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Discussion Starter #1
Hello All!

I recently put a diff from an '02 M5 into my 540i/6 and have noticed that it is slightly leaking from the front input seal (pinion) where the flange goes into the diff. It isn't a huge amount, maybe a quarter size in diameter overnight but I believe that it is dripping a bit more when being run.

I really should have replaced all of the seals prior to putting it in but excitment and a "want it now" attitude didn't see that through. So I have three questions:

A) Can the front (pinion) flange be extracted from the diff by simply unbolting it from the driveshaft? Or will I need to drop the exhaust and Center Support Bearing to back the driveshaft up a bit to get enough clearance to get the front out.

I REALLY do not want to have to drop the whole diff. as I will be working without a lift and by myself. The stupid diff was hard enough to get in and lined up and I'd prefer not to have to drop it again. The exhaust is a piece of cake to take out and I'd rather do that if I have to.

B) Does the diff have to be drained when I take the flange out or can I just let it seep out what it needs to when I take out the flange? I just put 2 quarts of RP fluid in it. It is really only $20 for two quarts of RP diff fluid, but $20 is $20...

C) Does anybody know the specific type of grease used in the joint b/t the flange and driveshaft? I had some from a friend that was BMW spcific but neithero f us know exactly what kind it is.

Thanks for the help!
 

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It's a pain in the $%^ job. Pay someone to do it. You need to buy a BMW $$$$ special tool to remove input flange and put a new seal. Yes, you need to drop the exhaust and drive shaft.
 

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Discussion Starter #4 (Edited)
Thanks for the reply azaytsev!

If I'm not mistaken the input flange shouldn't be that hard to remove. From what I've read you simply remove the locking ring to expose the nut holding the flange in, remove the nut, pop the flange out then extract the seal and reseat it using equal pressure all around the seal (a socket of similar diameter for example). Am I wrong?

I think you are thinking about the diff bushings which are fine and as yo usaid are a PITA. I'm looking at replacing number 14 below not the bushing holding the diff to the chassis: http://www.realoem.com/bmw/showparts.do?model=DE93&mospid=47592&btnr=33_1041&hg=33&fg=05
 

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No, I was talking about differential input flange number 11.
 

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Discussion Starter #6
I've looked into this a bit more and it looks like I will have to drop the exhaust and CSB on the driveshaft; no biggie.

The thing that I can't find too much info on however is the preload on the pinion nut. From what I can find it looks like these diffs use a crush collar b/t the bearings inside the diff. neck.

Does anybody have this specific value? On e36's I believe it is in the 200 ftlb range but I have no idea what it is for the M5 diff. I REALLY don't want to tighten it down too much and cruch that collar/bearing and have to pull the whole thing apart. Any other tips for this? Mark the nut and shaft to line up later? Count the thread? Preload adjustments, etc?

Again I REALLY appreciate the help guys!
 

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Discussion Starter #8
Once again thank you, thank you, thank you!

I've been quoted $300 to fix it, you think that is a good price should I be overwhelmed by the TIS procedure?
 

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Once again thank you, thank you, thank you!

I've been quoted $300 to fix it, you think that is a good price should I be overwhelmed by the TIS procedure?
Get the TIS first and see what is involved and if you can do it yourself. $300 doesn't seem that bad for this job. I replaced both output shaft seals myself and most likely will pay someone to replace input shaft seal
 
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I replaced the front differential seal when I did the differential bushing replacement, as you might have seen in that link azaytsev posted. As others have stated, yes-you will have to remove the diff from the car to do this properly.

I would say that you will need to drain the fluid to do this. You will be putting the diff in a vertical position, resting on its rear cover-the fluid could either seep from the side flanges or come out of the vent hole at the top of the diff. You can try it without draining, but be prepared to clean up the possible mess.

I used the TIS procedures, and they are HIGHLY recommended. Download a copy and study it. Now as far as the special tools-no, they are not required and I didn't use them. The only special tools that I used to remove and reinstall the input flange was a small block of wood and a 2lb. hammer.

First of all, clean out all of the old grease that sits inside the input flange where the large nut is. Once that is done, take a spring loaded punch (a few bucks at Autozone) and PRECISELY mark a spot on the inner shaft of the differential, and then punch another spot exactly in line with the first on the nut itself. This will tell you precisely how far to tighten the nut during reinstallation so that you can get the preload on the pinion correct. Also, take a picture or a mental note of how many threads are visible over the top of the nut so that you can make sure you have the flange at the precise depth.

Next, take a pick and remove the lock ring/washer that sits around the nut. The nut is on there with a fairly substantial amount of torque, and isn't easy to get off by yourself. What I did was take a very strong piece of metal that would fit thru one of the holes on the input flange, and was long enough to brace itself against the body of the differential-this will keep the input flange from turning while you remove the nut. I then had to use a long breaker bar to remove the nut-it ain't easy, but you can do it by yourself.

