Topic: Vintage Calfab swingarm pivot arrangement??

[slikwilli420]

So putting my racer back together and noticed lateral play in the pivot. Here is the arrangement, the arm has 2 needle bearings on either side, a spacer tube in the center and a shorter bushing on either side that the OD fits the needle bearing and ID fits the pivot shaft that goes through the frame. I didnt have any seals or dust cups with it so made a set that allow the overall width to match the mounting distance in the frame. When the cups are put on I can slide them back and forth 0.025"-0.050" (guessing here since I didnt actually measure). Is there supposed to be some type of thrust washer/bearing on one or both sides? How are the new arms from Moto GP Werks set up? The length of the center tube and two pivot bushings is slightly more than the arms pivot tube just like a stock arm, but it feels like I am missing something critical here.

[Tintop]

Did you do some frame mods over the winter??  If yes and you didn't have an arm installed that could have caused the issue.

[simon#42]

i use a thrust bearing either side , normally a radial needle bearing .

[turboguzzi]

simon's solution would be best, question is if you have the space to fit them.
if not, then two ground to measure washers, or a few calibrated shims will do the job, just grease them well.
would aim for a 0.1-0.2 mm play AFTER you torqued the axle nut properly.

[MRieck]

I agree with Simon and Turbo about the use of 2 Torrington thrust bearings....definitely the best set up. Here are MSC parts....many to choose from.  https://www.mscdirect.com/browse/tn/Motion-Control-Fluid-Power/Bearings/Thrust-Bearings?navid=12104206

[slikwilli420]

Good stuff guys. Thanks for the help. I made a thrust washer from some 7075 aluminum and was able to get the movement under 0.005" and it still torques to spec and has motion in the arm without forcing it.

[simon#42]

check for play once you have ridden the bike , i think the alloy shims will wear very quickly

[slikwilli420]

check for play once you have ridden the bike , i think the alloy shims will wear very quickly

I totally agree its not the best solution but if I have an alloy dust cup and alloy shim against an alloy arm, all greased up, all should wear less quickly than a hardened thrust washer between two pieces of aluminum right? I would like to see the arrangement on new calfab arms and maybe Im missing something.

[754]

The radial bearing should have a hard washer on either side..

[turboguzzi]

considering your timeline, go with it, just find a better arrangement after your first race. time to cut some corners
most bikes make do with washers there, it's not going to wear out in just a few sessions

[slikwilli420]

The radial bearing should have a hard washer on either side..

No room for radial bearings Frank. I had a .032" gap to fix so ended up with a washer nearly that thick. Still trying to understand how this thing goes together properly.

[seanbarney41]

I don't understand why the Calfab would use needle bearings instead of tapered rollers.  Here is the set up of my Dresda swing arm.
KIMG0098 by Sean Barney, on Flickr

[Tintop]

The swing-arm used in my sidecar was from a kz1000.  It used two needle bearings /side, a steel washer, and a steel dust cap (replacement kit also included a new shaft). This sounds like a similar set-up.

[754]

Oillite would be my choice. .

[slikwilli420]

The swing-arm used in my sidecar was from a kz1000.  It used two needle bearings /side, a steel washer, and a steel dust cap (replacement kit also included a new shaft). This sounds like a similar set-up.

Sounds like my setup except I made one thrust washer to take up the gap. I'll grease the hell out of it and see. Anything is better than the wiggle that was there.