Topic: Tapered Steering Bearings Thread

[squirley]

I have machined outside races before with no problems Crazyypj, and it has seemed to work fine.  Maybe your first reply just didn't read right for me.
As for buying the kit, what is that going to do for me, maybe you didn't read by initial post.
I am not trying to save money by changing my own ball bearings to fit roller bearings with factory specs, I need them to fit a larger inside diameter steer tube.  My plan was to buy a bearing with dimensions 30x50x15, and machine down the outside and be left with 30x48.5x15. 

[turboguzzi]

Squirley

The bearing you mention might work, guess it's best to go to a bearing shop with caliper in hand and measure how much meat you are left with after removing 2 mm

I can tell you that the ssh750 kit does have indeed extremely thin outer races, where the cone is the widest, there's hardly 1.5, maybe 2 mm of thickness.

15.2 is the total beraing height.

TG

[FunJimmy]

Squirley

It sounds like you are attempting the same conversion that I recently went through.
I swapped a Yamaha R6 front end and found that the steer tube measured 30mm for both bearings.
You can see how I addressed this issue at: http://forums.sohc4.net/index.php?topic=27159.0


Taper Roller bearing races are hardened steel and can not be turned on a lathe that is why they are precision ground.
Your CB550 doesn’t have adequate material to open the upper race landing to 50mm.
Another option is to turn the steer tube to 26mm and use the CB550 bearing kit or providing the steer tube is long enough, you could machine a bearing cup similar to a bicycle headset and press that into your CB550 head tube. This will but the 30mm x 50mm bearing on the top of the CB550 head tube so your transplant steering stem will need to be approx 20mm longer than the stock unit.

Good luck

[squirley]

Turboguzzi: I have been to alot of bearing shops, and found nothing.  But I will probably head back and find the bearing that I mentioned and measure it with minus 2mm like you said. 


FunJimmy: I was talking about opening up the inside diamter of the bearing landing race, not the landing on the headstem by 2mm.  And you are correct, I am putting on a gsxr inverted fork.  I have a 19" spoked wheel already hooked up and ready to roll with dual brakes and 320mm rotors, just need to get it on the bike.
I have read your build, (several times), and have thought about turning the stem, but I thought that I might try it this way first as it seems easier.

Thanks for all the input
Jens

[FunJimmy]

squirley

How about using a 30mm x 48mm bearing and wraping 10 thou aluminum or copper foil for a shim.
Better yet, use the foil style feeler gauges. That way you will have a selection in 1 thou increments.

BTW - Where are the pictures of your project?

[squirley]

The 30 x 48 bearing might work, and I would feel better about having a thin guage shim in there.  Do they make circular thin guage shims or feeler guages? I guess .5mm isnt to much of a gap to fill up. 

I have tried uploading pics, but it always tells me that the file is too large. I will have to go resize the pics or something and see if it works.

[754]

Regardless of how thin, try to machine the shim.. much easier to assemble and get a good fit.. I have made them with wall thickness of .020 or less.. so a mm or more on race od is not a big problem..

I never tried turning those races down.. it would be hard to get them nice without grinding equipment.

 And a whole lot easier to make a stem.. most stems are an hour or less of work if you have a few measurements..

[squirley]

I was initially going to just turn another stem, but was recently hired up by a new company, and now only have access to a lathe. 
Aluminum tape seems a little ghetto fab, but I guess once it is all tightly settled, it's not going to go anywhere.

[squirley]

here's an old pic for an idea

[FunJimmy]

Regardless of how thin, try to machine the shim.. I have made them with wall thickness of .020 or less

0.5mm is equivalent to 0.020” (that’s 20 thou. in diameter) equal to only 0.010” each side of the bearing.
Your only hope is steel foil type feeler gauge strips wrapped around the bearing to fit.

It's the top bearing and subject to much lower loads, you'll never notice the difference.

[CrisPDuk]

I may as well put it out here for anyone whose interested, this is the fruit of my recent research into this very issue:

All the the following is accurate for the '78 UK model CB550K (my bike) I'm not sure of it's accuracy when applied to other models or years.

Both the upper and lower bearings are standard bearings from the SKF (and probably others) range.  But - and here's the catch - they aren't from the range generally listed in their catalogues for industrial use.  They are in fact automotive bearings, which I discovered purely by hunting through the rather large stocks accumulated by me and a few friends over the years.

