Steering stem bearings

[omrimon]

Well, I had a custom steering stem made in order to fit an 06 GSXR600 front end.

One Issue I came across is that the lower bearing landing is about .1mm too narrow at 30.03 causing the bearing too slide on to the landing like the upper bearing, rather than having to be pressed on.

Would this cause any immediate problems or future problems such as steering wobble etc.?

[GeeP]

He missed the fit by .004"?

Fit the bearing with Permatex Bearing Mount.

http://www.permatex.com/documents/tds/Automotive/60940.pdf

It will take up the slack.

[omrimon]

Thanks GeeP (oops), I will look into that.

There isn't any slack really, but it slides down rather easily. What would the consequences be for installing the bearing without the Permatex?

[GeeP]

When the steering stem bearings lose preload the rider will complain that the steering becomes "vague" and wanders slightly.  I would expect a similar complaint if the bearing fit to the steering stem was loose enough.  Realize, any displacement at the steering stem will be magnified by a factor of 5 or 6 by the time it reaches the contact patch of the wheel.  .004" displacement at the bearing becomes .024" at the contact patch.

While I doubt that .004" diametrical clearance on one of the two bearings would cause a vague steering feel, bedding it in Bearing Fit would ensure you never had that problem.  It is a case of additive factors.  If BOTH bearings are loose, then you definitely have a problem and should bed BOTH bearings in bearing fit.

The product should be available in-stock or overnight at any decent industrial supply.   

[omrimon]

Should have mentioned I was using metric. doh!

Remeasured the stem's lower bearing landing again and it is right around 30.00mm  while the stock GSXR measurment is 30.05mm or so.

The bearing just barely slides on, exactly like the upper bearing.

I'll try to find some Bearing Mount online. Thanks for all the info! I will be using the bike for racing and vague steering is the last thing I want. 

[ohgood]

He missed the fit by .004"?

Fit the bearing with Permatex Bearing Mount.

http://www.permatex.com/documents/tds/Automotive/60940.pdf

It will take up the slack.

wonder if belzona is tough enough ? going to look into this bearing mount stuff you mentioned.

[GeeP]

Should have mentioned I was using metric. doh!

Remeasured the stem's lower bearing landing again and it is right around 30.00mm  while the stock GSXR measurment is 30.05mm or so.

The bearing just barely slides on, exactly like the upper bearing.

I'll try to find some Bearing Mount online. Thanks for all the info! I will be using the bike for racing and vague steering is the last thing I want. 

No worries.  2.54 centimeters to the inch, precisely.  Every machinist here knows that, because all of our manual machinery is graduated in inches.   

I get the impression your machinist decided that since the bearing had a 30.00mm I.D. that he'd hit 30.00mm on the shaft O.D.  I think Ohgood will back me up here, that it would have been a good idea to leave about .001" (.025mm) over the bearing I.D. to ensure a light press fit.  I'm suprised he didn't, as that is standard practice.  Obviously, Suzuki left .05mm, although that is towards the outside of the tolerance for a light bearing press fit.

You're very close.  Again, I would use some bearing compound, or non-removable strength loc-tite for that matter and assemble it.  Either compound will take care of the issue.  As long as you're clinical with your cleaning, application, and assembly you'll never have to touch it again.

wonder if belzona is tough enough ? going to look into this bearing mount stuff you mentioned.

Do they make a liquid?  The problem is, he's got a diametrical clearance that sounds like between .002" and .004" on the outside.  That's only a .001" to .002 gap to work with.  Loc-tite will wick that via capillary action.  I would suspect the bearing would wipe the paste off as you installed it.  Though, I haven't used many of their products...

It's like when making a high-precision jig.  The jig grinder guys will make a hole dead nuts on diameter for the pin.  Then, you spritz just a tiny bit of Loc-tite on the pin and then some accelerator and slide 'er in the hole with your thumb.  Can't be a press fit, because that might warp the jig plate or bend the pin.  Comes out with a little heat on the pin with a plumber's torch too, when it's time for repair. 

