Brake issue series one 4.2

andrewh · Post by **andrewh** » Mon Sep 14, 2015 12:11 pm

Chaps, I have a good friend who has a beautifully restored 4.2 OTS which he is totally pleased with other than a quirk with the brakes. Everything on the brakes has been replaced or refurbished and I blieve it has new master cylinder . The problem is that the first press of the pedal it is spongy , the second it is harder and the third it is perfect. To drive the car one really needs to pump the pedal quickly twice to get a good pedal. It has been bled several times and this would appear to not be the issue. Can anyone suggest what this could be please? Since it is his only issue it would be good to advise him on a fix. Thanks in advance.

Quattrofrank · Post by **Quattrofrank** » Mon Sep 14, 2015 12:46 pm

Hi

I have exactly the same issue. Bled thru 2ltrs without any difference.
However now 3-4weeks later and some 100miles driving it became better.
I`m going to bleed yet again because I suspect there is some bubbles that have moved towards the calipers.

Post by **1954Etype** » Mon Sep 14, 2015 3:46 pm

Common problem. We had a S2 2+2 where the first application was okayish but need a second press. We found the rear calipers had seized and the fronts ned rebuilding.

Now all is good.

Think about pad knock off - apply the brakes twice with the car stationary and see if you still need 2 applications.

Look at the routing of the brake pipes, if you have large loops, air can stay in the top. We have had success with a vacuum bleeder and an assistant pumping the pedal. No point bleeding copious amounts through though.

andrewh · Post by **andrewh** » Mon Sep 14, 2015 9:05 pm

Ok thanks guys, so far ! So I was speaking to a supplier of new rear caliper Pistons at Goodwood who suggested to me that the old Jaguar system of pad retraction means that there is always some Aslack to take up. I do t doubt that but my 3.8 does not suffer from this, the pedal is perfect. Must be a 4.2 issue

Anyone else please?

andrewh · Post by **andrewh** » Sun Sep 20, 2015 5:36 pm

It's not pad knock off as we tried it with the engine not running. Mthree pumps and it has a good pedal, then leave it a few moments and it needs doing all over again. If it is not air in the system what other things could it be? I have not had a 4.2 system apart and so I am not familiar with it.

vee eight · Post by **vee eight** » Sun Sep 20, 2015 10:30 pm

It might be worth trying another bleed of front and rear, but use an easi bleed kit or similar system.
Phil

abowie · Post by **abowie** » Mon Sep 21, 2015 8:19 am

andrewh wrote: It has been bled several times and this would appear to not be the issue.

I thought this too with one of my coupes. Recently re-bled the bugger; much better brakes. If everything's new, if it feels like air it usually is.

PIL3370 · Post by **PIL3370** » Sat Sep 26, 2015 4:26 pm

I had exactly this problem on my 2+2 that I bought after a semi/full restoration this year. I bled the system 4 or 5 times, but it made little or no difference, always 1 full pump to get a pedal. After a lot of part changing, head scratching etc, to isolate the problem to either front or rear, I removed the rear flexible hose, and fitted a bleed nipple, to effectively split the system front & Back. I then re-bled the system to that point ( so the braking consisted of the front brakes, and pipes as far as the rear cage) - and the pedal was perfect, which meant the problem was with the rear brakes. It had been rebuilt with new discs and callipers, so they should have been perfect: after re-connecting (and re-bleeding) the rear half of the system, it was obvious on inspection ( on axle stands with my son pressing the brake pedal) that 2 of the 4 pistons were "pulling Back" at least 2mm when the brakes were released, thus necessitating the pumping to get them out again when you re-apply the brakes!
Any road, I removed the rear suspension and plumped for changing the callipers for Aluminium coopercrafts, which I had always planned to do. after bleeding, presto ! perfect brakes!
good luck - and by the way, the member who first recommended the large syringe method of brake bleeding is both a genius, and worthy of a beer or 2 as thanks!!
Regards, Nick P

cactusman · Post by **cactusman** » Sun Sep 27, 2015 7:23 pm

Have to say it sounds like air to me. Having rebuilt the brake system on my 3.8 it took several attempts to get all the air out. My advice is avoid easibleed like the plague. All it does is spray brake fluid all over the reservoirs. Use a visibleed....basically a pipe and a jar with a non return turn valve at the end of the pipe. Open your bleed nipple. Attach the pipe and STAMP Really hard on the pedal four or five times. Then check the reservoir level and top up. Repeat again. The pipe from the nipple should be full of air free fluid. If so tighten the nipple, remove the pipe and do the other side. You really stamp hard and that blasts out any air. Worked for me. My brakes are now fabulous. And for those like me with Kelsey Hayes bellows....they do work so if yours don't it is because they are faulty and not because the are inherently poor. Julian and a 62 fhc

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Brake issue series one 4.2

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#9 Spongy brakes