Author Topic: M42 + Getrag 260? (Read 11784 times)

Hodge · « **on:** April 27, 2010, 10:06:27 PM »

I have been thinking really hard about this one and have searched the internet for a long time but can find no definite answers.

When the clutch is done on my E36 318, I would LOVE to swap the Getrag 250 for a Getrag 260 from an E30 so I can retain the very similar ratios, yet receive the much much much needed 5th gear overdrive that the Getrag 250 lacks.

I have seen on BF.c a guy did the swap in his E36 325i automatic to a Getrag 260 using the E36 manual driveshaft, E36 188mm diff, and assorted other parts. Of course, much like in E30 M50 swaps the tranny sits at a 10* tilt relative to the original box but I am not entirely worried about having to mod the shift selector rod and shifter carrier.

My problem is, according to RealOEM, the E36 325 and E36 318 show the same Getrag 250 tranny's but different part numbers. Should they not be identical? Do the M42 and M50's of the E36 era have the same bell housing bolt patterns? Did BMW make different length G250 transmissions for 318 and 325?

I saw that the 325 driveshaft is shorter than the 318 driveshaft, but my guess is that the length is due to the 318 differential being a 168mm diff housing compared to the larger 325's 188mm diff housing.

I want to be sure before I do anything, and of course, it will probably be a little while until I need a clutch, but I just want to get a head start.

I REALLY hate the 1:1 5th that the Getrag 250 has. Highway rpm is unnecessarily high.

If this doesn't work, I will have to change my diff ratio from 3.45 to something taller. I'm tired of the higher rpm on the interstate when going to and from autocrosses and other things. It is just so fatiguing to have the engine wound up for no good reason for hours on end.

Formulatwo · « **Reply #1 on:** April 28, 2010, 02:56:20 AM »

I'm not sure how it is for e36s, but for my e30, the 240 tranny was a lot smaller than the 260. The driveshaft was maybe 3 or 4 inches longer to compensate for that difference.

The differential wasn't that much different. Maybe a half an inch smaller on the small case.

Hodge · « **Reply #2 on:** April 28, 2010, 07:30:22 AM »

Interesting.

Also according to RealOEM, the 325's shaft is 1512mm long while the 318's shaft is 1561mm long. That would be around a few inches different. Maybe I am correct in assuming that the diff is that much smaller?

DesktopDave · « **Reply #3 on:** April 28, 2010, 02:04:07 PM »

When I swapped out my e30's 4.10 small-case for a 3.73 LSD medium-case, the diff input flange, output flanges and mounting holes were all pretty much the same. The medium case is definitely stouter...sticks out a bit more to the rear, and it's thicker but it fits in there the same way.

I'd guess that the 260 is mostly all of the difference, so the front half of the drive shaft will be the shorter part. It also wouldn't surprise me if that 260 shorter front half would fit into the 240 rear half you already have.

Hodge · « **Reply #4 on:** April 28, 2010, 08:44:14 PM »

This is for an E36 guys....

I have a Getrag 250 not a Getrag 240 that came in the E30's.

fabe · « **Reply #5 on:** May 10, 2010, 10:40:49 PM »

Just change the rear diff ratio to 3.15...
that's the setup i have in the E30, M42 + Getrag250 + 3.15 rear diff.
The engine pulls better with a 1:1 5th gear...

Hodge · « **Reply #6 on:** May 11, 2010, 08:00:30 PM »

Is it far more comfortable on the interstate? I am very tired of unnecessary RPM on the interstate.

BlueBMW · « **Reply #7 on:** May 11, 2010, 08:33:01 PM »

I installed a louder radio to help with the high rpm highway fatigue! :-p But I do agree it does seem excessive having a motor running at such high rpm on the highway. Are there any 6 speed gearboxes that fit our E30s or E36s?

Hodge · « **Reply #8 on:** May 11, 2010, 09:30:20 PM »

E36 can use euro 6-speeds IIRC.

Also my stereo can get really loud as well, but it really doesn't help, it makes thing worse if anything. More and more noise.

deekay · « **Reply #9 on:** May 11, 2010, 09:56:06 PM »

didn't ludiagsm do that with his m42 turbo car? i'd swear i read about that... check his thread.

NisseJ�rnet · « **Reply #10 on:** May 12, 2010, 07:32:17 PM »

Quote from: BlueBMW;92287

I installed a louder radio to help with the high rpm highway fatigue! :-p But I do agree it does seem excessive having a motor running at such high rpm on the highway. Are there any 6 speed gearboxes that fit our E30s or E36s?

Yes, M3 E36 3,2 and E46 for example

I have a 6 speed M3 3.2 gearbox on my M20 turbo.

BlueBMW · « **Reply #11 on:** May 12, 2010, 09:09:05 PM »

Before the E30 I drove an 08 Z4 so for the first month or so I kept trying to shift to the non-existent 6th gear.

Hodge · « **Reply #12 on:** May 13, 2010, 09:33:47 PM »

lol....I'm still going to explore options, but I will have to give Metric Mechanic a call and see what they'd charge to swap the ratios. It is an MM diff anyway.

I'd still rather have a taller 5th, but going to a 3.15 might be what I end up having to do.

fabe · « **Reply #13 on:** May 17, 2010, 01:59:43 AM »

on my E30 with M42+G250+3.15 final drive, it's doing about 105kph at 3000rpm.. It's pretty ok for me...
or instead of 'downgrading' to the E30's G260, go for the E36 M3 Evo's 6 speed manual or the E46 6speed manual... With the 6 speed box, can swap to a higher ratio final drive ie 3.91 which can give you much better acceleration while the extra cog retains the low RPM cruising speed..