Pinion angle question? - Chevy Impala SS Forum
 
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post #1 of 7 (permalink) Old 07-27-2017, 11:36 AM Thread Starter
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Pinion angle question?

Hey guy's, I've got a question for you guys that are way smarter than me. I've got a 95 SS I'm fixing up, I'm debating on extended rear trailing arms. I am lowering it with the Eibach pro kit and rebuilding the front suspension right now.

The question I have is, how much does lowering the car an inch decrease the pinion angle? And also how much would only changing to 1/2" extended LCA's increase it? Wonder if doing that would cancel each other out and be a good budget compromise? See what I'm thinking...
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post #2 of 7 (permalink) Old 07-27-2017, 12:50 PM
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Hey guy's, I've got a question for you guys that are way smarter than me. I've got a 95 SS I'm fixing up, I'm debating on extended rear trailing arms. I am lowering it with the Eibach pro kit and rebuilding the front suspension right now.

The question I have is, how much does lowering the car an inch decrease the pinion angle? And also how much would only changing to 1/2" extended LCA's increase it? Wonder if doing that would cancel each other out and be a good budget compromise? See what I'm thinking...

I've had two different brands of adjustable uppers, extended lowers on my car and never had to "fix" the pinion angle.

With that said, I'm currently on C3Fab extended/adjustable, and Hotchkis springs and my Ujoint area hits on the body where the rubber bumpstop once was (was ripped off when I had Sprints).
I'd be more concerned about this, than pinion angle (not to say it's not important).

I'm hoping to reduce the length of the uppers to bring my rear end closer to the front of the car, and lower the ujoints so it won't rub, all while allowing the rear springs to sit a bit more in line so they aren't "bending" and looking like they're going to fall out over one bad bump. I don't slow down for train tracks

96 DCM Caprice B4U
96 RMW Collector's Edition *Sold*


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post #3 of 7 (permalink) Old 07-27-2017, 02:00 PM Thread Starter
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Yeah, with extended uppers and lowers, the pinion angle would not have changed, but it would have changed some from the Hotchkis springs. By shorting your adjustable uppers, it would bring the pinion down some (increasing the angle) and bring the axle forward a little, just not sure how much or if the increased angle would be enough to cause vibrations. It may well put the angle back closer to what it was at stock height.

I'm thinking the same way with mine, by extending only the lowers, the pinion angle would increase and the axle would move back a little, and then the lowering springs will decrease the pinion angle some. Just not sure if it would be anywhere near equal amounts.
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post #4 of 7 (permalink) Old 07-27-2017, 09:24 PM
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Pinion Angle in and of itself is not very important, you need to also consider, engine/transmission angle, resulting driveshaft angle and planned usage (i.e. are you at the track with a ton of power or what).

I relocated my lower arm attach points and did a T56 with my relocated arms, I also changed out my spring perches and I spent a lot of time researching and aligning my pinion and transmission to get within some reasonable driveline angles.

I probably over did it but I have no vibration issues. Now if I could just figure out why this clutch fork over extends...

-Brian

'95 B4U LT1/T56 in Purple Pearl. 24x 355 with I believe most of the bolt-ons.
'63 C10 LT1/4L60E from B-Body. Rides like a Cadillac thanks to air bags.
'06 GTO LS2/T56 Torrid Red with CAI and Borla Cat-back thanks to the lady who rear ended me.
Still in Wichita.
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post #5 of 7 (permalink) Old 07-27-2017, 10:50 PM
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OP

Making spring and longer control arm changes will affect pinion angle....which is a component of correct DL angles.

You should use a $5 angle indicator on your engine/trans and rear yoke to measure BEFORE you change anything, then after you do measure again so you can make any, if needed, adjustments in either the tranny or pinon angle

\'96 BBB 383/T-56
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post #6 of 7 (permalink) Old 07-27-2017, 10:52 PM
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Quote:
Originally Posted by Sshockr View Post
. Now if I could just figure out why this clutch fork over extends...

-Brian
1. Install a pedal stop if you don't have one
2. If MC is adjustable, shorten pedal stroke

what bore size is the MC?

\'96 BBB 383/T-56
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post #7 of 7 (permalink) Old 07-28-2017, 05:12 PM
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I'll start a new thread after I get back in and double check my very recent clutch replacement. Tore the lip off the TOB on the 4th and put in another AZ special.

-Brian

'95 B4U LT1/T56 in Purple Pearl. 24x 355 with I believe most of the bolt-ons.
'63 C10 LT1/4L60E from B-Body. Rides like a Cadillac thanks to air bags.
'06 GTO LS2/T56 Torrid Red with CAI and Borla Cat-back thanks to the lady who rear ended me.
Still in Wichita.
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