Brakes seized on mid journey

Brakes seized on mid journey

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Discussion

PomBstard

Original Poster:

4,662 posts

210 months

Tuesday 11th May
quotequote all
No idea how this has happened as the car is being used once or twice a week, the brakes on my car have seized on. Not only that, but they have seized on mid journey.

First I knew was as I slowed at the end of a dual carriageway section and realised I was slowing down v quick. Got to a side street and that’s it. Stopped and stuck.

The only solution I can think of is to lose some brake fluid and gently drive using the gears and handbrake.

But any thoughts as to how this could happened??

rustednut

614 posts

15 months

Tuesday 11th May
quotequote all
What car, age, mileage etc?

Disc brakes, drum brakes, handbrake, electric handbrake?

PomBstard

Original Poster:

4,662 posts

210 months

Tuesday 11th May
quotequote all
Yeah, I left all that out in case there were any general pointers, but as you've asked...

1987 Porsche 928 S4, discs all round, conventional cable handbrake. No clues beforehand that something was awry.

I'm going back to have a look later and see if I can crack the two nuts where the brake lines come into the master cylinder to see if any pressure can be released.

finlo

2,404 posts

171 months

Tuesday 11th May
quotequote all
Seized caliper, disc rubs gets hot expands then locks had it on the motorhome.

PomBstard

Original Poster:

4,662 posts

210 months

Tuesday 11th May
quotequote all
finlo said:
Seized caliper, disc rubs gets hot expands then locks had it on the motorhome.
That would fit. It felt like a rear brake as I can go forwards, we’ll sort of, but not backwards. And the fronts were all looked at only a few months ago when I changed the pads and discs. The rears looked OK so I left them... Doh!

Right, if that’s the case then it should just drive home OK now - all cooked down.

Will report in later...

Hammer67

4,871 posts

152 months

Tuesday 11th May
quotequote all
Similar happened to me once in my old 300ZX. Only difference was I boiled the fluid and the pedal went to the floor, fortunately without hitting anything.

Stopped at a nearby pub, had an unplanned meal and a pint, by which time it had cooled down and it drove the 15 miles home at a crawl with no further problems.

Front 4 pot caliper had 2 seized pistons which was easily sorted with a seal kit.

Jakg

2,722 posts

136 months

Tuesday 11th May
quotequote all
Sticky caliper
Pads stuck in the carrier due to corrosion
Brake hose blocked internally

Plenty of things, especially on an old car.

PomBstard

Original Poster:

4,662 posts

210 months

Tuesday 11th May
quotequote all
Went back to the car this evening, and a full cooldown seems to have done the trick. It rolled forward when the handbrake was released, so I used that to get me home.

Tried the brake pedal when I got home, and the first push was squishy, though by the third it was back to normal feel.

Anyway, parked up until I can get to the rears for a proper look.

E-bmw

6,209 posts

120 months

Tuesday 11th May
quotequote all
PomBstard said:
Anyway, parked up until I can get to the rears for a proper look.
Don't ignore the fronts as the issue could be on any caliper.

finlo

2,404 posts

171 months

Tuesday 11th May
quotequote all
You should be able to narrow it down by feeling the wheels when I experienced it you could fry an egg on the front offside wheel.

GreenV8S

28,876 posts

252 months

Tuesday 11th May
quotequote all
I've seen that happen twice. Once was with a m/c which had so much gunk inside it that the piston wouldn't return far enough to open the port to the reservoir. The second time the pushrod was adjusted too tight which had the same effect.

LarJammer

1,968 posts

178 months

Tuesday 11th May
quotequote all
The porsche calipers suffer from corrosion under the plates which can squeeze the pads, locking them in place - google 'plate lift'. Also, the handbrake shoes can fall apart, jamming against the inside of the disc.

Huskyman

555 posts

95 months

Wednesday 12th May
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I started having problems with blueing discs on my 89 S4 and as LarJammer posted it’s from the stainless steel plate that the brake pad slides against gets corrosion underneath it, it lifts up and the pads bind in the calliper. Fairly well known issue, most decent specialists can deal with it. Have a look on rennlist for a how to if you fancy having a bash yourself.
edit to add link
https://rennlist.com/forums/924-931-944-951-968-fo...

Edited by Huskyman on Wednesday 12th May 21:55

PomBstard

Original Poster:

4,662 posts

210 months

Thursday 13th May
quotequote all
Thanks all. Well, it seems I can drive the car, albeit for about a mile before the brakes are locked on again. Booked in for a brake strip down and new hoses. Possible that the master cylinder is having a laugh too. As long as it’s not the servo, cos the engine’s in the way...

Huskyman

555 posts

95 months

Thursday 13th May
quotequote all
PomBstard said:
Thanks all. Well, it seems I can drive the car, albeit for about a mile before the brakes are locked on again. Booked in for a brake strip down and new hoses. Possible that the master cylinder is having a laugh too. As long as it’s not the servo, cos the engine’s in the way...
The engine in the way thing made changing the clutch master cylinder swap on my car a joyous experience on my 928 hurl IIRC correctly the brake lights are switched on by a pressure switch on the brake hydraulics, so if the brakes seize on and the brake lights come on then this could be the fault.

Krikkit

21,713 posts

149 months

Friday 21st May
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PomBstard said:
Thanks all. Well, it seems I can drive the car, albeit for about a mile before the brakes are locked on again. Booked in for a brake strip down and new hoses. Possible that the master cylinder is having a laugh too. As long as it’s not the servo, cos the engine’s in the way...
What's the word them PomBstard? Must admit it sounded like a stuck-on caliper to me.

PomBstard

Original Poster:

4,662 posts

210 months

Monday 24th May
quotequote all
Krikkit said:
PomBstard said:
Thanks all. Well, it seems I can drive the car, albeit for about a mile before the brakes are locked on again. Booked in for a brake strip down and new hoses. Possible that the master cylinder is having a laugh too. As long as it’s not the servo, cos the engine’s in the way...
What's the word them PomBstard? Must admit it sounded like a stuck-on caliper to me.
No news yet - can't get it into the indy specialist for another couple of weeks - there are a multiple 928s being worked on in that place, including a really rather sparkly GTS...

Did have a chat though, and we just won't know until its up on a hoist and being stripped. Looking in the engine bay, there's no way to get that servo out with the engine in place - and having seen one out of the car, I can see why.

I'll keep y'all updated when I know...

PomBstard

Original Poster:

4,662 posts

210 months

Thursday 17th June
quotequote all
Well, got it sorted this week. Brake master cylinder was the culprit - no problem with brake lines or hoses, or the servo - phew!. We’re not entirely sure of the mechanism of failure that caused the brakes to jam on, but oddly it was just the rears that were getting stuck.

Anyway, the 928 Doctor had already ordered one from Porsche Germany a couple of weeks ago when this first happened, so a spare was on hand. thumbup

Should note that this looked like the original master cylinder too - so that’s 35 years old…

So, just the A/C, springs/dampers, exhaust and wheels to go…eek

GreenV8S

28,876 posts

252 months

Thursday 17th June
quotequote all
PomBstard said:
We’re not entirely sure of the mechanism of failure that caused the brakes to jam on
My guess would be scoring or crud preventing the piston from returning to the rest position.

PomBstard

Original Poster:

4,662 posts

210 months

Thursday 17th June
quotequote all
GreenV8S said:
PomBstard said:
We’re not entirely sure of the mechanism of failure that caused the brakes to jam on
My guess would be scoring or crud preventing the piston from returning to the rest position.
Considering it’s age, that’s our best guess too, just haven’t seen these symptoms of failure before.