Removing differential

#1

I removed my differential but it wasn’t as easy as this instructional video.

http://www.youtube.com/watch?v=Br38lrQ_04Y

I had a heck of a time separating the differential mounting flange from the driveshaft. There are four bolts that hold the driveshaft to the mounting flange and couldn’t get all of them to budge, however in the process of persuading the separation process I was able to remove the differential while still attached to the drive shaft. The drive shaft separated at a joint upstream from there and the back half came out with the differential. Out of the car I was able to separate the mounting flange from the driveshaft

Questions:

  1. Have I created any problems with the driveshaft separation?
  2. Anyone know the part number for the nuts used to attached the mounting flange to the driveshaft
#2

If I were doing what you’re doing I’d call a BMW Club Technical Rep listed in Roundel (if a BMW Club member)… Or just contact Ireland Engineering for the part numbers. I also understand Bimmerworld is involved in SpecE30 and if you’re NorCal, Valley MotorSports is offering help on these questions.

#3

I think that those are just hardened 10mmX1.5 nuts. IIRC correctly Bentley has a torque spec for 8.8 and 10.9 grade driveshaft bolts. That assumes that the front of the driveshaft is the same as the rear of the driveshaft, because it’s the front that I recall.

We have a hardware store next door. I just bought you 4 of the nuts, 8.8 grade. I’ll bring them by your office on my way home. Merry Christmas.

#4

rackeu wrote:

[quote]Questions:

  1. Have I created any problems with the driveshaft separation?
  2. Anyone know the part number for the nuts used to attached the mounting flange to the driveshaft[/quote]

Realoem.com has a good online parts catalog with diagrams.

  1. If you don’t get the DS lined back up the way it came apart, you will likely have vibration issues. I don’t have a good solution for you on that one.

  2. Those nuts are 07-12-9-964-672. $0.50 each at pelican parts. They are actually slightly oval shaped on the top threads so they lock on better. I have used nylock nuts in a pinch, but there isn’t a ton of extra thread there for the nylon part to bite onto the stud.

#5

Call Chris At Bimmerparts.com and he can send you exactly what you need…

#6

Thanks all, I heard from Jamie at Bimmerworld. The part number is 07 12 9 964 672. Only 38 cents but he recommends getting them locally to save on shipping. Nice of him to recommend.

Yes, it appears that the entire drive shaft is balanced as a unit and it will need to get it back together the way it was balanced or I run the risk of vibration. I have been all over it and absolutely no clues how it was mated. I guess it is a shot in the dark or…how can I approach it with a more reasonable chance of success.

Looking at both shafts it appears that 2 small “tabs” (I assume weights) were welded on the rear shaft. Nothing on the front. Could it be that only the rear shaft required balancing and the front was already balanced? Or is the rear tabs counterbalancing a issue with the front. Anyone know of these things?

#7

rackeu wrote:

[quote]Thanks all, I heard from Jamie at Bimmerworld. The part number is 07 12 9 964 672. Only 38 cents but he recommends getting them locally to save on shipping. Nice of him to recommend.

Yes, it appears that the entire drive shaft is balanced as a unit and it will need to get it back together the way it was balanced or I run the risk of vibration. I have been all over it and absolutely no clues how it was mated. I guess it is a shot in the dark or…how can I approach it with a more reasonable chance of success.

Looking at both shafts it appears that 2 small “tabs” (I assume weights) were welded on the rear shaft. Nothing on the front. Could it be that only the rear shaft required balancing and the front was already balanced? Or is the rear tabs counterbalancing a issue with the front. Anyone know of these things?[/quote]

Your nuts are on your desk.

Don’t know what to tell you re. the driveshaft going back on the same way. I hit mine with spraypaint when I separated it from the tranny. Then I put it back on without paying attention to the barely visible paint. I’m gonna make a swag and say that the “put it on the same way it came off” is more a center bearing issue then an endpoint (diff and tranny) issue. I’m dubious that the driveshaft was balanced with the diff and tranny already connected to it. If that was the case, how would a person ever replace a drive shaft?

#8

Thank you Ranger, I appreciate it very much.

#9

The drive shaft is made up of two pieces. The front piece attaches to the transmission and goes through the center support bearing. The front piece mates to the rear piece after the center support bearing and the rear piece then connects to the differential. It is at this pont between the front and rear piece that I have it seperated.

I had expected the rear piece to seperate from the differential but it did not, removing the differential took the rear drive shaft piece with it. I have no clue how it was matched up between the front and rear drive shaft pieces.

#10

Al, unless they have been erased with age, there should be 2 white dots on each section of the driveshaft. Line up the dots and put the sections together. The driveshaft will be back to it’s original position. Hope they are still there…:slight_smile:

#11

IAP wrote:

That’s good info.

Failing that, there has to be scrape marks or something such that if you look really close you can figure how it was mated.

Forensic auto repair.

#12

The white dots were there if the center support was ever replaced…that is something you might want to look at, is you center support in good shape? The only other thing is that the ujoints are usually “lined up” meaning the yokes are oriented the same.

Be sure to put anti sieze on both the mounting flanges (driveshaft, diff) to avoid this problem again. Generally you see it more up in the north east where they have rust welded together…

Al

ps, get you nuts off the desk, that aint sanitary

#13

FARTBREF wrote:

[quote]The white dots were there if the center support was ever replaced…that is something you might want to look at, is you center support in good shape? The only other thing is that the ujoints are usually “lined up” meaning the yokes are oriented the same.

Be sure to put anti sieze on both the mounting flanges (driveshaft, diff) to avoid this problem again. Generally you see it more up in the north east where they have rust welded together…

Al

ps, get you nuts off the desk, that aint sanitary[/quote]

I have one white dot but still looking for another. From your answer this means that the center support bearing was replaced and I should be able to find another but damned if I can. I will look again later today with a fresh set of eyes.

Yes I understand that the car is originally from the northeast (it was JPs old car).

How does one check a center support bearing? It looks good, no obvious gaps although it does deflect some in all directions by articulating at the yoke.

You are correct, unsanitary and damn cold too

#14

Halleluiah, found the second white dot. :woohoo:

Moving forward,thanks all.