i have an 87 TII with 44.8k miles.

it has a drive train vibration i cant place my finger on. it starts at about 30mph and sounds like an old school air plane engine....it does not shake the car or anything like that, and it does not affect driving at all...its just a weird noise/vibration that i cant figure out. (possibly the driveshaft where it meets the rear end?)

today i got under the car to look at it and see if anything was weird, i noticed a little gear oil leakage from the seal where the drive shaft enters the rear end. while i was under there i flushed and changed the rear gear oil with 75w-90 (with limited slip additive)..the drain plug magnet had some metallic sludge on it, but nothing bad.

after i changed the oil i left the car on jack stand's, started the car, put it in 2nd gear and let the drive train reach 40-45mph...i didn't hear any noise/vibration so i figured it was solved, and was probably the LSD.

i put the car on the ground, and took it for a drive around the block...the vibration/noise is still there.

anyone have any idea of what it could possibly be?

i have a feeling it needs a new u-joint, but before i buy a new drive shaft, id like to be closer to being sure it is the drive shaft.


it sounds like : BRRRRRRRRRRR...like if you roll your tounge when trying to speak Spanish...that's the best i can describe it.


thanks for any and all help guy's.

 

anyone?

does it sound like it could be the driveshaft?

 

get under there and wiggle the drive shaft, are the joints loose, if so that's the problem, if not I would look elsewhere.

 

what else could it be? it is for sure coming from the rear end, and sounds like its coming from the center of the rear, which is why i thought it was the diff.

ill get under there and check the shaft for loose joints sometime this week....dealing with being sick right now.

thanks.

 

My 86 NA made a noise like that after I first bought it. 30-40 mph it would hum and get quiet,hum get quiet. Changed the rear end fluid and auto trans fluid it still made the same noise.
After searching it sounded like bad u-joints. I worked on fixing other parts of the car and in time the noise went away.

 

finally got a chance to get under the car, the driveshaft didn't wiggle at all, i did notice a rear diff leak near the seal where the shatf bolts to the diff....so im assuming the seal behind that area inside the diff will need to be replaced.

i was also thinking about having my rear wheels re mounted, and balanced?

its not a HUGE vibration, its more like a slight "hmmmm" that you can slightly feel.

i guess the good part is that i did not buy a driveshaft yet, and am going to hold off on that, the bad part is now i have no idea what the source of the noise/hum is?

 

pinion seal is a pain. probably one of your wheels lost a counterweight.

 

i really hope its just a wheel or 2 needing to be rebalanced.

how common is a pinion seal failure? it doesnt leak all over the place, and hasnt left a drop of oil on the floor in the last week and a half my cars been sitting in the garage. i just noticed that there is a little oil in that area when i was under the car gutting the secondary cat.

 

Check the oil level in the Diff?

 

i changed the rear diff fluid 4-27-09, thinking that would solve the problem...but it hasn't.

the rear diff is full, and hasn't leaked any oil in the 1.5 weeks the car has been sitting in my garage.

 

does it happen when it is in under load or when moving at all?

 

it happens when the car is on the ground...starts from about 30mph and continues from there...it doesnt get louder, or harsher...it just sounds faster...the vibration gets faster with speed, not rpm.

i tried to recreate the noise/vibration while the rear end was off the ground...i put the car in gear, and brought the speed up to about 40-45mph, but didnt hear the noise/vibration.

starting to think its the wheels that need to be rebalanced, but if that doesnt work...what else could it be?

 

yeah if your back wheels were in the air spinning and heard nothing then you fronts may need re balancing.

try putting your front wheels on the back and do the same thing with the *** in the air.

 

Ahhhh! Please keep us updated! I'm having having the same exact problem, but I just got the car and couldn't be sure if I was just going crazy or what X-D
I'm glad it doesn't seem horridly serious... Kind of annoying though!

 

funny you say that, i just got back from doing that!

i put the front wheels on the rear, and took the car out for a ride....still the same problem. so my wheels and tires are fine.

so now im back to thinking the U-joint is binding (it didnt wiggle when i wiggled the driveshaft...so its not loose)

i should have dropped the shaft and checked for easy articulation of the U-joint.

 

just thinking like a mechanic lol, once you start fixing cars you learn all these weird diagnostic stuff

 

is there a exploded view anywhere of the S4 TII rear end?

im thinking if its not the driveshaft, it may be a bearing or something in the rear end.

 

i really want to solve this problem...its holding me back from starting to buy other stuff. i just dont want to start throwing money at the problem to find out i spent $1,000.00, when i could have spent $4.00 to fix this problem.

im trying to narrow the problem down, but nobody seems to know what to do.

 

decided im gonna throw a little money at this problem, without knowing what it is.

im going to locate a used driveshaft and swap them out to see what happens to the vibration/noise.

 

I got my problem fixed today, turned out to be the wheel bearing! Maybe I heard a different noise? Well, just wanted to let you know, good luck.

 

interesting, ill look into the wheel bearings too.

thanks man, glad you got yours fixed.

 

Wheel bearings will vibrate under a slight turn of the wheel. Grip I would take the driveshaft off and check it for any binding.

 

yes, thats the plan...i just need to find time to drop the exhaust and shaft.

hopefully next week.

 

grip which driveshaft are you running? i have a t2 driveshaft im not using currently you could put in for a test and see if it fixes yer problem. wheel bearings will make a constant humming and groaning regardless of whether the car is on the ground or in the air. this sounds more like yer driveshaft is out of balance

 

im using the stock S4 TII driveshaft.


if you want to loan me your TII driveshaft that would be awesome!