Master Brake Cylinder (Disc Brake)

[Charlie Papa]

The master brake cylinder in my D2cT has failed, coincidently at the same time as the same part in a Ventus 2bX tied down near me.  The mechanic says they do far too frequently.  This has been a problem plagued system in my ship, and it seems the disc brake is from some obscure motorcycle; the mechanic and parts manager in a local motorcycle shop just shook their heads.  M & H appear not to have spare in stock, and just sold a used unit from a wreck to the other owner.

 

So, although the mechanic (Russell Brown if you need someone good in central Florida) has found one in California, I have two questions:

Anyone have a source for parts, or even part numbers?

Anyone  have an improved set of components to substitute, - more robust and readily sourced?

[Clay]

Have you checked Wings and Wheels?  He has some drum to disc conversion kits on there with master cylinder part nos. (not specifically for D2 though).  

[Mike the Strike]

My D2 brake slowly deteriorated from a leak in the brake cylinder until I could no longer ignore it.  My A&P got a refurbishment kit of seals and rebuilt both master and brake cylinders.  Bleeding the system was a right royal pain, but it has functioned perfectly since the repair about three years ago.  No idea where the seals kit came from, though.

Mike

[Charlie Papa]

Problem solved!

 

First, the part is from Magura, and the part number is M122000 7/8".  Also labeled SKU - 344485.

 

But the problem, which presented as failure of the caliper to retract after braking, - the brake stuck on, arose, I think, from a slight shortening of the cable to offer more travel for the lever, - to improve the brake's effect.  This was to compensate for the larger grip on the stick of the LX remote, which stopped the full travel of the brake lever, and was done at the recent annual.  It also prevented the fluid from returning as the cylinder was slightly engaged.  The cylinder itself was also very corroded.

 

It was after fitting the new cylinder and trying to bleed it, - (must be done from the bottom up), and discovering that the fluid would not flow through the cylinder into the reservoir, that the over-tension in the brake's bowden cable became apparent.  A slight adjustment of the cable and all is well. 

 

Thanks to Russell Brown, mechanic in central Florida, who sourced the part, and to Magura, who air freighted it overnight for $120 delivery included.