Vintage Dirt Bike Q & A

Greetings,

Need some opinions. On my '79 CR125, I had put new needle bearings, bushings, and dust covers in the swingarm years ago. Upon disassembly, found both bearing frozen and worn (as if they had never actually rolled).

Would it be a bad idea to use just bushings back there? I understand the previous years' bikes were bushed only. I don't race this bike.... mostly ditches and an occasional track day. I could probably turn some out of bronze or ??? on my lathe pretty quick. Any real reason not to?

I just found this forum a week or so ago and it's a great resource! When I first bought the bikes in '94 (two '79 CR125s as boxes of parts and a couple frames), I didn't have the internet and every problem took me days/weeks to resolve. I must have read that Clymer manual 10 times... and even so it can be very vague and sometimes incorrect.

Looking for your thoughts,
-Pat W.-

Pat,

I think in general a bushing can take a lot more force than a bearing. And once a bearing is damaged it only gets worse. A bushing can at least fix itself somewhat. (At least that's one of the few things I remember from HS auto shop class many moons ago.)

I never did see the need to put bearings, at least needle bearings, in high stress low movement points such as the swingarm pivot.

Other opinions?


Check with John or Sam at http://www.jastco.com/index.html I think they make bushings for your bike.


Loren

Did you clean the swing arm out really well before you installed the new parts? Bearing life is drastically reduced by dirt/debre and non proper lubrication. When you ride that swing arm is constantly moving. Needle bearings can take a radial load but can't take axial loading. An axial load will destroy the bearing housing ( a few thousands) and freeze the up the needles.

As a side note, bushings do not carry the majority of the load!! The bolt carries some of the load and the swing arm and frame carry the rest. Usually elastomers (rubber) add damping (isolator) and act as springs in tension or compression.

You can keep the needle bearings, they just need lubing occassionally. I have no problems in 2 years using real thick (very) waterproof grease I got from a boating store for outboard motors. I have seen swing arms with those zerk fittings so you can pump some more grease in without taking the arm. I will definitely do that next time I have the back-end apart.

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Michael,

Where did you get the needle bearing kit?

J

_________________
#829 The "Factory Novice"

1988 Honda CR250RJ
1983 Honda CR480
1981 Can-Am 250 MX6-B
1979 Honda CR250RZ
1979 Kawasaki KX250 A5
1978 Husky 250CR
1978 Honda CR250R
1977 Yamaha YZ400D
1977 Suzuki RM125B

I bought NOS parts, but since then I have seen kits on the Vintage Elsinores web site (http://www.elsinores.com/index2.ivnu). When I go to replace the bearings in the future, I'll get them over the counter at a bearing supplies store.

_________________
Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF