Swap 188mm auto pumpkin for 215mm? Diff cover options?

doublespaces

Administrator
Oct 18, 2016
7,055
AZ
So you were able to swap to a large pumpkin directly without changing any other parts? This is very interesting if so.
The pumpkins are functionally the same except for a few mm on the front. This is made up for if your drive shaft is telescopic(M4 shaft is not for example). The only other notable difference between them is the diff cover, this will vary from model to model and yes, you need the right one or you'll find yourself requiring the use of spacers and extended bolts because the distance to the subframe is not the same on all models which use this diff. Also, the Z4 diff has a weird pinion snout, I don't know wtf is going on with those cars but its entirely different. It may just be a euro thing actually.

EDIT:
@frontside0815 PM’d me that he has a European 135i which he said may have a slightly different driveline than the US. So confirmation from someone who has done the swap in the US would help provide confirmation.
Speaking of euro, based on this feedback there must be some differences with euro cars and not just the Z4, their diff pinion and driveshaft-end looks different. I was selling an LSD to someone over yonder and this ended up being the reason the sale did not go through. I'm told it may actually be a stronger design, but if it works for them, I can say it works for both, so long as you're using parts which match, USDM driveshaft with USDM differential.
 
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sirdaft1

Specialist
Nov 11, 2016
71
Chicago
The pumpkins are functionally the same except for a few mm on the front. This is made up for if your drive shaft is telescopic(M4 shaft is not for example). The only other notable difference between them is the diff cover, this will vary from model to model and yes, you need the right one or you'll find yourself requiring the use of spacers and extended bolts because the distance to the subframe is not the same on all models which use this diff. Also, the Z4 diff has a weird pinion snout, I don't know wtf is going on with those cars but its entirely different. It may just be a euro thing actually.

EDIT:


Speaking of euro, based on this feedback there must be some differences with euro cars and not just the Z4, their diff pinion and driveshaft-end looks different. I was selling an LSD to someone over yonder and this ended up being the reason the sale did not go through. I'm told it may actually be a stronger design, but if it works for them, I can say it works for both, so long as you're using parts which match, USDM driveshaft with USDM differential.
Perfect commentary. And FWIW @frontside0815 said his Euro 135i has a guibo at both ends of the driveshaft (transmission and diff). Suppose the more guibos the better in EU!
 
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jakkuh

New Member
Jan 6, 2019
1
redacted to not linespam :p
So hows the 188 to 215 swap holding up? I have a line on a large case master rebuilt MFactory differential for a really great price, but my car currently has the small casing. With that in mind I'm looking for some other peoples experiences with this kind of swap.
 

regbf99

Lurker
Nov 21, 2018
12
Bavaria
I have a 335i with the 215 diff and i also want to install the 650i cover.
Do i also have to remove 2 or 3 fins of the cover, so that the exhaust fits?
Because i saw a picture of a 335i witch didn't had removed the fins.
But that was a LCI with the 188 diff.

Is ther any 335i driver with the 215 diff and with the 650i diff cover, who can awnser my question?
 

doublespaces

Administrator
Oct 18, 2016
7,055
AZ
So hows the 188 to 215 swap holding up? I have a line on a large case master rebuilt MFactory differential for a really great price, but my car currently has the small casing. With that in mind I'm looking for some other peoples experiences with this kind of swap.
There really is no reason to switch to the large case, in fact I wish I kept the small one because there is more room for the exhaust. But its working fine, when you switch diffs the diff cover is often a different size which means you need to use spacers or longer bolts to connect to the subframe.
 

regbf99

Lurker
Nov 21, 2018
12
Bavaria
A longer bolt and a spacer is no problem, i already have them.
Only the fins are a big question.
Because my rear axle is comlitly disassembled, so i also can't measure.
 
Last edited:

doublespaces

Administrator
Oct 18, 2016
7,055
AZ
Now I answer this question by my own.
The 650i Diff Cover doesn`t fit with the OEM Exhaust at the 335i e92 with an 215 Diff.
But i did`t want to cut off the cooling fins so i worked the exhaust.
Nice job, glad to see people still know about this. Did you use the 15.5 mm spacer?
 
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