chassis dyno & saw the axle rocking on the leaf quite a bit.

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67 RS 327 original owner. 1965 Lola T-70
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post #15 of 18 (permalink) Old Nov 10th, 19, 07:27 PM Thread Starter
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Re: Pinion Angle Help

Thanks David! Appreciate the help.
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