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TR674

Brake issues

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Hello kind folk. I read in a recent forum topic about front brakes locking on. Mine did just that a few weeks ago.I have new master/booster/discs/rear cylinders for the last 3-4 years with no issue. Suddenly I have very limited pedal travel and the front pads are gripping the disc. A member suggested bleeding the brakes. I have just tried to bleed them. I managed to do the rear, but no fluid comes out of the front bleed valves. There is some fluid seeping out between the master and booster connection. Is it looking like the master has failed/jammed?

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Mike, opening the bleed nipples made no difference. I expected fluid to squirt out as the pedal is solid (under pressure). Also pedal remained solid with the front nipples open. I also just unbolted the master from the booster and there is approx 1/4 inch gap. I can't bolt it back on flush with the booster.

Regards

Craig

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Looks like your MC is stuck then. Time for revision or renewal.

Waldi

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It's interesting that I am replacing parts that are 40+ years old with new parts that can't do more than 3 to 4 years...............

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1 hour ago, TR674 said:

It's interesting that I am replacing parts that are 40+ years old with new parts that can't do more than 3 to 4 years...............

40 years ago these parts were used daily, there was never time for a hydraulic cylinder to seize. However, I do remember replacing brake and clutch seals fairly often back in the day.

Nigel

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I removed the master today. It's all looking and working as a spanking new master should. I can compress the plunger with my finger, nice and smooth, no binding. Both front brake lines are blocked?

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You have not mentioned the fluid leaking from the MC - servo connection. Is that water or brake fluid? If you are not using Dot 5, just "regular" brake fluid then as a priority I would pour lots of warm soapy water down over the servo & inner wing to try and mitigate brake fluid contaminating and stripping the inner wing paintwork. Whatever other issues the brakes may have that leak must be a priority. Fix an obvious fault and other unexplainable issues often miraculously are also cured. If it is leaking fluid that has to be a seal possibly together with the MC cylinder lining.

dumb question - the MC will not fit correctly back to the booster / servo; is the brake pedal returning correctly back to its position, is the pedal return spring still fitted and returning the pedal?

How far does the actuator rod protrude from the servo?

A good source of information:- https://www.buckeyetriumphs.org/brakes

Alan

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Craig,

there are 2 brake pipes connected to the side of the MC, the rear (yes) is for the front brakes.

There are also 2 pistons (each with their own seal) in the MC, the one you see first (and that you can move with your finger) is for the front brakes. So if you can now move that, but you had no oil coming out of the bleed nipples of the front calipers, you have to look at other things too.

You also wrote the front brakes are gripping (although no oil comes out the bleed nipples). Did you open the bleed nipples enough, and are they clear? If that was both ok, it could be seized calipers, but 2 at the same time is unusual. So it is more likely an hydraulic issue, with the MC, or pedal or servo.

Waldi

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I discovered the leak I saw was the rear brake line. It was weeping slightly and running along the underside of the master and down the booster. Very small leak.

There was no sign of fluid leaking out of the master internal seal.

With the master back in and no brake lines connected I get full pedal travel and it returns back all the way.

Next weekend I'll put some fluid back into the reservoir and open both the front bleed valves and see if I get some pedal travel.

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Hi Craig,

have you checked the flexible pipes at the front (and possibly the back)  These cab fail internally and cause a blockage.

 

Roger

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You might be getting pedal travel/return but your front discs could be still locked on. Like Roger say's  a flexible hose could be blocked.  When you open the bleeder nozzle and move the pads back, they should move freely and  displaced fluid should discharge from the  bleed nozzle.

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I think in that case some oil still should have left the bleed nipple, or would this be so minimal you don’t notice it?

But again, both hoses failing at the same time seems unlikely.

Waldi

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You would notice it- it would be a few cc. If the pads are gripping the disc then either there's pressure behind them or they're stuck in the calipers. If you open the bleeder and no fluid comes out then , unless both bleeders are blocked , there's no pressure in the calipers.

I'd make sure the pads can freely move for starters.

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Hi Roger, no I have not checked rubber hoses. I've had the car for 25 years and not changed them. I see Rimmer sell a full set at a reasonable price. I will replace them regardless. When I disconnect the rubber hoses, remaining fluid should drain out of the copper lines, hopefully.

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Hopefully cupro nickel lines. Copper brake lines have been banned in Australia for years- see the checklist Appendix 3 in this:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwjUpf2vz9TkAhWI63MBHRGmBjcQFjAAegQIABAC&url=https%3A%2F%2Fwww.rms.nsw.gov.au%2Fdocuments%2Froads%2Fregistration%2Fbrake-assessment-manual.pdf&usg=AOvVaw3jy_rJK2_LlkUwVW3_cbBL

I suspect the banning goes back to the days of widespread dirt roads and vibration work hardening of the copper leading to cracking.

 

 

 

 

 

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i have my brake system back together with refurbished callipers. I can't get brake pedal pressure and no fluid comes out of all four bleed valves. Do I need to use a vacuum bleed kit to get fluid thru the brake lines? The front brake lines have no fluid in them.

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9 minutes ago, TR674 said:

i have my brake system back together with refurbished callipers. I can't get brake pedal pressure and no fluid comes out of all four bleed valves. Do I need to use a vacuum bleed kit to get fluid thru the brake lines? The front brake lines have no fluid in them.

If you make up a couple of short pipes you can bleed the m/cyl into itself, that would prove whether it is working or not.

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Didn't some of the export market cars have a PDWA valve installed?

Could this cause such a fault?

There is not usually any need to use a vacuum bleed on a TR. Just fill with fluid and pump the pedal.

Jerry

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I put brand new brake lines on my Mk2 Jag and  had problem of master cylinder hydraulic lock up (solid pedal no fluid flow to wheel cylinders) which could only be releived by cracking master cyl outlet line connection. Pulled out master cylinder and checked ok. When I finally removed the brand new line from the master cyl to the booster i found it was blocked in a straight section not on a bend.

Replaced the new line with another new line and no more issue. 

 

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I tried to bleed the brakes again this morning and no change. As a test I loosened the front brake pipe from the master, just enough for fluid to drip. I pumped the brake pedal and no extra fluid came out. I would expect a squirt at least. When I pump the pedal quickly, the front reservoir fills. It's looking like the master seals are shot, and it's only a few years old. I'm kicking myself as I chucked the original master.............

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‘A few years ago’ there were a batch of faulty ‘new’ master cylinders for the 6 sold.

perhaps you have one of those?

steve

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I can’t remember the details, sorry

think they leaked and or didnt pump

if it were me i’d buy another if they’re easily available where you are, or refurb an original

Happy New Year to you too !

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I would have an original reconditioned by Part Parts-UK, they also install a SS sleeve.

maybe a similar service is available in Australia?

Waldi

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