Discussion Forum - Northstar Chevelle Club

Bowtieman427 · Active Member

Changing converter on TH400

Lost in the 60s · President

I use a bottle jack and 2X6 piece of wood under the pan. You want adjustability for the engine angle too. Letting it angle down makes it easier to get the trans lined up and allows use of a 3 ft extension to zing the bellhousing bolts in before raising the assembly to install the crossmember.

Bowtieman427 · Active Member

Thanks Mitch excellent idea.

Bowtieman427 · Active Member

yes raising the stall. It will be more inline with the engine. See where it takes me : ) dropped my headers off to get recoated as they were showing rust. I was pretty unhappy about that. The coater says they will make it right.

-- Edited by Bowtieman427 on Tuesday 17th of April 2012 09:30:53 PM

SShink · 3K+ Club

Jim, are you raising the stall rpm on the converter?

Bowtieman427 · Active Member

Had to shim the converter it was .295" (with NO shim) away from the flywheel I used .125" shim hope have enough crank engaugement sure looks like I do. I torqued to 45ft*lbs manuals are all over on torque specs my 68 manual states 33ft*lbs many other sources stated 40-45ft*lbs put a little blue lock tight on the back and antisieze on the front.
Waiting for headers. Starting on rocker adjustment have a couple .001-.002 off
can not wait to try out the new stall.

Bungy L-76 · Active Member

Bowtieman427 wrote:
Had to shim the converter it was .295" (with NO shim) away from the flywheel I used .125" shim hope have enough crank engaugement sure looks like I do. I torqued to 45ft*lbs manuals are all over on torque specs my 68 manual states 33ft*lbs many other sources stated 40-45ft*lbs put a little blue lock tight on the back and antisieze on the front.
Waiting for headers. Starting on rocker adjustment have a couple .001-.002 off
can not wait to try out the new stall.

I'm confused. Doesn't the converter slide forward and backward on the input shaft? Don't ya just slide it up to the flexplate? Where do the shims go? Between flexplate and TC bolts?

John D · 2K+ Club

Yup, shims are between the flexplate & TC.

Confused... the .295 measurement "away from the flywheel" meaning when the TC was "buried" into the trans it was .295 away??

Putting a .125 shim means you've moved the TC out of the front pump drive lugs nearly 3/16"... they're only about 3/8" deep to begin with...

Bowtieman427 · Active Member

I slid converter all the way into tranny the measurement was from converter mount to flexplate mount (the distance to slide forward before they meet) .295" is the gap a .125" shim was put inbetween to minimize this gap making sure it still mates to the crank. .295" -.125" = .17" total gap which yes is close to 3/16" = .1875"
ideally 1/8min - 3/16max still within range. Did not want to shim to much want to ensure good crank mating which is also critical.
Coan has a nice writeup on this and diagram

http://www.coanracing.com/PDFS/InstallInstructions/TransConv.pdf

"When bolting converter to flexplate, push converter back into
transmission and measure gap between flexplate and
converter. The converter will need a minimum clearance of
1/8", and maximum clearance of 3/16". The converter will
need to pull out of the transmission to the flexplate. If you
have less than 1/8" clearance, you will damage the
transmission. Before bolting converter to flexplate, confirm
converter pilot is engaged into crankshaft pilot. Always use
grade # 8 fasteners to attach converter to flexplate."

Hope this helps