[The Buddha]

I'd be tempted to try tin foil instead of permatex. But the bearing inner race should be tight on the stem. I think else it can wiggle and wear more and wiggle more and wear more and ... you get the idea.
The upper bearing is preloaded nicely by the lock nut on top. Lower is not.
Cool.
Buddha.

[ohgood]

Should have mentioned I was using metric. doh!

Remeasured the stem's lower bearing landing again and it is right around 30.00mm  while the stock GSXR measurment is 30.05mm or so.

The bearing just barely slides on, exactly like the upper bearing.

I'll try to find some Bearing Mount online. Thanks for all the info! I will be using the bike for racing and vague steering is the last thing I want. 

No worries.  2.54 centimeters to the inch, precisely.  Every machinist here knows that, because all of our manual machinery is graduated in inches.   

I get the impression your machinist decided that since the bearing had a 30.00mm I.D. that he'd hit 30.00mm on the shaft O.D.  I think Ohgood will back me up here, that it would have been a good idea to leave about .001" (.025mm) over the bearing I.D. to ensure a light press fit.  I'm suprised he didn't, as that is standard practice.  Obviously, Suzuki left .05mm, although that is towards the outside of the tolerance for a light bearing press fit.

You're very close.  Again, I would use some bearing compound, or non-removable strength loc-tite for that matter and assemble it.  Either compound will take care of the issue.  As long as you're clinical with your cleaning, application, and assembly you'll never have to touch it again.

wonder if belzona is tough enough ? going to look into this bearing mount stuff you mentioned.

Do they make a liquid?  The problem is, he's got a diametrical clearance that sounds like between .002" and .004" on the outside.  That's only a .001" to .002 gap to work with.  Loc-tite will wick that via capillary action.  I would suspect the bearing would wipe the paste off as you installed it.  Though, I haven't used many of their products...

It's like when making a high-precision jig.  The jig grinder guys will make a hole dead nuts on diameter for the pin.  Then, you spritz just a tiny bit of Loc-tite on the pin and then some accelerator and slide 'er in the hole with your thumb.  Can't be a press fit, because that might warp the jig plate or bend the pin.  Comes out with a little heat on the pin with a plumber's torch too, when it's time for repair. 

whew ! thought i was going to have to do some conversion at first. thankfully we regressed to inchers so i can comment. ya, i'd leave +.001" on the shaft. instead of pressing on things anymore, i'll use a bearing warmer. they make it so nice to not scar the shaft, not mis-align the bearing, and i really can't see well anymore.

suzuki prolly has some super-cool lubricant that allows for non-deforming of parts with 5 thou press on them. no need in re-working a shaft when you have a tube of 'make it fit!' sitting right there on the assembly line - or they just shrink them in

nope on the liquid belzona. i was thinking about an 'oh crap i made the shaft 2 thou too small!' fix. it's tough stuff, but on second thought with all that vibration and the amount of stress put on the steer tube, it's a bad idea. it might turn to powder after a while.

that loctite stuff is getting a small supply ordered soon as i'm in the shop again next week. wanna see how it sets up. (thanks for the recommend!)

ss - i'd use aluminum or brass shim on something that just needed tightening up, but not a load bearing/vibration experiencing thing that mattered like a steering tube. that's just personal opinion, no experience. i used coke cans for my mountain bike's bearing spacers forever. they're still fine. but i don't ride that thing 100 mph either

[GeeP]

NP  I dont' use it often, but it's a life-saver when I need it!

Be sure to get some of the accelerator spray too.  If it doesn't speed up the cure the fumes make the time pass more quickly.   

+1 on the coke cans!  They're usually pretty uniform in thickness too.  I have a stash, right next to the cigarette paper.   

