1M differential

[Shooto82]

Guys need your help and advice. Took the car to dealer with 30,000km on it. Have the car since June 2012 first owner, so you could say it completed 5 years now. I track it 3 times max a year. The dealer called me saying they noticed a slight oil leak in the differential which I saw while I'm with them, and being a dealer they called few hours later saying I have to replace the diff completely for around $4k. My knowledge is very limited in this subject . Few questions I need to know and feel free to add more comments I should consider before changing.

- how will I know if it needs to be replaced ? I Never heard any noise while driving on and off track.
- OEM or after market diff I could look for considering the cost of both?
- is the 1M differential is a complete mechanical diff or active diff? Which brings me to the next question
- Going for after market, do I need to remap the ECU for collaboration with the new diff?

Thank you

[Tinsta]

Its a mechanical diff, I would get a 2nd opinion to be fair.

A slight leak with no additional noises shouldn't mean a full replacement. BMW state the oil is lifetime, but it can be drained and filled they sell the fluid along with a friction modifier to keep noises down etc.

I've got a e92 m3 differential on my 135 conversion (3.15 ratio), same as yours and it was noisy at first, street driving at 20mph, you could hear noises, didn't stop it working etc. I also track mine too. Swapped out the fluid and its quiet as a mouse now, was very surprised.

[nachob]

Originally Posted by Tinsta

Its a mechanical diff, I would get a 2nd opinion to be fair.

A slight leak with no additional noises shouldn't mean a full replacement. BMW state the oil is lifetime, but it can be drained and filled they sell the fluid along with a friction modifier to keep noises down etc.

I've got a e92 m3 differential on my 135 conversion (3.15 ratio), same as yours and it was noisy at first, street driving at 20mph, you could hear noises, didn't stop it working etc. I also track mine too. Swapped out the fluid and its quiet as a mouse now, was very surprised.

All true. Get second opinion but 1M diff was not lifetime full. It included 1200 mile break in change and I believe 40k interval. Almost all diffs eventually leak a little though 5 years is earlyish. Just change the diff oil every two years and too off yourself every year. It's easy. The bottles even have a little hose. You just take one plug out and shoot some in until it runs out and wipe. Easy peezy lemon squeezy. If the diff blows one day you can worry about it then but if you keep fluid in it will be fine for long time. E diff wouldn't work because the software is tied in somehow to traction control which is specific to the car. I don't think the M2 software would work on 1M but that's next level stuff. Finally the 1M diff is a full lock diff not a limited slip so make sure you have those concepts down. Limited slip diffs transfer a limited amount of power to other wheel. Full lock can transfer up to 100% power. People call these LSDs all the time and would hate for you to end up with a limited slip differential in a 1M. For example the optional diff for M235i was limited. I think it's about 20%

[Shooto82]

Originally Posted by nachob

All true. Get second opinion but 1M diff was not lifetime full. It included 1200 mile break in change and I believe 40k interval. Almost all diffs eventually leak a little though 5 years is earlyish. Just change the diff oil every two years and too off yourself every year. It's easy. The bottles even have a little hose. You just take one plug out and shoot some in until it runs out and wipe. Easy peezy lemon squeezy. If the diff blows one day you can worry about it then but if you keep fluid in it will be fine for long time. E diff wouldn't work because the software is tied in somehow to traction control which is specific to the car. I don't think the M2 software would work on 1M but that's next level stuff. Finally the 1M diff is a full lock diff not a limited slip so make sure you have those concepts down. Limited slip diffs transfer a limited amount of power to other wheel. Full lock can transfer up to 100% power. People call these LSDs all the time and would hate for you to end up with a limited slip differential in a 1M. For example the optional diff for M235i was limited. I think it's about 20%

So after market 1M diff doesn't need a ecu remap for collaboration or error codes?

Any recombination of after market diffs?

[Rikx1M]

I was talking with service advisor about a noise i had in rear end and he said 1M diffs are not repaired as they are sent back to Germany for troubleshooting. Standard procedure is to replace diffs. They did mine under warranty.

[blackmist222777]

Originally Posted by Rikx1M

I was talking with service advisor about a noise i had in rear end and he said 1M diffs are not repaired as they are sent back to Germany for troubleshooting. Standard procedure is to replace diffs. They did mine under warranty.

interesting... learn something new everyday

my question is, are they doing this with E9X diffs too? considering they are supposed to be the same.

[Rikx1M]

If its an M diff i would assume so

[CarJunkie]

I agree to just keep running it if it is working properly, as long as it is not dripping oil fast enough to cause a safety issue on track. If it is easy to see, wipe it clean every few days to see how much it is actually leaking. Does it ever actually drip where you park it?

