bottom bracket wave washer necessary?

[chiasticon]

I asked this question in another thread I started but as it's kind of a different subject, I'll start a new thread. for reference, that one is here: http://forums.thepaceline.net/showthread.php?t=186656

anyway, I'm using a Wheels Manufacturing PF30 to GXP outbourd BB (as seen here (http://wheelsmfg.com/bottom-brackets/pf30-outboard/pf30-outboard-bottom-brackets/pressfit-30-to-outboard-bottom-bracket-for-24-22mm-cranks-sram-w-angular-contact-bearings-black.html)). this essentially turns my PF30 into a GXP BB. their instructions call for a wave washer to be installed on the drive side. because of the issues I'm seeing in the above thread, I'm wondering if I can get around using this to improve the chainline. my question is: how necessary are they? I know that they set the bearing pre-load and take up any slack in the BB/crankset interface, should there be any. but I have none if I assemble without the wave washer. there's no excess drag and no play in the cranks. moreover, when you buy a straight GXP bottom bracket, the wave washers aren't included; they only come with this PF30 to GXP all-in-one adapter kit. I assume the idea is that they *may* be necessary because the PF30 shell diameter can differ, as can how far the cups are pressed in. but if there's no play and no drag, will it hurt anything to ride it this way?

[shovelhd]

I have no experience with PF30, but plenty with BB30. The wavy washer sets the bearing preload for cranks that don't have a preload adjuster. Since this is an adapter, there is no adjuster, so you should use a wavy washer. Preload play is in the tens of thousands of an inch. Setting it properly is key to BB30 bearing life. Besides, the washer thickness is what, .100? How much is that going to affect your chainline if you remove it? It sounds like you're overthinking things a bit here.

[chiasticon]

The wavy washer sets the bearing preload for cranks that don't have a preload adjuster. Since this is an adapter, there is no adjuster, so you should use a wavy washer.as I said, normal gxp threaded BB's and their associated cranks have no pre-load adjustment either, and no wave washer.

Preload play is in the tens of thousands of an inch. Setting it properly is key to BB30 bearing life.these aren't BB30 bearings, they're basically normal gxp bearings (24mm) shoved into a cup which presses into a PF30 shell. they sit outboard of the shell, just like standard threaded external bearings do.

Besides, the washer thickness is what, .100? How much is that going to affect your chainline if you remove it? It sounds like you're overthinking things a bit here.I don't disagree that I'm probably over-thinking it! just want the problem solved! but removing the wave washer all but eliminates the noise, in the stand at least.

[kramnnim]

1. Add spacers as necessary to take up any play,
remove spacers as necessary if
binding occurs.


Standard GXP bearings don't use the wavy washer because the NDS bearing is pinched between the NDS arm and the step in the spindle between 24mm and 22mm. Not sure about the Wheels Mfg adapter, seems like it would be the same...

Copy/paste from random MTBR thread-

"IMO it's pretty optional on a GXP anyway, unless you need it to hold the DS dust shield in place; the press-fit of the left bearing cartridge in its cup laterally locates the crank well enough for most scenarios, although you'd probably need to bash the NDS side in after dropping it wrong or maybe striking the right pedal."

I'd call Wheels Mfg, they were helpful and knew their stuff the few times I've called.

Oh, and the wavy washer is indeed thick enough to affect chainline, when not compressed. But chainline should be set by the location of the NDS cup, since its GXP.

[chiasticon]

I'd call Wheels Mfg, they were helpful and knew their stuff the few times I've called.

But chainline should be set by the location of the NDS cup, since its GXP.called 'em and wasn't able to get through or get call returned so tried chatting and got someone right away. at first they said: "it's absolutely necessary to ensure your preload is right" but then after I described it more said: "if you're sure the preload is set right, then you should be good to go." I mean, there's no play in the cranks and they spin freely; how else do I verify preload, right?

