Noisy gpx bb / crank but only with chain on..

DodgeT

I've had alook in the faq's, but can't find anything like this issue..

Bits - sram 2200 carbon cranks, truvativ gxp BB, KMC chain, on spesh enduro.

So, spinning the cranks, its quite noisy, bearing kind of noise. But with the chain off, its as quiet as a mouse and seems very smooth. There's a tiny bit of movement if I hold the crank arm and try to move it against the frame, ie not turning it. It is very slight and no noise is apparent.

I did notice an occasional noise yesterday when under heavy load going up hill. Again from the BB area.

If the bb was shot, would it be noisy when spinning with no chain on too, or only if it was really buggered?
Might strip it down and clean/re-grease just as a precaution.

Chunkers1980

When you say spinning with the chain on is that under load?

Also, there should not be movement in the arms - something is up.

DodgeT

Just freewheeling the crank backwards.
Just stripped it down, seems the plastic seal which goes on the drive crank / shaft was fitted not too well and has let lots of crap in.. i'll post some pics in a bit..

DodgeT

The drive side bearing was absolutely full of crap and notchy, that's had a good clean now (both sides have) and all is re-greased and running smooth.

Might invest in some of the enduro sealings (thanks to stubs old post on here http://www.mountainbikecomponents.co.uk/items.asp?CategoryID=237&Name=Hollowtech+II+bearing+upgrade ) when they go gritty again.

This is what it looked like...

delcol

the problem lies in the gxp bb they cr4p.. google them and see the reviews...
the seals are poo on them there's reports of them failing after 2-3 weeks around 30-50 miles....
you can get hope and chris king bbs to replace the oem gxp bbs..

i gonna run a carbon noir on my hardtail with a hope bb...

DodgeT

I know... The enduro bearings are supposed to be a good upgrade though, so i'll see how it goes and probably buy some next week. Luckily, goldtec are quite close to me.

sanchez89

DodgeT wrote:

The drive side bearing was absolutely full of crap and notchy, that's had a good clean now (both sides have) and all is re-greased and running smooth.

Might invest in some of the enduro sealings (thanks to stubs old post on here http://www.mountainbikecomponents.co.uk/items.asp?CategoryID=237&Name=Hollowtech+II+bearing+upgrade ) when they go gritty again.

This is what it looked like...

that looks pretty rank in there. i can detect a slight hint of a noise from my BB, same as you only when the chain is on.

did you remove the BB cups to give them a good clean? and can i ask what you used to clean and re-grease them?

DodgeT

It was....

I removed both parts of the bb from the frame, took the retaining clip out (flick with screwdriver), then carefully took the seal off (using stanley knife) being very careful not to cut the seal.
Then, soak in plusgas or similar for half hour, give them a spin and keep spraying plusgas in till they're nice and clean.
Dry off, reload with grease (i just use some general auto grease) and re-assemble.

Didn't bother taking / pressing the bearing out as you can do a good enough job with it still in the cup.

Simples.

Chunkers1980

what about the play?

DodgeT

Don't actually think there is any. It's not that it moves, as if you would feel it going kind of dunk dunk.
I wonder if it's just flexing very slightly? Do carbon cranks flex a tiny bit, or it could be the tiniest amount of play in the bearing, being exaggerated at the end of the crank?
I don't think there's anything up with it.

Muttly1981

delcol wrote:

the problem lies in the gxp bb they cr4p.. google them and see the reviews...
the seals are poo on them there's reports of them failing after 2-3 weeks around 30-50 miles....
you can get hope and chris king bbs to replace the oem gxp bbs..

i gonna run a carbon noir on my hardtail with a hope bb...

One of the lads is/was (had his bike stolen the other week) on his 3rd Hope ceramic BB in the last 12 months my ceramic BB from superstar has not skipped a beat and at half the price. To be fair to Hope though they have sent a replacement BB each time within 24 hours of contact. As you say though the GXP BB that came with mine and my mates the Meta's were shot within 2-3 months.

bennett_346

That seal was on back to front i hope you realise...