The input flange will easily come off by lightly tapping the backside of the flange with the hammer, with a piece of wood in between if needed for protection. Get a seal puller, pull out the old seal being careful not to scrape the edge of the housing, then line up the new seal in the opening. I happened to have a large socket that was the perfect diameter of the new seal and was able to tap it in evenly. Take note how deep the old seal is in there-personally, I tapped the new seal just ever so slightly deeper so that the seal would sit on a new part of the flange for better sealing. You don't have to do it that way-its up to you.

Lightly tap the input flange back on with the hammer-once again it goes on pretty easily, so light taps are all that is needed. Once you get it on far enough to get the nut on, reinstall the nut and until you get it at the proper depth and get the punch marks you did earlier to line up exactly. Then reinstall a new lock ring/washer.

I probably didn't explain it too well, but it is a really easy job-you have to be very, very careful and precise during the procedure. The TIS says that if you reinstall the nut any further than it was originally set, the preload is shot and has to be reset-and that probably means a differential rebuild.

As far as grease-I asked the techs at the dealership and they said any heavy duty wheel bearing grease is fine. I purchased the Mobil 1 synthetic grease that comes in the silver can, and would be available at most any auto parts store. Don't be shy when regreasing the flange-pack as much as you possibly can in the driveshaft end and the input flange on the diff.

If you have any more questions, let me know and I will try to help.
 

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Discussion Starter #11 (Edited)
Get the TIS first and see what is involved and if you can do it yourself. $300 doesn't seem that bad for this job. I replaced both output shaft seals myself and most likely will pay someone to replace input shaft seal
I'm downloading it now thanks for the heads up! I'll look at the TIS and see what it says. Worst case I'll have my local Indy take care of it. Thanks again!


I replaced the front differential seal when I did the differential bushing replacement, as you might have seen in that link azaytsev posted. As others have stated, yes-you will have to remove the diff from the car to do this properly.

I would say that you will need to drain the fluid to do this. You will be putting the diff in a vertical position, resting on its rear cover-the fluid could either seep from the side flanges or come out of the vent hole at the top of the diff. You can try it without draining, but be prepared to clean up the possible mess.

I used the TIS procedures, and they are HIGHLY recommended. Download a copy and study it. Now as far as the special tools-no, they are not required and I didn't use them. The only special tools that I used to remove and reinstall the input flange was a small block of wood and a 2lb. hammer.

First of all, clean out all of the old grease that sits inside the input flange where the large nut is. Once that is done, take a spring loaded punch (a few bucks at Autozone) and PRECISELY mark a spot on the inner shaft of the differential, and then punch another spot exactly in line with the first on the nut itself. This will tell you precisely how far to tighten the nut during reinstallation so that you can get the preload on the pinion correct. Also, take a picture or a mental note of how many threads are visible over the top of the nut so that you can make sure you have the flange at the precise depth.

Next, take a pick and remove the lock ring/washer that sits around the nut. The nut is on there with a fairly substantial amount of torque, and isn't easy to get off by yourself. What I did was take a very strong piece of metal that would fit thru one of the holes on the input flange, and was long enough to brace itself against the body of the differential-this will keep the input flange from turning while you remove the nut. I then had to use a long breaker bar to remove the nut-it ain't easy, but you can do it by yourself.

The input flange will easily come off by lightly tapping the backside of the flange with the hammer, with a piece of wood in between if needed for protection. Get a seal puller, pull out the old seal being careful not to scrape the edge of the housing, then line up the new seal in the opening. I happened to have a large socket that was the perfect diameter of the new seal and was able to tap it in evenly. Take note how deep the old seal is in there-personally, I tapped the new seal just ever so slightly deeper so that the seal would sit on a new part of the flange for better sealing. You don't have to do it that way-its up to you.

Lightly tap the input flange back on with the hammer-once again it goes on pretty easily, so light taps are all that is needed. Once you get it on far enough to get the nut on, reinstall the nut and until you get it at the proper depth and get the punch marks you did earlier to line up exactly. Then reinstall a new lock ring/washer.

I probably didn't explain it too well, but it is a really easy job-you have to be very, very careful and precise during the procedure. The TIS says that if you reinstall the nut any further than it was originally set, the preload is shot and has to be reset-and that probably means a differential rebuild.

As far as grease-I asked the techs at the dealership and they said any heavy duty wheel bearing grease is fine. I purchased the Mobil 1 synthetic grease that comes in the silver can, and would be available at most any auto parts store. Don't be shy when regreasing the flange-pack as much as you possibly can in the driveshaft end and the input flange on the diff.

If you have any more questions, let me know and I will try to help.
...I owe you a few beers.

Honestly b/t your response and the TIS this IMO needs to be a sticky or at least linked to.

Everything you have said is pretty much EXACTLY what I was asking and concerned about! From researching everything it never seemed like that big of a job, but for some reason BMWs just have a way of "scaring" me with the details.

I will definately read up on the TIS and see what they say but between what you have said and what I anticipate the TIS to say I feel like I should be able to tackle this myself! Thanks for the generous note and for taking the time to put it together! I'm sure I won't be the only one who benefits from it.
 

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Exhaust has to come off for access to the driveshaft.
No need to remove the diff.

