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small end bearing installation advise needed

Posted: Mon Mar 28, 2011 7:25 pm
by mattcfish
I feel I should replace the small end bearings on my connecting rods. There is the slightest amount of detectable play. The big ends were polished down to the limits, so I think these have racked up quite a few miles. I have them off the bike right now, and I have a new set , so what the heck. Is this something that can be done in the home shop? I've got a big vise and the talent for fabrication. If not, is this one of those things that requires the expertese of an airhead tech...or can I bring them to a reputable local shop that does work on VW's and everything else?

Re: small end bearing installation advise needed

Posted: Mon Mar 28, 2011 8:25 pm
by R90Steve
A good automotive machine shop can press the bushings in and fit them to your pins.

Re: small end bearing installation advise needed

Posted: Tue Mar 29, 2011 10:22 am
by Duane Ausherman
Do not let anyone size them by pressing a ball through it. It is done by a special reamer, or hone. Parallel with the crank is a good thing too.

I have only done them on the /2 type built up cranks, so I have no other advice about your quest. Let us know what you find.

Re: small end bearing installation advise needed

Posted: Tue Mar 29, 2011 2:58 pm
by mattcfish
Duane Ausherman wrote:Do not let anyone size them by pressing a ball through it. It is done by a special reamer, or hone. Parallel with the crank is a good thing too.

I have only done them on the /2 type built up cranks, so I have no other advice about your quest. Let us know what you find.
Of course, It's getting more complicated. The simple airhead, as alway, requires specialized repair.
I take it that these aren't replaced very often. How much tolerance is allowable for pin fit? How does everyone else determine when they need to be replaced. The play in mine is barely detectable.

Re: small end bearing installation advise needed

Posted: Tue Mar 29, 2011 8:54 pm
by R90Steve
My factory /7 manual calls for .00059"-.00102'. So basically a half to one thousanth. Can you feel a thousanth? I think if you can feel play, they are loose.
A good automotive machine shop, will be one that re-sizes rods and will be able to take care of your needs.

Re: small end bearing installation advise needed

Posted: Tue Mar 29, 2011 10:52 pm
by Duane Ausherman
I too think that any play is too much. To get a pin into the bushing, you have to have it really lined up.