Finally getting around to a long drawn out project. I'm removing the BW35 from a 68 144. Replacing it with a M410 out of a 70 1800. I have the car jacked up and secure. I drained the BW35. Pulled the driveshaft and the linkages. Got the cross member bolts broken loose. I have some of the bell housing bolts out.

Looking for advise on how to proceed at this point. I was going to pull the fan off the engine and the radiator bolts to allow engine to tilt back a bit. Should I just take out the bell housing bolts or it appears I can get to a number of the BW35 bolts that attach it to the bell housing. I have the carpet off the tunnel and the plate removed on top. Is there a procedure for separating the transmission.

I have found out the driveshalf flange is smaller then the J output flange. I assume I need to try and find a smaller J flange if one exists and then maybe have the front part of the driveshaft shortened. I wanted to replace the rear engine seal of the B18 if a good idea while I have it down that far. Assume one has access to that once the tranny is out. I have a new clutch to install and have a 6 bolt flywheel for the B18 which I had surfaced by a machine shop.

Craig

Dont forget pilot brg.

I did the M410 conversion from BW35 on a '68 144 many years ago.
Most has been already said, but the two things that need to be paid attention to are, don't even try to remove the bellhousing from the M410, you will need to re-shim the input shaft bearings and replace seals that are not readily available, and the trans will leak profusely. It is not like an M41 at all.
You will regret putting the small rear flange on the M410 with old small driveshaft. Get the front 1/2 of an M46 or one from the 1800 where the M410 came from, along with the larger flange. That small u-joint will get eaten up in short time with the manual trans. If you can, go with the bigger driveshaft all the way to the diff.
As said the torque converter bolts need to be removed before you take the auto box out.

I'm probably picking up an M410 on Saturday for my '72 145 to do the same conversion you're doing, so I'm intensely interested in how everything is shaping up.

Mainly - Did you find a smaller output flange? Or a larger flanged driveshaft?

Was the BW35 frontshaft the right length?

As Goatman suggested--you need to remove the four torque converter to flex plate bolts. Take the dip stick tube out (drain the oil first, of course) before dropping the auto. The transmission will separate from the bellhousing with the six 5/16 bolts (these often loosen up and are worth checking for tightness for folks still running the BW35) but I'd pull the whole unit together. You can replace the rear seal housing with one from a B21-B230 made for the neoprene seal but remember to get the pan bolts for it too (metric--I paint those two so as to not mix them up). -- Dave

I usually loosen or remove the top bell housing bolts before I tilt the engine.
With a BW35, the bell housing will come off with the transmission. In a manual transmission equipped car, you would remove the transmission from the bell housing and then the bell housing from the engine.
Not sure how easy it will be for you to fit the M410 to the B18 with the engine remaining in the car considering you have to install it with the bell housing connected to the gearbox. Hmmm, never done that before. I'm sure it would be easy if the engine / transmission were out of the car and could go in as one piece.

You shouldn't have to remove the fan if you unbolt the radiator and have it tilt as the engine tilts.

You may be able to get an output flange from Don Thibult. He has had J-type to small flanges in the past. Not sure if a M410 to small was ever available though.

Yes, replace the rear main seal while you're in there. You may want to consider an update to a neoprene seal. Your existing rear main seal housing which accepts a felt seal can be machined to accept a neoprene seal. I have had good results with both felt or neoprene seals. Having said that, I have updated to the neoprene when possible.
--
'60 PV544, '68 220, '70 145, '86 745T

Drop the engine a bit,but not so much that it pinches the heater hoses on the firewall.
Take 2 or 3 feet of 1/2" extensions,and get the top bell housing bolts first.
Remove the rest of the bell housing bolts.
Wiggle the transmission and pull it off.
Remove the lower engine cover to get at the torque converter to ring gear bolts.
These bolts will be shorter than flywheel bolts.....
You have the smaller drive shaft in a pre 1970 140.
A complete later driveshaft,& larger center support retaining bracket would be best.
The BW 35 & M41 use the same short shaft length,IDK about the M 410.
--
71-145-S

Sounds like you're well on your way. I've done this same task two years ago. One tool which made the process easier was to use a motorcycle lift to lower and raise the transmission.

