Front brake master cylinder refurbishment

Hi All

Looks like the seals in my front brake master cylinder are sucking in air (brake showing signs of air in system and the fluid has bubbles when I bleed the m/cylinder). Part No: 61013001000.

US suppliers sell kits with everything (m/cycl, lever, reservoir, brake switch etc) for $200-$300USD. I'd be happy paying that. Sadly, US suppliers won't send to Australia. Local KTM suppliers want approx $600USD for the same thing.

Has anybody attempted to crack open the master cylinder and replace the seals ?

Cheers J

mate... use www.hopshopgo.com

they have been great to use... gives you an american address so they can ship it there... they then send it through to you

I've not done it but rebuilding the master cylinder is very much an option I believe.

Don't know how much it is but normally you just need the kit with the seal and so, not the reservoir, lever etc...
That is why it is so expensive. The repair/seal kit should only be a few tenners max.
Only order that if you need all the other bits.
You can check by taking it appart and inspect the bore. If the bore is OK just replace the seal.

If you still want it I can check how much it is in NZ. Two of my friends work at the KTM dealer and I can get them to send it to Oz no problem.
PM me if needed.

With KTMGuy on this one. I’ve repaired / restored enough bikes and their brakes to confirm his comments and if the bore has wear don’t waste your time with a new seal, you’ll be back to square one in no time.

Thanks for replies guys . I'll pull it down and inspect the bore.

Ktmguy: How do you pull this unit apart ?. I presume the boot pulls off giving you access to a circlip holding the piston in place ?. Thanks for your offer about getting parts from NZ. I'll get back to you

Regarding KTM Australia's 300% markup on OEM parts and KTM preventing Australians accessing international suppliers. Does anyone know KTM's reason for doing this ?. I'm sure Consumer Affairs would be keen to know as well. I don't bitch about things like this and I have never really minded waiting 1-2 months to get parts via local dealers, but this is bullshit . I am buying a new bike in a few months. This issue will probably cost KTM a return customer.

J

I pulled down the m/cylinder to inspect seals and bore. Here is the break down:



The boot is easy to get off. It retains the piston. There is a small hole at the bottom of the cylinder. You just push a small jewellers screwdriver through the hole and pop the boot off. Once that is removed, the piston and spring comes out.

The piston is double sealed. I'm not sure why. Would this require a special priming/bleeding procedure to stop air getting pumped into system when I rebuild ?

The leading seal (the seal on the right of the blown up inserted image) is retained with a circlip and is easily removed. I'm not sure how to remove the rear seal (left seal). The edging seal looks to be the primary one that pressurises the fluid. The chamber between the two seals is in contact with the reservoir outlet, so it would presumably fill up. I'm not sure how you would extract all air from this chamber, or if you would need to ?

Inspecting the bore and seals. The bore looks good from running my finger down it (I can't feel any wear), although you can see that bore has been polished from the seals. The leading seal looks a bit shagged.

J

From the look of it a new seal kit would fix it. As long as the bore is smooth, which I can't really see from the pic.
Feel probably will not tell you much, shine a torch light in it and look for scratches, imperfections and a "rim" where the piston always stops, if it looks good it should be ok.
Sometimes they can be honed too but don't try that unless you have done it before.
If it was me I would try with just a seal kit anyway regarding the cost of the other stuff.

no luck whatsoever finding a rebuild kit from the genuine parts fische, either here in australia or a UK based company.

http://shop.jimaimracing.co.uk/acatalog ... 05-06.html

this is the cheapest m/cyl i can find, anyone know where there's a cheaper one?

http://www.yoyodyneti.com/ProductInfo.a ... 10.8210.51

paul.

Sounds like you need to do some Google time.

The US comapny I used for Brembo parts seems to have gone.

Try this link, may not be the end answer for you, but could put you on the trail;

http://www.moto-racing.co.uk/cat--Bremb ... pares.html

New m/cylinder arrived a few days ago. I fitted it today. Also fitted new brake pads. It's brakes like a brand new bike again . Thanks for help guys

where did you end up getting the m/cyl from? can you tell us what it cost you too?

cheers,
paul.

Just a suggestion...... you could investigate having the M/cylinder resleeved in brass or stainless. Then buy a cup or piston kit from KTM, if available. Otherwise a lot of these common bore size brake and clutch cups are interchangable between car manufacturers parts.

Just takes time and a bit of legwork. Most brake part shops have individual cups if you take a sample and old cylinder/bore size in they may match it up. If you wipe the cup inside there should be a part number/brand. Try Repco in Australia too.

There used to be a cylinder resleeving service in Lismore NSW, called Hallidays years ago. Otherwise some of the Brakeshops can sent it away to be resleeved, takes a few days.

Cheers