Bloody back..brake

[roymichaeldean]

Hi

The pistons in the rear brake seem to be seized in.....I've given them a good clean, and drained the brake fluid out..through both drain nipples...Mmm...I am about to use C clamps..to squeeze them back in......is this a normal problem ??.....and solution ??

Roy

[roymichaeldean]

Hi

Good news is that after a Trip to B & Q for some C Clamps...which have now taken on an entirely new shape, together with some wood and an extremely large hammer, I have managed to push the pistons back into the seals......lets hope that when I put some pads in and some new fluid, that they will work, as they should !!!!!

regards

Roy

[Max]

Sounds to me like you need to overhaul it. Replace the seals and clean the gunk out of their grooves. You might find a fair amount of damage on the pistons as well, hopefully you can buff them out.

[roymichaeldean]

Hi Max

Does this mean...dismantling the whole Brake....will I need to obtain new piston seals...and..anything else ??........

regards


Roy

[Max]

No, you can do it by (carefully) removing the pistons. You'll probably need access to an air gun with a rubber cone nozzle (and a compressor, of course) to pop them out, especially as tight as they seem to be...

You'll first need to order new seals and dust rings. They're fairly cheap. You will also need some moly brake seal (rubber) grease that you can get from an auto parts store.

First, remove the caliper. Drain what fluid is left out of it.

Insert a piece of flat bar through where the disc would go through. and put something soft to shim like some thin wood or rubber on either side where the pistons are. insert air into the caliper and pop the pistons out to where they meet the flat bar / cushions you have put in. Clean them and the surrounding seals as well as you can at that point and then lube them with something like WD40 and carefully work them back in. This should free them up a bit for the next step.

Pop them out again with the air gun and remove your flat bar. Find which of the two moves easiest by hand and push it back in about halfway. Then try to work the other one completely out. If it doesn't budge, you'll have to find a way to shim the 'free' one in its current postion and without any shim or cushion on the other side, blow that one out to its full stroke possible. Hopefully it will pop all the way out and you can remove it. Now you'll have to horse the 'free' (of the two) one out with your fingers as air pressure will no longer be possible.

Mark them so you know which piston came from which side of the caliper... They should go back in the same pots...

Once you have them both out, remove the dust rings and seals being careful not to scratch anything and then thoroughly remove any corrosion from the grooves. Clean the pistons carfully, if you have corrosion, try buffing them with some fine compound (don't recommend sand paper unless you are using #1000 or above). If the chrome has flaked off, you should probably replace them...

Clean everything with brake parts cleaner, no water...

Lube the new seals and dust rings with the moly grease between your fingers and carefully insert them in the proper grooves. LIGHTLY coat the piston sides as well, and carefully push them back in.

Attach the pads and mount the caliper back on the bike, put in new fluid and bleed them. You should now have 'like new' brakes.


The more often you do this, the easier it is to remove them. If you wait until they are binding up, life becomes difficult.

When I was road racing, we'd do it every other round or so. Some guys before every race. Not only will the 'touch' improve, but your pads will release freely and not be rubbing on the disc, creating heat and wear...

Hope this helps.

[CULater]

You can check out our D.I.Y. guide here:

http://tdmtrx.forumup.nl/viewtopic.php? ... rum=tdmtrx

Or if it's restricted for members only,( and i believe it is, try this one

http://s2.photobucket.com/albums/y47/Su ... 20revisie/

These are just the pics with no text, but you don't have to be a rocketscientist to figure it out!
It's a guide for frontwheel caliper overhaul, but backbrake works just the same!
No spare parts were used, just a good cleaning, use lots of brakecleaner
and make sure everything is spotless clean before putting it back together again.

[Max]

Good photos. However, I think you'll find the rear gets a lot more corrosion damage than the front. I was surprised at how nasty mine looked and I hardly ever ride in the rain (probably guilty of over washing it though...). If the grooves are corroded, you should probably replace the rubber seals / dust rings. They're going to be deformed anyway and you won't want to put it back to gether only to find they leak when everything's clean and free moving again.

[roymichaeldean]

Hi

Thanks everyone for your help so far....I have found some rubber grease, available in the U.K....called Castrol Red Rubber Grease...and reading and looking so far I think I will have to go to local Yamaha Dealer to get them to ' pop out ' the pistons......the actual pistons look pretty good anyway as the bike is a 1999..........but to push them back in took lots of wood.....and a lot of hammering with a big hammer...there isn't a lot of room between the seal and the piston...so air pressure might be the only way to go..
Although I have enough tools to fettle a Centurian Tank, I don't own a compressor.......and they are a bit too much to buy for 1 job...

regards

Roy

[Max]

Speaking of air compressors... Mine is a little Chinese cheapo 1.5hp 100volt job with an 18 litre tank that I have plumbed into a 100 liter sub tank in my garage and another in my attic (for modeling work)!

Sucker (blower?) has run like a champ for about 8 years now with only a few oil changes and is the handiest tool I own!

[roymichaeldean]

Hello again

I decided to go down to local Yamaha Dealer....to check on the replacement seals etc...and after learning they were £18.00 have decided to wait until I extricate the seals etc...........and check the condition.
No-one has the Castrol Red Rubber Grease near me but I think I'll order a tin.... off the Internet...as I have a feeling I may need..to use it quite a bit...with 4 bikes.
Also the Yamaha Dealer warned me not to use air pressure as one of his mechanics was almost killed with the piston flying out...sounds to me like the on-the-job training was poor quality........he suggested using grease and a grease gun...Mmmmmm

Thanks for all the advice...so far


Roy

[phuk72]

Pretty sure I have a spare caliper in my garage gathering dust - IIRC the pads are dead but the caliper etc is all ok.

Yours for the cost of postage and a pint?

Or I also definitely have a 1999 R6 non blue spot caliper, braided hose and mc that you can have for £20 posted (although I am not sure if that bolts on or needs modding to fit as I had a carrier made for an R1 blue spot rear caliper)

Or for £25 posted I can just stick the whole lot in the post for you and you can use what you want and flog the rest on ebay.

Let me know if you are interested and I'll check it is all still there

[phuk72]

Just checked and I've still got it all but it doesn't look like the R6 caliper is a straight swap

Let me know if you want the TRX caliper

[roymichaeldean]

Hi Phuk72

That would be ...maybe..best idea....I've sent a message....

regards

Roy