Question about stem bearings and front end swap

erock85

Been Around the Block
I have a newer CBR front end that has a 35mm stem and no one is making a bearing that is 35x48.5x15 upper and 35x50x14.25 lower to mate to the CX500, or any other older Honda. So my question is, wouldn't it be possible to just fab my own bearing cups for the stock CBR bearings to be used, 35x55x14 upper and lower? And just cut the old ones off the stem and weld the new ones on. Is this something that is done? I ask because the task of making new cups and welding them are not the issue, but I've never seen this done before and would be a hell of a lot cheaper than a new stem. Do you guys see any issues with this or have you seen this done before? Thanks.
 
Yeah, solution is to have a new stem made and NOT cut the neck and weld a new cup on it for the bearing race
Its cheaper than having your head reconstructed or a spine transplant
 
Maybe I don't understand what dimensions are what, but I'm trying to understand why you guys are talking about cutting anything at all. What year and model CBR are we talking about. What year CX500 and C or D?
 
irk miller said:
Maybe I don't understand what dimensions are what, but I'm trying to understand why you guys are talking about cutting anything at all. What year and model CBR are we talking about. What year CX500 and C or D?
2009 CBR1000rr and a 79 CX500c
They changed the stem in the cbr in 2008 to a 35mm O.D. and there is not a bearing, that I have been able to find, that will match the CX neck. 35x48.5x15 upper and 35x50x14.25 lower. So my idea was to cut the cups, or bearing retainer or whatever they are called from the neck of the CX frame and weld in some new ones to accommodate the stock bearings from the CBR 35x55x14 upper and lower. There are some guys doing something similar on chop cult http://www.chopcult.com/forum/showthread.php?t=34136 with harley fronts mated to yamaha and honda frames. I may adapt that idea. Or the other option is to get triple trees from an older cbr with the smaller stem, assuming the fork tubes are the same diameter.
 
This is what I did to match an RM front end to an XL neck. I machined the RM cup...

1d96bcd8597d10fa7240c78209633207.jpg


To fit into the XL neck...

4413f6bac343d7d524493e0595b1785c.jpg


b11e8f4aeaeafe86d0e9b0d882cd0e4f.jpg


Are you good on the length?
 
irk miller said:
This is what I did to match an RM front end to an XL neck. I machined the RM cup...

Are you good on the length?

Nice!! thats what I'm talking about doing! Yes length is fine...just don't ask my ex
 
You bruised her cervix and she left you? HAAAH!

Eric has a solution but a stem cell replacement is only like a buck and a quarter, shows up in the male (pun) and you insert it into the tree you pushed the old one out of you see


Sent from my iPhone using DO THE TON
 
Tune-A-Fish© said:
You bruised her cervix and she left you? HAAAH!

Eric has a solution but a stem cell replacement is only like a buck and a quarter, shows up in the male (pun) and you insert it into the tree you pushed the old one out of you see


Sent from my iPhone using DO THE TON
I actually understood all of that first read through.
My only concern with a new stem is I believe the top of the stem is 35mm all the way to the retaining nut. So if by machining a new stem down to say 30mm I dont think it would work in the top triple mounting hole. I could be wrong and there may be a solution there with the top triple but again i look for ideas and opinions.
 
I do admit, my solution came BEFORE I got a press. Had I had a press, I may have swapped stems. When I put a VZ800 front end on my R100/7, I pressed the BMW stem into the VZ lower triple. I machined a slotted sleeve to expand the lower part of the stem, as the BMW stem was a smaller dimension to the VZ stem.
 
irk miller said:
I do admit, my solution came BEFORE I got a press. Had I had a press, I may have swapped stems. When I put a VZ800 front end on my R100/7, I pressed the BMW stem into the VZ lower triple. I machined a slotted sleeve to expand the lower part of the stem, as the BMW stem was a smaller dimension to the VZ stem.
good tip, thanks. I may get a stem from an '07 and see if i can make it work.
 