When I pulled mine, I removed all the bell housing bolts and took the tranny and bell housing off as one unit. Don't forget to disconnect the wires that are on the drivers side.

Jack

I'm no expert on this but:


You MUST remove the torque-converter to flex-plate fasteners before continuing!


Goatman

Thanks for all the advice on how to proceed. Records with the car show the engine and transmission were rebuilt or had work sometime in the past. Getting the bolts loose seem to have proved that so far. I do have the proper cross member as well.

Talking with someone now about a neoprene rear seal. Hoping the short front driveshaft from the BW35 works with the M410 J OD combo without modifying it. Sounds like I need a small J OD flange which seems not all that common.

My U joints have grease fittings. U joints seem tight as does the center support donuts. I can't see how one would get a grease gun on the fittings at any angle even off the car.

Craig

If you don't care about the old BW35, you should be able to pull it with the flex plate and torque converter still attached... been a while, but I seem to recall doing that. Not that it's any easier, but... it give you the satisfaction of getting it out of there ASAP!

As for the comment about having to attach the M41 bell housing to the engine before you put the new transmission up.. don't worry about that... there's plenty of room to install your M41 with bell housing (and throw out bearing) attached as a unit. Think 164 where there is no choice but to have the bell housing attached to the transmission.

One note when you put it together... you'll want to have your top starter bolt in the bell housing before you put the bell housing to the engine. There's not enough room to get that bolt in later.

Your auto driveshaft may well work.. you'll just have to measure. Worse comes to worse, you can have a custom driveshaft made up of the two... big flange and U-joint at the transmission, small flanges everywhere else.

Perhaps you mentioned... but I forgot.. what year is the 140? At some point the tunnel changed, along with the rubber donut size, and I think finding the earlier smaller rubber donut to fit the newer, larger carrier bearing might not be possible. I think that change was twixt 69-70, but it might have been '68-'69. In any case, if it's '70 or later, it will have the larger tunnel.

*edit*.. I see now you are working with a '68. That will almost certainly have the smaller carrier bushing, so you may very well have to have a large flange and U-joint yoke welded up to your older smaller driveshaft. Perhaps someone else can confirm...

That said, small J flanges do exist I think... my 122 has a J overdrive and small driveshaft I think.

*/edit*
--
-Matt I ♥ my ♂

Matt B--it's not possible to pull the auto trans along with the flex plate. You can pull the trans staight back off the torque converter and leave it attached to the flex plate but you still need to remove the torque converter to get to the flex plate bolts to the crankshaft. -- Dave

yea... I guess I wasn't clear. That's what I meant... leave the converter and flex plate, yank the transmission.. then worry about the other stuff.

Sounds like he's all on his way though with flanges, crossmember, pedals... etc. and what not.... should be good to go



--
-Matt I ♥ my ♂

"As for the comment about having to attach the M41 bell housing to the engine before you put the new transmission up.. don't worry about that... there's plenty of room to install your M41 with bell housing (and throw out bearing) attached as a unit. Think 164 where there is no choice but to have the bell housing attached to the transmission."

He said he was installing a M410. I thought that unit was like a M46 - it has the gearbox bolted from the flywheel side inside the bellhousing.
Am I wrong?
--
'60 PV544, '68 220, '70 145, '86 745T

ah yes.. I didn't read. So yea, the M410 must have bell housing attached when it goes in.

All fine, but the starter bolt thing applies (ask me why there's not top starter bolt in my M410 equipped '70 wagon that I converted from auto :-) )

--
-Matt I ♥ my ♂

I did locate the small output flange for the J and the neoprene rear seal kit for the engine today. I also got a new donut for the driveshaft and a spare clutch cable. Parts on the way.

I put the pedal box in late last fall. I have the factory OD switch for the dash column as well as the OD plugin light for the cluster.

Craig