I haven't posted in a long while...got really sick for a long while and am finally getting better.
I have been dealing with clutch judder in my 1950 3600 since the first day it was driven after the restoration. every single time I took off in 1st gear, it chattered and bucked horribly. I have a rebuilt 261 with T5 in it, with an S-10 input shaft and an adapter plate. I have been through three clutches, trying to fix this problem. I laid underneath the truck while my wife held the brakes and slowly engaged the clutch- it wasn't leaf spring wind-up, it wasn't bellhousing or engine mounts- you could see that everything was happening right inside of the cover plate...
I found the bellhousing to be misaligned- runout was .0085 and parallelism was .006" Dave at Vintage Metalworks made me a special T5 adapter that eliminated almost all of the misalignment- it is now .0025 runout & .003" parallelism
While talking to my clutch guy, he mentioned that he had run across a similar issue with a truck with a 235. It had excessive crank endplay (a LOT of end play), which caused the crank to move in one direction during acceleration, and in the other direction when the throw-out bearing was pushed into the cover plate fingers.
I just went and grabbed my flywheel (trans is out right now), and I can move the crank fore-aft with a distinct "clunk-clunk"... it is obviously WAY out. I'll get the dial indicator out and measure this, but it shouldn't be moving like this...
[EDIT]: Crankshaft end play measured 0.014" with dial indicator at the flywheel. Spec is .003 to .009"
Can babbitt be added to #3 bearing halves and then machined to take up this play? We're talking about .009 to .010" increase in the thrust surface (on one side of the bearing or split 1/2 for each side).
I don't know if I have it in me right now to pull this engine and tear it all apart again- Hell, it's going to be a real chore just pulling the pan off and getting everything ready for a new gasket & seals....
I know now that the crank thrust surfaces should have been welded up and re-machined at the machine shop, when the crank was ground undersize. Since it has new main bearings in it, the play will not be due to a worn #3 main bearing thrust face.
Are there #3 main bearings available with an oversize thrust face?? Can a #3 bearing be modified/made to fix my problem? Or am I destined to do pull this engine and do a complete tear-down?
(Also- my 261 does not use the bearing shims) I believe the 235 uses the same main journal bearings, but I am not sure- hoping that someone has had some experience addressing this issue "in situ".
Any help or ideas are greatly appreciated.
Thanks
Dave
