Stuck crank arm bolt

Discuss light weight issues concerning road bikes & parts.
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pekruhnium
Posts: 74
Joined: Thu Jun 26, 2014 1:42 pm

by pekruhnium

Hi, i have just bought a bike second hand, and I want to remove the existing chainset for another..
BUT. The left crankarm (two bolts) has one bolt rounded and I cant get it out.
The chainset is a Shimano 105 /5750..
The bolt is a 5mm allen.
How do I get it out?

I have tried the torx method, the 5.5mm allen and i just bought a set of extractors, but I dont want to risk it. <br/>

Help much need and appreciated! :evil:
Last edited by Frankie - B on Mon Mar 26, 2018 2:54 pm, edited 1 time in total.
Reason: Removed the shouting from the topic title and cleaned out the non phpbb coding.

alcatraz
Posts: 920
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

I used a torx bit and hammered it in at least 2mm.

Then I greased up and overtorqued the other bolt, to put less pressure on the bad one.

Then with a 1/4 inch socket wrench and a lot of body weight on it, I managed to get the damaged one out.

If that hadn't worked I would just have drilled the bolt out which is not easy.

Because the bolt head is in a recess it limits your options.

Heat is your friend. Alloy (arm) expands more than steel (bolt) so get everything nice and toasty like 80 degrees and try again as mentioned above.

/a

pekruhnium
Posts: 74
Joined: Thu Jun 26, 2014 1:42 pm

by pekruhnium

thanks for the answer :-)
witch torx bit size did u you on a 5mm?
Can i heat it with a hairdryer?
I dont own a socket wrench, but will a screwdriver work?

pekruhnium
Posts: 74
Joined: Thu Jun 26, 2014 1:42 pm

by pekruhnium

Also, did you remove the plastic crank arm bolt before doing it?

kode54
Posts: 1184
Joined: Tue May 23, 2006 9:39 pm

by kode54

there are also extractors that are similr to what @alcatraz mentions that are specific to extracting rounded bolts. most hardware places sell them or on Amazon.
- AX Lightness Vial EVO D + DA9150 + Enve SES 3.4 carbon hubs
- Parlee Altum + DA9150 + Enve SES 4.5 carbon hubs
- Parlee ESX + DA9150 + THM SRM PM + Enve SES 6.7 CK hubs
- Independent Fabrication Ti FLW + DA9100 + Enve 3.4 CK hubs

pekruhnium
Posts: 74
Joined: Thu Jun 26, 2014 1:42 pm

by pekruhnium

I have a extractor but it dosent work by itself.. Should i buy a metal drill first and when try to extract it?
The chainset is barely new, so I would like to remove it and reinstall with new grease..

kode54
Posts: 1184
Joined: Tue May 23, 2006 9:39 pm

by kode54

the extractors have a reverse knurled and sharp edges which 'grabs' the inside where its rounded (on a hex) and digs in to extract it. no drill required.
- AX Lightness Vial EVO D + DA9150 + Enve SES 3.4 carbon hubs
- Parlee Altum + DA9150 + Enve SES 4.5 carbon hubs
- Parlee ESX + DA9150 + THM SRM PM + Enve SES 6.7 CK hubs
- Independent Fabrication Ti FLW + DA9100 + Enve 3.4 CK hubs

moyboy
Posts: 164
Joined: Thu Aug 18, 2016 12:19 am

by moyboy

Take it to the local bike shop? let them take it out?
Hate to see more damage done, as they might have the proper tools.

pekruhnium
Posts: 74
Joined: Thu Jun 26, 2014 1:42 pm

by pekruhnium

I will take it to the LBS. I tried a blacksmith, but he surgested a screwdriver and a hammer.. Didnt work..

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