Hi all, Finally found the correct Tokico M/C for my Z, to replace the existing Sanyco M/C. However the brake booster piston is too long. When depressed the Tokico stroke is 1 1/8”, whereas the Sanyco is 2 1/4”.
Does anyone know the length of the booster piston for the original M/C?

2 hours ago, bluez said:

When depressed the Tokico stroke is 1 1/8”, whereas the Sanyco is 2 1/4”.
Does anyone know the length of the booster piston for the original M/C?

I'd think that most people know the factory setting, assembled, but few know the length of the rod.  Not sure why you're talking about depressed and stroke.  It's just a starting point and the stroke distance is determined by the pedal travel.

Also, the "piston" in the booster does not resemble a piston.  Maybe you're talking about one of the rods?

Thanks, am referring to push rod.  The Tokico m/c stroke is substantially less then then the Sanyco, (approx 1 1/8” shorter). This will minimize the pedal travel. Additionally the gap difference between the Tokico m/c secondary piston cup is approx 9/16” less then the Sanyco (when not depressed). A total of 1 11/16” less travel then the Sanyco. From the inside, the booster threaded valve rod allows about 1/2” of adjustment.

So it looks like the push rod needs to be shortened approx 1 3/16”. Am I missing something?

The available stroke will not affect brake operation if both of them offer "enough" stroke.  (That's what he said?...).

I don't think that you should worry about the MC stroke.  When working on the brakes most of the adjustment is in removing the play in each transfer of power, and getting each part in its proper starting position.  If you can get the #2 rod adjusted as the FSM describes, and the other rod to the pedal, #13 in the cabin, the brakes should work as well as they could.  The extra stroke of the Sanyco will not be needed (he said...).

I copied the instructions above from 1972.  Here is the from 1970, that I downloaded from CZCC.

 

Are both master cylinders similar in size?

Is the depth from the mounting flange of the master to the back of the piston the same on both units?

23 hours ago, Zed Head said:

The available stroke will not affect brake operation if both of them offer "enough" stroke.  (That's what he said?...).

I don't think that you should worry about the MC stroke.  When working on the brakes most of the adjustment is in removing the play in each transfer of power, and getting each part in its proper starting position.  If you can get the #2 rod adjusted as the FSM describes, and the other rod to the pedal, #13 in the cabin, the brakes should work as well as they could.  The extra stroke of the Sanyco will not be needed (he said...).

I copied the instructions above from 1972.  Here is the from 1970, that I downloaded from CZCC.

 

That’s the issue, when assembled, pedal travel was about half way. There was no play. Thanks for the pics, I saw them in my FSM. Will try making up a test push rod, before cutting the original one.

 

13 hours ago, Patcon said:

Are both master cylinders similar in size?

Is the depth from the mounting flange of the master to the back of the piston the same on both units?

The Tokico M/C is 7 11/16” long, the Sanyco is 8” long. The biggest difference between them is there is about 1 11/16” less travel with the Tokico.

 

What's the measurement?  Sounds like you're mixing and matching parts.  If I interpret your posts correctly it sounds like you're saying that the rod #2 is sticking out of the booster by almost an inch and is causing the Tokico piston to bottom out in the bore.  Can't imagine it came that way.

No offense but your words don't present a clear picture.  How about a real picture, of the booster with the rod sticking out?

Overall travel doesn't matter as much as the assembly at rest. If the booster pushrod doesn't sit out too far to assemble the parts then you aught to be able to adjust it to work. I dont believe there were different length booster push rods

42 minutes ago, bluez said:

The Tokico M/C is 7 11/16” long, the Sanyco is 8” long. The biggest difference between them is there is about 1 11/16” less travel with the Tokico.

They're very close to the same length and should work the same way.  Sounds more like there might be something wrong with the "new" Tokico.  Make sure you're fixing the correct problem.

I have a memory of a "stop" screw in the M/C's that stops the travel of the piston in the bore.  I wonder if your "new" Tokico has been reassembled incorrectly.  The position of the piston at the opening of the bore should be the same for both MC's.  They both have the same ID.  All signs point to incorrect Tokico, or Tokico assembly.  I'm going to guess that somebody put the piston on the wrong side of the stop screw.  Post pictures of those same two MC's but from the open end.

The screw I vaguely remember.  p.s. there's a circlip that keeps the piston in the bore.  Should be visible.

Edited December 1, 20213 yr by Zed Head