Pinion Angle and Lowering

[Dean85GT]

Recently I installed a new rear end in my car...Its an 8.8 with 4.10s. I went from totally stock suspension to Southside Machine Co lower control arms, lakewood 50/50 shocks, stock boxed upper arms, and ford racgin b springs. I think I have a problem with my pinion angle in that the car shakes and vibrates as soon as soon as I start moving kinda fast (4th and 5th). I was wondering if my pinion angle could be out because I lowered the car. Should I put my stock springs back in the car? Does anyone think that will allieviate the shakes...Thanks alot :SNSign:

 

[meangreen92lx]

Check the pinion angle first. You may need adjustable upper control arms to bring it back into specs. When I lowered my car and put in Steeda control arms, my trans started puking fluid and vibrated like crap. My trans was worn out and was masked by the loose factory bushings in the rear arms. 1 new T-5z later and it is smooth as silk. You may have the pinon angle off or may have a trans/driveshaft/rear axle problem. Good luck.

 

[302RollinHard]

You could also try clocking the drive shaft. That may help the situation as well.

 

[94GT347]

Recently I installed a new rear end in my car...Its an 8.8 with 4.10s. I went from totally stock suspension to Southside Machine Co lower control arms, lakewood 50/50 shocks, stock boxed upper arms, and ford racgin b springs. I think I have a problem with my pinion angle in that the car shakes and vibrates as soon as soon as I start moving kinda fast (4th and 5th). I was wondering if my pinion angle could be out because I lowered the car. Should I put my stock springs back in the car? Does anyone think that will allieviate the shakes...Thanks alot :SNSign:

Two u-joints combined are capable of forming compound angles. That means unless you have a bad u-joint, pinion angle is not your problem.
I would index the driveshaft on the pinion flange to fix your imbalance issue. You're supposed to mark the way the driveshaft is oriented to the flange before you remove it, that way you can put it back the way it was. I've forgotten to do that, and have had to do what you are about to do.
There's a good chance this will fix your problem.
Good luck!

 

[Dean85GT]

Two u-joints combined are capable of forming compound angles. That means unless you have a bad u-joint, pinion angle is not your problem.
I would index the driveshaft on the pinion flange to fix your imbalance issue. You're supposed to mark the way the driveshaft is oriented to the flange before you remove it, that way you can put it back the way it was. I've forgotten to do that, and have had to do what you are about to do.
There's a good chance this will fix your problem.
Good luck!

See there lies the problem...This is not the original rear end...so how would I know where to mark the driveshaft.

 

[94GT347]

See there lies the problem...This is not the original rear end...so how would I know where to mark the driveshaft.

Just index it 90* at a time until it smooths out.
PITA, but you gotta do it.

If the driveshaft is unknown to you too, it might need balancing. Look and make sure the balance weight is still on it up near the transmission yoke.

Try indexing the driveshaft first.

 

[Dean85GT]

So I just gotta rotate it 90* and see if it eventually smooths out....Well thanks I'll give it a go tomorrow...That beats pulling out my rear springs again thats for sure.

 

[Dean85GT]

Well I indexed the drive shaft today....I started at 90*..it smoothed out a tad but the high speed shake was still there. Next I put it at 180* then I developed a slight shake at 2500rpm in third and the bad high speed shake. Then I put it at 270* and its smooth until 2500 in third where it shakes a tiny bit..Then high speed is still basically the same. What should the pinion angle be at so if I can figure out how to measure what mine is, I know how off I am. Thanks

 

[jerryD]

you can get a angle meter/finder thing at sears. you just place it under the rear axle at the pinon/yoke area to get your reading. i think around -2* is ideal. others will have a better answer.

 

[jerryD]

something like this would work. you may need to look for one with a finer set of degree marks though.

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00939830000

 

[89white50]

i also do not think it has to do with the pinion. is this the stock driveshaft? if so i would rebalance or just the the aluminum FRPP one.

 

[jerryD]

also if your dogbone thingie is off of the rearend it may be part of the prob. it is supossed to help keep vibrations down. some folks it helps, others it doesn't. and sometimes just the gear change can do it too.

 

[Dean85GT]

What dogbone thingy?

 

[jerryD]

it sits under the carrier and looks like a dogbone kinda. think it is hard rubber.