Topic: SUPER VIBRATIONS!!! in 4th and 5th gear!!!! HELP

[binojames]

94 toy pickup  sas'ed,geared & locked and stacked cases  Rear diff is a High Pinion.   When i'm driving about 45-50 4th gear a vibration starts, and when there is no load on the driveline  (right before i have lett off the gass completely and when i have just started pressing the gas) it vibrates so bad i think something is going to blow up seriously it is that load.    What could it be. I was happening before i got the daul cases, then i put the cases in and still does it.   

I was thinking rear pinion angle coming out of the rear end is almost exactly straight so if there was alil bit of slop or of balance it might vibrate  (not much pinion angle was changed when cases installed) 
 
 That or a trany problem

[Duffil]

pinion angle, trans, rear wheel bearings, d-line out of phase, loose flange...

[binojames [OP]]

what do you mean by loose flange?  tighten the flange nut possible?

[Loosekannon]

 I had bad vibes and my d-saft bolt were loose. Friend of mine helping me put my tranny back didn't tighten the rear d-shaft bolts to t-case.  Said he did, can't trust anyone  And that cause the flage bolt on the t-case to come lose also. Another time I had that was when the d-shaft was to short and the slip joint was barlely together.
Haven't heard much good news about running a HP third in the rear, just my 

[twistedtoy92]

make sure if you took the drive line apart at the slip yoke you want to line the u joint yokes up when you slide it back together having a high pinion in the rear might be part of the problem as well
 

[46&2]

Haven't heard much good news about running a HP third in the rear, just my 

x2

I have heard that it is not a good idea.

[twistedtoy92]

X3

[SACD_Runner]

what kind of DL are you running? just a normal Double Cardan? If so look into getting a CV shaft made up, i had the same vibrations and i had one made and everything is all better.

[89toy]

did you break in the 3rd correctly and drain the fluid after 500 miles?  When I bought my truck, I am guessing that the previous owner did not do that.  I don't know exactly what happened to cause it (I had the same problem...not really on the gas or off the gas, but I could feel the vibration all the way to the trans...and everything from the tranny to the gears was tight).  I pulled the 3rd and found that I BADLY needed new gears.  I put new ones in and broke it in really carefully...hasn't made the noise or vibration since.  5.29 gears and it may have been the bearings being fried from not letting it cool off during break in.

[Hottrod81]

Have you checked for broken motor mounts?

[binojames [OP]]

I'll look into what you guys have said i appericate the help. I'm going to swap out my 3rd with my old 3rd that is broken in and if that is the problem i will see if my installed one needs gears or what.   if not i will throw it in the front!   thanks agian

[idacurt]

cv joint,drive shaft out of phase?

[Cheesemaker]

Co-worker just had a similar problem, it was the driveline itself.  The part of the driveline that slips (splined end) into the larger portion of driveline, had enough slop that was only felt at higher speeds!  It was in a 94/95 4-runner.  Put it in neutral and and climb under and push up on the driveline right at the spline/slip and it would move!  Bought a used one at a u-pullit and solved his problem.

Have you tried different speeds in the same gears?  Does it happen at the same gears no matter what speed your going!  Will it do it in 4 lo in the same gears?  If it does in 4-lo it may be your trans!





Most rear HP diffs fail due to lack of proper oiling!  I'd be checking the oil on that diff on a regular basis!

[79coyotefrg]

Hi Pinion in the rear 


how much lift on this truck??  how long is the rear shaft??   what is your pinion angle??     regular u joint on each end  or  cv on tcase end ??

[SACD_Runner]

Hi Pinion in the rear 


how much lift on this truck??  how long is the rear shaft??   what is your pinion angle??     regular u joint on each end  or  cv on tcase end ??

That what i asked, cause we all know it just needs a CV DL and all the noise and vibrations will go away. oh dont forget to throw that pinion angle up towards the t-case flange.

[~tc~]

Most rear HP diffs fail due to lack of proper oiling!  I'd be checking the oil on that diff on a regular basis!

Well, that, and the fact that they're approx 30% weaker due to running on the coast side of the gears...

[79coyotefrg]

That what i asked, cause we all know it just needs a CV DL and all the noise and vibrations will go away. oh dont forget to throw that pinion angle up towards the t-case flange.

whats weird  is  i dont run a cv  in the rear shaft  on my truck  and i have no vibrations at all  up to 75mph 

[SACD_Runner]

whats weird  is  i dont run a cv  in the rear shaft  on my truck  and i have no vibrations at all  up to 75mph 

How much/what kind of lift are you running. It's recomended that anyone running 5+" of lift should run one. getting a stock DC drivline to work sucks. Hit up Jesse at High Angle DL if any of you dont believe me. Just saying i had the same probs and i kept denying it untill i got one, put it on, and all my probs were gone.