Warning if you do a Porsche caliper upgrade

[orsum]

My brakes failed. Lucky for me I was in a safe area and managed to come to a stop.

I purchased a front set of calipers and rebuilt them myself. Easy job.

The only thing I never did was replace the cross over pipe, I never saw it to be required. BIG MISTAKE

It appears that the pipe rusted inside the rubber and eventually it burst when I applied the brakes.

Lesson when overhauling a used parts check everything.

All that glitters is not gold.

My fault should have done a better overhaul job.

[k.alle]

Wow, that is scary!
Glad you're OK.

Need to check mine I think..

[Cordoba16vt]

I always do a monkey test - after bleeeding brakes , give hard press on the pedal almost as much as you can - if something should fail , let it fail on the spot. I had a recent rear brake line failure - less than 2 years old ( dont remember the brand ) , and it failed at 160km downhil.....

[Error404]

After I open the brake circuit for any reason, I always do a test at standstill with assistance (vacuum or hydraulic) using full braking force. Good to check for leaks also
If you are so inclined, you can buy new cross-over pipes from Porsche

[orsum]

In SA the Porsche cross-over pipes are Rand 780 each. That is 42.77 UK pounds each. I contacted my local brake specialist and they had some pipe they use on boat trailers that go into salt water and last much longer than the normal pipe.

They made me a new set for 100 Rand for the two which equals 5.48 UK pounds total.

The brakes have done 5000km since I fitted them so pressure testing them may not have shown a problem, there was no signs of a leak the pipe just burst.

With respect to the S2 Coupe brake system if one of the circuits fail (front or rear) should the brakes on the good section still work? I am a bit concerned as it felt like I had no brakes when the front pipe burst.

Can anybody confirm what should happen when a brake pipe bursts.


goodall said the following

13th February 2009, 14:44

the standard system used a fixed ratio bias valve, part 13, located under the master cylinder
the system is longitudinally split rather than diagonally, which means the front circuit pressure is used to restrict rear pressure, ie in event total front brake failure due to a leak the rears get full pressure

other option is break in gear, that way torsion diff will balance the breaks, i think....


Last edited by goodall; 13th February 2009, 22:11.

[peter20vt]

I do not agree
If one brakeline failes you loose al brake power
it is the same when you bleed the brakes

[Bowie69]

Erm, I seriously doubt that.

Any modern braking system (by that I mean post-morris minor) would be twin circuit, giving some sort of failsafe.

Of course if you have messed with it, who knows what it will do.

[peter20vt]

When you bleed the system you get pedall to the metall
and no brakes
same happens when one brake hose breaks
you will lose al your oil
exvept for the clutch

[steve briance]

But there are 2 lines coming off the master cylinder, one does one pair of wheels, the other deals with the other pair. Pressure from the master cylinder wouldn't dissappear from both lines if a hose bursts. This is why some braking remains even if you do start having a catastrophic leak somewhere. What I'm unsure of is of the coupes are front pair / rear pair or diagonal split. Diagonal split is more common as you still get at least one front caliper which does the most braking and, you pull up in a straight line.

[Bowie69]

Exactly.

Having air in the system is not the same as a leak.

[Wrath]

When i refurbished mine a friend told me to change the pipes, im glad i did as they where in bad shape aswell. Looked okay on the outside

[orsum]

Could be worth making this caution into some sort of sticky.

Save having a possible accident.

[orsum]

I will be checking into the Coupe braking system but I think the front and rear are two separate lines.

It could be possible the rear section has air in it.

[s2driveruk]

Good shout and i will be taking a good look over mine now. Probably need to do a decent overhaul given they have been on for years now.

[s2driveruk]

Made sticky...!