Sud Brake problems

[computid]

Right, so I've managed to sort out quite a few problems with the minari but one thing I've never been particularly clear on is Brakes. I can do them on a bike, but car brakes I tend to stray away from.

Anyway, I was driving the minari today with the roof off in the nice weather, took it up a long stretch of duel carriage way, all was going well. I turn off into a town and as I approach a roundabout I press the brake pedal and.... nothing. Luckily the car in front moved off so I carried on past the roundabout through the town and drove into my works car park, all without brakes (just used engine braking, probably not the best move but there was nowhere safe to stop). I parked up in the car park stopping with the handbrake and had a look at the master cylinder, no leaks. Looked at all the brake callipers and visible lines, no leaks. Ok.

I then got back in the car and sure enough I still had no pedal pressure till right at the very bottom of the travel where it felt really spongy. I pumped the brake pedal and after 3-4 pumps the pressure came back and then sort of faded away again. I went into the building to sit down and calm my nerves, called my mum to get her to bring me the roof for the car and then went back out after 15mins. Got back in the car and the pedal pressure is back completely. I cant get it to go down like it was before. I carefully drove the car forwards and the car stopped on the pedal. Same when I reversed back.

Could I have boiled the fluid or have I got a leak somewhere? (master cylinder?) I wasn't driving hard or fast at all, wasn't hard on the brakes or anything. Thinking about it, I doubt the last owner of the car bothered to change the brake fluid, and the last time that would have been done is 1999 at the latest! The master cylinder is still full of brake fluid up to just before the max line. Does brake fluids boiling point decrease that rapidly? The car made it from Bristol to Leigton Buzzard without brake issues so I've got no idea.

The only way I can think that the brakes would have boiled is if one or more of the callipers were binding. I'm pretty sure they are but with the fronts being in-board callipers I have a feeling it may be the handbrake that's causing the binding.

Anybody got any views? I'm going to have it picked up by the AA tomorrow and get them to take it to a garage since I have a loathing of car brakes but if anybody has any suggestions then I'd love to hear them.

[Alfasixnut]

That seems really weird! But it could be that the brake fluid has absorbed a lot of water over the years (I believe it is Hydroscopic?)so the boiling point is much lower and a few bubbles of steam in the system could, I think, give you those effects. A flush through with new fluid may well be a cure.

[David C]

Originally Posted by computid

...Thinking about it, I doubt the last owner of the car bothered to change the brake fluid, and the last time that would have been done is 1999 at the latest!

Following everything to the letter, the brake fluid should have been changed at least 6 times since 1999...!!

[computid]

Originally Posted by David C

Following everything to the letter, the brake fluid should have been changed at least 6 times since 1999...!!

Well, I wasn't driven at all from 1999 to 2012, so thats why it didn't get changed.

[brit01]

silly answer but it's not the vacuum pipe that joins to the inlet manifold is it?

I've put the valve on the wrong way round twice and no brakes - al spongy.
Or the pipe could be leaking/loose or broken.

if there is no vacuum from the inlet manifold then the brakes will not work at all.

[kammatic]

hi mate

you could have boiled the fluid, its hard to say without seeing the car and feeling pedals and looking at the brakes.

if you getting to a garage for work i can recommend kris and ross at autoserve in dunstable. kris aka badpanel who used to hang about on here know suds pretty well and ross his boss has been doing it for 30 odd years. tell them exactly what happened and im sure they can sort you out. both are very good :O) let them know lib send you

[David C]

If it has been stood unused for 12 years with old fluid then the whole brake system needs properly servicing.

[Greek]

Similar problem i had. Sprint was still for 6 years and the brake pump had problems with seals. When applying steady pressure , it would gradually loose it and the pedal went to the floor and i needed to press 2 or 3 times to maintain it. I changed it along with fresh DOT4 fluids and no problems since then.

If you are about to change brake pump , consider using one from 75 as it is the same , only with bigger diameter ....

[sprint_veloce]

Wow - best to change the brake fluid before using the car again. You were lucky not to have an accident. The brakes could be binding - typically handbrake arm (where cable attached to caliper) not returning when released or rear pistons.

Greek - the slowly sinking pedal under steady pressure is classic master cylinder failure. The seals leak inside the cylinder allowing fluid to flow from one chamber to the other. But why replace with a larger one from a 75? Doesn't that make the pedal a bit firmer, and more pedal pressure required for same braking effect? Sud pedal force required is already high compared to other cars. Maybe 33 brakes are different? OP has sud system though.

[computid]

Ok, AA picked it up yesterday and the garage came back to me today. I need two front brake calipers as the ones that are on there are seized solid. The only ones I can find are £105 each fully reconditioned from Just Suds. Does anybody know of a cheaper source or is this the right price to be paying? I intend to order this evening if nobody else has any suggestions.

Thanks!

Adam

[kevjtd]

this place lists them at under £60+ VAT, if they have/can get them?

Brake Parts for Cars

[alfapud]

just on a side note, related topic though. im getting no pressure from my brake pedal either, put through new fluid and they have been bled. but when pressing on the brake it's firm until the bottom, then it feels like air is escaping and you can then push it to the floor. any ideas?

[Greek]

Probably you need to bleed also from pump side , not just calipers....

[jahcee]

You may need to prime the master cylinder, I had this problem when I fitted a new master cyl last year, effectively had to bleed master cyl first, then the whole system.