Manaul trans. torque ratings

[Don S]

does anyone have data regarding the torque ratings of the various transmissions used in e28s? i am aware that some are stronger than others but are actual torque ratings available? It would seem that some of you guys are putting out about 350 ft*lbs. This is substantially more than than the trans. was intended to handle. Has anyone blown a trans.? As if so what recourse was taken to avert a repeat performance. Has anyone tried a trans. swap to a 6 speed (e.g. tremec T56)?

[Boru]

I tore a handful of teeth off the 3rd gear layshaft on my G260 with a good 20 psi romp but that's the only catastophic, torque induced failure I know of.
It all comes down to what the weakest link in the system is... hopefully it's traction.
I also have no idea what the condition of the transmission was before the failure.

[gol10dr1]

well i have an e34 and the tranny is really starting to shit the bed. i have had the rubo for a little over a year now. most of that year was spent at 5 psi but the last 2 months (1000 miles total maybe) were spent at 13 psi and 360+ rwhp. keep in mind that the transmission is OEM and has 232,000 miles on it but first gear is all but done and i am currently looking for a replacement tranny, probably going to go with the stock replacement although i have toyed around with the idea of a e34 m5 6 speed but todd tells me it isn't worth the hassle.

[Bill in MN]

All of my equipemnt was OEM with 160k on the clock. I'm on my second tranny (an auto) but I'm 100% certain the A pack was shot to start with. My driveshaft is now on its way out. It's old as well and probably would have crapped the bed anyway. I'm not expecting issues with the tranny or driveshaft (once replaced) but will bet the farm the rear end will eventually have something to say about it. Like most guys, I'm working with parts that have a lot of miles on them. Shit's going to break!

BTW, I'm not sure it's been done yet but I've a one piece driveshaft on the way. It's being built next week. It won't be installed until next spring when the car goes back on the road so we'll see what that does to the equation.

[gol10dr1]

WHOA WHOA~!!!!!!!! more info about this one piece drive shaft! common now ~0

[Bill in MN]

I've only seen the parts prior to fabbing. I see no reason it won't work, nor does the shop that's doing the work. When you see the parts you'll understand why I say that the diff. will grenade before this thing does!

This does beg the question as to whether or not the auto is better equipped to take high torque conditions as opposed to the manual. Not being much on transmissions myself, I'd still have to guess that the auto can take more.

[Don S]

Relatively new to the e28 world, but just by eyeballing the drivetrain in these things i would guess that 300 ft*lbs is limit for reasonalbe reliabilty. Once under way, traction will not be the weak link. So we have the trans., driveshaft and diff. Would prefer to lose the driveshaft but i believe the trans. is the week link in chain. Anyone try a swap to a Tremec T56? These are used in Vipers, camaros and firebirds.

[T_C_D]

My 535i made 427rwtq and never broke anything in the drivetrain. Nothing. Wasted the stock clutch and M5 clutch but the SPEC S3 held fine. My car had the G265 and it is currently doing duty in Sweeney's car. Mileage is unknown but the car had 301k on it when it was removed.

Todd

[Bill in MN]

BTW, the only real reason I'm doing the one piece shaft is that I can have it built cheaper than it would cost to replace with a reman. or new unit. It's overkill and really not neccessary but hey, what's wrong with overkill, right??