[drwillb]

I would check where the leak is located. Rear cover: easy gasket. Output flanges: very doable repair with new gasket, not too $$$. Input flange: repairable as well.

Leaks are repairable on these diffs.

[LukeM3]

I'm with Tinsta and drwillb on this one. Firstly, leaks can be sealed. If it's coming from the cover it could be as easy as replacing a gasket or using a hi temp sealer (out of a tube). If it's leaking at the flanges it's just a straightforward seal that has to be removed and replaced. I guess BMW just goes ahead and replaces them, just like they do transmissions. It's quicker and more cost effective for them I guess. Try an indy shop, they ought to be able to tackle it. It's a messy job, but definitely doable. I wouldn't mess with the internals but leaks are easy. Just find where it's originating from.
Keep us posted on your find

[1&done]

They can leak where the input shaft is, M3/1M diffs are clutch style and fluid should be changed 30-40k based on what I was told. I just did mine at 20k. Tranny is lifetime, but people change that too.

If you go aftermarket "mechanical" is cheaper (wavetrac) lifetime warranty...there are benefits to both, clutch style is tunable but more maintenance.

Change the seals, and fluid and be done with. Wouldn't worry unless it's making noise and even that can be normal..depending on friction modifiers... LMAO at the stealership

[1&done]

Pic

[M3 Adjuster]

Originally Posted by Rikx1M

I was talking with service advisor about a noise i had in rear end and he said 1M diffs are not repaired as they are sent back to Germany for troubleshooting. Standard procedure is to replace diffs. They did mine under warranty.

sop for dealers these days because techs at dealers don't actually repair things any more because of their workflow which is set up to move boxes.


blown motor ? Remove and Replace

Bad auto/DCT gearbox ? remove and Replace

Bad Diff - remove and Replace

Rotors warped - remove and Replace

Nail in tire - remove and Replace ...



I agree with the others have an independent bmw or German dealer find the leak and actually repair it.

[Traf]

Originally Posted by nachob

All true. Get second opinion but 1M diff was not lifetime full. It included 1200 mile break in change and I believe 40k interval. Almost all diffs eventually leak a little though 5 years is earlyish. Just change the diff oil every two years and too off yourself every year. It's easy. The bottles even have a little hose. You just take one plug out and shoot some in until it runs out and wipe. Easy peezy lemon squeezy. If the diff blows one day you can worry about it then but if you keep fluid in it will be fine for long time. E diff wouldn't work because the software is tied in somehow to traction control which is specific to the car. I don't think the M2 software would work on 1M but that's next level stuff. Finally the 1M diff is a full lock diff not a limited slip so make sure you have those concepts down. Limited slip diffs transfer a limited amount of power to other wheel. Full lock can transfer up to 100% power. People call these LSDs all the time and would hate for you to end up with a limited slip differential in a 1M. For example the optional diff for M235i was limited. I think it's about 20%

What's wrong with a real limited slip diff ? If i was him i would repair the diff and upgrade to a ZF 45/45.

[nachob]

Originally Posted by Traf

What's wrong with a real limited slip diff ? If i was him i would repair the diff and upgrade to a ZF 45/45.

Limited slip ok but taking a step back. Going from 100% to less. That means that if inside wheel spins it will only be able to transfer 20 or 45% of power to wheel with traction. Our diff can transfer up to 100% power to other wheel. This discussion came up when I visited M Design in Garching when I was speaking with the head of M Sales in Europe and I called it a limited slip differential. I was enthusiastically corrected a couple of times myself and this was reiterated to me. Traction is already an issue on 1M. If you go limited slip you will probably end up with more wheel spin with traction control off or even more traction control interruption with it on.

[Traf]

Originally Posted by nachob

Limited slip ok but taking a step back. Going from 100% to less. That means that if inside wheel spins it will only be able to transfer 20 or 45% of power to wheel with traction. Our diff can transfer up to 100% power to other wheel. This discussion came up when I visited M Design in Garching when I was speaking with the head of M Sales in Europe and I called it a limited slip differential. I was enthusiastically corrected a couple of times myself and this was reiterated to me. Traction is already an issue on 1M. If you go limited slip you will probably end up with more wheel spin with traction control off or even more traction control interruption with it on.

That is true, the stock GKN viscolok can indeed lock 100%, but that is only the maximum amount of lock it can provide. Main issue is, which you might already know, the gkn viscolok is reactive thus not locking very often.
A wheel needs to be spinning for it to lock, it is good for daily driving because it is smooth in operation but thats it.
A 45/45 ZF diff will actually have a permanent 45% lock under load, plus you get lock under deceleration, which might not be a good thing for everybody tho.
All of this to say that a real LSD is better than our stock units, not as friendly, but better.
That is just my modest opinion of course.