Agreed on the bearing heater.  It is nice to just "drop it on" and is the preferred method.  The deep freeze and redneck bearing heater (toaster oven) come in handy 'round here.   

[The Buddha]

Yea you 2 are 100% ... just the redneck in me wanted to slap it back with tin foil. Knurling it may do ? prolly not. Yea these are interference fit ... That's why I had to make a bearing install tool for lower outer and inner races. ... Oh ... Oops .. buddha's secrets  are out ... Oh no ...
OK weld a inner tace to a tube. That is inner race fitting tool.
Weld a outer race narrow side to the plate. That = outer race tool. Repeat for upper outer. OK well ... flat plate is OK too.
Cool.
Buddha.

[GeeP]

Knurling is another trick, yes.  Since knurling is a metal displacement operation it will "grow" a diameter.  It doesn't take much!  A full #12 knurl will grow the diameter over .012".

I've used knurling on shaper and moulder shafts when I ws in too big of a hurry to make a new one after a spun bearing.

[The Buddha]

To knurl it right, you really have to yank the stem from the lower triple and chuck it up and knurl it. Its almost as much work as getting a new stem made. OK fine, not quite ...
Anyway, knurling can be a way. Whatever you so, do not weld to it if its aluminum. The shock situation in the lower stem will get that aluminum to go brittle/work hardened if welded.
Cool.
Buddha.

[ohgood]

cough, i'll just be over here kicking a pebble until the knurling subject moves away from knurling. i've only produced 2-3 decent knurls in my life. the rest i hid under a pile of chips, out back, in the snow, behind the rusted pile of scrap. tall grass works too.

[The Buddha]

Ohgood - think about this though. Its 6061 aluminum, and it oughtta be perfectly round. If it was out of the lower stem and there was 100% access to it, I dont think its that hard to do. Of course operator's skill and tool quality always is a factor. As is material its made from. 6061 is good, so is 7075. However if it was 20 series, or maybe 6063, common to have pipe made in 6063 and it behaves similar to 6061 except has a tendency to chunk up when you machine it. I bought a good quantity of 1 inch tubing from a place cos they couldn't machine it.
Cool.
Buddha.

[omrimon]

Ordered the Permatex stuff, the 20297 compound for worn parts. Fills gaps up to 0.020" which should do the job, I think.

Would freezing the stem and lower triple do the same job as heating up the bearing? Do you heat the bearing up already packed with grease?

Thanks for your help guys!

[GeeP]

The only time you need to heat the bearing and/or cool the shaft is when installing a press fit.  You don't have that problem.

But yes, I routinely freeze the shaft in in the deep freeze and heat the bearing, with grease, in the toaster on the "keep warm" setting.  That's about 150F.  The seals will keep the grease inside at that low temperature, and the oils should not disassociate with the filler permanently at that temperature.

[The Buddha]

I put outer races in the freezer before putting them in the frame. Usually the frame is just sitting in the sun.
The stem of course is frozen and inner races slid on after you leave them in the car sitting in the sun a few hours. Not that it makes too great a diff though. My install tool does way better no matter what. BFH ... and transferring all that impact to the required location ... 
Cool.
Buddha.

[ohgood]

Ohgood - think about this though. Its 6061 aluminum, and it oughtta be perfectly round. If it was out of the lower stem and there was 100% access to it, I dont think its that hard to do. Of course operator's skill and tool quality always is a factor. As is material its made from. 6061 is good, so is 7075. However if it was 20 series, or maybe 6063, common to have pipe made in 6063 and it behaves similar to 6061 except has a tendency to chunk up when you machine it. I bought a good quantity of 1 inch tubing from a place cos they couldn't machine it.
Cool.
Buddha.

i always assumed the stem was steel. huh, go figure. that'll cut like butter with a little wd-40 and higher speeds, sharp points.

[omrimon]

How long should I put the outer bearing races in the freezer? Can something happen to them if left in for too long? (It's -20c in my freezer)