Thread: Spongey brakes

Originally Posted by Vetcar1

Chaps,
Am now starting to wonder if in fact my front brake plumbing is correct – just as 350RRC said to check!

Just to reiterate, my car is an ‘88 with the Lucas Girling brakes, not Lockheed.

Attached is a diagram from my manual (noting it’s for a LHD vehicle). Looking at the end of the MC furtherest away from the servo (ie closest to the viewer) you’ll see two pipes exiting either side of the MC. These two pipes form the secondary circuit. If you follow these two pipes to where they join their respective flexible hoses on either side of the car you’ll note that the pipe going to the LH wheel sits REARWARD of its primary mate, ie it is furtherest away from the front of the car – however the pipe going to the RH side, goes through the proportioning vale (which is correct) but then it sits FORWARD of its primary mate, ie it’s closest to the front of the car. Can I please ask if anyone with the same brake set up as mine could physically check their own brake plumbing to see if it matches this diagram? If so, I think I may have found my problem. Thanks in advance.
Brakes.JPG

If '88 is the same as '92 I can check the cars here.

Thanks for the offer DoubleChevron, but I think the 92's might be quite different in that they have ABS etc. Others may have a view on that?

Originally Posted by Vetcar1

Chaps,
Am now starting to wonder if in fact my front brake plumbing is correct – just as 350RRC said to check!

Just to reiterate, my car is an ‘88 with the Lucas Girling brakes, not Lockheed.

Attached is a diagram from my manual (noting it’s for a LHD vehicle). Looking at the end of the MC furtherest away from the servo (ie closest to the viewer) you’ll see two pipes exiting either side of the MC. These two pipes form the secondary circuit. If you follow these two pipes to where they join their respective flexible hoses on either side of the car you’ll note that the pipe going to the LH wheel sits REARWARD of its primary mate, ie it is furtherest away from the front of the car – however the pipe going to the RH side, goes through the proportioning vale (which is correct) but then it sits FORWARD of its primary mate, ie it’s closest to the front of the car. Can I please ask if anyone with the same brake set up as mine could physically check their own brake plumbing to see if it matches this diagram? If so, I think I may have found my problem. Thanks in advance.
Brakes.JPG

The plumbing layout should be the same for AP and L-G, they use the same callipers, the MC's are the same in the way they work apart from the warning switches.

My POS is currently AP, but about to become L-G with a brand new M/C and D1 pedal box with a double diaphragm booster.

Easy to check............... it's 10 feet away.

Secondary circuit pipes are to the rear each side. They then go through (braided stainless) flexi lines to the top solid line to each front calliper. They then end up at the lower port on each calliper, as per workshop manual 'Brakes 70, p.21 fig RR868M)

I'm not saying this is technically correct, but one would think that the secondary circuit pipes should go to the same respective ports on each calliper.

Yours is possibly the same problem I had 20 years ago, except it was on the passenger side.

DL

Should also add that the 77 I had was 'slightly' modded with all sorts of stuff, including a L-G MC, the later proportioning valve and a D1 pedal box.

The plumbing layout was the same as mine and it bled no probs when I had to change a brake hose at the front. Had awesome brakes.

Gonna crack one of the nipples at the back tomorrow and go for a little drive to make sure the back up system works up front as designed. Just down my driveway.

DL

Originally Posted by Vetcar1

Thanks for the offer DoubleChevron, but I think the 92's might be quite different in that they have ABS etc. Others may have a view on that?

Any info on the wash up with this thread....... ?

DL

Well the wash up is that i'm no closer to solving the problem. Had a look at another '88 nearby and was able to confirm my plumbing of pipes and hoses is identical to it, so that's not the problem. The car is very close to becoming the start of an artificial reef somewhere! I actually have it booked in at a brake place for next Monday to see if they can do anything with it. I'll post what the result is. Thanks.

OK - well just got it back from the Brake place. They got a little bit of air out of the fronts, but not much. They acknowledged the brakes weren't great, but at the same time, didn't seem to think they were too bad - they reckoned it would probably pass a roadworthy. They conducted various tests -like drag alignment, left to right inbalance, front to rear etc and it seemed to pass those tests. The one thing they did say that may be causing what i describe as the 'spongy feel' is the fact that the pads would benefit from bedding in, or to use a pad with a different compound on it. I've fitted new Ferodo pads back and front, and new slotted rotors all round too. I've only probably done about 3 klms on these new components. What does the collected forum wisdom think of the importance of bedding in - and its possible ability to fix my problem?

Did you actually try the suggestion of making sure the same circuit lines end up on matching mirror front callipers and then bleed it?

And then drive it?

DL