I've done this and it's not a difficult job but take care if you're on your own and removing a standard, untouched exhaust system, it's in one piece and rather heavy!
Secondly mark the nut carefully and clearly (in a way that solvents won't affect it), you need to align the marks up on refitting it all, you'll be glad they're clear.
Make sure the nut lockring it snug.
I'm sure it should not be staked in position (as it can be lose afterwards, I tried this and that's how I know!). It should just press in, relatively gently and grab the cylindrical surface, two 'ears' will form in the cutouts and it should stay put (remember, it's of no use if it rattles free). I'd welcome more thoughts regarding this lockring.

Have a look at a how-to by vantaam5 (iirc), he's shown it in great detail. Find a post by him and usually there's a link in his sig.

Hth.
 

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Hi Eric, I saw a posting you did on the M5 Board (4 years ago) about working on the differential and in it you mentioned the vent hole on the top of the diff. Mine is leaking from all seals slightly and has begun to leave a small drip on the floor. I read that if the vent hole gets clogged, pressure can cause this symptom.

Can you help point me to the vent hole to clean it? Is it accessible while the diff is in the car?

Jeff
 

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I replaced the front differential seal when I did the differential bushing replacement, as you might have seen in that link azaytsev posted. As others have stated, yes-you will have to remove the diff from the car to do this properly.

I would say that you will need to drain the fluid to do this. You will be putting the diff in a vertical position, resting on its rear cover-the fluid could either seep from the side flanges or come out of the vent hole at the top of the diff. You can try it without draining, but be prepared to clean up the possible mess.

I used the TIS procedures, and they are HIGHLY recommended. Download a copy and study it. Now as far as the special tools-no, they are not required and I didn't use them. The only special tools that I used to remove and reinstall the input flange was a small block of wood and a 2lb. hammer.

First of all, clean out all of the old grease that sits inside the input flange where the large nut is. Once that is done, take a spring loaded punch (a few bucks at Autozone) and PRECISELY mark a spot on the inner shaft of the differential, and then punch another spot exactly in line with the first on the nut itself. This will tell you precisely how far to tighten the nut during reinstallation so that you can get the preload on the pinion correct. Also, take a picture or a mental note of how many threads are visible over the top of the nut so that you can make sure you have the flange at the precise depth.

Next, take a pick and remove the lock ring/washer that sits around the nut. The nut is on there with a fairly substantial amount of torque, and isn't easy to get off by yourself. What I did was take a very strong piece of metal that would fit thru one of the holes on the input flange, and was long enough to brace itself against the body of the differential-this will keep the input flange from turning while you remove the nut. I then had to use a long breaker bar to remove the nut-it ain't easy, but you can do it by yourself.

The input flange will easily come off by lightly tapping the backside of the flange with the hammer, with a piece of wood in between if needed for protection. Get a seal puller, pull out the old seal being careful not to scrape the edge of the housing, then line up the new seal in the opening. I happened to have a large socket that was the perfect diameter of the new seal and was able to tap it in evenly. Take note how deep the old seal is in there-personally, I tapped the new seal just ever so slightly deeper so that the seal would sit on a new part of the flange for better sealing. You don't have to do it that way-its up to you.

Lightly tap the input flange back on with the hammer-once again it goes on pretty easily, so light taps are all that is needed. Once you get it on far enough to get the nut on, reinstall the nut and until you get it at the proper depth and get the punch marks you did earlier to line up exactly. Then reinstall a new lock ring/washer.

I probably didn't explain it too well, but it is a really easy job-you have to be very, very careful and precise during the procedure. The TIS says that if you reinstall the nut any further than it was originally set, the preload is shot and has to be reset-and that probably means a differential rebuild.

As far as grease-I asked the techs at the dealership and they said any heavy duty wheel bearing grease is fine. I purchased the Mobil 1 synthetic grease that comes in the silver can, and would be available at most any auto parts store. Don't be shy when regreasing the flange-pack as much as you possibly can in the driveshaft end and the input flange on the diff.

If you have any more questions, let me know and I will try to help.
Hi Eric!

Thanks for the fantastic info. Am planning to do this in a couple of weeks and I'm not sure about the markings on the nut and input shaft which you mention. Do you mind explaining this further?

Much appreciated,
Qamil
 

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Looks like I'm waking the dead on one of the best input seal posts I've seen :)

How far does the new input seal go? I didn't take note of how far the old one was pressed in. The new seal is sticking out just a _hair_ above being flush with the diff housing. I've diligently tried to push it in further with a rubber mallet and a block of wood. Part of me believes that it's the proper depth.

Should the face of the new seal sit flush with the diff housing? Should reinstalling the input shaft seat the seal in to the exact position it needs to be? Rather than force it, I figured I'd ask.

Thanks!
-dant
 

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Ok, think I figured it out. This is just to document my findings.

I found a witness / wear mark in the input shaft that shows a significant amount of brightness as compared to other areas. I drew a line on where the bottom of that mark would be. I sat the input shaft in to dry fit it and it lined up perfectly with the new seal and its placement, even protruded a hair above the diff housing.

It's also worth noting that the dust guard (#7) is actually attached to the wide tapered end of the input shaft - it does not float.


RealOEM.com - Online BMW Parts Catalog
 

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