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Technical & Reference Section => Tech and Restoration => Topic started by: firebird4130 on May 14, 2008, 09:37 PM

Title: difficulty banging sealed crank bearings into cups
Post by: firebird4130 on May 14, 2008, 09:37 PM: installing a 3pc crank ,can anyone tell me if it's normal to have to beat the bearings into the cups like a man possesed? I seem to remember it not being easy but it seems just too tight, any tips for getting them in ?
cheers,
fraz
Title: Re: difficulty banging sealed crank bearings into cups
Post by: SaMAlex on May 14, 2008, 09:47 PM: they are often hard to get in. Its usually cos they aint going in totally straight.

The best way is a bearing press. Failing that, press them in in a Vice.
Title: Re: difficulty banging sealed crank bearings into cups
Post by: firebird4130 on May 14, 2008, 09:52 PM: I knew you would know :LolLolLolLol: I just pm'd to ask!
Cheers!
Title: Re: difficulty banging sealed crank bearings into cups
Post by: Gary72 on May 14, 2008, 09:57 PM: I find it's down to the bearings, got a new set of cranks, see my other postings, got bearings not a matched pair and one pushes in by hand and the other needed some HELP :knuppel2:
Title: Re: difficulty banging sealed crank bearings into cups
Post by: firebird4130 on May 14, 2008, 10:01 PM: It's a nightmare, I've already banged the cups in thinking the bearings would just press in, they were hard enough to fit now I'll probably have to hammer them out tomorrow, and try the vice alex suggested. Great getting advice on this site though I have killed bikes before when there's no one to ask :2gunsfiring_v1: :LolLolLolLol:
Title: Re: difficulty banging sealed crank bearings into cups
Post by: Gary72 on May 14, 2008, 10:10 PM: I'd leave the cups in but dont forget to put the spacer in before the 2nd bearing ::)
Title: Re: difficulty banging sealed crank bearings into cups
Post by: firebird4130 on May 14, 2008, 10:20 PM: yeah I'm glad you said that , as I was beggining to convince myself that I didn't need it! I've always had this with doing bikes I'm like a perfectionist with setting them up, but have to go through several catastrophic errors before getting to the end result, I should know as I've even fitted cranks recently but it's just gone from my head! Every time is like the first :LolLolLolLol:
Title: Re: difficulty banging sealed crank bearings into cups
Post by: sonic-1 on May 15, 2008, 02:44 PM: Quote from: fraz4130 Every time is like the first :LolLolLolLol:
[/quote
ooooo that sounds like so much fun :LolLolLolLol: :LolLolLolLol: :LolLolLolLol:
Title: Re: difficulty banging sealed crank bearings into cups
Post by: pickle on May 15, 2008, 02:49 PM: i'll tempt fate but say i've never had trouble fitting bearings in a BB, my fly spanish ones just needed tapping in....and the ones on my Sugino CT just pressed in with my fingers :-\

with regards the spacer, i just put one side in, then put the spindle through with the spacer on, then push the other bearing onto the spindle and push it in :daumenhoch:
Title: Re: difficulty banging sealed crank bearings into cups
Post by: perry on May 15, 2008, 02:56 PM: so youve put the alloy cups into the frame without bearings in them ?

knock em out and push the bearings into the cups . the bearings are the only part thats guaranteed to be made properly

they WILL fit into the alloy cups , its putting the cups/bearings into the frame where the problem is as no one ever decided what size it shoud be ;D

ive had cups that were 2mm bigger than the shell ::)

get a digital vernier caliper ( few quid these days ) and see what the tolerance is , but i can see you having to sand the cups to fit