Triumph Herald 1200 Spongy Brakes

[Shiv K P]

Hello all !

I am having a bit of an issue with my Herald's brakes. They were working fine one day and a few days later I was about to take it out when I felt the brakes were spongy and saw that there was no brake fluid left. I topped it up but the brakes are still spongy. The pedal hardens up after four or five times of pumping the pedal up and down but after about five seconds is back to being spongy again. I have bled the brakes at the front quite a lot and still no improvement. Does anyone know what it could be or / and how I can sort it out ? 

Thanks in advance !

[johny]

Well to lose fluid there must be a leak. Most likely are drum slave cylinders and the master. The former will be easy to see when the drums are removed while the latter can be more difficult as the fluid runs down inside the car and disappears in the carpet. Find the reason before driving the car again!

[Shiv K P]

Ah I may not have explained too well. I meant I hadn't checked my brake fluid levels for a while despite driving quite often so over the course of that time, the fluid had run out. There is definitely not a leak as I have checked. I feel that there is air trapped somewhere but have tried to bleed the brakes in order to remove the air but with no success. Is there anything you think it could be ? Thanks mate

[johny]

But the fluid level should never go down no matter how long its left, its a sealed system so somewhere there must be a sign of where it came out as it doesnt evaporate. It might be very slow loss but it could quickly get worse😳 Have you got a servo fitted?

[Shiv K P]

Oh goodness me, yes it is probably a very slow leak then. Don't think I've not had to replace the brake fluid for about a year now but I have used it quite a lot over the last year with trips all over England. But when I usually do top up the brake fluid, the brake pedal still acts normally but this time it has chosen not to 😂. But no, I don't have a servo fitted 

Edited June 2 by Shiv K P

[Shiv K P]

*not had to replace

[johny]

If its not air in the system (have you bled the rears as well?) then the master cylinder can be knackered. If you look in the workshop manual you can see it has two seals. As you start to press the pedal the first seal closes the hole to the reservoir and then the piston with its seal can start to pressurise the cylinder and operate the brakes. If the first seal wears it can take several pumps before it closes the hole well enough to allow pressure build up. You can check this by watching the level in the reservoir carefully. If it goes up as you push slowly on a soft pedal then thats your problem...

[Shiv K P]

Ah that's a fair point ! I haven't tried bleeding the rears. How would I go about bleeding drums ? I'll certainly check the second point you mentioned. I did think that it may well be the master cylinder but wasn't too sure how to check but now I'll have a look. Thanks mate

[johny]

Yes theres a set bleeding procedure in the manual to try to work the air out of system otherwise it could be pushed from one place to another. However I would find the leak first as no point bleeding everything only to have to replace something and do it all again👍

[Pete Lewis]

the rear wheel cylinders each have there own bleed nipple    often lack of use means they can shear off if seized.

you must also set the shoe adjustment up or you will have excess cylinder movement.

so when the suns out   disconnect the hand brake cable ,fully wind the squared headed adjusted to really lock up the shoes on the drum , reconnect  and adjust the cable to a nice fit , so its not taut or slack , now back off the adjust to free the drum to rotate .

this can have a big efffect on pedal travel and while youre in the rear check the trailing shoe has the unused handbrake lever slot at the bottom , too many rea shoes get fitted upside down

Pete