Fitted a LSD to my e85 Z4 3.0

Well.....you extrude a completely different conclusion from that than me.... but it's your car.

My car runs fine, no thumps or what. I find it hard to believe that a lsd always will make a thump, no matter what....
It would also mean that the thump comes from the inner diff, not the crown/pinion (as the normal diff doesn't have the thump, but exactly the same gears...)

And I certainly wouldn't take conclusions for a guy that never physically fitted the diff himself but had everything done.
The post form Mfactory could have something in it, but the centerbearing is still the same, so it is impossible to suddenly create a thump after install.
Also the centerbearing isn't hard at all to align. TIS has all the answers (there is no special alignment or pretention on the centerbearing needed with the e85 chassis...). (imho if you find it hard to align or pretention the centerbearing of a propshaft you have no place under the car....)

But still the thump can come from anywhere. A propshaft installed incorrectly, rear bushing installed incorrectly etc etc.
But that a lsd will automatically create a thump......bollocks.
There is only one way to find out: first of all measure the backlash! The correct way (than means getting a competent mechanic that knows what he's doing). Really, it's a 15 min job! Thàts why it should be done always when installing a car. That 15 minutes really pays off when you do have a problem (like now). That's why it's in the manual I guess.

If the driveshaft was installed incorrectly....oh boy how much else could they have fucked up.....Now you don't know if it's the diff or any of the other 50 parts on the outside that they had their hands on.
 
GuidoK said:
....My car runs fine, no thumps or what. I find it hard to believe that a lsd always will make a thump, no matter what....

....But still the thump can come from anywhere. A propshaft installed incorrectly, rear bushing installed incorrectly etc etc.
But that a lsd will automatically create a thump......bollocks.
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Yep, I have a Quaife, same as Guido - no thumps - Machine Monkey and Yorkie Z have both installed MFactory diffs and neither of those have reported anything like that
 
Actually the driveshaft was installed by an employee not the shop owner. A young guy who is apparently mistake-prone.

The lsd in the diff was installed by the shop owner who is known for his work with diffs. Also he installed another two lsd's in the same week as i mentioned on another two cars. I cannot imagine that he could be a specialized diff mechanic and not know how to measure the backlash in all three cars.

I am not disagreeing with you actually, on the other hand i too would like not to have the thump and that is actually why i posted here also, even though after reading quite a bit on the net, i saw that it is not something uncommon.

I will make a visit to have the backlash checked.
 
Do you have anywhere where you could get the car lifted up and have a look underneath. Could find something else loose.
 
Yorkie Z said:
Do you have anywhere where you could get the car lifted up and have a look underneath. Could find something else loose.
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I went to another shop to get it looked at which resulted in fixing the major sound which was from the loose propshaft. I had them also check if anything else is loose. They did not find anything else.

Please read here also the comments from #143 and on.
http://www.e90post.com/forums/showthread.php?t=409095&page=7
I am just saying that apparently the chances are that many have it. If it is a problem due to the installation? Probably yes.
 
GuidoK said:
If it is backlash he has a very big problem as there is no real way to correct that.
The only way is to use circlips in different thicknesses...... try to get hold of those!!

If he has a backlash problem there might be a number of ways how the previous installer has made a faulty install (switched bearing races.... switched circlips... tampered with the alignment of the pinion etc etc... no way to tell).

Anyway it is the first thing you check when you install a diff. It's probably in the manual too with the correct tolerances.
I checked the size of my diff too with the crown gear offset and compared it to the original bmw diff prior to install to see if the manufacturer got his work done right (which was the case, after I torqued the bolts on the inner diff). I don't remember if I used a normal style micrometer for that or a height gage.
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The other way to adjust it is by using shim's between the gear and the flange it bolts into. If you had a head for maths it probably wouldn't take to long to work out the correct size. I'm crap at maths :rofl: so would try lots of different sizes. To be fair it's really easy to strip the thing down once your used to it..

image_zps9cf6a474.jpg
 
Fanatic said:
I will make a visit to have the backlash checked.
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Backlash is something you check to determine (or get a general idea) of the condition of the diff.
I don't know if you can check it on the car (I don't know if the rear lid goes off), or if the diff has to come off again.
So that's why you do it at the install.
You have the diff on the bench. You drain the oil (also sensible to do, change the oil), remove the 8 rear bolts, get out your micrometer clock on magnetic base, put it on the diff, wiggle the cogs, read the micrometer, and close the diff again with some silicone sealant. A very simple and fast procedure. Just as when you buy a second hand car, you also pull out the dipstick and look at the oil.
I'm not saying that he installed the diff wrong in the first place, but someone drove it, so something could have changed (wear etc).

Measuring the backlash only says something about the crown/pinion, not about the inner diff. To look at that, it has to be dismanteled completely (a lot of work).
But also have him look at the bushings, the hardy disc, propshaft etc etc. Too much backlash also generally produces a whine, but that could be dampened by the rubber bushings.
If he takes the diff off the car, maybe do an ink wear pattern analysis too?
If that dodgy mechanic decided to thighten the pinion shaft bolt too, it'll show up there :lol:

I haven't heard your thump, but if it's really there, it should be solved one way or another imho.

