hi all - just introduced myself in the new member area. I have a 98 evo motor in pieces I have to rebuild. Split the cases and found that the pinion race (crankshaft side) that the pinion bearing sits on walked a little. It chewed the bearing and blew up the oil pump and some gears. The pinion shaft race seems to have walked a couple cm and not sure what to do. Did I simply press it back in or remove it and buy a new one and press that in. Btw seemed like the reason the race walked was whoever rebuilt this before forgot to put the puck pinion bearing lock ring lol. Attaching a pic that shows the gap between bearing and lock ring - I only realized the figment issue after putting the cases together. Any help much appreciated - I am thinking just press the race back in but worried about tolerances etc

 

First, chances are that metal from some other damaged part is what chewed up the pinion bearing and extremely doubtful the race drifted. (I've done a lot of bottom end work, but "I wasn't there" so take that as uninformed advice)


The inner race does not fit flush against the wheel. The outer edge of that race should be 1.420 - 1.410 measured from the flywheel face. That leaves enough clearance to get a bearing separator behind the race in case it does need to be replaced. Gap between lock ring and bearing is of no consequence.


There are 4 different bearings available to set the pinion clearance which should end up being between 0.0002 - 0.0009. Needless to say you're going to need to do some meticulous measuring to do this right. (1"-2" micrometer graduated in .0001 and a bore mic 1.5" - 2" also graduated in tenth's of a thousand) And don't trust any bearing you buy, even from a dealer. They are color coded by size but I've found more than a few of them incorrectly marked. Measure the bore, the race and then do the math and measure at least 4 rollers of the new bearing.


There's nothing complicated about what you're into and you clearly have mechanical ability to get this far but I highly recommend you get a Genuine HD Service Manual. It'll explain all this in easy to read text with photos and save a lot of time and internet ink

 

Thanks for the really detailed answer. The race has definitely moved. It measured about 1.507 from the inside of the crank to the outside of the race. In the parts that came with this project there was a 1993 crankshaft too that I measured that is exactly 1.42 and the bearing sits snug.

Should i I just try to press this race back in a little or should I remove it completely and find a new one?

 

Always more fun when you have more than one basket to work with!

There's no lateral force on the wheels with the tapered bearings on the drive side so this makes me wonder if the race was previously replaced and improperly installed to begin with...
anyway, if it will mic true to round I'd be tempted to tap it on down to specs and go from there. But DO be picky about the clearance on the race/bushing/bearing since they hold the pinion side true to the gear assembly. And support the pinion side of the wheel by itself, else you could knock it out of true. Once in the cases the flywheel assembly is near bullet-proof but it takes very little to screw up the works when they're out rolling around. Also, don't worry about the bearing cage not butting against the lock ring or wheel. They have a lot of room to move around end to end and will settle in to the outer race - some run against the lock others will run against the wheel some settle I in the center. They each have their own personality

 

replace it don't trust it will stay in place

 

Thanks for all the help.

 

Not much help when you get conflicting advice I imagine?

That race cannot move in or out without a lot of pressure unless it or the shaft itself is totally compromised. That's why I suggested it may have not been properly installed (even by the factory) and tapping it on in, assuming it mic'd round. Almost as often as not, installing a new race will require grinding (like a crankshaft) to make it round and true. Being in a big city an automotive machine shop probably won't be too hard to find.


Anyway, good luck with your project. We'd be interested to hear what you decided and how it turned out.

 

 

I've been out of it for several years and had never seen or heard of the walking pinion race issue, but have wrenched enough decades to know I've neither "seen nor done it all." With that said, I'll apologize for having doubts the inner race moved by itself.


Saw an old post link when reading your last that reminded me to always be humble concerning mechanical oddities - https://www.hdforums.com/forum/evo-c...lking-out.html


So, if ever I do another 3 piece flywheel, it'll get Loctite 641 or 638 even if a new race is needed... just sayin'