I'm not sure what you mean by setting chainline via the location of the NDS cup...:confused:

[kramnnim]

With standard GXP bearings, the nds bearing is sandwiched by the nds crank arm and the shoulder of the crank spindle, where it goes from 22mm to 24mm. There is no lateral movement since the bearing is fixed in place. I would think the wheels mfg adapter would act the same way. The wavy washer would just apply light pressure between the ds arm and the ds bearing...

BB30 and Shimano are not like this...the spindle is the same diameter on both ends, and can move laterally if there is space for it to move. (Spacers and wavy washer fill the space)

[donevwil]

As far as I can tell the Wheels Mfg GXP BB uses the Enduro solution that does require a wave washer, evidently merely to keep the DS bearing seal in place.

1697919886

[kramnnim]

Having a hard time trying to describe what I mean...

With a Shimano crank, you slide the ds arm through both bearings until the inside of the ds arm hits the outside of the ds bearing. Theoretically you could put a spacer in there to force the ds arm away from the center of the bike.

With GXP, you slide the ds arm until the 22/24mm shoulder contacts the inside face of the nds bearing. The inside face of the ds arm may not contact the outside face of the ds bearing. The wavy washer would fill the space. But the shoulder of the spindle would still be stuck tight to the inside of the nds bearing, because the crank arm bolt is compressing the nds crank arm against the outside face of the nds bearing.

...hopefully that was a better description, maybe not. Typing from my phone.

[kramnnim]

I don't really understand why the chain noise goes away when the wavy washer is removed, though. It shouldn't be affecting the chainline. :confused:

[donevwil]

The last step (last page) of the Wheels MFG installation instructions (http://wheelsmfg.com/tech/PDF/PF30-OUT-SRAM-AC-INSTRUCTIONS.pdf)mentions:

"Add spacers as necessary to take up any play, remove spacers as necessary if
binding occurs."

So do you need to remove a spacer to allow room for the wave washer ?

This wouldn't be necessary if the design actually did pinch the NDS inner bearing race as the SRAM/Truvativ design does.

[kramnnim]

Maybe the nds bearing is narrower than normal, and the crank bolt is tightened until the crank arm bottoms out on the spindle. This would allow the spindle to move laterally, as long as there is space for it to...

[donevwil]

Maybe the nds bearing is narrower than normal, and the crank bolt is tightened until the crank arm bottoms out on the spindle. This would allow the spindle to move laterally, as long as there is space for it to...

I'd just like to know the logic in changing and complicating a perfectly good, simple design.

[kramnnim]

Maybe the angular contact bearings need light preload or something?

[donevwil]

Maybe the angular contact bearings need light preload or something?

Good point, the question should be why are they using angular contact bearings when radial bearings are a far better solution if axial load can be avoided, which is the whole intent of the GXP design.

[Tony T]

I asked this question in another thread I started but as it's kind of a different subject, I'll start a new thread. for reference, that one is here: http://forums.thepaceline.net/showthread.php?t=186656

anyway, I'm using a Wheels Manufacturing PF30 to GXP outbourd BB (as seen here (http://wheelsmfg.com/bottom-brackets/pf30-outboard/pf30-outboard-bottom-brackets/pressfit-30-to-outboard-bottom-bracket-for-24-22mm-cranks-sram-w-angular-contact-bearings-black.html)). this essentially turns my PF30 into a GXP BB. their instructions call for a wave washer to be installed on the drive side. because of the issues I'm seeing in the above thread, I'm wondering if I can get around using this to improve the chainline. …

I would install the wavy washer, and if you get the "noise" described in the post you linked ("when I'm in the big ring and lower three cogs, it gets increasingly noisier"), on the road, not in the stand, then I would remove it to see if there is any change. If no noise, leave it in (as the instructions do "call for a wave washer to be installed on the drive side")

[chiasticon]

fwiw, the Praxis conversion uses the exact same wavy washer concept (linked below). also, the WM version I have is indeed the angular contact one, but it appears the instructions are exactly the same for the ABEC-3, hybrid and ceramic variants. the Shimano one is not, of course, since Shimano you can adjust pre-load as needed.

http://www.praxiscycles.com/wp-content/uploads/GXPISIS2-CONVBB-INSTR.pdf