Pinon angle calculation

[El_Capitan]

Does anyone know or have a link to tell me how to set pinion angle correctly? Ever since I re-geared to 4:88's I've had a vibration/noise around 45 or so mph. Drive slower it's fine drive faster it's ok also. I thought it was the driveline itself, so I had a whole new unit built and balanced, still the same. I've experimented with different angles using different lift blocks/shackles. and made it slightly better but it still does it. I'm not sure how detrimental this issue is, but I am concerned that it could shake the pinion nut loose or damage the t-case..

Soo, please if anyone has dealt with this let me know what you did to fix it


I forgot to say that this is in no way a tire balance issue I've worked at a tire store for 15 years lol

 

[brinker88]

Do you have a lifted 1997 and down x-cab? If so, your problem is the carrier bearing. If not:

 

[El_Capitan]

It's a first gen SWB. So no carrier bearing, It has a double cardan rear shaft, and honestly it may have been wrong for years. The driveline probably just didn't spin fast enough to feel it. And to be more clear it doesn't shake under accel or decel, just has a vib/droaning noise around 45-50 mph, and I've read it could be the angles..

 

[brinker88]

Sounds like it could be inproperly setup gears or it could be a bad u-joint , which requires getting under the vehicle to check for excessive play...

 

[El_Capitan]

Hopefully not the whole rear shaft is brand new..

 

[brinker88]

I cant tell you dude. You''ll have to physically go out, get under the truck, and look for yourself.

 

[kcm1582]

Do you have a lifted 1997 and down x-cab? If so, your problem is the carrier bearing. If not:

Pinion angle and transmission angle should be the same. If its new since the re gear then I would suspect something in the rear end more than the driveshaft.

 

[El_Capitan]

All the joints are good, I guess I should have said that differently in my previous post. From what I understand if the angles are wrong all kinds of unwanted things can happen..

 

[El_Capitan]

Wouldn't that drawing be incorrect for CV (double cardan) style shafts??

 

[kcm1582]

That is true, but if the only thing that changed was that you put new gears in, that's where I would start looking first.

 

[Snoranger]

Pinion angle and transmission angle should be the same.

Nope... Not on a double cardan (DC from now on) shaft. Everything shown above is 100% correct for a driveshaft with a single U-joint on each end, but a DC is a whole new ballgame.

With a DC shaft you want the rear pinion to point directly at the output of the T-case.

 

[kcm1582]

Yup, I assumed it was a single u-joint shaft.

 

[El_Capitan]

I guess ill bust out the angle guage again.. I doubt its in the rear end though. Maybe a bent pinion flange I'll have check that..

 

[Snoranger]

It's a first gen SWB. So no carrier bearing, It has a double cardan rear shaft,

Yup, I assumed it was a single u-joint shaft.

I read his post instead of assuming.

 

[El_Capitan]

Nope... Not on a double cardan (DC from now on) shaft. Everything shown above is 100% correct for a driveshaft with a single U-joint on each end, but a DC is a whole new ballgame.

With a DC shaft you want the rear pinion to point directly at the output of the T-case.

I swear I've tried that too.. I'm starting to believe it's just my luck lol