Rear master cylinder bracket

veravista

veravista

Senior member
Location
Derbyshire
The Jarama failed it's MOT for the first time ever earlier, had to go to an unsympathetic dealer to get it done as my usual place has closed.  Only reason for failure was the rear brake was deemed not powerful enough (who knew?  Don't think I've ever used it).  Having a look at it it appears that the cobbled together bracketry I made to fit it for the home grown rear sets I put on it fouls at various points on the frame.  I've noticed a few people have moved the M/C up with plates and stuff to straighten the linkage so I suppose I'd better do the same to get the brake to work.  Anyone got any pics of the placement so I can get an idea of how far to move it?

Have attached a pic of mine, and on reflection it's a bloody mess. (And that's not rust, it's patina, OK?)
 

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That's a very strange looking setup. It's nothing like a normal setup for a left foot brake with rearsets. I particularly don't like that offset from the M/C bell crank across under the rear footrest frame tube. It looks like could foul on the frame and it prevents you getting a good angle on the bell crank (link needs to be at right angles to the bell crank when brake pressure comes on). I'm not surprised it doesn't work as it is.

There's a piece of tube welded across the underside of the lower footrest support, just below and forward of the footrest. It's just visible in your photo. That tube normally holds a bearing (brass bush) through which a short crossover shaft takes the linkage to the back side of the footrest bracket. This thread will explain all http://www.laverdaforum.com/forum/index.php/topic,90399.0.html

You could probably source the bits and pieces needed to assemble a conventional right brake rearset linkage. Wolfgang could most likely supply what you need.

Alternatively, a simpler solution for you may be to mount the master cylinder on a bracket that allows you to run a linkage bar across the top of the footrest bracket, something like the photo below. But if I were doing it, I'd try to move the M/C further to the left so the link bar has a straighter run and avoid putting the kink in it as in the photo.

tt2%20024.jpg


 
Think the MOT inspector did you a favour by failing it. :-X
 
I can honestly say in all the years I've had the bike I've never used the rear brake in anger, even when it had the original footrests on it (pre and post crossover), and it does work - just.  Suppose that's just me.  Anyway, I'll have a look at the thread and see what I can come up with - and cheers for the photo.
 
With standard non-rearset footpegs and the long alloy brake lever it's possible to lock up the rear wheel.
The linkages, positions and leverage ratios are all to cock with the rearsets.
 
So I thought, bugger it.  Have jacked the brake lever up to give some clearance, put it to the outside and it works fine now - well at least until it gets through it's test (it only just failed after all....)
 
The Monty uses a curved link rod to avoid the frame and still operate reasonably once you get the angles right, but with very little weight on the back you
don't want anything vicious.

My MOT guy would have failed it for the lock nut on the front rose joint not being nipped up to the rod.
 
Personally I think he failed it because I had to give him a hand getting it onto the centre stand and he couldn't keep it running.  Bloody kids of today, eh?
 
It is possible to get the rearset brake linkage to work well enough with the original master cylinder so that it will lock the back wheel without much effort. A rear brake is a useful thing. I like to have one that works.
 
Probably a stupid question but has anyone tried a remote reservoir version off a modern bike (must have, surely) - only I've got an old CBR400RR sat in the garage, on a quick glance it looks like a decent shoe-in replacement although I've not really looked at piston sizes or such.
 
The CBR400 is a nice pocket rocket. Does your's have the gear driven cams? Being the RR I believe it does.

Veravista if your pads have been installed forever and a day try a new set of pads first. I'm using the Lucas MCB19 organic pads in my Jota and they work fine with the original rearset set-up.

Tom
 
veravista said:
Personally I think he failed it because I had to give him a hand getting it onto the centre stand and he couldn't keep it running.  Bloody kids of today, eh?
Click to expand...

When I took my Jota in for the MOT the lad couldn't get her restarted for the brake test. I suggested a touch of choke to get her going. He said 'CHOKE'? as if to say 'what the heck is one of those and where does it live'?
 
The 749/999 series D*****i has a tiny bare horizontal rear master cylinder with a remote reservoir that is only 53 euros new.
If the bore was suitable it would allow you to vary the external pivot to give the lever travel required.
Cant see the breakers having a huge demand for them if you wanted to try one out.
 
That's the idea but by the time you put a new piston seal kit in it wouldn't be far off the cost of a new one.
There is a much newer KTM rc8 one with a trimmed brake sensor & braided hose that looks a better option for ?55.
Many of the newer Japanese bikes also use Brembo parts. 
 
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