Triumph Rat Motorcycle Forums banner

1 - 14 of 14 Posts

·
Registered
Joined
·
77 Posts
Discussion Starter #1
Hi All,new Here ,but Not To Old Triumphs ,but Do Need Some Help,putting The Final Touches On My Bike,76 T140v,ive Rebuilt The Mastercylinder,rebuilt The Brake Caliper(rear)installed New Pads,i Installed Everything Last Night Onto The Bike,ive Bleed The Brakes And They Pumped Up Fine,problem Is......all The Pressure Does Not Seem To Be Bleeding Down/releasing On The Caliper,therefore Not Releasing The Rear Disc Fully.there Is Way To Much Drag On The Rear Wheel,i Can Turn The Rear Wheel By Hand When The Brake Is Released,but Its Really Tough,usally I Get By Just Fine With My Haynes Manuals And Chiltons,but This One Has Me Stumped,any Sugestions Or Help Would Be Great,thanks
 

·
Registered
Joined
·
95 Posts
Hello,

Have you checked the master cylinder operating rod adjustment?...it says in the manual to have 8.9-9.4mm gap between the adjuster nut and MC body, not sure if that would cause the problem though.

I had a similar problem that turned out to be a worn/pitted MC, i replaced it with a stainless steel MC.

I also put springs inbetween the pads(splitpins) to stop them from rattling.

HTH
 

·
Registered
Joined
·
1,654 Posts
The problem you are having is because the master cylinder needs to be adjusted in it's casting / holder. You will need to dis-assemble the brake lever assembly and screw the master cylinder further in a bit. There is a procedure for this in the workshop manual, but I did it by trial and (lots of) error, 1 turn at a time. The internal pushrod will be 'pre-loaded' by this (rather than floating free), but that is correct. You will get to be very good at taking the rear wheel out & in and assembling greasy pedal return springs.

The adjustment Monty mentions will need to be made after the cylinder is adjusted in its mounting.

I have PDFs of the relevant pages out of the manual but they are too large to post here, if you want a copy of them send me a pm with an e-mail address. Adds up to about 8Mb.
 

·
Registered
Joined
·
794 Posts
Just before you go delving back into the master cylinder, check that you have fitted the caliper assembly to the wheel/swing arm properly. The torque stay arm goes on the outside of the lug welded to the bottom of the swing-arm, with the head of the special bolt on the outside, and the nut on the wheel side. If you put the torqe stay arm on the inside of the lug, the whole assembly gets twisted, and the pads make permament "hard" contact with the disc.

With the axle nut loosened right off, the swing arm moves outwards away from the wheel hub, and the torque stay arm does align on the inside of the lug - don't be fooled by this.

This is a peculiarity of the underslung rear caliper on the 76/77 model.

If all OK, check the MC as suggested by Monty and Dave.
 

·
Registered
Joined
·
1,598 Posts
I have side stepped this issue by never using the rear brake...its not the greatest design ,is a pain to properly bleed,etc.
I rebuilt mine,including the remote reseviour and hose,adjusted it,got it working fine and left well enough alone.
 

·
Registered
Joined
·
1,628 Posts
It will be the brake hose. The inner of the hose is affected by brake fluid over the years, it goes soft and swells.

The m/c has a huge mechanical advantage and squirts the oil through the hose fine, but the return relies on the m/c piston sucking it back up = it has no mechanical advantage or postive force.

Take the hose off, wash it in water/ wipe it clean and then try to blow through it, after going red in the face trying and finding you can't, throw it over your shoulder and buy a braided set, do the front one at the same time and save yourself from the next accident.
 

·
Registered
Joined
·
38 Posts
I second the brake hose, Check that before you tear everything back apart. I had same problem with my front brake on my 79 T 140E , Threw alot of money at it and found out it was a 20 dollar Rubber brake hose:eek:
 

·
Registered
Joined
·
70 Posts
brake hose...

I've seen a similar situation on a chevrolet truck and it ended up being the brake hose. Every time you let off the brake, the truck pulled to the right. It wasn't releasing the pressure.
 

·
Registered
Joined
·
1,628 Posts
You can check this out by releasing the pressure through the bleed valve. If it free's the rear wheel but the next time you use the rear brake it binds again then you know its the hose.
 

·
Registered
Joined
·
77 Posts
Discussion Starter #10
76 T140 Rear Disc Brake Problems

