T5 transmission to Iron Block M116/117 - PeachParts Mercedes-Benz Forum

Tony H · #1 03-04-2020, 09:41 PM

I'm starting a new thread specific to my project as to not further dilute the original non MB transmission thread. I dropped off my design, bellhousing and T5 input shaft bearing retainer with the fabrication shop today. I should be able to pick it up in a few weeks. I'm having it made as a rectangular plate with no bolt holes. When I fit it up I can determine the shape to provide for the overlap of the 2 mating surfaces. Not sure of the cost but I can't imagine it would be that much for a steel plate with a hole and a groove. I may have the plate surfaced to assure absolute flat and parallel surfaces.

Tony H · #2 03-14-2020, 12:31 AM

The adaptor plate is done but I can't go get it until next Thursday. Anxious to see the fit.

Tony H · #3 03-18-2020, 01:15 AM

Picked up the parts today. It is exactly as I expected. At this point it is a rectangle. I don't want to cut the final shape until I determine the layout and hole locations to insure there is adequate material. I may need to machine some of the bellhousing center to allow for the TO bearing. After cutting and drilling(but before tapping) the plate I'm going to have it surfaced to insure it's flat and parallel. I did not want to do any cutting or welding on the bellhousing and affect it's integrity. The 7.85" T5 input shaft gave me enough length to use a interface plate without cutting the bellhousing. total cost:$265

Tony H · #4 03-18-2020, 01:15 AM

Last picture

Tony H · #5 03-18-2020, 03:22 PM

Also I wanted to use the original 3.5 flywheel/clutch/starter to decrease the complexity of the project. The transmission input shaft/interface plate combination gave me enough pilot shaft engagement with the pilot bearing I did not need a custom flywheel with integral pilot bearing.

cth350 · #6 03-19-2020, 09:08 AM

I have 2x factory 4 speeds for the cast iron block, but no viable flywheel. Where did you acquire one? 10+ years ago, a new one from the classic center was like 1,500$. Hate to think of what it is now.

-cth

Tony H · #7 03-19-2020, 10:43 PM

My car is a Euro 111 3.5 coupe with manual so it was always there. I would think one could have a custom flywheel made for less than an original. I started to go down the custom flywheel route then decided the original will be fine for my use. My main motivation for this project is to use a common, un expensive 5spd transmission in place of my un replaceable original stick shift(with poor gear spacing). Of course this would be useful for someone converting a iron block engine to stick shift. I will have less than $1k into the bell including parts and some of my time so that's a lot less than I figured when I started. Once I get it mocked up on an engine block I can see where the TO bearing needs to go and deal with that. I can have a pilot bushing made of C932 for very reasonable. I would rather have a bushing than a bearing-the bearings break apart. The TO bearing in my car was broken when I pulled the trans off. The input shaft was basically unsupported.

Tony H · #8 03-30-2020, 12:20 AM

I was doing some driveshaft research and came across this and had to share it: https://www.youtube.com/watch?v=CuGqNOhvL1M
The comments are pretty hilarious. I hope the guys that did this are not driving next to me on the freeway when it breaks

Tony H · #9 03-31-2020, 11:33 PM

Got the plate back from the second operation-cutting to shape and surfacing. Now it's ready to drill/tap. Total cost of plate-$480. I'm very pleased with it.

t walgamuth · #10 04-01-2020, 05:16 AM

That looks very professional! Good planning.

Tony H · #11 04-01-2020, 07:59 PM

The design was pretty low tech. I used Masonite cutouts of the bell and transmission overlayed to come up with the shape. I probably left more than the necessary amount of material at the perimeter but what's a few extra lbs for peach of mind. The transmission mounting surface is a-symmetrical but I made it symmetrical so if the shop messed up with the pattern it would still work-a little extra material. The machine shop did an excellent job with the fitment of the bell and output shaft. A light tap seats them.

Tony H · #12 05-09-2020, 11:48 PM

Got the plate pretty much finished. The bolt patterns between the bellhousing and transmission were close so there was some interference since I used as many nut/bolt connections as possible. I was able to nut/bolt the 4 transmission bolts and 5 of the 11 bellhousing bolts. On the interfering bolts I used socket head bolts so the relief cut would be as small as possible. Overall happy with the result. Next step is to bolt it up to a engine and check the bellhousing alignment.

Tony H · #13 05-09-2020, 11:51 PM

More pics

Tony H · #14 05-11-2020, 10:18 PM

The next aspect I am looking at is the driveshaft. I have wanted to stay as close as possible to the original design and not go the one piece route as a 1 piece will be too long with the 3.27 rear axle and would be too large dia to fit in the tunnel. I had believed a 2 piece shaft might work with the rear longer section center bearing lining up with my front bearing mount. After obtaining the shaft and comparing I find the 1/2" difference falls within the slots for center bearing adjustment. My intention was to shorten the front section and have a new tube yoke welded in to accommodate a 1310 u joint to interface the slip yoke. the small front section is 1.78"OD and 1.606"ID with .087" thickness. I can get a tube yoke with a slightly larger OD and have it turned down the few thou in needs. The 3 piece shaft in the pic is the original one from my coupe.

Tony H · #15 05-19-2020, 01:12 AM

Took the yoke and tube to the machine shop today. They said they would turn the ID of the tube rather than the OD of the yoke. So not much to do until I can get the length established and the shop will cut the tube square, turn it to the correct ID for a press fit to the yoke and weld it. Then I will have the u joints/CB replaced and balanced.