E30 Replacement Diff

The time has come to do something about the noise from the back end of our 1990 320. I'm thinking about installing new wheel bearings and swapping in a reconditioned/low milage diff. Mine has about 130,000
miles on it. The noise is a whiring/whining increasing in pitch with road speed. It is a bit worse (almost grinding) when you accelerate from low revs (lots of torque load i assume) and also a bit worse when accelerating out of tight corners.
Does anyone know of a good source of reconditioned diffs in the UK? I think it's a 1:4.10 that i need. Thanks. -- Mark
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MarkS wrote:

Not sure I'd replace a diff on a whim and a recon will be
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MarkS wrote:

I'd take a good look at wheel bearings, center bearing and driveshaft before pulling a diff.
lj
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I think it is definitely in the back axel somewhere, as it is considerably louder if I drive without the back seat base installed. Don't think this would be the case if it were the centre bearing?
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I'd look at all those other bearings first and if I was sure it was the diff I'd consider redoing the bearings in it. Don't know how available a reconditioned unitmight be but I'm sure it would be expensive. There's a place her in Orlando that will rebuild the one you have provided it's not worn slap out.
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Hi, I think you're right, I'll certainly do the wheel bearings first. Do you know what's involved in replacing the bearings in the diff? Are they parts available through BMW dealers? I'll happily do it myself, I hadn't really considered that it was possible until you mentioned it. Thanks!
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IIRC, the proceeder for both is in the Haynes manual. But don't have one to hand to check.
--
*The man who fell into an upholstery machine is fully recovered.*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Thanks, I've got a Bentley and a Haynes so I'll check them after work.
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I would suggest that you not start tearing things apart until you are sure where the problem lies. Differentials can become very noisy without suffering catastrophic failure so you still have plenty of time to come up with the correct diagnosis. I drove my noisy '84 318i over 10,000 miles before I replaced the failing differential at 300,000 miles. If it is the differential you should be able to change the noise with the gas pedal. High throttle settings should produce more noise which I think you have already stated. It should also make a very different noise under engine braking than it does under accelleration. The noises should be most noticeable as you start off from a dead stop and be kind of a waa waa waa at very low speeds. Differential noises also tend to disappear into the background noise at higher speeds while wheel bearing noises tend to resonate the springs and become a 'low tone' at higher speeds. After you have the car jacked up and the drive shaft and axles disconnected, it will be very easy to turn the differential shafts by hand to see how rough it feels/sounds. I replaced mine with a $150 unit from a wrecking yard. At the time a rebuilt unit cost $1700 and a new one from BMW $3200. It was still performing perfectly 40,000 miles later when I hit some black ice on a freeway overpass in Montana and totalled the car. Rebuilding differentials requires special tools and skills and is not covered in any of the popular maintainance books so I wouldn't suggest that you attempt to do it yourself. If you decide to get one at a wrecking yard be sure to replace the seals before you install it. That will take a couple of hours and cost you $40. Be sure to measure how deep the axle seals are pressed into the housing before removing them because there is no shoulder to control their depth and it doesn't warn you about this in Bentley.
Good Luck Jack

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