Im still confused to this day on why i needed a new torque tube with my 85 transmission install. the 84 transmission failed at the 5th gear coupling. the torque tube was ok, but it was advised to get a new torque tube and transmission. Is this right, or could I have just swapped in a new 85 borgwarner transmission with my existing torque tube? I thought there was a good reason for the new torque tube , but I just cant remember what it was.

 

is it the diameter of the shaft ?

~Dave (ss) and Nicole no comments for East Coast Pizza are needed ~

 

Are the early Euro trans any more stout?

 

Where do you guys send yur trans for new syncros. I want to get my 1980 5spd freshed up this winter.

 

Same tranny as US for the model year, sometimes different gear ratios.

Stoutest order seems to be
GTS
GT
S4
85/86
Everything else.

No idea if the 3 spd and 4 spd automatics handle different amounts of power, but both I think exceed the limits of the manual transmissions.

 

I plan to take a whack at rebuilding the tranny out of my US 83 myself. There is a good guide thread around here, and I have another already rebuilt I will be putting in, so no problems if it takes me a bit to finish.

BTW most places do a flat price exchange for rebuilding, but some may also do a time and materials if you want your old trans back or something. Doesn't take much to burn through $1k in parts though.

FYI, if you are careful, and fully drain the tranny, a 5 spd double boxed in heavy cardboard is just under the UPS 155 lb limit, but personally I would stick to as local a rebuilder as possible.

 

I'd like to know some solid information as to what specifically breaks and under what conditions. I've understood it to be heat related "loosening" the boxes as they expand marginally. I've heard of third stripping, but was it really from the power? or maybe someone got a little air with slicks at a track and the motor revved up momentarily. Is it the actual gear teeth themselves, bearings, shaft, maybe a synchro hub explodes. Also, are the cases essentially the same to where a dog tooth tranny would fit multiple years without creating a CF to fit different years? I've been looking at the faceplate modification liberty transmissions does, and I think someone I know with a good cnc shop could make the parts. Weld the dogs to the gears a little bit at a time and cryo.

I plan to push my 81 box to the limit soon. I have a spare one I can swap the lsd into. I may disassemble it and start exploring possibilities soon. I think I can have a complete dogtooth unit made for around $6000 from a company in Australia.

 

Mark Anderson has gone through a few 5th gear seets.

All the power always goes through the 5th gear as I understand it from his posts. Though dont take my word 100% on that as I have not disassembled or fully studied the boxes yet.

 

Just my own two cents, my guess is that within 5 or 10 years somebody will have worked out swapping a modern automatic for the 1985 era Mercedes automatic, and all the other options will take second place.

 

All speeds have a gear on the input shaft. Perhaps it uses 5th somehow as part of the cluster assembly.

 

Kibort the splines on the drive shaft inside the torque tube can get beat up some when the 5th gear input shaft breaks and the driveshaft spins inside a partial coupler. It was a probably a reliabilty issue preventive recommendation to change the tube. And yes all the power all the time flows into the trans on "5th gear" .

 

mine was a clean break just after the coupler. Im sure if it was recommended for that reason, I didnt doubt it. the real question is, is it required, or would have the old 84 torque tube work on a 85 transm. in otherwords, is an 85 transmission a drop in replacement.
as far as my break went, I did a dyno run with the ebrake partially engaged. it make a huge vibration. power was down 70 hp and we figured it out quickly. then the second run............ blllllllinnnnnnnnnnng! as the rpms went to redline as it broke at 4500rpm. I might of weakened it with that vibration or it was just its time. if so, luckly it happened at the dyno. flat bed home and rope tow to the shop the next day. (CT)

mk

 

I've got an 86 5sp with LSD at Greg's now. He should finish the rebuild next week I imagine.

 

Does Greg have some "secret recipe" for transmissions as well? Is he just rebuilding it, or building it up?

 

Greg's secret recipe is that he knows what bad parts look like and replaces them.