DodgeT

bennett_346 wrote:

That seal was on back to front i hope you realise...

The one on the shaft? Don't see how?
There isn't one on the other pic, as its the same one you can see on the shaft, thats the drive side bearing.

bennett_346

The one on the shaft should be on the other way round. With GXP, there is always a gap between where the spindle ends and where the bb starts, and the idea behind this seal is that the tube around the spindle spaces the face of the seal against the BB cup. The way you have it round means the face of the seal is sitting a cm away from the BB cup.

Source: I have made this mistake myself once and seen the consequences.

DodgeT

Well, this is how it came from the factory.. So I just put it back exactly as it came off. It all seemed to be fitting properly, will have to have another look tomorrow. Could explain the lack of sealing i suppose.
Don't suppose you have an exploded diagram to show for sure?

bennett_346

Mine have also came this way from the factory, but you cannot look at me and tell me it's correct. The seal doesn't even near touch the BB in that setup. Unfortunately there are no diagrams of this which may be why there's so much confusion over it, but if you swap that over and put it back together you'll soon see how it makes more sense

From SRAMtech manual online:

NOTE
GXP seals are designed to prevent contamination and therefore must rub against their sealing surfaces. Press external seals into place so that the outer lip seats firmly in bottom bracket cup groove.

DodgeT

Wasn't questioning you, just saying that's how it come. Even stranger then that both ours were like that. There's a lot of reviews saying they fail very soon, no wonder if they're being assembled wrong..
Shall have to strip it down again tomorrow night.. Least it's only a 5 minute job, takes as long to get the chain routed on as it does to fit the cranks

So, the seal must fit into the groove on the inside of the drive crank then I take it? It did look like there was a recess there.

bennett_346

DodgeT wrote:

Wasn't questioning you, just saying that's how it come. Even stranger then that both ours were like that. There's a lot of reviews saying they fail very soon, no wonder if they're being assembled wrong..
Shall have to strip it down again tomorrow night.. Least it's only a 5 minute job, takes as long to get the chain routed on as it does to fit the cranks

So, the seal must fit into the groove on the inside of the drive crank then I take it? It did look like there was a recess there.

The trick is getting that seal back off the spindle in one piece, it seems to be a very tight fit and i wrestled for a long time to get it off. It is doable though.

I'm not sure what it means by groove. But i know it sits flush against the face of the bb cup, and it turns with the cranks. My BBs have lasted longer with the cup seal like this because it keeps a lot more of the crud out without relying on the actual bearing seal.

Hope this helps!

DodgeT

Came off easy enough, just did it gently with a screwdriver, in between the rings so could get a nice flat angle at it.
Like I say, makes sense then why so many are going wrong so soon if they're blatantly fitted wrong..

Cheers for the info, i'll report back with a pic tomorrow night so hopefully it'll help others.

DodgeT

Stripped it tonight and took some pics

This is the seal


and from the other side


the outside of the non drive bearing


the spindle with the seal fitted in the opposit direction


It ( to me ) just doesnt look right with it fitted the opposite way. Also what is weird is that if standardisation were to apply, the outer of both the seals would show GPX, as it does in the very few tech docs you can find. So the first way would be right.
I placed the spindle into the bb with the sel on opposite and it was a mile off going in, felt as though it would crush the seal on tightening.
So, i pulled it out, swapped the seal back to original and fitted it back together....

All looks ok, but, upon closer inspection, you can see that the seal is nowhere near touching the outside of the bearing.....

You cant see it from here, but here's a pic anyway


So, i'm going to go swap it over again and hopefully the seal wont crush and all will be fine.

Just doesn't seem like it should go together the other way, and why are the "factory" fitting them the other way round????

Will report back shortly

DodgeT

Done. Fitted OK, didn't feel as if it was being squashed. All lines up OK and you can see the seal now and not the side of the bearing.
Feels like there's more drag in the crank now than before though and the "play" is back.

