DDK - Die Deutschen Klassiker

Whe I Get the car back from its posh wash, I’ll give that a go Ian. The issue only really started after i had all 4 calipers refurbished, before that the brakes would hold pressure over winter, so I think something is wrong somewhere, thing is, how do I solve it or do I resign myself to bleeding brakes every year

Have you got aero quip brake lines from the callipers or rubber hoses. The rubber hoses can break down, and ballon under pressure. Hence you would not see a leak, but the balloting would take up the lack of pressure you are feeling?

sladey wrote: ↑Sun Feb 16, 2025 7:41 am
For bleeding I use a pressurised system from Sealey - think it was about £60 and is really excellent and easy to use

I bought something similar (may even be the same) several years ago when I was having trouble getting the last remnants of air out after a major brake system overhaul on my Giulietta Sprint & it was a revelation - made bleeding the system a doddle (single handed too) - wished I bought one years ago !


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Nine One One wrote: ↑Sun Feb 16, 2025 10:47 am Have you got aero quip brake lines from the callipers or rubber hoses. The rubber hoses can break down, and ballon under pressure. Hence you would see a leak, but the balloting would take up the lack of pressure you are feeling?

Just standard brake lines, been on a few years mind

Ok, car is back from its posh wash. Didn't actually realise on the first press, the pedal goes all the way down to the floor. I have got one of these pressure bleeders. If I connect this up, pressuize it and leave it, if it looses its pressure i have a leak, yes. If so, should I to have a wet spot to sow evidence of a leak?

Remember to BLANK OFF the over spill/ air outlet/ breather to the side of the reservoir, otherwise you are going to have fluid everywhere before you even start.

markm wrote:Ok, car is back from its posh wash. Didn't actually realise on the first press, the pedal goes all the way down to the floor. I have got one of these pressure bleeders. If I connect this up, pressuize it and leave it, if it looses its pressure i have a leak, yes. If so, should I to have a wet spot to sow evidence of a leak?

Yes - subject to clamping off the overflow pipe

So went out to the garage today to tackle the brakes, simple enough job. However the new Sealey pressure brake bleeder thing I’ve got had other ideas. New unit bought last year in May doesn’t get any pressure build up, so pretty feckin useless really, £60 odd well spent on that then. New unit ordered to try again

Although checking the brake system thoroughly, no visible leaks, so I’m scratching my head. How can the pedal go soft with no leaks? How is the air getting into the system?

I have two way to do this, both work.
1
Get the helper/wife in the car, car level.
Make sure the fluid reservoir is to the top.
Attach the bleed tube to the nipple of the caliper furthest away from the reservoir, ie either of the rears.
Crack open the caliper nipple and helper told Down to the floor, full action in 1 or 2 seconds.
Lock off that nipple and helper allows the pedal to rise to the upper stop.
Repeat 8 times, keeping the reservoir topped-up.
Do the same to the other rear, the NSF (if LHD) and finally the 4th caliper.

Pedal should be firm/solid with a good emergency braking pressure. Note that the 911 has an unusually long 'free-play' before the brake pads are all in contact to the disc faces firmly.
If soft or long travel, the air bubble is still in there acting like a spring, the softness is the air volume compressing with the fluid pressure. Hold the pressure long enough and the pedal will go hard as the air has been absorbed by the fluid. Over an hour the air will form again as a bubble = soft pedal.

2
Replace the helper with a motorsport bleeder, a receiver vessel with a tube from it which connects to the nipple. The tube has a one-way valve in it.
The pedal can be depressed by you (or the helper) and each pedal release closes the one way valve. Next down stroke blows the valve open and fluid/air is squirted out into the vessel.
Repeat 8 times etc.

I have done this sequence several times on the 73T I have and my full race Lola hillclimb car with giant Brembo brakes and 8 nipples, always works reliably.

If no fluid is leaking out under pressure (the pedal would gradually sink to the floor) then i doubt air is getting in. I would think you have an obstinate air bubble somewhere which needs flushing out.

Finally, I know too well how frustrating this can be!

Result. So bought a second pressure bleeder from that well known next day delivery company, first thing to check, does it hold pressure. Yes. So crack on. Bled the rear off-side, some air come out. Bled rear near side, nothing, no fluid nothing coming out under pressure, hmmm. So after a bit of messing about, moved to the front thinking I’ll come back to it. Eventually all 4 corners bled resulting in a firmish pedal.

So, we resorted to the old Spanish version, manuel. Dragged Mrs M out explained the simple instructions, push, off, think she understood and went around the car again. The rear near side must of had a blockage as loads of air come out of it with Mrs M push, off’ing

So happy days, have a firm brake pedal. Happy now. Might treat myself to a jammy dodger biscuit

Nice one … so as suspected.. just a bit of air

Ha!
The old methods do work so well..