[Rich.Wolfson]

Over the holidays I bought myself a present, the M-Performance Diff. I ordered it from GetBMWparts.com and service was great. Two weeks ago I put it in with no issues. It was 33-10-8-659-989 as that was the part listed but it turns out I should have ordered 33-10-8-659-987. I tried to do my homework before the order but sometimes....

When I hit 70MPH, the transmission says that there is an error. Further testing says that the rear diff ratio is not correct. <Damn>

I do not want to remove the diff so I have two questions?

1-What is the difference in the ratios? It seems that the one in there is for the M240i. I can live with a little more low end or top end if necessary. And,

2-Can I get the error coded out at the dealer? And what should I tell them so they a)don't lecture me. b)laugh or c)rip me off.

I really, REALLY don't want to remove and sell this diff. Any helpful insights appreciated. Tell me all is not lost.

///Rich

PS-I have iCarly but I don't suppose that will help at all.

[williesm]

That sucks!! But at least I'll learn for when I do it. Please keep post updated if you find out what's different

[P2]

GetBMW did not error check the part with your vehicle?

[Rich.Wolfson]

Originally Posted by P2

GetBMW did not error check the part with your vehicle?

Frankly I thought they did. But at this point it is what it is.

///Rich

[BEM-S4]

Originally Posted by Rich.Wolfson

Frankly I thought they did. But at this point it is what it is.

///Rich

Seems like they should replace it with the right one...

[Rich.Wolfson]

Originally Posted by BEM-S4

Seems like they should replace it with the right one...

First let me figure out what the actual difference is before I go there. And if I can code the warning out.

///Rich

[BEM-S4]

Originally Posted by Rich.Wolfson

First let me figure out what the actual difference is before I go there. And if I can code the warning out.

///Rich

One thing to keep in mind BMW does sometimes change part numbers. For example my BBK is the "old" version and the same thing now has a different number. Just an idea of something to look into.

[XutvJet]

Yeah, the issue is you've installed an M240i automatic diff with a 2.81 final drive into your M235i auto which has a 3.08 final drive. Now the automatic's TCU isn't happy about the discrepancy in the information.

I don't have an answer for you BUT I do know Diffsonline sells custom built diffs for BMWs including M235s and M240s AND they offer a 2.81 diff option for the M235. I would suggest calling them and asking how they are getting around this issue. I do know guys with 6MT M235s have installed 3.46 final drives to replace the 6MTs 3.08 final drive and no codes were thrown. Though the 6MT doesn't have a TCU.

https://diffsonline.com/bmw-f22-m235...l#.XGMcIVVKhaQ

[Rich.Wolfson]

Originally Posted by XutvJet

Yeah, the issue is you've installed an M240i automatic diff with a 2.81 final drive into your M235i auto which has a 3.08 final drive. Now the automatic's TCU isn't happy about the discrepancy in the information.

I don't have an answer for you BUT I do know Diffsonline sells custom built diffs for BMWs including M235s and M240s AND they offer a 2.81 diff option for the M235. I would suggest calling them and asking how they are getting around this issue. I do know guys with 6MT M235s have installed 3.46 final drives to replace the 6MTs 3.08 final drive and no codes were thrown. Though the 6MT doesn't have a TCU.

This is very helpful. I think I can live with a bit taller gear as I didn't notice it around town as the ZF probably has a low enough 1st gear for whatever I do. And a tiny bit better mileage on the high end might be nice. It's the same ZF in the M240i so there has to be a code. I'll call DiffsOnline and see what they say.

Now that I think of it, I was seeing the code at 70mph but it was probably just when it kicked into 8th. Hell, I wonder what would happen if I go past 70 in 6th? Hummmmmm.

Thanks again.

///Rich

[Poochie]

@XutvJet is correct. You ordered the wrong part and since you already installed it, your only recourse is to sell it back and purchase the correct LSD or go back open diff.

I've been down that road before with the part number discrepancies but the folks here was able to clarify it.

I know after spending close to $3,000 on the diff and it being the wrong part sucks big time but I wouldn't leave it on the vehicle due to possible damage it could cause to the transmission.

M Performance LSD models? 33108659987 vs 33107555610 https://www.2addicts.com/forums/show....php?t=1237605

[Rich.Wolfson]

Originally Posted by Poochie

@XutvJet is correct. You ordered the wrong part and since you already installed it, your only recourse is to sell it back and purchase a the correct LSD or go back open diff.

I am not sure that is the only recourse. I do have the open diff and can do the swap again, but...

Originally Posted by Poochie

@XutvJetI know after spending close to $3,000 on the diff and it being the wrong part sucks big time but I wouldn't leave it the vehicle due to possible damage it could cause to the transmission.

M Performance LSD models? 33108659987 vs 33107555610 https://www.2addicts.com/forums/show....php?t=1237605

I am not thinking that there could be damage. The ZF8 is solid. And in the lower gears I didn't even notice the difference which is not really a big difference at all. I don't track the car and although i do have some fun sometimes, it's my daily driver and I am not hard on it. But I cannot live with the warning once I get on the highway. But now at least I think I know what is triggering it.

In the lower gears, I am thinking only a watch could tell the difference.

I have to do some more research before I make a decision.

///Rich

[kivyee]

I don't believe having the diff with a different ratio will physically damage anything. The only thing unhappy will be the TCU as it is expecting a different RPM at the indicated speed. The only other concern would be the TCU going into limp mode but I'm not familiar enough with the BMW TCU to know if RPM mismatch is a trigger for it.

[Poochie]

Keep in mind that the MP LSD works in tandem with the brake-based E-diff and DSC which has a predetermined algorithm for the 240i's gear ratio.

Using a different final drive without altering the transmission's ECU set mapping might possible throw off the vehicle stability control and/or speedometer.

