Needle bearing in 250R case for shift-shaft support/smoothness

[Billy Golightly]

I was looking at this on my Rotax cases the other day (They are getting ready to come back apart and do some touch ups before I start throwing bearings and trans in them ) and I wondered if you couldn't put a needle bearing the size of the shifting shaft to slide through and ride in? It looks like with some welding there would be plenty of room to do it, and would have to shift smoother and would have to work better since it wouldn't be riding right on the aluminum directly -any thoughts?

[oscarmayer]

nice idea, we have a Chinese motor that had that last yr when racing, the issue I discovered was the "seal" used was small and did not properly keep out the dust and dirt, this allowing extra trash into the case there when normally it would not be an issue. On my friend's R we had a machine ship cut a small groove all around the center in the shifter hole of the stock case (similar to a piston clip retainer grove). We then used axle grease in the hold and when we shoved the shifter through it felt like butter. 5 yrs later still perfect and butter. that may be your fixing. allows you to keep stock seal and ensures no extra trash while lubing shaft for smoothness.

that may also be an easier approach than trying to use needle bearings.

[ironchop]

I was looking at this on my Rotax cases the other day (They are getting ready to come back apart and do some touch ups before I start throwing bearings and trans in them ) and I wondered if you couldn't put a needle bearing the size of the shifting shaft to slide through and ride in? It looks like with some welding there would be plenty of room to do it, and would have to shift smoother and would have to work better since it wouldn't be riding right on the aluminum directly -any thoughts?

sounds like a great idea to me.....prevents wear on the shaft journal where it`s aluminum.....keeps the shaft stable to keep the flex and wear on the seal lips to a minimum which I would guess would make them last longer....sounds like a no-brainer

[Billy Golightly]

Could I get one of ya'll generous fellows to slide a caliper over a shift shaft you have laying around this afternoon? I'm at work and anxious to look up bearings in my spare time

If not I'll take a look at one later this evening.

[Billy Golightly]

Great power of the internet;

http://www.ebay.com/itm/like/1414234...ectorid=229466

14x24x6mm

[Dirtcrasher]

Absolutely. Shift drums have needles on one side and with your shops equipment, you can make anything happen.

Personally, although I love all your work, the simplest was the best; That hill climbing front grab bar you made to save the rags as they tumble!!

[atc007]

Back when I was gutting these weekly,this was one of my ideas. No reason it wont work great, and I think the meat is there no problem! Make it happen lol!

[dave ytz250s]

I was looking at this on my Rotax cases the other day (They are getting ready to come back apart and do some touch ups before I start throwing bearings and trans in them ) and I wondered if you couldn't put a needle bearing the size of the shifting shaft to slide through and ride in? It looks like with some welding there would be plenty of room to do it, and would have to shift smoother and would have to work better since it wouldn't be riding right on the aluminum directly -any thoughts?

Good idea, it could also be a good way to fix a worn out hole that creates a seal leaking problem.

[Billy Golightly]

Needle bearings are dirt cheap on ebay;

http://www.ebay.com/itm/390656479121

Think I'll give it a whirl

[El Camexican]

Can wait to see the photos of your Dad checking it out!

Never could figure out why the factories don't at least put a bronze insert in applications that have the shafts sticking way out of the cases. Some old street bikes have worn the hole in the sprocket cover out so badly that you can't keep the seals from leaking. I used to wrap the shift shafts with brass shim stock and flair it out to keep it in place all the while wishing they came with a caged needle bearing.

[Dirtcrasher]

I've always told myself if I had a bad head I would just tram in the Bridgeport and use dial indicator and a boring bar or chucking reamers verses the cost these shops want for saving peoples heads.

All I wondered about was how much crush do they need to REMAIN concentric?? And to keep the needle from spinning.I'd probably use carbide on the cage and a pin in the head to keep them from rotating. If I got all set up, I could do a bunch!

Same principle anyhow.....

[oscarmayer]

defiantly interested to see how this turns out vs. my experiences. yea Chinese stuff can be junk, so being your quality, i am hoping ti works out good. if it does, you may have a lot of people wanting this done.

[onformula1]

Bronze lite oil bushings work great as well.