Upgrading the 1983 Rear master cylinder

[Steve83]

'80 - '83 all have the same rear MC mount holes.

 

[weightlifter99]

Really? Those three years will interchange bolt pattern wise? And isn't the line hook-up different on the 83 due to linked brakes? Or is this just a specific model for this year?

 

[Steve83]

The '83 rear master is a one-year-wonder. It uses a steel line and threaded fitting instead of the rubber line/banjo fitting used on earlier 1100's. It also has a larger bore/piston. 1200's changed completely - different mount, different linkage, and 2 outputs for the linked brakes.

 

[83gl1200]

You may have to drill one or two new mounting holes in the frame mount to fit that, but thats no big deal. I almost ordered the same part for my 83 before I took my master apart and found it was salvageable. I spent more on the kit to rebuild the stock master, in retrospect I wish I had just replaced it. People also fit 1500 rear masters to 83s if that doesn't work out, I saw a thread on that somewhere, try google.

 

[dan filipi]

Mc arrived.
It looks good.
Haven't had a chance to look at fitment.

It comes with banjo fitting, looks like an adaptor to hard line could be an easy deal if there is a male threaded fitting to a hard line adaptor available.
Tiny reservoir but the stock one should hook up.

 

[weightlifter99]

Dan that new m/c looks pretty sweet and I'll bet with a swap of the stock res...you'll have er go n in no time! I'm very interested in how you mount it so please keep the info coming!

 

[Steve83]

Any idea what the piston diameter is?

 

[dan filipi]

Steve83 » Thu Jul 17, 2014 10:26 pm[/url]":10kbpopn]
Any idea what the piston diameter is?

13 mm.
Do you know size of 83?

 

[Steve83]

'83 is 15.870 - 15.913mm, or 5/8". '80 - '82 is 14mm. You'll have a bit longer pedal travel, and power brakes!

 

[dan filipi]

We'll cool, so this sounds worth doing then.
Longer travel concerns me but there is lots of adjustment. I'll make sure of it.

 

[slabghost]

Since you may have to mount the master a little to the rear of stock and the master has a longer travel. you may want to add to the brake pedal where it mounts the mc pushrod. more distance from the pivot point will increase the pushrod travel and decrease the pedal travel.

 

[Steve83]

You'd need to weld an extension to the pedal arm, the hole for the MC pin is at the very end. But, you have a welder, so it's cool.

 

[dan filipi]

I have the old MC out.

Rod length is the same.
Total travel is about the same at 1/2".

Bolt up to frame is all together different but I expected that.
My plan right now is making an adapter plate from 1/4" steel.

First up, pull the muffler for working room.....

 

[slabghost]

Looks to me like the rear bolt hole might mount up. Might need to elongate the hole. Could maybe plug the banjo hole with a set screw and drill and tap a new hole for the hardline fitting?

 

[joedrum]

thats quite the miss on the line sheesh

 

[Ansimp]

Is it possible to go all flex braided line from MC to caliper?

 

[83gl1200]

Ansimp » Sat Jul 19, 2014 5:09 pm[/url]":49nk7sgx]
Is it possible to go all flex braided line from MC to caliper?

His 83 has linked front and rear brakes, he'd loose that feature plus have to replumb the front brakes. Mine is the same

 

[weightlifter99]

On the line maybe a couple 90 degree brass adapters? And if the back hole was lined up couldn't the throw be shortened just a bit to compensate?
Then maybe as you said a piece of steel ...bolted to the frame and then drilled and bolted to the m/c keeping it lined up?
Is there enough clearance for the bolts to do it this way maybe?

 

[83gl1200]

weightlifter99 » Sun Jul 20, 2014 9:19 am[/url]":1gl8um6a]
On the line maybe a couple 90 degree brass adapters? And if the back hole was lined up couldn't the throw be shortened just a bit to compensate?
Then maybe as you said a piece of steel ...bolted to the frame and then drilled and bolted to the m/c keeping it lined up?
Is there enough clearance for the bolts to do it this way maybe?

I'm in need of a 90 degree brass adapter with male threads on both ends for my rear brake line, if you know where to find one let me know please.
(Because i had to cut off the hard line mount, and removed the hard line to replace it with one piece front soft line. So from caliper to proportioning valve will be an 83 front brake line.) Cleaned up the frame to fit new shorty mufflers that follow the lines of the frame.

 

[weightlifter99]

On a brass adapter with male fittings on both ends....possible oreilly's and may have to add a male nipple to one end or lowe's has a pretty good selection of brass fittings. May not be the correct threads...not sure what they are on the oldwing.