Author Topic: which gearbox? (Read 3765 times)

spike318is · « **on:** May 03, 2011, 08:44:04 AM »

ok so a quarter way through a 1000 mile trip to a car rally in Killarney County Kerry in the south of Ireland my gearbox give up the ghost on me, i've owned the 90 e30 318is for 3 years now and it has always had a noisy gearbox espically in 5th gear but i always put this down to the diff which is a lsd from a 325is (fitted by a previous owner so not sure and the tag is missing) which was not great but locked up fine and a short shift lever which had no rubber bush between it and the connecting rod (causing vibration through the gear stick). i believe the lsd put extra strain on the gearbox causing it to fail. there is a loud knocking sound and there is oil being forced out the output shaft so there is obviously a bearing gone inside the box. what i want to know is what gearbox should i be looking for as a good replacement or even upgrade, for example will any 4 cylinder e30 or e36 bmw gearbox fit and if so what would the best ratio box be to start looking for.
many thanks
Cathal

DesktopDave · « **Reply #1 on:** May 04, 2011, 07:02:36 AM »

Any late model Getrag 240 will work, of course, but there aren't a lot of M42's running around. I'm pretty sure the M40 and M42 are identical except for heads, that's where I'd look.

Not sure if you had the early '84-'85 M10 318i over the pond...similar G240 'box but that model has a thinner input shaft, so that's out. I'll bet the later ZF from an e36 will work as well, but I haven't heard of anyone installing one in an e30.

I'm told the common Getrag 260 will work too (m20), but the six-cyl gearboxes are tilted slightly differently. Your shifter will point in a slightly different direction and you'll have to adjust the length of the drive shaft with that center nut.

MikeDE · « **Reply #2 on:** May 06, 2011, 05:33:12 PM »

If you use an M40 box, you HAVE to use the M40 driveshaft. The output yoke on the M40 box is shallower, the driveshaft is thereore a bit longer. Also keep in mind that the M40 driveshaft is noticeably skinnier.

spike318is · « **Reply #3 on:** May 06, 2011, 06:53:50 PM »

best 2 stay with a e30 318is box then?

spike318is · « **Reply #4 on:** May 08, 2011, 08:08:31 AM »

looks like i'm going to go for the m40 box. Cant find a m42. I've been told that the output flange is not the same. Does this mean i'll have to use a m40 prop shaft. By prop i mean the drive shaft from gearbox to diff.

DesktopDave · « **Reply #5 on:** May 08, 2011, 09:06:57 PM »

I wonder if you can re-use the output yoke from the M42 'box?

This thread shows that the output yoke is different:
http://www.m42club.com/forums/showthread.php?t=9583

Maybe it's the only difference? I'm way out on a limb here, but I'd definitely try it. You need a thin-walled socket & an impact driver to get that out though.

spike318is · « **Reply #6 on:** May 09, 2011, 11:17:32 AM »

i was thinkin the same myself dave. Have not got round to taking my box out yet, was waiting until i got a box sourced for it. Does anyone know if an e36 m42 box work?

DesktopDave · « **Reply #7 on:** May 09, 2011, 05:23:19 PM »

They're different transmissions, but supposedly a direct fit. The e36 box is said to be stronger too, I've heard stories about stroker builds used with the newer box.

None of this is firsthand though, YMMV...I hope you find a more definitive answer.