Dumb Question Thread - No Flaming Allowed

[r4dr]

SAF-XJ and SAF-XJ+FM are two different BMW products, aren't they?

Bimmerworld's SAF-XJ product page says it's a recommended replacement for the +FM version in M-LSD cars, but seems like everyone's had a different experience with their diffs.

[ejendow]

so it’s really a gamble of saving $100 or getting a possible groan from the diff. decisions decisions

[IamFODI]

I'm sure people have had all kinds of experiences with aftermarket fluids (#carlife), but have people really reported issues with Castrol Syntrax Limited-Slip specifically? If so, have those issues gone away when swapping to OE-labeled fluid?

Friction modification is weird. Sometimes it doesn't require any FM-specific additives at all because that job is handled by other ingredients that were going to be in there anyway (most have multiple functions whether you want them to or not). As I said, the point is for the finished lubricant to end up with certain friction characteristics. I don't think the diff cares how you get there.

[Tbonem3]

I used syntrax and got groaning. I tried valvoline LS (so it def has additive) and got groaning. In my experience, with 2 different diffs, GL5 lubes with a standard amount of LS FM added, has not been enough to quiet them; only SAF XJ + FM booster or one time where I added (too much, I think) an aftermarket brand FM booster, did the trick. I drained that concoction I made and went back to OE BMW. I'm more concerned with too much slip than some noise on tight turns. I want the grip/lock.

[IamFODI]

I used syntrax and got groaning. I tried valvoline LS (so it def has additive) and got groaning. In my experience, with 2 different diffs, GL5 lubes with a standard amount of LS FM added, has not been enough to quiet them; only SAF XJ + FM booster or one time where I added (too much, I think) an aftermarket brand FM booster, did the trick. I drained that concoction I made and went back to OE BMW. I'm more concerned with too much slip than some noise on tight turns. I want the grip/lock.

Got it. Hard to argue with direct experience.

[Tbonem3]

But that doesn't mean someone else's diff won't be happy as evidenced by not all cars coming into the dealer back in 2000s to get FM booster!

I still think if you plan to drive a fair amount and keep the car, OE BMW from FCPeuro is the way to go as you'll do 2 or 3 changes and spread out the $140 fluid cost.

[DropTopKingM3]

2 dumb questions.

1) Do I need to code my 2001 M3 for a Zhp steering rack ?

2) What does an mk20 car mean ?

[Thoglan]

DropTopKingM3

1. No
2. Older DSC Module which cannot be coded for different rack ratio.

Some people note that there are issues with DSC with a quicker rack and the old module because it cannot be coded to correct the difference in ratio. Personally I have yet to experience it but I am a very gentle driver on the street majority of the time and haven't done too much testing with it. However, judging off the forums it seems DSC issues with a different rack and MK20 seem inevitable. Supposedly things like tyre size play into it as well. If you are certain you want a different rack I would say err on the side of caution and keep your old rack handy in case you have issues, or drive with DSC off. But IMHO after having done the swap it probably isn't worth the hassle, minimal difference in steering feel.

[DropTopKingM3]

Thoglan thank you! I’ll keep my original rack. If I don’t notice that much of a difference then I’ll just switch back to the M3 rack to avoid any problems.

I read so many reviews stating that the yellow tag rack made such a difference on our cars. I guess it’s only for later model M3s.

[S3diment]

Doing the wheel bearing job and the 46mm is not behaving at all.

I’ve hit it with the impact wrench and no dice. Do I need to get the 4ft breaker bar?

[Tbonem3]

I used a massive 1/2 drive breaker bar 24'' long.

[S3diment]

I used a massive 1/2 drive breaker bar 24'' long.

Just got back from HF with a 1/2 25” breaker bar. Still no dice. Almost feels like I’m about to snap it.

[Tbonem3]

Soak it with penetrant? Did you undo the "crush" of the nut enough?

[jbfrancis3]

What kind of impact wrench are you using?

[S3diment]

Was using a 1/2” Milwaukee M12 Fuel Stubby. Ended up using the breaker bar with the tube from the jack.

i think it’s a straightforward DIY, except most of the stuff has never been removed so it’s a royal pain.