Brake failiure! But only temporary?

[Welsh Warlock]

A I headed off to Bonnie Scotland for the SARR meeting I noticed that one of the front calipers was binding a little (car pulling to right) but this has happenend before and it frees after a few miles so I didn't worry too much. Sure enough it seemed to free up.

After about 10 miles, as I entered one of the villages, I went for the brakes and the pedal almost hit the floor. I brought the pedal back up immediately & re-applied and got some brakes.

I pulled onto a nearby filling station forecourt and recovered my composure.

I decided to return home and dump the rover and go in the everyday hack.

As I headed back, the brakes seemed to be working OK but I didn't have time to investigate.

I have taken the car out of the garage today and done a 12 mile run, during which I tried the brakes several times to varying degrees but can detect no problems at all.

Is it possible that the sticking claiper, although it appeared to have freed, had boiled the brake fluid? Would that cause the temporary loss of pedal pressure?

Any other ideas?

[theroveringmember]

I had that problem on mine a few years back, but only when you braked hard. A change of Servo cured it.

[Phil Nottingham]

The Servo is an obvious firts cehck but I think you calipers are ready for reconditioning as I have had this happen a number of times over the years. The chrome on the pistons flakes and causes sticking but waht the real problem is that a ring of corrosion forms round the top of the piston bore in the caliper which when hot grips the piston causing overheating a vapor lock which is why you got brakes back on the second push.

A collapsing flexi coudl also cause the same problem so it may be as well to replace these if they look old at the same time.

The sticking/rust would have been made worse whilst the car was standing idle during engine work, This problem does not go away only get worse usually at most incovernient times - it can actually set fire to the pads and crack discs so it needs sorting fast

My 3 litre is just starting to do it again after 10 years when I reconned the calipers last - I have got a pair ready to put on now!

Pity it did not make it to Scotland this time to try out your engine

[Welsh Warlock]

Thanks Phil. It sounds like the problem is pretty much as I suspected.

I've had a sticky caliper on and off for several years but never caused this problem before.

I had a NOS master cylinder which I have fitted today.I took it apart first to check its condition and clean it up with meths and it seems A1. The reservoir had a fair amount of black particulates which are normally a sign of the seal breaking down so I thought it best to change it anyway. Haven't had time to bleed the brakes properly but Already have a decent pedal.

I will have the calipers overhauled but its a nuisance having the car sat on the driveway while they are away being overhauled.

[Colin McA]

I had a similar problem with my V8 range rover.

A few times the pedal was pretty much on the floor and my heart was booming.

There was a lot of heat in the engine bay but no loss of fluid, the next time it happened it was the same thing. I had be driving a little hard and fast over back roads. I put it down to the fluid being old.

I have just had a brake refurb done by past parts and they are pretty decent.

Colin

[Welsh Warlock]

arthuy said:

I had a similar problem with my V8 range rover.

A few times the pedal was pretty much on the floor and my heart was booming.

There was a lot of heat in the engine bay but no loss of fluid, the next time it happened it was the same thing. I had be driving a little hard and fast over back roads. I put it down to the fluid being old.

I have just had a brake refurb done by past parts and they are pretty decent.

Colin

FRont calipers have gone off to Past Parts today.

Anyone had any experience of the kits available for making ones own brake pipes? I have a few that need replacing and though maybe it would be better in the long run to make my own.

[johnwp5bcoupe]

I looked into kits and it was far less money to make my own but I did have my own Flaring Tool I used Kunifer pipe which is Copper and Nickle a bit harder to bend it wont rust and to me it looks better than copper also it is more robust


www.stevsonmotors.co.uk/home.htm

www.vehicle-wiring-products.co.uk/VWPweb2000/brakes/brakes.html

[Phil Nottingham]

If copper pipes are used instead of Kunifer type ensure that its mounted securely as copper hardens quickly under stress and cracks

[park01]

a company called amec do make the brake pipes ready flared with connectors and cut to length at a very reasonable price. i think they advertise in practical classics. i have a invoice at home with the number if you require it.
i was always under the impression that copper pipes shud not be used with a servo?

[Phil Nottingham]

The only disadvantage with copper pipes is that of work hardening - a Servo does not makes brakes better it just makes for less foot/leg effort so they are entirely suitable if precautions taken as above

[Deleted]

I had this problem a few years Ago, it was the master cylinder at fault, washers were "inverting" after wear accumulaated. changing master cylinder and piston cured it.

[Welsh Warlock]

Just a quick update.

I had the calipers overhauled at Past Parts and they're now refitted and a test drive confirms that they appear to have been the problem.

It was only on the test drive that i realised I was always waiting for thje wheel to snatch and must have become accustomed to this and adapted my driving style (of the P5) accordingly. It took a few minutes to rrelax and trust that the brakes were no longer pulling.

unfortunataly i've not been able to do much mileage due to the bad transmission leak but that's another story.

Park01, I would be interested in the details of "a company called amec do make the brake pipes ready flared with connectors and cut to length at a very reasonable price" as i can't find them on t'internet.