THANK YOU ALL FOR THE ADVICE,HERES WHERE I STAND ON THE PROBLEM.......1.I DID HAD A LITTLE BINDING FROM THE BRAKE STAY ARM,THATS FIXED,2.THE BRAKE HOSE IS CLEAR,REMOVED SAME AND I CAN BLOW THUR IT BOTH WAYS.I THEN REMOVED TH MC FROM THE BIKE AGAIN!! LOL DAVEFORTY SENT ME A PDF FILE ON PRE LOADING THE MASTERCYLINDER,WHICH GAVE BETTER VIEW AND INSTRUCTIONS THEN MY BOOKS,SINCE I HAD IT OUT I DECIDED TO TAKE THE MASTER CYCLINDER APART AGAIN(I REBUILT IT 8 MONTHS AGO,AND IT WAS JUST HANGING AROUND TILL I NEEDED IT)UPON DISASSEMBLY I FOUND THERE WAS SOME CRAP BLOCKING THE PORT HOLES,I HVE NO IDEA WHERE IT CAME FROM,CAUSE I THOUGHT I CLEANED IT UP NICELY THE FIRST TIME!!!ALSO FOUND THAT I HAD THE SMALL CURVED METAL PISTON WASHER IN BACKWARDS(DAVEFORTYS PDFS FILES SHOWED A BETTER DETAIL THEN THE HAYNES ON IT)INSTRUCTIONS SAY UPON REASSEMBLY TO PRELOAD THE MC BY PUSHING IN THE BRAKE PUSHROD WHILST SCREWING IN THE CASTING ONTO THE THE MC BARREL ALL THE WAY,,THEN PUT YOUR FINGER OVER PORT (A)OF THE MC AND BLOW AIR THUR THE OUTLET SIDE OF THE MC BARREL,NO AIR SHOULD COME OUT OF PORT(B) ON THE MC BARREL ,AT THIS POINT UNSCREW THE THE CASTING OR MC BARREL DEPENDING HOW YOU HAVE IT SET UP IN THE VISE UNTIL AIR IS HEARD TO ESCAPE FROM BREATHER PORT (B)THEN UNSCREW 1 MORE COMPLETE TURN AND LOCK IN PLACE WITH THE SET SCREW,WELL AFTER ALL THAT,AIR NEVER ESCAPED FROM PORT(A)NO MATTER WHAT I TRIED ,SO I BACKED CASTING AND PUSH ROD OFF UNTIL AIR ESCAPED FROM PORT (B)AS INSTRUCTIONS SAID AND SET WITH SCREW,HOPE THATS IT!!!TODAY ILL PUMP UP THE MC BARREL WITH FLUID AND REINSTALL AND SEE WHAT HAPPENS,OH...I PROB GOT AHEAD OF MY SELF AND REPAINTED THE THE MC BARREL AND REPOLISHED THE ALUMINUM ON THE CASTING. LOL HOPE IT DOSENT HAVE TO COME APART AGAIN!!!!:eek:AFTER ALL THIS WHAT DO YOU THINK DAVENORTY?YOUVE READ THE SAME THING FOR WHAT TO DO??
 

·
Registered
Joined
·
1,654 Posts
Sounds like you are doing what is required. I would expect a brake hose of that age to start hardening and possibly cracking, so inspect it well before re-assembling. If you keep the rubber hose note that it has a red stripe along it, this is to assist assembly - the stripe should be straight, not twisted. This would be a suitable opportunity to get some Goodridge (braided) brake hose.

When I adjusted the master cylinder on my bike I did it by trial and error 'cos having got the system bled I didnt want to drain it down and have to re-bleed it all, or get a taste of brake fluid by blowing into the cylinder.
 

·
Registered
Joined
·
77 Posts
Discussion Starter #12
Triumph 140v Rear Disc Problems

Sounds like you are doing what is required. I would expect a brake hose of that age to start hardening and possibly cracking, so inspect it well before re-assembling. If you keep the rubber hose note that it has a red stripe along it, this is to assist assembly - the stripe should be straight, not twisted. This would be a suitable opportunity to get some Goodridge (braided) brake hose.

When I adjusted the master cylinder on my bike I did it by trial and error 'cos having got the system bled I didnt want to drain it down and have to re-bleed it all, or get a taste of brake fluid by blowing into the cylinder.
THANKS DAVENORTY!!!!REINSTALLED MASTERCYLINDER,JUICED IT UP AND ITS WORKING GREAT!!!!ALSO ABOUT THE BRAKE HOSE!! MINE WAS GOOD BUT I THOUGHT WHAT THE HELL...I FOUND YOU CAN USE PRE ASSEMBLED 1/4" STEEL BRAKE LINE TUBING WITH THE FITTINGS ATTACHED,THEY CAN BE BOUGHT IN VARIUOS LENGHTS FOR UNDER $2 AT ADVANCED AUTO,THEY THREAD INTO BOTH THE MASTERCYCLINDER AND CALIPER,YOU JUST HAVE TO BE HANDY WITH A PAIR OF TUBING BENDERS AND MAKE THE CORRECT BENDS TO USE UP ANY EXTRA LENGHT(IM A PIPEFITTER/WELDER),THEY WORK GREAT ON A CHOPPER LIKE IM FINISHING UP NOW,BUT I HAD THE BRIGHT IDEA OF POLISHING THE FINISH AND IM NOW BACK TO THE RUBBER HOSE AS THE TUBING GOT SUCKED UP INTO THE BUFFING WHEEL AND WRAPPED ITSELF AROUND THE MOTOR SHAFT ON MY PEDISTAL BUFFER/POLISHER(LOL)I SHOULDA KNOWN BETTER.....DUH!!!! THANKS FOR THE HELP DAVENORTY
 

·
Registered
Joined
·
62 Posts
, check that you have fitted the caliper assembly to the wheel/swing arm properly. The torque stay arm goes on the outside of the lug welded to the bottom of the swing-arm, with the head of the special bolt on the outside, and the nut on the wheel side. If you put the torqe stay arm on the inside of the lug, the whole assembly gets twisted, and the pads make permament "hard" contact with the disc.

With the axle nut loosened right off, the swing arm moves outwards away from the wheel hub, and the torque stay arm does align on the inside of the lug - don't be fooled by this.

This is a peculiarity of the underslung rear caliper on the 76/77 model.

.
Would the above apply to 79 T140E ? Have underslung caliper

cheers
 
1 - 14 of 14 Posts
Top