Issue fitting hollowtech chainset

dodgyknees

Removed Shimano SLX chainset (hollowtech) in order to replace a worn middle ring.

Changed ring ok but now have an issue when I re-connect the chainset to the bike.

When I tighten up the chainset (using the little hollowtech tool) enough to eliminate any wobble in the crank the chainset becomes too tight and doesn't spin round freely. But if I leave it loose enough for the chainset to spin freely there is play when I wobble the crank.

Has anyone experienced this or have any suggestions?

Danlube

Pinch bolt tightened up?
Does the chainset slide in by hand?
If not did you tap to hard with the hammer?
Axle sitting correctly in the bearings?
Damaged bearing?

dodgyknees

Have removed it and re-fitted it a few times now trying to get the chainset to rotate smoothly.

I slide the drive side chainset in by hand and then tap it a little to push it through. Then connect the crank to the other end and use the hollowtech tool to hand tighten the cranks and pull them in towards the bottom bracket.

Chainset moves freely whilst tightening but once I tighten it (by hand) sufficiently to eliminate any crank wobble it seems to become too tight and then the chainset becomes stiff and difficult to rotate.

Was all fine before I removed it to replace the middle ring so don't think anything should be damaged.

Is there some sort of spacing that should be in place between the cranks and the bottom bracket?

cooldad

The one(s) you took out. Answer is yes.

Danlube

Pinch bolts tightened up? The hollowtech tool simply pulls both crank arms together preloading them against the bearings, doing up too tight will put excess stress in bearings stopping them spinning smoothly. The pinch bolts hold on the crank arm. Are they tightened up?

dodgyknees

Yes, the pinch bolts are tightened up but I did this after I had used the hollowtech tool to eliminate any wobble of the cranks.

Having attached both the drive and non-drive side crank arms to the bottom bracket I assumed that I needed to use the hollowtech tool to tighten them up sufficientlly to stop any movement of the cranks. It is whilst doing this that the cranks then become too tight and don't move freely.

If I pull the crank arms together using the hollowtech tool but leave the crank moving freely then there is play in the cranks and they move slightly. If I leave them like this and then tighten the pinch bolts will this eliminate the movement?

bluechair84

You didn't respond to cooldad about the spacers - all of my frames have used spacers in the past, I don't know if there is such is such a thing as a frame that doesn't require spacers. If you don't have any, maybe you dropped them - check the chainline to see if the middle ring lines up with the middle of the cassette. If the spacer isn't attached driveside it will allow the axle to pass too far throught the BB shell and the splines on the non drive side won't be deep enough for the crank to thread onto leaving a small amount of room.

otherwise;
In what direction is the wobble? When holding the non driveside crank does the end move around more than the axle (suggesting it isn't done up tightly) or does the whole thing move in and out (suggesting it isn't wound into the axle tight enough - lacks spacers). Or do both cranks 'knock' together (suggesting the bearings are shot allowing the axle to move).

dodgyknees

I didn't remove the bottom bracket itself. I just removed the non-drive side crank and then pulled/tapped out the drive side crank in order to change the middle ring which was worn.

Apart from the little spacer between the pinch bolts on the non-drive side crank there were no other spacers I could see.

It was quite difficult to get the drive side crank off and I had to wiggle it about a bit to remove it. When it did come off there was a washer/spacer attached quite tightly to the axle part of the crank as I pulled it out. This washer/spacer was tight fiiting but could be moved along the length of the crank axle and was still in place when I replaced the cranks.

dodgyknees

The wobble I could feel when I didn't tighten up the crankd fully using the hollowtech tool was side to side movement not in out.

cooldad

Yes, the spacers are between the bearings and BB so you wouildn't have taken those off.
The bearings just need to be preloaded finger tight, then the pinch bolts just hold the non drive crank on. Tigtening the pinch bolts will not eliminate axle mobement.
Bearings could be dead.

anjs

Has the plastic top hat come off one of the bb cups? If so try removing from the spindal and putting it back on the bb before refitting the cranks

njee20

When it did come off there was a washer/spacer attached quite tightly to the axle part of the crank as I pulled it out

Sounds like a bearing top hat, are either of the BB bearings exposed? You may need to take that cover off the axle and snap it back into place.

cooldad

Might just mean the o ring, between the crank and top hat.

dodgyknees

BB bearings aren't exposed and BB looks fine. Haven't tampered with this at all.

Think the washer/spacer I could see on the drive side crank axle is probably the O ring mentioned by cooldad, that goes between the crank and the bottom bracket.

Cranks were solid (no movement) and fine prior to removal so can't see why bearings should be faulty now.

Very frustrating that such a basically simple job is causing so much hassle.

bluechair84

If you never removed the BB cups, it can't be anything other than the bearings or the crank isn't seated right so try to isolate one thing at a time;
With the axle in place, pinch the junction between axle and bearings and wiggle the drive side about (as you would do when feeling for play in the headset). Can you feel any undue movement around the tophat or axle/bearing junction? If so, probably bearings gone.
Put the crank on as you would expect to and put a thumb down the hollow feeling for play between the crank and axle - if you can then it might be the spindles are shagged and the crank can't interface properly.


You say side to side movement; as if the crank is moving around the axle and not locking to the spindles properly? Mentioned already but - are the pinch bolts tight enough?

MrChuck

External BB sets don't spin as freely as cartridge ones when you're just spinning them by hand. Are they definitely worse than they were before?

dodgyknees

I had connected the crank firmly with the pinch bolts. The side to side movemnt I could feel was the axle itself through the BB.

This movement is eliminated when I tighten the crank further with the hollowtech tool but then the free spinning of the chainset becomes restricted indicating it is too tight.

I am still only hand tightening with the hollowtech tool and can't really see how I can be over tightening it.

Anonymous

dodgyknees wrote:

once I tighten it (by hand) sufficiently to eliminate any crank wobble

There's the problem.
The little preload cap shouldn't eliminate crank wobble - the wobble won't go away until you tighten the pinch bolts.

The drive side crank is stuck to the axle, which fits perfectly through the BB. The wobble won;t be coming from there.
The non driveside crank clamps on to the axle using the pinchbolts - and will wobble until they are done up.