Hi Guys,
My Bw rear is whining during float (not accel or decel). Do you guys know what causes this? It has 120,000miles on it and fluid was changed 15,000miles ago (Gm additive added as well).
Thanks for the help!

 

anyone?

 

`are you sure its not wheel bearings ???
although the 9 bolt can get a little noisy when the bearings are worn out
1 check and make sure its not the wheel bearings
2 if not bearings then the centre needs to be pulled new bearings installed and ring and pinion re lapped

 

What oil type and weight are you using?

 

Hmm, don't really remember. Whatever the dealer gave me. I'll go check, still have some left over...
All it says is GM rear axle lubricant. On the back it says it's for standard and posi rearends. I added the additive as well. I'm thinking that it may be the wheel bearings.

 

A wheel bearing wont whine...maybe a pinion bearing or the gearset, but I doubt an axle bearing would/could whine....grumble maybe.

Re-lap a gear set? Huh!?!!

If you want to save some money and diagnose it yourself....jack up the rear, (use stands for saftey) pull the tires off, disconect the drive shaft.

Now, turn the pinion yolk and have a feel. Does it feel gritty? Now go to each axle, do the same thing....just turn it by hand....

You will be able to narrow it down this way, but I'm bettin its pinion bearings.

 

Thanks for the input man. So, is the pinion bearing directly behind where the driveshaft meets the rearend? If so, is it accessible from the outside or from the inside.

 

Yes.

There are two, an inner and an outer. If they need to be replaced, replace them both....and no, the differential has to be disassembled to accomplish this.

 

How much does a full rebuild on a rear like this usually cost?
I'm thinking since they gotta pull it apart, that they might as well do it right.

 

Labor about 275.00
Bearings/crush sleeve/pinion seal 125.00 (use Timken only)
cleaner/sealer/locktite 50.00

 

1 is hard to diagnose noises over the net
wheel bearings CAN sound like a rear gone bad ...specially when the noise is there all the time
easy way to tell however if it is a bearing turn a corner IF the noise gets quieter (on the wheel with no weight on it) it will be a wheel bearing
1 re lap in a gear set
what do you do ?? stick new bearings in and bolt it all together without checking the wear pattern on the c/w and pinion ?????????????(called "lapping ") if so i would not recommend anyone take a car to you !

 

The noise is not there all the time. It sort of makes it way through around 80km/h and goes away around 90ish (slowly accelerating). If I give about 30% throttle or above, the noise goes away. Cruising at 80km/h or 120km/h yeilds the most noticable noise. It is getting louder as the days pass...and I don't even drive it much.

Next Tuesday, I'm bringing it in the the shop.
Do you guys think it may be the driveshaft?
I've also heard of bent output shafts on T5's causing the noise - but from inside the car, I had a buddy sit back there and he swears it's coming from the rear end somewhere.

 

I still say it's bearings. Might as well replace them all while it's apart.

Miles
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