Yet another HTii btm bracket question

twonks

Merry Christmas all

I've asked this before and not really got anywhere, so thought I'd give it another go and try to word my question better.

I have the below cranks on a new style SC Superlight.



Having just replaced my btm bracket this morning for a Hope HTii number, I am again having the same problem as I did with the original Superstar BB.

I just can't get the left hand crank arm to tighten up enough so as not to have any play or come undone, or more importantly not to put too much pressure on the bearing.

Either with the bearing cup finger tight or torqued up it is always the same.

I have the correct spacers installed and the btm bkt is faced and cleaned.

Does anybody have any thoughts on what might be giving me issues. ?

The left crank arm needs to be so tight to stay solid that it almost crushes the bearing cover and the cranks only spin backwards maybe 1/8th of a turn if pushed with no chain on.

Something doesn't feel right and I simply can't imagine how to solve it without going to a crank that ises pinch bolts to hold it onto the btm bkt .

Edit. This is the left side of the axle. Does it suggest that the crank should be tightened until it reaches he dead stop at the end of the spline things, as if so I need a couple of spacers removing I reckon.



Iggnore the missing bolts as that was another reason for taking the crankset off.

twonks

I had a look at it closer today as I won't be beaten by a bloomin bit of thread.

After searching around and actually thinking, I have concluded that the Aerozine crankset needs things to be exactly mm perfect.

I took the btm bkt out and had a play with the c/set and bkt out of the frame.

Because the crank has the single bolt to tension and tighten it all up, the width has to be exactly spot on.

My bike with the 3 washers in (68mm width) is approx 1mm too wide at the external BB extremes for the cranks to nip up against there stop.

So I either need to get a variety of spacers to give me the exact tolerences needed, machine some off the frame or get a new crankset that doesn't work the same way.

How do Shimano cranks with the 2 grub screws to hold it on work?

I suspect it is like a headset with the centre bolt to apply the correct pressure and the outer bolts to nip it all together. Seems a much better idea.

If this is the case than I need to find a deal on a good c/set without btm bracket as I habve just spent £60 on the hope bb... doh.

turnerjohn

right firstly dont go anywhere near the frame with a saw !

Your nearly correct with your second posting...its a spacer issue.

Ive a set of RaceFace Deux and with the (so called) correct spacers the cranks were too tight, I took out a spacer and re-tired...hey presto perfect alightment. Dont forget that when torqued up correctly the cranks need to be snug against the bottom bracket bearing but not tight. You just need to play to find whats best. Make sure the bottom bracket is in the frame tight as well.

Oh for reference, the bolts on the shimano cranks are to hold the left side crank on; you still need to torque the crankset together tight beforehand.

Hope this helps !

mattv

Also, I have seen coke cans be used to make thin shims for BBs and other parts. Get the shims the right thickness and it'll all work fine.

twonks

Cheers...

I wasn't quite thinking of sawing my frame up, but could get a shop to face it and grind some off.

I took out a spacer and it is too much as the middle section of the Hope BB is then stopping the cup from screwing all the way in, and the crank would bottom out about 1.5mm away from the face, leaving it wobbly.

I'm now readin up on how the Shimano system works. XTR seems to work how I want it to, with the centre bolt pulling the left arm down splines to torque up the set and then the outer bolts to nip it all up.

This is what I want as it gives adjustment and tolerence to work within differing widths (within reason of course)

I really don't want to have to match things with spacers and leave it at that as when it wears there is no adjustment.


Bring back SQ taper

nicklouse

so what does the maker/reseller give as fitting instructions?
it aint HT2.

twonks

Not sure what it is exactly, but it fits the HTii bottom bracket (in theory) as that is what it was supplied with initially.

I've always had the problem I have now with the bearings being too tight, and just put it down to how it is without ever looking further into it.

Now replacement time has come I've done some more research and tinkering and found the above.

I've got some 1 and 1.5mm spacers coming tomorrow and if these do not fix it properly I'll be looking for a new crankset - probably SLX as there seems no point going to XT nowadays.