z4 with m conversion

[mad2rass]

i have a 2004 z4 and i recently swap a m3 engine,gearbox and rear subframe with diff from a e46 into the z4..i would like to know if the z4m driveshaft would fit it?thanks

[DarkstarZero]

Wow thats crazy. If I were going to do that, I would have put the 4.2L V8 in there. That would be awesome.

Sorry, can't help you with the driveshaft.

[epbrown]

According to BMW it doesn't fit without modification, which is why the Z4M uses the transmission and driveshaft from the Z4 3.0si. According to numerous internet pundits that haven't tried it, it should fit.

[vachss]

Hmm... I knew that the Z4M rear clip (subframe/diff/suspension/axles/hubs/brakes/wheels) was a direct swap into the non-M Z4, but I didn't realize that the E46 M3 was the same. This dramatically broadens the field of donor vehicles for those of us who ever want to perform this swap.

[trsbmw]

Very cool.. So the gearbox from the e46 m3 fit without modification? If so, that settles the "m3 transmission doesn't fit the z4, therefore BMW didn't use it in the Z4M" debate...

[epbrown]

Originally Posted by trsbmw

Very cool.. So the gearbox from the e46 m3 fit without modification? If so, that settles the "m3 transmission doesn't fit the z4, therefore BMW didn't use it in the Z4M" debate...

Err, no. BMW's claim is the driveshaft doesn't fit and none of the post above claim that it does. And it's long been known the rear of an M3 would fit, Graeme Watson in the UK swapped one onto his supercharged pre-facelift Z4 in 2004 or 2005 when no one thought there'd be an M.

[trsbmw]

I dont understand what you are saying "err, no" to, to the only question I asked?? I said nothing about whether a driveshaft or rear end would fit..

The OP clearly states that the gearbox is in the car now,, so therefore your claim that "According to BMW it doesn't fit without modification, which is why the Z4M uses the transmission and driveshaft from the Z4 3.0si. " doesn't make sense. Why would the mis-fitment of a driveshaft prevent BMW from fitting a transmission that does fit?

[DarkstarZero]

Originally Posted by trsbmw

I dont understand what you are saying "err, no" to, to the only question I asked?? I said nothing about whether a driveshaft or rear end would fit..

The OP clearly states that the gearbox is in the car now,, so therefore your claim that "According to BMW it doesn't fit without modification, which is why the Z4M uses the transmission and driveshaft from the Z4 3.0si. " doesn't make sense. Why would the mis-fitment of a driveshaft prevent BMW from fitting a transmission that does fit?

I understand what you're saying, why didn't BMW use the M3 tranny and make a new driveshaft that fit? The answer is because BMW made the Z4M out of spare parts, not because they're cheap, but because they wouldn't be able to sell it if it cost more than the current M3. There were definitely compromises made between the engineers and sales gurus on this car.

[epbrown]

I don't get why this is such a hard concept to grasp. From a corporate perspective, the decision on whether or not to build a low-volume model like the M Coupe/Roadster comes down to cost per unit to build. The easiest way to keep such costs down is use the existing parts bin from the outgoing M3. The added cost of modifying the M3 parts to fit is not as insignificant as everyone keeps saying -it was a matter of make the car work without any additional tooling/development, or skip making it altogether.

Yes, any Bubba with a hacksaw and a blow torch will be able to "git'er done" - but Bubba's got none of the concerns of a multinational corporate entity. Fitting it was possible, but it wasn't practical from their perspective.

[trsbmw]

Originally Posted by epbrown

I don't get why this is such a hard concept to grasp. From a corporate perspective, the decision on whether or not to build a low-volume model like the M Coupe/Roadster comes down to cost per unit to build. The easiest way to keep such costs down is use the existing parts bin from the outgoing M3. The added cost of modifying the M3 parts to fit is not as insignificant as everyone keeps saying -it was a matter of make the car work without any additional tooling/development, or skip making it altogether.

Yes, any Bubba with a hacksaw and a blow torch will be able to "git'er done" - but Bubba's got none of the concerns of a multinational corporate entity. Fitting it was possible, but it wasn't practical from their perspective.

Just like BMW skimped on building the M3 GTS, right? It's not that I can't understand your "corporate descision making principles" lesson, it's just that BMW has not always been, and I believe, still not, a company that makes every decision based soley on practicality / profitability. I've said it before, and I'll say it again, saying "BMW said so" means nothing to me and should mean nothing to anyone with a lick of healthy skepticism unless there are verifiable sources that can be referenced...

[marcusfalden]

So does this mean I can install an M3 LSD into my 2007 Z4 3.0i with steptronic transmission? If so what year M3 do i need to find to get the LSD.