in need some rear drive shaft info

[only 31s]

suburban rear shaft-i heard the pinion and t case are supposed to be equal but opposite angles-am i supposed to be setting the pinion 2 degrees lower [at park] to allow for the pinion to raise under load to meet my t case angle?- or is that only for a cv style shaft-I only have the oe style Thanks for any info-Rob

 

[trevmountain]

As far as I know for OE style you want your out put shaft on your t case and your pinion to be at the same plane. If you were to draw a line through your tcase and pinion they would make two parallel lines. Your pinion does not point up at the t case, this would be for a cv style shaft. If you are lifted the geometry of your ujoints gets compromised and you may get some vibrations. Just depends on how lifted. I personally have a CV style shaft and have my pinion set a degree or two below so that when under load it raises up a bit and points straight at the t case. I would assume it's the same deal with an OE set up as well.

If you go check out Hight Angle Drive line (Do a quick google search, can't remember the website) he has a whole bunch of drive shaft info on there.

 

[boz42]

suburban rear shaft-i heard the pinion and t case are supposed to be equal but opposite angles-am i supposed to be setting the pinion 2 degrees lower [at park] to allow for the pinion to raise under load to meet my t case angle?- or is that only for a cv style shaft-I only have the oe style Thanks for any info-Rob

You are correct. Equal but oppisite angles. Driveshaft angle should be set at ride hiegth. In other words were your axle will be when cruising. If you set your angle taking axle wrap into consideration you could have a vibration at freeway speeds. The rear axle will spend more time at regular ride position than it will loaded. Unless this is some extreme drag racing burb.

 

[496truck]

In a stock app, lets say the t-case points 8* down. You would want the pinion to point 7* up. U-joints can work within 1* of difference between each other without vibration. That 1* difference will account for spring wrap.

 

[only 31s]

Thanks guys

you guys have confirmed all my info thus far. Im writing because Ive done all the above and still get vibes -this is only lifted [spring lift] 2.5 with 3ich body-and ive gone over every other poss for vibes,my last attempt [fri] was point the pinion down 2 degrees and when at speed it should rise up and match my t case angle which is 4.5 -all the numbers seemed correct but my rig wouldnt even get to 30 now without heavy vibes- heres my set up so far 2.5 pinion-11dgree Dshaft-4.5 Tcase, am i crazy isnt this supposed to be a good set up- my biggest prob is i dont have the big gun to keep changing my shims it gets pricy around here-plus i HATE other people workin on my rig.

 

[chulisohombre]

the pinion should be turned slightly up torward the transfer case with a lift.the lift will turn the pinion slightly down and you would need a degree shim to get it pointed slightly up back torward a stock angle.sounds like either the u joint has something wrong with it or your driveshaft is bent or unbalenced.enen if the u joints are good it would vibe out once it gets up to speed if it has a good enough ding in it or something is bent.look at the yolks on both ends and also where the the driveshaft slip yolk for play and see if anything moves.it can be a few degrees off and still be good on angles for it not to have too much problems.i have 4 inch lift with a 4-5 degree shimmed zero rate with no vibes.so you should be somewhere in the ballpark with a 3-4 degree shim to point the pinion up slightly at the transfer case.

 

[only 31s]

i wish it was as easy as that

ive had it up before[ pinion]now im trying down ill prob have to go 1or 2 -degree shims -trial and error to get it right- just sucks to have to pay a guy to do it each time-my shaft has been balanced and no hits or weights coming off good yokes and shafts-Thanks anyways for your inputs-im just getting back into it again and its getting me very frustrated

 

[cooldad76]

Hey, I was just wondering if you have Automatic Locking Hubs or Manual Locking Hubs? I had the exact same problem. Heavy vibrations around 30 mph. I had the driveshaft balanced, changed out both u-joints at the yoke and at the rear axle, put in shims, and nothing helped. It about drove me crazy. My problem turned out to be the driver side front Automatic locking Hub, it would engage and vibrate the whole Blazer. Warn Manual locks solved my problems. May not be your problem but I Hope this helps!

 

[only 31s]

i wish

no. i have manuals--i def know its the shaft angle -just gonna have to sink some money into it---im thinkin about going to the local shaft shop to see if he will turn my shaft end to cv and give me a decent quote-Thanks guys

 

[K85 Octane]

you really shouldn't need a CV for 2.5" lift. I had that lift, and the PO dropped the T-case for some reason too. I put the T-case back to factory and found no vibrations afterwards. Even at 80mph.

Have you changed U joints and made sure it's balanced? Maybe the yoke on the axle is loose? What T-case do you have? If it's fixed yoke, check the bolts for that. If it's slip style, maybe you have problems with the splines.