seizing rear master cylinder

Hi All,

Has anyone had trouble with replacement SS rear master cylinders seizing in the hot sun?
I had the same problem with a re-sleeved front cylinder - ended up buying the Andover upgrade unit - very happy.

I purchased the rear one from Rocky Point and no trouble till now except very little power no matter how I set it up as far as screw-in / screw-out.
In the hot weather (33 deg C) over the last few days it has seized up twice and then frees up once left in the shade for a couple of hours.

New re-build kit? Better quality replacement assembly? I note Britt Cycle list one for the front of Triumphs - any better?

Any advice appreciated.

Thanks

That sounds remarkable that "the sun" could heat up the master cylinder and cause it to seize.. (thats if im reading it right) Any racing conditions would produce considerably more heat for cylinder and fluid... I would change the fluid to a type that is more "heat resistant" ........ and "go the Dockers"......

Try these blokes, i got both front and back std kits for my Mk3, Based in Vic was 5 days delivered..

http://www.ebay.com.au/itm/Master-Cylin ... OC:AU:3160

It's old. :?:

I once had a problem with brake staying on turned out to be a perished brake hose fluid was getting between the laminations of the hose causing a blister inside the pipe and preventing fluid flowing back to master cylinder,after a while it would seep back and free brake.

Besides what's mentioned above its not uncommon for resleeved master cylinders to do this in sun or racing until the plunger on the piston shortened a few 1000th to let retract enough to bleed pressure. I've read of Norton factory rear kit having some issues like this too but I've only drum rear brakes so don't know the fix but had something to do with assembled adjustment.

thanks for the input guys.
I assume it is just the heat as it seems the same as the sleeved front cylinder. By process of elimination I was satisfied that was the problem then. I have read threads by others having the same problem and covering the front cylinder with a rag or hat as a preventative. I suspect the thermal expansion of the cylinders is the culprit.

The whole setup is only a couple of years old with good quality Spiegler hoses.

I think I might try a kit from Chris' supplier and check the setup as per your suggestion Hobot. I had not thought of thermal expansion making the piston setup longer and thereby masking the hole. From memory the seal edge is very close so it would not take much. I had imagined the cylinder binding the piston/seals as the problem.

MCG in Sept next year with different result Chris - Heave-ho!

A resleeve caught me out after couple seasons Mt ride use till full summer hit, still fine, until on 1000 mile trip with my '71 mate Wes we stopped at old mc shop and when I got back on and let clutch out Ms Peel and cargo and me hit the cement. Only thing saved the trip was the foot forward bar mounted on RGM fork brace or would of broken off brake lever, cracked throttle took out underslung mirror on tank and of course the stupid signal. I thought and thot on sidewalk till a fix occurred to me, rub the plunger/spacer between lever and piston on side walk then put in pump brake and repeat till it released each time then scratched off a bit more slim extra heat expansion reserve. I had hardly used the brake as just touring sightseeing legal no police notice hwy speed, and if not for the tri-linked wonder of Ms Peel I too would depend more on brakes to turn so would of heated it up to loose it over a bluff railing. Makes my gut reflex tighten up even now knowing if I'd not gone bonzi but rode normal I may not be here. Did find out you can ride a locked rear down to side of road if it happens on a straight up section but if dragging rear brake in conditions it needs to help the front, SPLAT>

Bloody lucky Hobot.
Only good thing in both cases for me was it happening before you get moving. In the act of getting under way you generally end up touching the brakes in some way.
Still not safe and very inconvenient having to put the thing in the shade for a couple of hours to free up.
Seems the "air cooling" of riding prevents it happening then - still I would not like to push my luck.

I have ordered a kit from Chris' contact and see how I go. I will also change brand/grade of brake fluid.
BTW the Andover front brake upgrade is great. I had bought a Grimeca caliper and 12" RGM disc at a swapmeet to try to improve the front setup, but decided to fit the Andover thing.
- anyone want to buy a disc and caliper? The upgrade has a lot more power and feel.

Will update when I tear it down and fit kit.
Cheers,

Well in Peels case it was level spot so I did not touch brake at all, it was locked up all by its self Splat. Wes and i stopped soon after to eat but no shade to park in so I put a hat or a wet rag over the brake for 2 days until I got some security sense back I'd taken enough off. Compromise as the more ya take off plunger or piston end or lever contact, the less it has for the pressure stroke distance to work. Seems like there is some adjustment on Norton rear linkage to compensate but I don't know them that well. In panic stops, I tend to stab rear an instant before front which tends to squat whole bike then can get on front a bit faster harder that takes rear out of useful traction. On my loose or wet steeps I feather in front till its too scary to depend on alone then do the fine tuning of slowing with additional rear brake. Also on my modern with disc brakes both ends which easy can lock up so harder to stop as short as on a Commando with decent brakes in a panic.

