changing brake fluid

[butthead]

Hi, i want to change my front and rear brake fluid , on the front ,as the bike has a T piece feeding the two front discs is there an order that you need to flush one side first ,before the other
? if so which side, orientated as if you were sat on the bike.


TIA

[BBROWN1664]

It doesn't matter which side first.
Take the reservoir cap off, bleed one side until you get clean fluid through then bleed the other side making sure the reservoir remains full .

Job done.

[butthead]

ah great !  thanks just wanted to check that first, thank you 

[Gnasher]

Strictly speaking with any branch system you should start on the longest leg, so in the case of a Fazer's front the left.  But as mentioned it makes little difference, as the branch is just a tube.   That said I always do the leff first with standard lines and give the branch that joins to two lines going down to the calipers at few taps during the process, while the leaver is in the at rest (fully forward) position.  This will help push any trapped air up and out of the master cylinder     

[butthead]

thanks gnasher , i did read or hear somewhere that the join or T is susceptible to getting air trapped within it , ill do the tapping on it during the change of fluid   

[BBROWN1664]

thanks gnasher , i did read or hear somewhere that the join or T is susceptible to getting air trapped within it , ill do the tapping on it during the change of fluid   

When changing the fluid, you dont drain the old stuff out first. You push the old out with the new so dont gat air in the system.

[butthead]

thanks for all the advice , today i went to see if the bleed nipples would crack easily , they dont seem at all willing , didnt want to apply any more force, theyre only  something like 8 nm , so should be easy to undo.  so its an age old problem, ive used some plus gas on the area in the hope that after a few days it might help to crack the nut.  any other tips for this issue?

[Trebus]

Bit of heat often proves helpful.

[BBROWN1664]

Dont use a double hex spanner or socket if you can avoid it. Less likely to round it off using a single hex spanner/socket

[Gnasher]

Bit of heat often proves helpful.

A bit can't be stressed enough.  Heat the caliper body at the base of the bleed nipple not the nipple, remember they're made of aluminium and there're rubber seals in them be careful or it will end in     

[butthead]

ok so we talking hair dryer or blow torch ? the caliper body is cast ally the nipple is steel , so the ally will expand first ? right , thereby loosening the grip ?

[Gnasher]

ok so we talking hair dryer or blow torch ? the caliper body is cast ally the nipple is steel , so the ally will expand first ? right , thereby loosening the grip ?

Pretty much yes.  A hair dryer won't cut it, a heat gun the type you strip paint with should or a mini blow torch.  When using direct heat be careful of the coating/finish, basically the heat required to expand it enough shouldn't get anywhere the near point to damaging the surface.
 
Put a nipple spanner on the nipple as you apply the heat and slowly apply pressure, it should just undo.  Don't be tempted to over heat, you may need to repeat a few times, cool the area after each attempt with water.   It's also possible it won't work or you strip the threads from the caliper body which is always a risk.

[butthead]

so an update on the nipples , good news , after watching a couple of tricks on you tube , one being to put a socket end on and then tap the socket a few times first to help loosen and another tip was to use either a drill shank or a nail shank ( cut down to suit ) i found an old busted drill bit that snugly fits the nipple hole to help strengthen the hollow before trying to undo , well along with spraying plus gas the night before and the above tricks , managed to successfully undo all nipples without any damage at all 
after undoing i worked them back and forth plenty 1/8 turn on/off to exercise the nipple thread.
im now going to wait until the weather is dryer and warmer as brake fluid absorbs water easily and my garage is unheated and inclined to be damp , so now ive freed them up , ill wait a couple of months  before renewing fluid but ill exercise the nipple threads once a month to keep them from locking up again.
well pleased ! cheers guys

[Gnasher]

Glad you got them out.   

Now check the tapered seat on the nipple if it's scored or damaged it's highly likely the taper in the caliper body is to.  It's this taper between the nipple and the caliper body the forms the seal, not the thread.  They get tight mainly through over tightening which stretches the thread and damages the taper seat in the caliper body, it being aluminium and much softer.  Over time owners and stealers nip them up more and more eventaily you can't undo them in the normal way and new nipples won't seal without over tightening and in short order you're right back where you started.

The amount of water the fluid will absorb while refilling and bleeding the system in your garage, will be undetectable this side of laboratory and even that it will be so small as to make no difference.  You'll be fine to fill and bleed the system, obviously if it's just too cold to work that's different  Be sure not to drain it, leave the system full and check the nipple/s periodicly if they start weeping the taper seats are shot.