Hollow Tech II Problems

ollietrex

I have been working on replacing the front crank rings on my crank which is an XT Hollow Tech II. In doing this I need to remove the once piece crank which requires undoing two bolts on the opposite side to the crank rings which hold everything together.



When I was doing this I used a 5mm hex and started turning it and it instantly started to strip the inside of the hex bolt so it seems it was probably a dud hex or a very soft metal. So I have two problems:-

1) Any one know if those bolts are steel of aluminum and a good way to remove them?
2) Can you buy the bolts without the crank or do I have to buy a new crank?

kona

ollietrex wrote: »

I have been working on replacing the front crank rings on my crank which is an XT Hollow Tech II. In doing this I need to remove the once piece crank which requires undoing two bolts on the opposite side to the crank rings which hold everything together.



When I was doing this I used a 6mm hex and started turning it and it instantly started to strip the inside of the hex bolt so it seems it was probably a dud hex or a very soft metal. So I have two problems:-

1) Any one know if those bolts are steel of aluminum and a good way to remove them?
2) Can you buy the bolts without the crank or do I have to buy a new crank?

those bolts are made of ****e, id be guessin alloy.

you have a few options here.
1)how badly rounded is it??soak the crank in wd40 and leave for a hour, if its not too bad, try it again but this time concentrate the force, down into the bolt and turn, this usually works.

2) if they are ****ed, you may need to drill em and tap them, afaik they are a m6 bolt, so you will need a hardend steel m4 drill bit bit and a tap and die,(unless you know what your doing, get someone else to do this)
drill it out and remove as much bolt as you can, then use a m5 tap and cut/clean the threads, using lots of cutting fluid along the way.
now find out how big those bolts are before you do this, i THINK they are a M6!!!

you will need new bolts anyways.:o
why are you removing the cranks, if its for the BB cups you need a special tool, which is different to the hollowtech 1 tool.

EDIT: if its the crank rings you should get 3 and 2 out without removing the cranks at all???maybe try this before you go any further???

ollietrex

I am removing it as I need to replace all the crank rings on the other side and I cant do it without removing it and a lot of hassle. I have done the damage to the bolt now so need to sort it sometime as it will just catch up on me later when I do need to remove it.

I think I will either have to drill it out or knock in a bigger hex to then screw it out.

Does any one know the sort of bolt these are (M6?)?

Can I just go into B&Q or Woodies and buy another one or are they specific to biking? If so any idea which bike shop might be able to help.

kona

ollietrex wrote: »

I am removing it as I need to replace all the crank rings on the other side and I cant do it without removing it and a lot of hassle. I have done the damage to the bolt now so need to sort it sometime as it will just catch up on me later when I do need to remove it.

I think I will either have to drill it out or knock in a bigger hex to then screw it out.

Does any one know the sort of bolt these are (M6?)?

Can I just go into B&Q or Woodies and buy another one or are they specific to biking? If so any idea which bike shop might be able to help.

cycleogical should be able to help you....just find out what kona has xt hollowtech and tell him its broke:eek::o
any M6 with a allen head on it will work, you may need to cut it.
i dont know if the other screw on the ****ed one will work as those bolts are stupidly soft

ollietrex

Some one sent me a link to a PDF file

http://cycle.shimano-eu.com/media/techdocs/content/cycle/EV/bikecomponents/FC/EV-FC-M760-2261D_v1_m56577569830608893.pdf

Seems that they are a Clamp Bolt (M6 x 19) & Washer so I just need to find my self a M6 bolt that is 19mm long at a guess

kona

thats the lad so,:D:D
id try and get a shimano bolt as there is probably a reason they are so ****.....then again maybe not:D
best to be safe than sorry, i reckon the threads could be soft so they put a soft bolt in.

im having a similar problem with a set of all mountain sl, they are ****ty post mount, and the top bolt has ripped the threads out, so i have to replace the insert or change my arm with a tap...which is larger so ill have to modify the brake calliper....fun times:D

kona

actually i just though of a better way.

drill the opposite side(non allen head) with a 3mm drill bit, tap it to 4mm, screw a bolt in and it will come out easy. this way you dont risk wrecking the crank arms:o

Freddy687

Kona's suggestion is probably the best.
I was going to say you could drill form the other side all the way through. This will ease the pressure on the threads and should mean less force to turn the screw.
The prob with this is you need a pillar drill or a very steady hand to stay on center when drilling.

If you got any bit of a turn out of the screw try and remove to other one, this way the crank may release and you can work on the bad screw easier.