I realize this is an old thread but here's an interesting observation:

Road into work today, coolish summer morning, approx 16C at 7:30 am. Front brake seemed a little soft. Put the bike in the shade out front of my building and went to work. Noon, I go out to look at the brake issue and its warmed up considerably. The bike is now in direct sunlight; maybe 25/26C and the brake is locked solid. Not wanting to deal with it then and there, I left it until an hour ago. It's now 4:30, the sun has passed over and the bike is in the shade again. Brake is once again on the soft side.

Thinking about the MC from the Philippeans or Colorado MC, but I have to wonder if the problem would still occur?

http://www.ebay.com/itm/201103609277?_t ... EBIDX%3AIT

Any thoughts on this?

BC

Thinking about the MC from the Philippeans or Colorado MC, but I have to wonder if the problem would still occur?

http://www.ebay.com/itm/201103609277?_t ... EBIDX%3AIT

Any thoughts on this?

well having sold around 100 of these mastercylinders and I use one daily and this week the temperature was up to 44 degrees C
I have never experienced this happening.

Have you gone back to Rocky Point for resolution? Maybe you just got a bad one.

madass140 said:

Thinking about the MC from the Philippeans or Colorado MC, but I have to wonder if the problem would still occur?

http://www.ebay.com/itm/201103609277?_t ... EBIDX%3AIT

Any thoughts on this?

well having sold around 100 of these mastercylinders and I use one daily and this week the temperature was up to 44 degrees C
I have never experienced this happening.

Click to expand...

That's what I need to hear! I've tried the re-sleeve and it just didn't work. Please PM me and I'll make the purchase. Thanks.

BC

Stillreel said:

I realize this is an old thread but here's an interesting observation:

Road into work today, coolish summer morning, approx 16C at 7:30 am. Front brake seemed a little soft. Put the bike in the shade out front of my building and went to work. Noon, I go out to look at the brake issue and its warmed up considerably. The bike is now in direct sunlight; maybe 25/26C and the brake is locked solid. Not wanting to deal with it then and there, I left it until an hour ago. It's now 4:30, the sun has passed over and the bike is in the shade again. Brake is once again on the soft side.

Thinking about the MC from the Philippeans or Colorado MC, but I have to wonder if the problem would still occur?

http://www.ebay.com/itm/201103609277?_t ... EBIDX%3AIT

Any thoughts on this?

BC

Click to expand...

IMO........ 10c ambient temp causes your brake to "lockup".......... Really, I dont think so!!! There are other issues re adjustment that require attention not a $600 maybe fix!......... Sorry, but i think operator/mech error is your problem.. Have another go at it and rebuild and adjust with what you have.. I've read many posts re binding rear brakes on this forum and its not real hard as the DT's say it is..

Thats not to say that the products from Colorado and the Phillipines not are worthwhile, they both have a 99.9% positive rating IMO...

ol Chris:

The fact is that as the system heated up (in the sun) the brake seized. It was fine on the ride in, cool, seized while sitting still in the sun during the day, and fine again once cooled later in the evening. If you can offer another explanation I'll go with it. But operator error is incorrect. The bike was sitting still.

Stillreel said:

ol Chris:

The fact is that as the system heated up (in the sun) the brake seized. It was fine on the ride in, cool, seized while sitting still in the sun during the day, and fine again once cooled later in the evening. If you can offer another explanation I'll go with it. But operator error is incorrect. The bike was sitting still.

Click to expand...

Please dont take my "abrupt" way of trying to explain things as an inya face critisisum .... it is unfortunate the way things come out for me sooooo with a lower tone!!!! in my reply i suggest you may need to "rework" the adjustment of the Rear M/C.

There are thousands of those M/C's on different bikes doing the same thing (being a brake MC with greater ambient temps)... The differance between your upper and lower temps over the day is not your problem.. im sure there are many other forum members that have a greater ambient temp to deal with (eg 20dC+ variant over the day).. me for one..

With a careful reply about "operator error" i did say operator/mech !!, maybe i should have elaborated on the mech(anic).. I have made a squillion mistakes with my nut's bolts and wheel addiction..

:lol: :lol: :lol: .. there are hundreds of members here that have experienced your problems but are toooo shit scared to offer advise cos they "may" be wrong or cant spell propper..

No worries. I know its a mechanical adjustment but no manner or shimming or trimming can get the hydraulic system properly balanced. I re-sleeved the cylinder (its the front brake that's the issue) but I am still in a situation where the caliper pistons are initially set off the disc, but after warming up, they start to bind. Easing the pressure, by even the slightest fraction and the system goes soft.

Both Madass and I think that perhaps the master cylinder manufacture was inconsistent and as such, the piston may not work properly with the sleeve provided. At any rate, the new cylinder should arrive this week. Hopefully this will resolve the issue but at the very least, this will determine if its the cylinder or calipers.

BC

A "Front resleeved M/Cylinder" .. :shock: :shock: :shock: :shock: Well that a complete different story.......... I thought you were talking rear M/C..........