The lower bearing is 50 OD x 29 ID x 14 over faces
SKF part no: BT1B 329013 - These are definitely from their Ford range, most probably non-driven wheel bearings

The upper bearing is 48.5 OD x 26 ID x 15.2 over faces
SKF part no: H284815 -  This is from an Italian car, most likely an Alfa, again given the size it's again likely to be a non-driven wheel bearing.

I've checked with my local automotive factors, and the lower bearing is generally available ex-stock, the upper bearing is a special order item (but is available).  This information is obviously only applicable to the UK, I can't speak as to availability elsewhere.

[FunJimmy]

Chris

You bike measures different that the others.
Our CB550's have a 30 x 50 mm lower bearing.
Are you sure of your measurments?

[754]

If you only have access to a lathe..ummm.. how would you do a stem otherwise??

I can make the sleeve thinner, it is just that it gets a bit tougher as you go thinner (and measuring gets harder). You could use shim stock.. just cut a piece with snips. the nice thing about a machine shim is you can leave a bit thicker are sometimes to help it stay on the bearing, it grabs part of the radius on the bearing... easier than fighting a thin band that is popping out on one side..

ghetto fab.. I like that,,lol!!

Shims can  make a pretty tight assembly if fitted properly, it is just not the preffered metod..if it is metal, fills the space and cant pop out, it is not going to screw up.

[squirley]

That is my mistake 754. It should read.

"I was initially going to just turn another stem, but was recently hired up by a new company, and no longer have access to a lathe, just a mill. 
Aluminum tape seems a little ghetto fab, but I guess once it is all tightly settled, it's not going to go anywhere.

[CrisPDuk]

Just checked my bike again Jimmy, since it ain't assembled yet, and it's definitely 29mm, the bearing is 28.93 ID the steering tube is 29.07 OD.

If the norm is 30mm, it seems that one of my (numerous) previous owners may have performed a modification somewhere down the line

In which case, before using the information in my previous post, people are best advised to check their individual applications

[FunJimmy]

Interesting! Thanks.

[CrisPDuk]

I think I have another set of 550 triples buried in the mountain of crap that masquerades as my spares store, I'll dig them out tomorrow and check the dimensions.

[squirley]

FunJimmy, is there a reason why you chose to mismatch bearings and races on your front rather than do a .010" shim?  To me, it seems that mismatched race and bearing could contribute greatly to premature wear, especially if they may have different inner angles that won't disperse the load evenly. Even if the bottom stem bearing sees the most applied load, there will still be considerable forces on the upper bearing especially when torqued down.

[FunJimmy]

squirley

As you know, getting specifications on these taper roller bearings is like finding a needle in a hay stack.
I had no idea that there was even a 30 x 48 mm bearing available until your thread.
I called All Balls Racing and had them do a search of all the bearing that they supply but no such luck, so I thought a mismatch set was at least a start. Remember, if it fails I have a back up plan to machine the steer tube, but I would go the 0.010" shim route first.

FJ

[squirley]

Thanks for the reply funjimmy, I just wanted to see if you would have done the ship before the mismatch bearing and race.  Looks like I am going the shim route.
Jens

[Ernest]

I changed my steering (cb750 k4) over to a set of tapered bearings from partsnmore.  The set didn't come with anything to seal the bottom of the neck.

Surely someone else has dealt with this, what did you use if anything?

Any ideas on what you could use to fab a lower seal?  Gasket material?

Anyone sell just the seal only?

[dusterdude]

personally,if you`re not going to run the baja 1000 with your bike i wouldnt worry about it.them bearings will last your lifetime without it.

[paulages]

i always reuse the stock dust seal. the rubber part can be slipped out and over race before you start banging at it. the thin metal part always gets pretty banged up removing the old lower race, but it flattens back out quite easily with a hammer and flat surface. what always surprises me, is the lack of any kind of real seal on top. the bearings don't quite sit all the way in the neck, and the spanner nut and triple don't really cover it all the way.

[possum2082]

okay, got my tapered bearings in from pyramid parts. 
i've noticed that the shaft portion of my lower triple has two different thicknesses.  one of the bearings they sent me seems to fit snug on the thin part of the shaft.  the other bearing seems to be too big for the shaft as it can move around the shaft when placed on.

any ideas?

thanks, per usual

[fuzzybutt]

the larger one goes at the bottom of the steering stem
that portion is larger in diameter