Wheel Bearing Spacer Machining

[Kestrel]

Question for machinists in the house...

I am putting a GS500 wheel (rear wheel to follow later) on the front of my DR350, and have found the appropriate bearings from Suzuki that'll work with my later dirt forks, which have the 17mm axle. That's all good and dandy.

That said, the inner bearing spacer from the GS500 can't be modified, as it was hardened beyond belief from the factory. So, I will need to fabricate a new spacer with the appropriate length and dimensions to match the inner race on the new, larger ID bearings. Have lathe access, and making that myself isn't a problem.

Question for you all is.. How hard do I really need for a bearing spacer? We have some cold rolled 1018 lying around which would be quite convenient and easy to machine. Also have a few rods of mild stainless in our lab - I'm guessing it's something like 4140, though I'm not sure of the exact makeup. I've worked with it before ;it's harder stuff, but certainly machinable.

Do bearing spacers for a relatively light load application (torque spec on front axle is 40 ft/lbs) require insane hardness? Will what I have on hand work? Or do I need to look into higher carbon steel and DIY hardening / quenching / tempering?

Advise much appreciated!

 

[auntiebling]

Why not anneal the factory spacer, machine it, and try to harden it again?

The inner bearing spacers in have seen are all aluminum.

 

[corndog67]

I've made them out of aluminum for flatrackers, road racers, streetbikes and dual sports. Never had an issue. When the axle is locked down, everything is pulled up tight and they don't move. The only thing I can think of is where the seal rides might wear after a while. Make it out of cold rolled if you are worried about it. The ones on my KTM aren't hardened.

 

[Kestrel]

This is the center spacer between the two wheel bearings, and the worry is that if it goes out of spec, you're applying an axial load to the bearings... which would trash them in short order.

The KTM *INNER* spacers are really made from aluminum? Interesting. Aluminum is also what I've seen on the outside, but never inside... Outer deformations would probably be taken up by the forks flexing in just a little more as things get tightened up. If aluminum would work, that would certainly be easiest.

This OEM spacer is definitely hardened stainless of some sort. Perhaps 'ye olde back in the day overkill Suzuki' or whatever, before cost cutting and light weight was a thing. Didn't consider annealing, then reattempting to machine. That said, I already killed an 11/16'ths drill bit thinking I could bore it out, and I'd rather take the easier way out at this point without experimenting the same piece. And... honestly, it's probably better to remake the spacer anyway, to ensure full contact with the inner race, rather than partial contact from a reduced ID via boring out the old spacer.

Thanks for the feedback.

 

[ircsmith]

of all seven bikes I have the inner bearing spacer is made from aluminum. I got my hands on a set of CBR1000 rims and the front went on my RVF400. I was surprised at how thin the inner spacers was. if you are worried about it fab the spacer from 7075-T6. its yield is almost the same as 4130 (Chromolly steel) around 52000psi. Its Poissons ratio is .33 where 4130 is .29 so it will have a little more spring to it, but like you said torque is only 40ft/lbs on the nut. at that torque its hardly going to get into the elastic range of the 7075.

 

[corndog67]

of all seven bikes I have the inner bearing spacer is made from aluminum. I got my hands on a set of CBR1000 rims and the front went on my RVF400. I was surprised at how thin the inner spacers was. if you are worried about it fab the spacer from 7075-T6. its yield is almost the same as 4130 (Chromolly steel) around 52000psi. Its Poissons ratio is .33 where 4130 is .29 so it will have a little more spring to it, but like you said torque is only 40ft/lbs on the nut. at that torque its hardly going to get into the elastic range of the 7075.

Damned engineers.

What he said.

 

[planegray]

Damned engineers.

What he said.

:laughing
SCIENCE

 

[Kestrel]

of all seven bikes I have the inner bearing spacer is made from aluminum. I got my hands on a set of CBR1000 rims and the front went on my RVF400. I was surprised at how thin the inner spacers was. if you are worried about it fab the spacer from 7075-T6. its yield is almost the same as 4130 (Chromolly steel) around 52000psi. Its Poissons ratio is .33 where 4130 is .29 so it will have a little more spring to it, but like you said torque is only 40ft/lbs on the nut. at that torque its hardly going to get into the elastic range of the 7075.

Ugh, silly me hadn't thought of the different varieties of aluminum.

Will most certainly take the 7075 advice. Need to order some plate anyway for making the caliper relocation bracket, and will throw the 7075 rod into the same order.

Big thanks on the suggestion! Will certainly post a thread up here in BARF once the project is wrapped up.

For attempt #2, I believe I'm going to use a boring bar. Haven't used one before, but the principle is simple enough, and there are plenty of folks around who can show me the ropes.

 

[kuksul08]

I made a couple recently out of 303 Stainless and polished the surface where the seal rides. It machines very easily and, well, it's steel. With aluminum they are typicallly hard anodized for better wear properties.

 

[Lunch Box]

For attempt #2, I believe I'm going to use a boring bar.

Is that one of those bars that serves juice instead of booze? :dunno

:laughing

 

[ST Guy]

High grade aluminum will work. Or as someone mentioned, just use 303 SS. Though not like aluminium, it's still easy to machine.

 

[bambamb43]

I'm a machinist, you can use that mild steel since you have it already, the weight savings from aluminum is minimal, it is only a spacer