If you were working with a manual transmission, I would say you're fine but an auto tranny operation is tied directly to the ECU's logic. The fact that you're getting an MIL is telling the computer that something is not plausibility, which might have consequences you're not anticipating.

I hope it works out for you but I would do some solid research before I leave it as is. Good luck and keep us updated.

[Rich.Wolfson]

Originally Posted by Poochie

Keep in mind that the MP LSD works in tandem with the brake-based E-diff and DSC which has a predetermined algorithm for the 240i's gear ratio. ...

I hope it works out for you but I would do some solid research before I leave it as is. Good luck and keep us updated.

All correct but I have the M235i so I am not sure that is an issue. I am looking now at someone who can help code out the check in 8th gear for the diff ratio. If I can find someone local to help with that, I will try it. If not....

Anyone interested in a good deal on a M240i M-Sport Differential for a good price? It has only 200 miles on it. Send me a DM if you are.

///Rich

[Mason Hatcher]

I am reading this with interest, and have a dumb question and an observation.

1) Dumb Question- Other than to change the rear end ratio what is the point of changing out the rear end?

2) Observation-Doesn't changing the ratio at the rear end change the indicated speed on the speedometer?

[Rich.Wolfson]

Originally Posted by Mason Hatcher

I am reading this with interest, and have a dumb question and an observation.

1) Dumb Question- Other than to change the rear end ratio what is the point of changing out the rear end?

2) Observation-Doesn't changing the ratio at the rear end change the indicated speed on the speedometer?

Not a dumb question at all. My M235i came with an open differential and this is an M-Sport Limited Slip Differential. I was not looking to change the ratio and indeed this might not have been an issue if I had the manual transmission. But the ZF8 does all sorts of checks. Alpine Motorsports can do the coding remotely but I am not sure what I will do. I may just bite the bullet, get the right one, sell the one I have, and move on.

And yes, if you change the diff ratio, the indicated speed will change just like if you changed to tires with a different circumference. But that issue is easily coded. I think.

I wish I knew someone who wanted an M-Sport Diff for their M240i and this decision would be easier. I'd even arrange for the install if someone was in Northern NJ. For me, just a couple of hours work and a loss on the original that would be someone else's gain.

///Rich

[Rich.Wolfson]

Originally Posted by Rich.Wolfson

...
I wish I knew someone who wanted an M-Sport Diff for their M240i and this decision would be easier. I'd even arrange for the install if someone was in Northern NJ. For me, just a couple of hours work and a loss on the original that would be someone else's gain.

So I made the decision to get a replacement differential and it will arrive early next week. I was confident that the warning could be coded out and I could also have coded a correction for the speedometer. And there would not be any problem with the ZF8 either. But in the end, I want it to be right as I really love driving this car.

The install is not difficult, 2 hrs (If you've done one before), and hopefully someone can use the M240i Differential 33-10-8-659-989. I am willing to let it fo for a good price and if you're on the fence on getting an LSD, this will be a good deal for you. AND, if you are anywhere near northern NJ, I can arrange for the install as well for a great price.

So that is the end of this story. I hope.

///Rich

[williesm]

Who did your install in northern NJ?

[XutvJet]

Originally Posted by Rich.Wolfson

So I made the decision to get a replacement differential and it will arrive early next week. I was confident that the warning could be coded out and I could also have coded a correction for the speedometer. And there would not be any problem with the ZF8 either. But in the end, I want it to be right as I really love driving this car.

The install is not difficult, 2 hrs (If you've done one before), and hopefully someone can use the M240i Differential 33-10-8-659-989. I am willing to let it fo for a good price and if you're on the fence on getting an LSD, this will be a good deal for you. AND, if you are anywhere near northern NJ, I can arrange for the install as well for a great price.

So that is the end of this story. I hope.

///Rich

You should post this in the FS section and also a regional forum. I would think you could get back 60-70% of the cost on the part.

[Rich.Wolfson]

Originally Posted by williesm

Who did your install in northern NJ?

Eddie Tonono in Montclair.

///Rich

[m3driver999]

Hello,

*edit * You currently have the part 9987 3.08 which is for manual 235i (auto, too?), so TCU is seeing too many output shaft rpms, so it thinks it is slipping, but it is not; thought you could correct by taller tires..but tires 245 to 265 would be 2.5%, 3:08 to 2.81 is 9.5% *

Somewhat familiar with the topic, had it been a manual, no problems.
Likely the code the ZF auto is setting is a 'slip' code. It is seeing too many output shaft rpm's;
7th and 8th are overdrive.

TCU logic looks for 'too much rpm' = rationale high / slip or 'too little rpm' = rationale low

From prior research I'd done for 235i
215W 3.08 33107555610 33108659987 Man
215W 3.23 NA 33108659988 Man
215W 2.81 NA 33108659989 Auto
Though info I found has several models listed, not sure all of them are exact fit.

Your 215W 2.81 diff may be valuable for the 335d or 135i crowd; some 215W were welded diffs, which are more desirable than the bolt diff.

At any rate, good decision on your part to make it right; though a re-code or a 'black box' device to convert output speed sensor could do the trick, but can get more involved.

Perhaps check that the output speed sensor at AT is plugged in correctly?
Not sure if that gets disconnected at time of diff swap/output shaft.
But seems it is a 2.81 vs 3.08 issue

Seems you have Carly OBD, that would show the specific code and also output rpm; in 6th which is 1:1 during lockup, or also M6, engine rpm = output shaft rpm. Then 245-35-18 tire at 60mph turns about 840 revs.
Then some quick driving check gives the diff ratio. (output/wheel = diff)

Hope this helps,

Good luck,

[JVM2]

Hi Rich,
Is the LSD still available?
Thanks,
Joel V.