Pinion angle adjustments question...

[fdjizm]

So I adjusted my pinion angle this weekend, it took my "80mph harlem shake" to about 95mph, so I think I am heading in the right direction.

I have what I believe to be -1.5 on the pinion angle, I was aiming for -2 but didn't want to push it as I didn't know the effects yet.

I had the car up on just ramps in the rear since it doesn't matter if it's level or not because I am just measuring a difference between the trans flange and the pinion flange.

Oh yes.. the question.. lol

Should you adjust your pinion angle while sitting in the car? having someone tell you where the gauge is at?
I adjusted mine with just the weight of the car, I imagine the pinion angle changes a bit with my 220lb self in the driver seat. I imagine this can get complicated depending on how much gas there is in the tank as well.

???

 

[AnotherS197GT]

I adjusted mine with the suspension loaded. I ended up with -3 or -4 with my lcas in the middle hole of my relo brackets. No vibration or wheel hop. Stock driveshaft.


I don't remember how much gas was in it and my 170lb skinny ass wasn't in it.

 

[drive_55_not]

I've been working on getting rid of the vibration my rear picked up after rebuilding it. Those 4.56's/TrueTrac I had installed seem to have induced a driveline vibration I can't rid of.

I've the car on jack stands and the wheels of with my BIL( who's >> 220 ] holding the speed at 75-80 while I was adjusting the PHB and it didn't seem to make any difference.

For me -1 on the pinion and the rear shifted slightly to the drivers side got the vibrations livable.

.

 

[JesseW.]

something that helped mine out a lot, look that the differential flange and see if there are any holes drilled in the outside of it. line up the rear driveshaft weight with it. my car went from filling rattling to dead smooth just by clocking it 90 degrees and lining up these holes with the driveshaft weight.

 

[fdjizm]

^ i was wondering about that I had some clutch work done at a dealership and I'm not sure if they moved it around but there are quite a few holes in my pinion flange, so line the least holes up with the driveshaft weight?

I will see if I can get a pic of my pinion flange.
btw I have a shaftmasters 3.5", I had the 80mph vibe start after the 4.10's were installed even with the OEM shaft.
I like that the vibe is up higher now but if I can get it to move to the 100mph area I will probably never run into it exept when at the track for a second or two.

 

[JesseW.]

^ i was wondering about that I had some clutch work done at a dealership and I'm not sure if they moved it around but there are quite a few holes in my pinion flange, so line the least holes up with the driveshaft weight?

I will see if I can get a pic of my pinion flange.

mine had 4 holes, all near each other on one side. I did my best to put the driveshaft weight closest to the flange in the middle of those holes. I also have a 3.5" shaftmasters. it was unbareable until I clocked it right. its not in any instructions.... I did 145 mph in some half mile drag racing Saturday and it was no worse than the stock ds.

 

[DTony]

I had a slight vibration and traction issues when right around 0º. Over the winter I set it to -3º and the car never spins now and no vibration at all.

I adjusted mine on blocks (under the tires) so I could crawl under it with the weight on the suspension. I didnt have the car scaled but this method worked very well for me.

 

[PNR Welding]

I just set mine this weekend also. Im at -1.5 with solid lowers and poly upper with a solid bushing in the upper housing.

 

[fdjizm]

So the fact that my 220lb ass sits in the car doesn't bother my pinion angle?

if it's at -1.5 now when I sit in it doesn't go to say -3 or something?

 

[DTony]

So the fact that my 220lb ass sits in the car doesn't bother my pinion angle?

if it's at -1.5 now when I sit in it doesn't go to say -3 or something?

It will change a little, get someone close to your weight to sit in it while you adjust. I weigh 170 and just set mine without me in it.

 

[skwerl]

I have been adjusting mine with the car on jackstands and my floor jack under the rear end to load or unload the rear suspension. I set mine with the suspension loaded but to be honest there was no perceptible difference with the suspension unloaded. The entire purpose of the upper and lower control arms is to keep the rear end square as the suspension travels up and down.

Saying you need an extra 200 lbs in the driver's seat to set pinion angle is like saying you need to stand on one foot and balance an apple on your head in order to get an accurate measurement.

 

[one eyed willy]

I use ramps on all 4 tires with 4x4 blocks of wood under the ramps.

beleive it or not but the trans measurement will be off if the front tires are just hanging. the unsupported weight will make the motor/trans angle tilt up in the rear.

 

[fdjizm]

Yea my car was under load when I adjusted it, just minus 220lbs in the driver seat.
the suspension compresses when I sit in it, doesn't that clearly change the pinion angle?

 

[Mustang30212]

Subbing for the discussion....bad vibration from 70-80mph. Turns on and off like a switch.

Another question...can a poorly adjusted pinion angle eat up the pinion bearing? I switched to 4:10's last year and when we removed the factory 3:55's...the pinion gear pretty much fell out of the carrier.

RH

 

[fdjizm]

I just set the pinion angle to (what I believe to be -2)
this is -2 isn't it? lol

This is measured from the driver side.

Going to see where that puts the vibe now.

 

[skwerl]

If the trans and pinion were level with each other, would the pinion be pointing above or below the transmission?

 

[fdjizm]

it would be pointed slightly below I believe.

 

[skwerl]

If the trans and pinion were level with each other, would the pinion be pointing above or below the transmission?

it would be pointed slightly below I believe.

OK, can any of our pinion experts tell us if this is correct? I think it is, but I've heard it described so many different ways that I'm unsure.

 

[one eyed willy]

Easiest simplest way to help, made by Kelley at BMR.

 

[fdjizm]

^according to that I am at -2 and good to go!