[ROSKO]

For a swingarm pivot using bronxze plain bearing, wondering what I should ream the S/A pivot to for press fit. Does .002-.003 sound right??

 

[joe c]

needles my friend....needles. i hope youre not working on your race bike, its a little late for that!


jc

 

[ttilghman]

OEM bushings ya bunch of slow-ass cheaters.

-fasterwank36

 

[jbranson]

Rosko....yeah...002-003" should work fine. I'd lean towards .002.
JohnnyB

 

[ROSKO]

thanks johnny.

guys, first off this season is only over for the lazy.

second, i don't work on the fcb till two days before the season starts. AND I'm lazy. 2008 is over for me.



so what does that mean?

 

[joe c]

i was going to say probably the closer you can get it the better. of course without it binding.

j

 

[kenessex]

Rosko,
I don't think them little numbers really matter. To me it is whether to use a 2lb or 3lb hammer to drive them suckers into place. Then take a rat tail file to smooth out the inside. Good to go. If you whack them into place on the garage floor or a cinder block, you may need to use a coarse bastard file to smooth off the ends, too.

Ken

 

[ROSKO]

"I don't think them little numbers really matter." they don't. But that's because the engineer/ designer took care of the little things for you beforehand.









I must admit, I am a cinder block aficionado myself.

 

[HackAsaw]

0.0015" would be as tight as I would go regardless is powdered or otherwise

 

[jbranson]

Rosko.... something else I've run across in bronze plain bearings...if the fit on the pivot bolt is very close (free moving but very close), then when you press the bearing into the pivot tube it can tighten up the fit on the pivot bolt just enough to be a pain in the ass. I've had to hone out the bushings after pressing them into the pivot tube.
So.... Might want to consider Hack's suggestion of going even less than .002". It's not going to spin in the tube if the fit to the bolt is right.
JohnnyB

 

[ROSKO]

Exactly why I asked Johnny, the deformation from the press fit was enough to bind a bit. Not a lot but more than I am comfortable with. On a bicycle I always ream/ face bearing surfaces after welding to insure fit. With the input from you guys I guess I'll be mcmaster-ing a new reamer to do the same for this app.

Thanks!

 

[jbranson]

A reamer that size ain't gonna be cheap.
I've used a brake cylinder hone before.
JohnnyB

 

[kenessex]

I think I suggested a big rat tail file before, or just get a drill bit that fits and wiggle it around in there till it all works smooth. Come on, this stuff is easy. Of course, why replace the bushings in the first place, the big nuts on the ends of the pivot bolt hod it all together anyway. Just get a 4 foot piece of pipe on a big breaker bar and crank it down a little tighter.

Ken

 

[parks61]

ken
bet you don't know the bikes you've rat-tailed have vicious speed wobbles. to find out for sure, you'll need to ride faster
-parks

 

[kenessex]

I thought all bikes wobbled at speed. That's why we have steering dampers. If you use the ld friction dampers that came stock on the old Hondas and such, you can just crank them down tight. Add 2 or 3 hydraulic dampers and it is all good. It also helps if you tighten down the steering head bearings really tight too.

Ken

 

[ROSKO]

I'm gonna go with Ken's technique and put a damper on the swingarm at the pivot just to be sure.

Too much material for a hone. I had hoped I had an adjustable reamer at the shop that size but no luck. Damn, mcmaster is pricey sometimes. Luckily Victor Machinery is down the street. Best prices on this type of stuff and almost half the mcmaster cost for and adjustable hand reamer. www.victornet.com if anyone cares.