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Thread: Final drive noise :-(

  1. #1
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    Default Final drive noise :-(

    What many months ago seems from the driver seat to be a bad tire noise that amplified since than is in fact a noise source coming from the final drive (differential).

    After eliminating the tires, the wheels bearing and the rear disc protectors touching the discs as possible cause i than suspect drive shaft bearing (the central one) so we raised the car on the lift yesterday and run it at about 75 mph (80 km) in third speed, from under the car moving front to rear and listening with a long screw driver from place to place it was obvious that the hissing / groaning noise source was the final drive and

    I am glad because we finally pin point the noise source, but i am afraid of what the solution could be and could cost !

    Following this test on the lift it's difficult to say what within the final drive could be generate the noise (main central gear bearing ? Else ?). The picth of the noise is directly proportional to the speed of the car, no noise change for exemple if i put the foot on the clutch when driving, neither when i accelerate or decelarate abruptly.

    The three oil seals of the final drive was replace by the dealer at 265000 km 2 years ago the car as now 289000 km. The final drive start to leaks a bit few months before but the final drive oil level was always fine (never miss oil)

    What's your experience ? your comments ?

    Is it possible to rebuild the final drive ? or will i have to replace it by a used one ? Cost order

    My 535 is a manual one i don't know what is it's ratio used one could be rare, could 535 automatic or 525 final drive be an alternative ?

  2. #2
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    replacing it with a known used one is the simplest way to go about it. Should be able to puck one up on the cheap from ebay or a scrappers. 535 manuals are not rare at all so you should be in good shape.
    95 E34 530I V2.17
    ===========
    Those who make peaceful revolution impossible will make violent revolution inevitable.

    John F. Kennedy

  3. #3
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    Quote Originally Posted by 632 Regal
    replacing it with a known used one is the simplest way to go about it. Should be able to puck one up on the cheap from ebay or a scrappers. 535 manuals are not rare at all so you should be in good shape.

    Could this one http://cgi.ebay.ca/BMW-E32-E34-3-91-...QQcmdZViewItem be a replacement for mine, my VIN # Being .... KBF08148 ?

    According to the picture from http://www.realoem.com/bmw/showparts...04&hg=33&fg=05 my differential does not look like the 735 i one !!

    Will it fit under the car without holding brakets changes ??

    The limited slip version could be an improvement, but what about the effect of this final drive ratio change from 3.46 (mine) to 3.91 ?

  4. #4
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    Better acceleration, maybe even higher speed (since with the stocker you can't pull max revs in 5th anyway) ... higher rpms at crusing speeds on the highway.

    If my diff went, I would sure as hell go for a 3.91.

  5. #5
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    Quote Originally Posted by Claude
    Could this one http://cgi.ebay.ca/BMW-E32-E34-3-91-...QQcmdZViewItem be a replacement for mine, my VIN # Being .... KBF08148 ?

    According to the picture from http://www.realoem.com/bmw/showparts...04&hg=33&fg=05 my differential does not look like the 735 i one !!

    Will it fit under the car without holding brakets changes ??

    The limited slip version could be an improvement, but what about the effect of this final drive ratio change from 3.46 (mine) to 3.91 ?
    Dealer probably overtightened the pinion nut and put too much preload on the bearings. I've rebuilt a BMW diff, and they're not too bad at all, the hardest part is getting the bearing preload just right.

    E32 diffs will fit an E34 with no problems (direct bolt in), the only thing to watch out for is the pinion flange, as there were two sizes of those used (depends on motor/trans combination). If you get the wrong one, your driveshaft won't bolt up to it. You can swap the flange, but you risk screwing up the bearing preload.

    Going to 3.91 will make 1st gear very short, you'll probably be starting out in 2nd gear all the time with that diff. Fuel mileage will go down, acceleration will go up, top speed will remain the same or go down (depending on if you hit the rev limiter before the speed limiter with that gear).

  6. #6
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    Quote Originally Posted by Claude
    I am not tough at all for my car so my differential failure it's for sure not due to the way i drive it. As mentioned before my 3 oil seals have been change 2 years ago by a BMW dealer, tel me when you say "Dealer probably overtightened the pinion nut and put too much preload on the bearings" could they have done that mistake when they replaced the oil seals ?
    If they replaced the pinion seal (which they must have if they replaced three seals), then yes, they had to properly load the pinion bearings.

    Worth a trip back to the dealer?

    Dave M

    10/90 Build 525im, 630,000+km, Eibach/Sachs, Engine Rebuild
    *RIP Oskar the DOG *

  7. #7
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    Quote Originally Posted by icesoft
    Dealer probably overtightened the pinion nut and put too much preload on the bearings. I've rebuilt a BMW diff, and they're not too bad at all, the hardest part is getting the bearing preload just right.

    E32 diffs will fit an E34 with no problems (direct bolt in), the only thing to watch out for is the pinion flange, as there were two sizes of those used (depends on motor/trans combination). If you get the wrong one, your driveshaft won't bolt up to it. You can swap the flange, but you risk screwing up the bearing preload.

    Going to 3.91 will make 1st gear very short, you'll probably be starting out in 2nd gear all the time with that diff. Fuel mileage will go down, acceleration will go up, top speed will remain the same or go down (depending on if you hit the rev limiter before the speed limiter with that gear).
    I am not tough at all for my car so my differential failure it's for sure not due to the way i drive it. As mentioned before my 3 oil seals have been change 2 years ago by a BMW dealer, tel me when you say "Dealer probably overtightened the pinion nut and put too much preload on the bearings" could they have done that mistake when they replaced the oil seals ?

  8. #8
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    Quote Originally Posted by ahlem
    I have the 3.91 in my car and got 17.4 mpg today in 36 degree F temp at 70 mph. I was told the auto trans and M5 both had this ratio. I have gotten up to 21 mpg on the highway and hope to again once I figure out my AFM issue. I don't have to start in second and it goes pretty well on acceleration.
    With the 3.64 gear in my 535, 1st gear is pretty short, I couldn't imagine a 3.91. I already start in 2nd gear roughly 40% of the time. I average around 23 mpg (calculated, not OBC) with 80% highway driving at 65mph. It seems to be a pretty nice ratio (for me anyway), it came out of a 1/87 build 735i manual. A lot of it is how you drive it, I've found that 3 speeding tickets in under a year's time will slow you down a bit.

  9. #9
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    Too bad you can't pursue the dealer as its quite the coincidence that it went bad after some work.

    Anyhow, I don'y know the details, but the original LSD in mine has 330k. No issues, no noises, no nothin, so I'm not sure if one would consider the LSD a liability. I certainly wouldn't balk at another. I'd concern myself more with the state and ratio of the used one you find rather than the type (open/lsd).

    Good luck with it,

    Dave M

    10/90 Build 525im, 630,000+km, Eibach/Sachs, Engine Rebuild
    *RIP Oskar the DOG *

  10. #10
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    Quote Originally Posted by Dave M
    If they replaced the pinion seal (which they must have if they replaced three seals), then yes, they had to properly load the pinion bearings.

    Worth a trip back to the dealer?

    Dave M
    Brrr. /%?*&... too late, those seals was replace sept 05 (cost me 407$), noise started low late in 2006 and amplified during last summer, suspect center bearing, detected that this noise come from the differential last week, were now end 2007; the car as 289000 km; can't prove any thing, can't figure out the dealer will accept any responsability We learn some thing each day !

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