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Tips to separate M21 from small block clutch/engine
Hello:
Have recently pulled engine & M21 tranny together out of '68, in hopes of swapping engine out. I cannot get the M21 to separate from bellhousing/clutch (the 4 tranny mounting bolts to the bellhousing have been removed). Car has been sitting for 15+ years in various uncontrolled, covered climates. Rust on tranny shaft is my initial suspect. Even with a chisel and hammer I can barely get the tranny case to show any sort of movement or separation. I don't want to apply absurd force and risk damaging anything in tranny, tranny case, etc. Perhaps the mice-in-residence are a factor somehow...
Any suggestions on how to get these two to part ways reasonably without damage?
engine & tranny removed as a unit - which iInow wish to separate drivers-side view of the 4 tranny mount bolts that I have removed
does engine turn? if trans won't separate from bellhousing and bell won't separate from block, pull dust pan and bend up a 9/16ths wrench to unbolt clutch from flywheel. if engine won't turn, you just gotta go postal on it. does trans turn in neutral? you might be able to get to clutch bolts through the clutch fork hole. i think the fork can be popped out and you will also have a big hole to spray WD40 into to try to free up input shaft in clutch disk.
if engine does not turn, start with pulling heads and sanding bores above pistons with 180 grit and WD40ing up the pistons. then with some beating on piston tops you can usually free it up. put a starter on it and jumper cable fire it. big screwdriver on flywheel teeth where starter goes can also move it. sounds like engine is being redone or replaced anyway.
Take out the bellhousing bolts and separate it there. May not make a difference but worth a try.
After the bell housing is unbolted, push/ tap/hammer on the clutch fork. The fork pivots on the bell housing and you now have a lever to help you separate the bell from the engine. If possible, I would try to spin or jar the engine from the back of the transmission. This may break the rust between the clutch splines and pilot shaft.
Last edited by 2mnyvets; May 10, 2020 at 09:01 AM.
I am pretty sure that both the bell housing and transmission case are aluminum. There was an earlier suggestion to remove the bell housing from the engine. Do that. Then, using a board or something like that, Tap the bell housing off the transmission
From: At my Bar drinking and wrenching in Lafayette Colorado
Remove the bellhousing dust cover and then remove the 6 bellhousing-to-engine attach bolts. This will allow you to separate the engine from the tranny assembly. With the tranny/bellhousing assembly removed from the engine, you can then do some tapping/jarring using a large plastic or hard rubber mallet (or using a wooden board to protect the bellhousing as Gary suggested above) on the bellhousing to break it loose from the tranny.
Lars
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I had a hell of a time trying to get the bell housimg to realese so I pulled the tranny off the bell housing. You need to support the engine and keep it level then block the tranny. You want the tranny to slide out and not drop so keeping them both supported is important. Once those 4 bolts are you you can twist it and give it a good yank or use a small pry bar between the tranny and the bell housing. Do not pry on the ears that the bolts go through, they will snap off. once you get the tranny off, I had to whack the crap out of the bell housing with a rubber hammer. You will have to work it side to side but eventually it will come off.
Tips to separate M21 from small block clutch/engine
