FL Pinion Case Race

[billpedalino]

I must re-locate the pinion race in a 1953 FLE motor case by re-boring the hole and/or possible sleeving and re-boring. I seem to remember that if the race is fit too tight, it can cause the often-seen crack between the race and cam bushing. I believe that the case-to-race clearance is 0.001 tight. Can someone confirm this tolerance??

Thanks,
Bill Pedalino

[koanes]

I usually shoot for .0015. If you end up with a very smooth bore in the case I'm sure your number would be fine. I think a lot of those cracks you spoke of were generated by people pushing the race in without any prep. I use press fit lube, freeze the race for several hours, and warm the case to 150-200 degrees. At .0015 you can just push the race in by hand, just a smooth drag from the parrafin based lube.

[MJW]

My 51 FL case had a bad pinion race as well, My builder found an oversize replacement and did like Koanes suggests, heating the case and freezing the race. The only difference as I recall was a bit more interference, and a gradual cool down in the oven. I'm not an expert by any means but I would think if you can press the race in by hand with the case at 200 degrees, how secure is it at normal running temp? Mike

[Jerry Wieland]

Mike The reason you can push it in by hand is because they are at 2 completely different temperatures. That will never happen under running conditions and .0015" interference fit is good. I've run with as little as .001" and never had a problem with a race coming loose.

Jerry

[MJW]

Thanks Jerry, my motor confidence just went up a notch...Mike

[Carl Olsen]

As an extra bit of insurance I made a jig for angle drilling and tapping the case for set screws like the factory used in 1954. I do this step to all of the straight bearing motors that I build, but you must use a Jim's race as the other ones do not have the relief for the set screws in them. This works very well on blind race cases as there is not a lot of material left once the machining processes are completed for the conversion to later races. You will never have to worry about your pinion race moving because it is now locked into place as well as locked into the fully seated position.
Carl

[Jerry Wieland]

Carl My opinion on that is that it is a big waste of time and money. If that race has an inkling to move, no set screw in the world is gonna stop it. If the hole is round and the race is fit right it isn't going anywhere.

Jerry

[exeric]

If there is a detent in the race for the set screw to interlock; the race will not move. . . . . Something else will move.

[flat-happy]

exeric----i like the way you think. i didn't want to say anything though because i have too much respect for carl

[Carl Olsen]

Everyone has their right to an opinion, but opinions are like a$$holes, you know the rest. I in no way implied that the set screws were a replacement for shoddy workmanship or a loose fit, but instead an extra bit of insurance. I have been doing this to well over 100 motors in the last 12 years and none of them have failed, plus why do you think the factory started doing it in 1954and had shop dopes for dealer mechanics back in the day. I have never torn an engine down that had pinion race movement problems with the set screw alteration. I build engines for reliability and our engines stand the test of time and stay together, the reason for that is by using the latest technology combined with professional workmanship. I never waist time and money on my own engines or my customers, as it says on my business card, when only the best will do.
Carl

[Jerry Wieland]

Carl

If the race was fit right you'd have had zero failures in the last 100 engines without the screw. Did you ever notice that when you first start lapping a new race with the screw that it sometimes shows up in the lap pattern. That is called distortion and remember it is doing the same thing to the case and I agree it is probably very minor but none the less it is there...

I just like nice round races pressed correctly into nice round holes and you will never have any problems.

Jerry