Pf30 install with loctite 641

wayne17

Hi all
Had a creak on my fsa pf30 Bb when peddling hard so swapped it for a sram pf30, it's now creaking all the time. The fsa pf30 came out looking as good as new so I am planning to reinstall it with loctite. I have ordered some 641 and some 7469 activator, I understand I have twenty minutes to complete the install do I install the cups one at a time and then leave to cure for 24 hours before installing crank or do I install crank straight away and then leave to cure for 24 hours ?
Many thanks

lesfirth

My thoughts are that if you complete the crank installation before the loctite cures it will set with everything in its final operating position but It probably does not matter how you do it.

wayne17

Cheers, that was what I thought too but thought I would check

sungod

even loctite 641 will make it harder to extract in future, before going down that route have you tried just greasing it all? using waterproof/marine grease, don't forget the axle needs greasing as well

if you do want to use loctite, first fully degrease the contact surfaces, then apply the 7649 and allow it to completely dry

cure time varies with material, temperature and how big a gap there is, with just al for instance it can be pretty slow, but if you use activator it goes much faster

imho 20 minutes is pushing it

get everything ready up front so you can go at a decent speed, put a thin coat of 641 on both contact surfaces and assemble it fully, making sure bearings are fully seated

once assembled leave it alone for at least 24 hours, it may be longer before it reaches maximum strength, warmth will speed curing

wayne17

I think the creaking is coming from the plastic cups in the aluminium bottom bracket shell. I greased up the sram plastic cups before fitting and put some grease on axle. Will try greasing up the bearings and putting more grease on the axle but I don't hold a lot of hope but worth a try. I take it if it does not cure the creaking and I use loctite 641 I have to use the activator with plastic cups and a aluminium insert in the carbon frame?

sungod

hmm, yes i'm sure you'll need activator as al is an 'inactive' surface, without it the cure time can be days

loctite advise care using 641 with plastics, but i've not read anyone having problems with it

creaking with press fit assemblies usually indicates poor tolerances (al+plastic, who'd have guessed!) aside from loctite there's a non-setting compound for slack tolerances, i forget the name but might be worth searching

wayne17

sungod wrote:

hmm, yes i'm sure you'll need activator as al is an 'inactive' surface, without it the cure time can be days

loctite advise care using 641 with plastics, but i've not read anyone having problems with it

creaking with press fit assemblies usually indicates poor tolerances (al+plastic, who'd have guessed!) aside from loctite there's a non-setting compound for slack tolerances, i forget the name but might be worth searching

Cheers thanks for your advice