Fanatic said:
Please read here also the comments from #143 and on.
http://www.e90post.com/forums/showthread.php?t=409095&page=7
I am just saying that apparently the chances are that many have it. If it is a problem due to the installation? Probably yes.
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Remember that all is on a different car. The thump they talk about could just as easy come from the gearbox. That obviously also has play in the gears (sometimes can be felt when reversing the car, and it still rolls slowly backwards in neutral, shifting into 1 you can feel the play between the cogs when you slowly release the clutch.
That is the play between the reverse side and drive side of the teeth of the cogs. that is normal to a certain point.
But the guys from e90 post say they feel a thumb when shifting up... that's not normal.
So it depends on what you feel as a thump exactly.
 
Two Zs' and one 335 with the same exact thump. If this is not normal obviously the guy is doing something wrong. None of the three cars had the thump before the lsd swap.
 
When I first brought my Z I used to get a thump noise when I put it into first and driving coming out of first going into second. This was on the original diff.
When I fitted the LSD I also brought another diff (second hand) to fit it into. I noticed that when I striped down the original diff the backlash was at the top limit to what BMW recommend. When I fitted the LSD in the new diff and checked the backlash it's was at the lower limit, so nice and tight with not much play.

Anyway once it was fitted and I took it for a drive no more thumping noises. Year and a half in and the diff is still perfect..

The thing is the Lsd unit is a machined part, you only need one of the faces to have an extra 0.02 mm machined of the face and that could give you an extra 0.04 on the backlash. Trust me I've spent 16 years working in toolmaking machine shops, it doesn't take much.
 
So tou are saying that even if the backlash is within specs, the upper or lower limit of it could make a difference in the thump?
 
Fanatic said:
So tou are saying that even if the backlash is within specs, the upper or lower limit of it could make a difference in the thump?
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Yeah I found mine was at bottom limit and I've not had any problems.

If you look on here for "DIFF CLUNK " you will see quite a lot of stuff come up.

I wouldn't go panicking mate :thumbsup:
 
Babw said:
If anyone wants the ultimate diff for their Z4, I think I might have a contender for sale.
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Interesting diff with true ball bearings (instead of the normal needle bearings)
But the drive flanges for a 3.0i z4 differ from the 330i e46, so that is something to be looked at (especially because those drive flanges are custom!)
Z4 3.0i has a LK of 86mm, the e46 330i has a LK of 94mm (not all versions though). So maybe it doesn't fit.
Obviously a set of used 330i driveshafts are mostly cheap to find (£100/pair or so). But swapping out driveshafts can sometimes be a bit of a nightmare if they're stuck in the outer drive flange....
 
Yorkie Z said:
Fanatic said:
So tou are saying that even if the backlash is within specs, the upper or lower limit of it could make a difference in the thump?
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Yeah I found mine was at bottom limit and I've not had any problems.

If you look on here for "DIFF CLUNK " you will see quite a lot of stuff come up.

I wouldn't go panicking mate :thumbsup:
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Cheers!

This makes sense since its possible that the mechanic used the same spec for the backlash on all three cars and obviously it is on the loose side.
 
GuidoK said:
Babw said:
If anyone wants the ultimate diff for their Z4, I think I might have a contender for sale.
Click to expand...

Interesting diff with true ball bearings (instead of the normal needle bearings)
But the drive flanges for a 3.0i z4 differ from the 330i e46, so that is something to be looked at (especially because those drive flanges are custom!)
Z4 3.0i has a LK of 86mm, the e46 330i has a LK of 94mm (not all versions though). So maybe it doesn't fit.
Obviously a set of used 330i driveshafts are mostly cheap to find (£100/pair or so). But swapping out driveshafts can sometimes be a bit of a nightmare if they're stuck in the outer drive flange....
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I have written correspondence from Drexler confirming this will go straight into a Z4 as the internal splines are the same across the E85/E46 188 casing. Also no worries about any sticking flanges considering this is new.
 
Babw said:
I have written correspondence from Drexler confirming this will go straight into a Z4 as the internal splines are the same across the E85/E46 188 casing. Also no worries about any sticking flanges considering this is new.
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Right, so you use your own flange hubs. That's possible too.

Yorkie Z said:
On I side note my old E46 M3 used to really clunk, thing was like a bloody tractor...
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Backlash factory tolerance/play on the m3 210 diff is much bigger.
It's clutch based so it also will get much hotter (hence the more play needed). It also needs a larger multigrade scope oil (70w140 or something like that)
 
Fanatic said:
Yorkie Z said:
On I side note my old E46 M3 used to really clunk, thing was like a bloody tractor...
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Yes this is something I have heard
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Just a thought. Put the car in first gear and jack both wheels off the ground. Then turn them both ways by hand to check for a clunk.!!
 
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