Why the need to weld the cups in? A press fit would be better. I made aluminum cups, when I fabricated my frame, for tapered bearings. I like that they are removable for frame work or powder coating or whatever. You should drill out the rivets on the ID tag and remove it to keep from damaging it, easily reinstalled.
 
o1marc said:
Why the need to weld the cups in? A press fit would be better. I made aluminum cups, when I fabricated my frame, for tapered bearings. I like that they are removable for frame work or powder coating or whatever. You should drill out the rivets on the ID tag and remove it to keep from damaging it, easily reinstalled.
Are you talking to me? The cups are pressed and welded. Extra insurance. How many dirtbikes have you jumped with pressed in cups or non-welded cups? How many motorcycles have you bought have cups that aren't welded in. The damage on the tag was already there, and it's just folded over, and no more damage was made. And not removing something is easier than removing it, buying proper rivets, re-rivetting it, and re-installing it.
 
irk miller said:
Are you talking to me? The cups are pressed and welded. Extra insurance. How many dirtbikes have you jumped with pressed in cups or non-welded cups? How many motorcycles have you bought have cups that aren't welded in. The damage on the tag was already there, and it's just folded over, and no more damage was made. And not removing something is easier than removing it, buying proper rivets, re-rivetting it, and re-installing it.
I didn't realize you were building a dirt bike you were going to go jumping with. I've owned many bikes with press in cups, stock on most Harleys. Doing nothing and causing damage to the tag is definitely easier than trying to paint or powder coat or weld after easily drilling out the rivets. there's nothing special about the drive screws that hold it down.
Let me ask you "How many dirtbikes have you jumped with pressed in cups or non-welded cups?"
 
o1marc said:
I didn't realize you were building a dirt bike you were going to go jumping with. I've owned many bikes with press in cups, stock on most Harleys. Doing nothing and causing damage to the tag is definitely easier than trying to paint or powder coat or weld after easily drilling out the rivets. there's nothing special about the drive screws that hold it down.
Let me ask you "How many dirtbikes have you jumped with pressed in cups or non-welded cups?"
Do people actually ride dirtbikes without ever jumping with them, or riding over rocks, or other debris like logs? And there's this shit called tape that takes about 33 seconds to cover a plate with while you spray. You're such an idiot with your bullshit criticism all the time- like that post you made to me where you tried to correct me by saying there was no such thing as a Honda MR250 motorcycle. The bike we're talking about in those pics is a frankenstein bike purely built to run ragged on backcountry Georgia and South Carolina trails. I did not powdercoat it. I will not ever powdercoat it. It's an untitled frame that I got for $40 to cut up and put an RM suspension on. Know the whole story first, dumbass.

Also: If you look really close in the pic, you'll notice remnants of yellow paint where I machined down the stock RM neck to fit inside the XL tube. Those are welds. So, basicallly what I did there was essentially copy the stock RM design.

1d96bcd8597d10fa7240c78209633207.jpg
 
Without adding to the love on this thread,,, Why not have someone cut a new stem for you to an available bearing size? Is it just a budget or time issue? I've turned my own stem for my TX project bike and have 2 others who have asked me about turning new stems for them as well. It would solve the issue with having to cut/weld new cups in the neck, and make future repairs/bearing replacing much simpler.
 
esmoojee said:
Couldn't you just buy an older cbr triple off of ebay and use it or swap out the stem?
That's what I'm thinking of doing, just replacing the triple tree with an '07. But now I'm not sure the fork tubes are the same diameter. I know this one on the '08 is 54mm at the bottom triple and 50mm at the top. If I just swap the stem I will need some adaptor rings pressed in the triple clamps because the top but is 32mm and the older cbr is 30mm or less. I don't have one to check. I would say a new stem with rings is the best bet. I was just wondering if the cup thing was viable or not. And as irk has shown it definitely is. And I'm not sure what that other dude's problem is but it appears this is "normal" for him. I will update this post with what I do. Should be able to get it done this weekend.
 
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