7.5 rear end bites the dust....maybe, IDK

[84cutlass383]

what certain speed does the "roaring" begin and stop? low? High? Any vibrations?

it starts around 45 50 mph area. its a roaring+vibrations. when i let off on the gas and get below that speed it stops.

At this point you may have to put it on jack stands and run it up to speed and see if you hear the noise. Sometimes applying the brakea helps here too. If you do have the noise, and a second person, use a stethoscope or length of hose to listen to various parts of the rear for where its loudest.

yesterday i got it up on my buddys lift and we got it up to around 50mph and it sounds like its coming from the driveshaft again. but what gets me is, i drove the car 30 miles with this going on and the ****er didnt let go. im going to get it rebalanced again and see what happens. i got a few leads on a few 8.5 but to much for me rite now.

 

[megaladon6]

Did you check the volume at both ends of the driveshaft? It may be possible for the pinion bearing or the trans tailshaft bearing to transmit the sound through the shaft. The only other thing i can think of is that the pinion angle is off, causing extra stress on the bearing.

 

[1980PontiacWagon]

Your tires might be out of balance...look to see if your missing a wheel weight.

 

[84cutlass383]

Your tires might be out of balance...look to see if your missing a wheel weight.

First thing i checked

Did you check the volume at both ends of the driveshaft? It may be possible for the pinion bearing or the trans tailshaft bearing to transmit the sound through the shaft. The only other thing i can think of is that the pinion angle is off, causing extra stress on the bearing.

i checked the pinon angle when i broke the first two shafts and it was good. the only thing i found this time is the yoke on the rear is off a bit and i mean a BIT. i gave up and took it to a shop, i knw they r gunna rape me but man im done with this freaking car, problems after problems. All this sh*t started from the rear seal on the trans leaking, so i changed the slip yoke...boom!! broke the OG shaft, ok i get another shaft...boom broke it again, now this sh*t. im so ****ing over this ****ing car!!!!! end of rant sorry

 

[85GPLef41]

Hope you find the cause! sounds like a driveshaft issue to me.. are the u-joints "clocked"?

 

[84cutlass383]

driveshaft checked good.....WTF can i check now!!!!!!!!!!

 

[pontiacgp]

I'd check the transmission mount next and if that checks out if the front pinion bearing is gone the seal normally leaks, it could be the rear pinion bearing you won't know that till you disassemble the rear end. If you can put the rear of the car up in the air on some axles stand and have some start the car up and bring to the speed where you have the vibration and take a look under the car to see you can see anything causing a vibration...

 

[Phoenyx]

I can't help much. But every 7.5 I've had crap (and it's been quite a few) made that sound for a couple moths before dieing.