My brakes, my brakes, why doth my brakes not work Part 2

[handi_andi]

Hi all
Have finally managed to give my old girl a test run having finally persauded the flywheel and cluth to part company, so that I oculd check out the brakes and see how the engine was running with the Ignitor ignition. The engine is running great although still needs a bit of a tune up and need to find out why when one touchs the throttle it shoots up to 3000rpm and hangs there even when throttle has been realised for 5 to 10seconds. Anyway, more importantly my brakes, I have fitted a new master cylinder, which after the advice I had before on this subject I bench bleed with it in the vehicle, before pressure bleeding the system again, checking all of the flexibles and have fitted new pads all round. I haven't done anything to the servo but based on the advice before I suspect this is where the problem is. Basically, if I press the pedal to the floor the car slows done but doesn't brake sharply, however, if I release the pedal and then press it again I get full brakes that light up the Yokohoma A-Drives and the car stops very quickly but it feels like the brakes lock on and when the pedal is released the pedal momentarily hangs before releasing. Suggestions anyone?

Thanks

Andy

PS That was so much fun and I have to say a smaller steering wheel really helps

[Elanintheforest]

Make up a pipe to bypass the servo...bet it'll be fine then, but if not, you know the servo's OK.
Mark

[timliggins]

Do you have a Girling or Lockheed servo? This is a common problem with the Lockheed.

[handi_andi]

I dont think it is either of the standard ones, looks like an after market replacement, think its called a powerstop of something like that. Looks only to be a few years old as it is anodised aluminim in goldy sort of colour. Don't think I have picture on computer of it unfortunately and away from home at the moment otherwise would post one to see if anyone could identify it.
Andy

[timliggins]

It's a Lockheed Powerstop.

On the side of the servo is a white plastic cover. If the servo has been fitted according to Lockheed's instructions this will be pointing downwards so you will have to remove the servo to get to it. Remove the plastiic cover and underneath there is a small piston. This is tricky to get out - may need a squirt of air from a footpump. Don't do this over an inspection pit as I did! The piston will have either one or two 'O' rings. Lockheed added the second 'O' ring at sometime. If there are two, remove one of them.

I carried out this mod and it made a huge difference but there was still a slightly discernible 'hang' on the brakes. Classicar Automotive have had a spring manufactured which fits under the plastic cover to assist the piston. They sent me one free of charge. Unfortunately my car is still off road so I can't verify that the mod has worked.

Regards, Tim

[richardcox_lotus]

I've just fitted this spring mod to my (sticking servo), with many thanks to John Clegg.

However, as I only managed to bleed the brakes yesterday, I've not had chance to do a road test yet. I'll report back when I do. Oh, & Classic automotive will happily make you up a bypass pipe to put in the boot.

[archigator]

I had the exact same symtoms start a couple of weeks ago and figured that it must be the brake pistons sticking. I too have a Lockheed servo, and I guess I am now in need of a spring. (Beats replacing all of the pistons!) Does anyone in America carry them? Classiccar Automotive doesn't appear to have a website. Thanks!

Gary
'71 Elan Sprint FHC
Miami, FL

[Lincoln62]

If you pump the pedal and then the brakes work it is because of air in the line.

Air will always accumulate at the highest point of the brake line, if your lines go upward from the master cylinder before going down to the booster the air will be accumulate up there. You probably need to pump a fair bit of fluid through to get it out. You need to get the fluid moving and keep at it. Every time you stop the air starts to go back toward the high point.

The momentary hanging of the brakes on Plus 2's seems common. I tried to cure this on my friend's car when he first got it. We tried 3 different boosters, all the same, rebuilt the pedal box, rebuilt master cylinder, still the same.

The booster is driven by the little vacuum valve at the side and I think the lag is due to the fact that the booster is so far away from the master cylinder. He was happy to live with it knowing the system was all safe. I think I would bypass the booster and try it that way.

Peter
66S2

[handi_andi]

Interesting guys, can someone send me contact details for classic automotive please. I have a feeling my servo may not be fitted correctly then as the white plastic bit is on the top and not the bottom, should I also consider turning it around at same time as doing mod? Has anyone got the details for the spring?

The brakes have been pressure bleed several times with alot of fluid run through them, now amounting to over 2litres so I don't think that there can be much in there, however, I am wondering if there is a way to bleed the system to just ont he brakes side of the servo before doing the brake lines themselves to ensure that it is clear. Suppose I oculd introduce a three way union with a bleed nipple in the T.

Am determined to cure this one and for all.

Cheers

Andy

[MintSprint]

Classicar Automotive

Address: Unit A
Alderley Road
Chelford
Cheshire
SK11 9AP


Telephone: 01625 860 910

Email: salesclassicbrakes.co.uk

[handi_andi]

Excellent thanks, can feel a little trip coming on as am down in Chesterfield at the moment so that would be a nice run out.

Cheers

Andy

[Robbie693]

Andy,

Just a thought but, you mention the throttle sticking - have you checked the pedal shaft for wear?

After I replaced my master cylinders and put the pedal box back in (for the second time ) I discovered the throttle sticking when I pressed on the brake pedal and 'heeled' the accelerator pedal. on inspection there was noticable movement of the shaft in the pedal box. I had a new pedal shaft made up and this cured the problem. I am wondering if this could contribute to your sticking brake pedal also...?

[handi_andi]

Haven't checked it, but you might have explained the sticky throttle problem as have just put a load of silicon sealant in between the box and the wing which has cured my leaking footwell but it could be causing the spindle to stick as you say. Brake problem was there before hand though thanks
Andy

[tdafforn]

Fitted one of John clegg's springs 3 years ago. Completely sorted the problems I had had with brake hang.
Probably one of the quickest fixes I have done in the +2
tim

[john.p.clegg]

Andy
If you're in Chesterfield and going to Chelford feel free to call in SK13 2NX and I'll have a look in the shed to see if I've any springs left,just sent one to "Richard Cox lotus" could of been the last?

John