As above - this is on my ktm 525 supermoto. Im having a right nightmare trying to get the front brake bled....before anyone says you need to do this that and the other, use a syringe, vacuum pump it etc etc...I just use a simple length of pipe back into the master reservoir, undo the nipple half a turn, pull the brake, bleed some out through the tube, do up the nipple, release the brake...easy. No fluid is lost, you don't have to keep refilling, and ive used this method for years on clutches, brakes, all different bikes manufacturers and systems...its always worked.... Anyway, I cant get the system bled on the 525....there are a number of factors here though.... 1. the pistons were leaking, so I ordered a seal kit off of the net. It was an aftermarket one (brembo apparently have discontinued it as a part - so fowlers tell me - the front end is from a 640smc). The caliper however is the same as an old ducati monster 2. The master cylinder doesn't have a bleed nipple at the top which makes it more of a pain in the arse...not the end of the world but just thought id say. 3. No matter what I cant get the lever to harden up but at the same time I cant get any air out of the system, nothing comes out. Ive taken the caliper off and mounted it in a vice alongside the master cylinder so there are no trapped air issues. 4. Tried taking the master cylinder off and tapping it to get the air out, but nothing comes out.... So, heres my question....should I quit while ive not put much into it....? Assuming I did have this issue in the future and I did get them bled....I don't want to go through all this fucking hassle just to bleed a single caliper...in comparison using the same method I replaced all three brake lines on my zed inside and hour, bled and all back together. I thought about buying a brembo front brake master cylinder but, im not sure which one to go for - seen 16x18 as an example but not sure what that means, plus I need one with a front brake light microswitch and cant see that either. Down at the caliper I don't think ive got hardly any options if any....although I did think about going to riders and seeing if ducati would supply a genuine kit for their caliper as its the same..... Anyway...stuck, not really sure which way to go at the moment....any suggestions would be nice!
I did forget to say that after fitting the aftermarket seal kit and after bleeding the system and still getting a spongy brake lever I can see tiny bubbles around the edge of the pistons telling me that its not sealing (the aftermarket seals didn't feel as good a fit as the original ones). But if I cant get an original set then im knackered as I don't think there are any alternative calipers that can be bought for it....
I'd look at the Frando mate. New Frando 15mm Radial brake master cylinder, suit single front disc | eBay You want the smaller bore of the 15 as only a single disk system. This is the best way to get the adjustability you need.
As regards the caliper, I'd be very nervous about the behaviour of those seals. Even if you can get lever pressure with more bleeding, the idea of it disappearing again when on the road is fairly terrifying. If you're not confident about the caliper, it might be worth asking these people about possible refurbishment - they must have a massive stock of seals: Caliper Seal Kits - Honda, Caliper Seal Kits - Kawasaki items in Powerhouse Automotive Ltd store on eBay! Some might question the wisdom of the "recycling the fluid back into the master reservoir" approach, but that's certainly not going to explain the failure to get lever pressure. Both times I have had trouble with this in recent months it was down to air in the master cylinder (once through having changed hoses, the other due to incompetence during routine bleeding, and letting the level fall too low). The bike with a nipple on the master was easy, but the other one simply took a long time, and a lot of gentle squeezing at the lever watching tiny bubbles come out in the reservoir - I think the trouble is that there's only a small part of the lever travel when the port is open, allowing the air out.
That's the people that I bought the kit from.....IMO it doesn't fit very well....I think its more to the crappy design of the ktm master cylinder, its very small (but then it was design for a smaller disc!) and has no bleed nipple on it either....its funny as when I was assembling it all I did look at it and think "this is going to be interesting..." - this is the thing - do I push on with what ive got or go for new....and safe....
Two things you could possibly try. Undo the union at the master cylinder and fill it and then put your finger over the screw thread to the union and pump the cylinder, this will help to prime the master cylinder, then reconnect when you can feel fluid pushing your finger off the union. After that open the bleed nipple on the caliper and use a syringe and tube to put fluid into the brake line and if you then see the master cylinder level rising then you know fluid is mostly in the (a lot) whole of the line. Then bleed as per normal. Did you use red brake grease to lubricate the pistons and seals prior to assembly? if not the seals might be holding the pistons too tightly and acting like a seized piston, in which case the piston won't move easily. If however as you mention above the seals seem to be "leaking" then possibly the kit is not doing the job properly.
Yeah - that's my thought at the moment....ive messaged them to tell them its leaking....rock and a hard place though...ive fitted the kit, it (IMO) is baggy....the other thing is the very edge of the pistons have got a nip mark on them (where ive had to use pliers to get the pistons out) but it is on the edge and doesn't go back into the caliper to touch even dust seal....I would like to buy some more pistons also (just to be sure) but if I cant get a genuine seal kit then what chance of I got of getting pistons...as I say....monumentally stuck at the moment...
tonight ill take the master cylinder off, drain it, take it apart, clean and ill stick the master cylinder in the dish washer...see if that helps......
They're owned/made by Venhill, you can find the info on their website. Same prices as ebay. I rang them last year and the feedback about warranty/spares etc was excellent, obviously venhill have been doing brake stuff for many many years
Well, that looks like the whole shooting match right there....ill try the cleaning option tonight but if that doesn't work then i think ill go down that route....id rather over engineer something like that, as its that critical....many thanks for the link...its in my watch list now.
These may be able to help, although aimed mainly at cars they seem to be able to do pretty much anything Brake Caliper Rebuild, Painting, Repair and Refurbishment Specialists
Thanks, that's an option....off the cuff question and just to ask again....is there some sort of conversion so i can put a monoblock on there?
Nothing that won't cost the earth. You'd be looking at a £1100 Beringer kit, Magura kit etc. You could go down the road of say a 690 front end on there if you wished. I'd be looking at something like a 560SMR stuff or maybe even a Husqvarna. All big bucks though.
Yeah - but thall means new forks....i was kinda thinking a lump of billet to convert the mounting point from one to the other...i sold the 525 front end to get the 640 front end (wider by an inch) so i could get the excel rims in there...
I've seen conversion fits for mounting just now lowers onto non-radial forks. I've even seen a bracket on something to convert a 65mm caliper mount to a 100mm radial... but in all honesty I don't know when/what it was on and doubt very much it would be compatible for you.
Yeah - i thought as much....ill try the master cylinder clean tonight....when i had the 525 forks i did have a block of alloy billet to convert the caliper type but then i couldn't get the wheels that i had to fit....so, sold the lot, got the front end from a 640 and then got the excels - the whole lot went together in about an hour....easy - now the brake doesn't work!! doh!
yeah - that's where my build thread is based....although theyre not too quick to answer...its not as busy as this forum...