Going to get some enduro bearings at the weekend and be done with the stupid GPX seals...

bennett_346

DodgeT wrote:

Done. Fitted OK, didn't feel as if it was being squashed. All lines up OK and you can see the seal now and not the side of the bearing.
Feels like there's more drag in the crank now than before though and the "play" is back.

Going to get some enduro bearings at the weekend and be done with the stupid GPX seals...

Agreed they are a terrible design. IMO neither way round is perfect, i just live with it and prefer it this way.

sanchez89

is the seal that sits on the crank spindle meant to be there? too me, even though i have no experience of these, i would say that the seal should fit into the bearing first, the way you took it off, and the way the factory fit it, the outside edge of the seal should fit into the outer race of the bearing, in the way a normal rubber or metal shield should.

while the small diameter part fits inside the bearing so the crank spindle isnt in direct contact with the bearings inner race.

if you understand what i mean?? basically the way you took it off from factory, remove the seal from the crank spindle and insert it into the bearing as far as you can, the GXP thats embossed on the seal will need to be visible, thats why its there.

bennett_346

sanchez89 wrote:

is the seal that sits on the crank spindle meant to be there? too me, even though i have no experience of these, i would say that the seal should fit into the bearing first, the way you took it off, and the way the factory fit it, the outside edge of the seal should fit into the outer race of the bearing, in the way a normal rubber or metal shield should.

while the small diameter part fits inside the bearing so the crank spindle isnt in direct contact with the bearings inner race.

if you understand what i mean?? basically the way you took it off from factory, remove the seal from the crank spindle and insert it into the bearing as far as you can, the GXP thats embossed on the seal will need to be visible, thats why its there.

You'd think. This just pushes the seal back to how he originally had it as the sleeve on the seal doesnt fit between the axle and the bearing race.

Welcome to GXP.

386ka

Hollowtech all the way!

Anonymous

How old is the BB anyway? They've made improvements to seal up a little better. Hard to tell but looks like a straight edge on the cups whereas new ones have a curved inwards edge.

Old factory fitted ones did seal more flush against the spindle, or at least mine did (the cup was deeper than the new ones).

The current ones the seal definitely goes flush on the cup and there's a gap between that and spindle. That's normal.

Some discussion here too http://forums.mtbr.com/drivetrain-shift ... 28751.html

Not really had problems with the GXP aside from the confusion over the gap. BB lasted for several years on the old GT and that was the old style BB too. Any grinding I got was always from crud in the chainset and in the suspension pivots, and never got any play. Got GXP on my current bikes and they're deal simple and spin perfect even months later with no play developing.

DodgeT

About 6 months of riding, dunno about manufactured date.

Well, in that thread, everybody seems to be happy that it should go on the original way and state that fitted the opposite way would cause side loading, which could be why my crank is now dragging..
The idea of fitting an o ring or similar to fill the gap seems a sensible option too.

nicklouse

DodgeT wrote:

The idea of fitting an o ring or similar to fill the gap seems a sensible option too.

why?

not needed and can cause more issues.

DodgeT

Well if you look at the pics I posted, its obvious that the drive side bearing has got full of crap due to there being a gap between the bearing and the plastic seal. Funnily enough the non drive bearing is covered flush with the plastic seal and this was clean and like new.

The o-rings/spacers people were using on the other forum served to fill the gap, so no water ingress could occur.

So are you saying that you would just run it with the gap and the side of the bearing exposed? To be fair thats how its designed and how I had originally re-assembled it, but it sure doesn't seem right.

Just to clarify, I won't be doing that myself, i'll be getting some enduro bearings fitted at goldtec at the weekend.

1mancity2

It's designed to have the gap, filling it with a "o" ring or similar may cause problems, cranks dragging, dirt sitting between "o" ring and bb causing more wear.

DodgeT

So why have a gap between the seal on the drive side, but none on the non drive?
And the drive side fills with crap, while the non drive side doesn't?

Its a funny one, which as I've said, just gona get rid of as don't want the hassle like a lot of people seem to get with these not lasting long at all, me being one. I'm surprised you didn't hear it clunking away up those climbs on saturday..