update:dinan believes they know whats wrong with the 3.91 [Updated w/ Dinan reply]
Gustav addition in green below: Official reply from Dinan:
Answer from Steve D:
shipping ten per week
Noise is attributed to: (1) BMW gears and (2) not following BMW install procedure in TIS
"In addition we have seen the rear cover hit both the stock gears and Dinan gears. Dinan gears are larger, so ours hits worse than stock. We are now including clearanced rear covers with the diff."
"We got a cover with each of the 50 differential cores we purchased from BMW. They are already clearanced and on the shelf."
"...we have been using he same ring and pinion in the E46 M3 for 5 years."
The following is Steve Dinan's official response to Gustav
(I'm posting for Gustav because he's traveling in Germany at the moment)
Originally Posted by Steve Dinan
It looks like a further explanation is in order. TIS instructions and photos inserted.
I was asked to explain what we know about the situation on noisy E60 M5 differentials and that is what I did. Based on comments I feel further explanation is necessary.
We use both BMW gears and Dinan gears depending on availability. All of the ones that we have received back for noise so far have been BMW gears. That does not mean that BMW gears are no good it also doesn't mean that we will not get Dinan gears back with the same problem, it just means that all of the ones we have gotten back so far have been BMW gears. I have heard of an install causing a whine and BMW has a procedure with a warning on it (see BMW instructions below) that says that it might make noise if done incorrectly. We assume if BMW warns against this that they likely have a good reason. I have never had a clearance issue on an M3 rear cover either. The rear cover on the M5 is slightly revised by BMW from the M3 cover (see photos). The recess for the ring gear is smaller on the new M5 and M6 than it was on the M3 and the lip at the bottom of the recess is protruding more. It was pointed out by one of our dealers that this cover is very close and in some instances hits. When reviewing covers, we saw some witness marks on the covers from the stock gears. Our conclusion is that BMW cut it a little close. These are sand castings and as such are not very consistent parts.
There of course could be other causes for the noise as well but I do not know of any so I can't report them. These are just what our investigation has turned up.
Some people have posted that they are not sure if they hear anything or the noise is very small. As I stated before most of the gears are fine out of those delivered on the M5 and hundreds on the M3 we have had 13 warranty claims related to this issue, 5 are currently open. I think if there was a problem with Dinan gears, BMW gears, or our procedure, it would have come up years ago. It could just be that we got a bad batch of gears from BMW. Of the many 3:91 sets we sold in the last six months a small number were BMW gears, so not all of those have bean bad either. Every unit that has been returned has been inspected, a tooth pattern run and back lash checked. No assembly error has been found. I personally have inspected each one.
There were some concerns posted about warranty. The differentials have been and are still being replaced, parts and labor at our expense. It is always a complete unit and the new diff will come with a modified cover. The warranty applies to all Dinan differentials whether they have BMW or Dinan ring and pinions inside them. We treat them the same.
There were some concerns posted about catastrophic failure. In my experience a small whine does not result in a catastrophic failure.
just got a call back from dinan, so he tells me that he's having a meeting with technichal to adress the issues !! i didnt tell him i was a board member but he told me that there are a lot of the diffs coming back for the whining noise and when they open them all the gears are perfect,and how he thinks that the driveshafts are not being installed correctly or the bearing are not being repacked properly.he also said this was the problem with the e39's diff's when they were hot..i said so what about the one i blew up he said they just can't wait to get it back to see what the hell happened..
this was what i posted yesterday, well this morning i got a call from louise he says mr neil i have good news !! we had a meeting with tech and we think we have found out why the rear diffs are having problems !! thats great i say,what do you think it is,well apparently when installing the diff the dealer is supposed to just use the stock cover that works on the stock diff,but with the larger gears the pinion(gears) are touching/rubbing the top of the cover,causing a whine and also causing metal shavings to fall in to the diff..from now on they will send a modified cover for the diff along with the core..he was very optimistic that this was the problem..i should have a new diff and cover in about 2-3 weeks..he said to keep using this diff until then..
for anyone who is thinking/getting/ordering a diff i'd wait a couple of weeks till they can get a bunch of these covers and modify them so you don't have any complaints..ANDREW THIS MEANS YOU BUDDY !!
allow me to say this:througout all this dinan has been right there in contact with me keeping me informed on everything thats happening, im very impresssed with their service and customer service..the even called me before calling the dealer..i now know why they are a little pricier, you know what IMHO its well worth it..
again i asked about break in !!
THERE IS NO BREAK IN,JUST ABOUT 10 MILES(WHICH THE DEALER DOES AFTER INSTALL) TO GET THE FLUID AND SEALS ALL LUBED UP.. IF THE GEARS TURN, THEN THEY ARE IN LINE SO YOU REALLY DON'T HAVE TO BREAK IT IN !! 2ND TIME I ASKED HIM
Great news Neil. So what's the deal with the ones who already have the diff installed. and have the whine also? Did they specify they will put the new cover on the existing customer's diff's? Mine still whines slightly..
Thanks for the information, LI. I wonder whether Dinan intends to send the new covers to all who already have the diffs installed, or whether we need to request them.
nope !! if the diff is making noise its certainly rubbing, its causing metal shaving to fall in to the gears,you'd want them to replace the entire diff..which from what i got they have no problems doing so..
This is interesting. Probably means we all have a problem. Thanks
for the information!
If the gears were touching at all then it would indicate that some damage
has probably occured. I called Dinan but unfortunately had to leave a
message for Louis. I suspect he's probably got about 50 messages about
now. Seems to me that they need to replace the whole diff for everyone.