Best place for custom bearings?

biggraham

New Member
Hi, I'm looking for a bearing w inner 25, outer 43 by 13, to put a RD400f wheel on my GSXR front end, rear is easy, any help would be greatly appreciated!
123114809_10222171715938197_4326974113646813213_n.jpg
 

teazer

Over 1,000 Posts
DTT BOTM WINNER
No guarantee that's the right bearing. I took a few minutes to see what I could find online. Worst case, you may be able to find one with 25mm bore and OD that's "too small". Then you could get a steel ring machined to take up the difference and have that pressed into the wheel housing.

If the only available bearing with the right bore but OD is too big, it may be possible to machine out the wheel to take that larger OD.

Worst case would be a custom axle and sleeve nut to fit the 15/17mm wheel and the GSXR forks. Think of a stock GSXR axle with stock large diameter end and smaller diameter shaft mated to a new aluminum sleeve nut with stock GSXR OD but with smaller bore and thread to take the new axle. That would probably be the most expensive solution, but at least you have options.

BTW you will also need a new bearing spacer to work with that larger axle shaft if you go with GSXR shaft.
 

chickenStripCharlie

Been Around the Block
Are you sure its 43mm?

My gsxr front end swap required a 42mm od 25mm ID and even that was not available anywhere locally.

43/25 is definitely oddball and too close to 42mm to have a "sleeve" made up.

Why cant you use a smaller axle and compression bushings on the ends to fit the fork legs properly?

Before I did my swap all the threads I had come across used original Honda axles. It seems that up until a few years ago 42/25mm bearings hadnt even been manufactured.
 

teazer

Over 1,000 Posts
DTT BOTM WINNER
If you have to get a new bearing spacer, make one that's 1mm longer.

Shims are not the best idea because they will tend to drop out of position making it difficult to get the axle back through the wheel.
 

biggraham

New Member
If you have to get a new bearing spacer, make one that's 1mm longer.

Shims are not the best idea because they will tend to drop out of position making it difficult to get the axle back through the wheel.
Won't that make the bearing be 1mm proud of where it's supposed to sit? I was thinking an inner spacer, 42 by 26(so it won't ever touch the axle) by 1mm, so the bearing would be spot on. Going 1mm thicker on the spacer would be the same as a 14mm bearing, that may easier to locate... Thank for any advice!
 

biggraham

New Member
If you have to get a new bearing spacer, make one that's 1mm longer.

Shims are not the best idea because they will tend to drop out of position making it difficult to get the axle back through the wheel.
Won't that make the bearing be 1mm proud of where it's supposed to sit? I was thinking an inner spacer, 42 by 26 (so it won't ever touch the axle) by 1mm, so the bearing would be spot on. Going 1mm thicker on the spacer would be the same using a 14mm bearing, that may easier to locate... Thank for any advice!
 

teazer

Over 1,000 Posts
DTT BOTM WINNER
Let's try that again.

If stock bearings are 13mm wide and the new ones are 12mm wide, you probably want to make a spacer that is 2mm overall wider (longer) bore should be say 26mm to clear the axle and OD should be say 30- 34mm as long as there's enough room inside the wheel. A 43mm spacer/shim in the recess where the bearing goes will touch both the inner and outer races and will wear out or seize.

You could make a 42mm OD spacer with a bore that's large egough to clear the inner race and you would still need a bearing spacer ( the long tube) that's 2mm longer (wider) than stock.
 

chickenStripCharlie

Been Around the Block
I dont get why he would need a wider spacer.

The bearing-to-bearing distance is going to be unchanged. The bearings sit where they sit.

The only thing that changes with the narrower bearings is the left/right outside spacers.

I went from a 13mm bearing with to 9mm and I just had a new inner spacer made to the exact length of the old one. Everything fit fine.
 

teazer

Over 1,000 Posts
DTT BOTM WINNER
Yes, the inner races will be in the same locations as stock and the outer faces will be 1mm (or whatever the difference is) But......

He is replacing a 15 or 17mm axle with a 25mm axle and will need a new spacer to clear that larger axle anyway, so he has the option to move one bearing out slightly and use a slightly longer spacer.
 

Tim

Administrator
Staff member
Yes, the inner races will be in the same locations as stock and the outer faces will be 1mm (or whatever the difference is) But......

He is replacing a 15 or 17mm axle with a 25mm axle and will need a new spacer to clear that larger axle anyway, so he has the option to move one bearing out slightly and use a slightly longer spacer.

I think the concern is the bearings should sit in their 'seat'. But, that being said, at least on Honda CB wheels one bearing floats - it doesn't get pressed in against a lip. Then there is a retaining ring that threads in and gets punched to lock in place against the hub.

So it largely depends on the hub design. If it has seats for the outer race of both bearings, then you'd press both bearings all the way in (with the stock inner spacer in place of course) and then make up new spacers to position the wheel in the forks or between the drop-outs in the rear.
 

TresCuatros

Active Member
Yamaha did us dirty with their bearing selection, and yes they did use some 23mm ID's on their early, baby, steering stems.

All balls racing has the best resources for bearing info including conversion bearings
https://www.allballsracing.com/media/productshowcase/AllBallsSteeringBearingSizeChart.pdf
https://www.allballsracing.com/forkconversion


My build thread on the DT3 goes into pretty good details regarding the trials and tribulations of identifying the appropriate front end to swap onto my 1973 DT3 Frame.

The easiest way I've found is to pick a bearing OD that fits the frame, then turn the stem down to match a conversion bearing ID that has the appropriate matching OD. That way you don't need to modify any of the frame. If the replacement bearing is thicker than expected (by 1-2mm) these stems and clamps have enough tolerance to accommodate. If the bearing is thinner, a simple spacer can be made.

The results of my extensive research and a bunch of f** ups finally worked for me :)
https://www.dotheton.com/index.php?threads/yamaha-dt3-small-garage-large-ambition.77541/page-2
 

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