Brakes- Assistance Please!

[nico506]

Hi All,
I know this has been listed before - but i am nearing the completion of my 1968 S3 Elan and have been chipping away as and when I have time for the last 5 years etc and reached the point where I am frustrated such that I am making no progress in resolving the brake problems.

I have a new master cylinder fitted, new brake lines, overhauled calipers all round including brand new set to front.
Replaced the Girling Servo with Lockheed powerstop type and despite the wife helping bleed the brakes on the pedal .

I have checked all round for leaks - none are present.

I have a very soft pedal - no pressure on the discs when depressed and after numerous pumps - 10-20 or so the pedal firms up- albeit slightly at bottom of travel.

I am bleeding from the far caliper first and then working round each time towards the master cyclinder.

I am lost for further actions and is there anything I am missing here ?????

I live in Leicester West Midlands and only 15-20mins from Donnington - so would welcome a pair of expereinced eyes over the system and advise what I am missing here as I am at the moment racing to finish the car in time for Silverstone Classic.

Any tips advise or pointers welcome.

Thanks in advance.

Nico

[memnon]

My advice,

Is take the servo out of the loop, you can bypass is easy enough with a copper pipe.

If you can get a good pedal after this, the problem is the servo. You can go further with this technique, but start there.

Jason

[neilsjuke]

The outlet of the servo needs to be pointing up 30% to bleed think of the bubble in a level
Neil

[rdssdi]

Did you retain the original type fittings into the calipers?

I used stainless flex lines which used a banjo fitting at each caliper. The banjo will seal at the top of the caliper on the housing surface. As opposed to the original fittings which seal at the bottom of the threaded hole in the caliper. It took me a while to get the correct ID and OD copper crush washer to seal properly.

Bob

[AussieJohn]

Have you got the calipers on the wrong sides of the car? Are the bleed nipples at the top of the calipers?

[andyelan]

Hi Nico

I think it can be very difficult sometimes to bleed brakes if the system has been completly empty, it's as if the master cylinder has nothing solid to push against. Assuming you not assembled anything incorrectly, all you can do is keep going round the four calipers in turn untill you start to get some feel in the pedal.

One technique I have heard of, is to fill a clean oil can with brake fluid, connect it to the caliper bleed nipple, and then try to force fluid into system in the reverse direction. Do make sure everythigs clean though, and take it easy or you'll finish up with fluid everyware

Regards
Andy

[terryp]

Hello
You may or may not be doing it this way but I thought it worth saying ......and its always worked for me
I saw it on an very old Girling leaflet when I had my Ford 100E - when bleeding brakes - Do one press of the pedal, then lift your foot half way up , then 3 very very rapid half strokes , slide your foot of , then to the floor to tighten. Fill the reservoir and do again , perhaps 2 or 3 times per wheel. On the three rapid strokes the air comes out for some reason?
Hope you cure it

Terry

[paddy]

I've bled the brakes on countless cars and never had the problems I had when doing the Elan after replacing the master cylinder a while back.

I'd tried the "wife" method once before and it wasn't really an option again as I didn't want an axe through the bodywork (or me).

In the end I used one of these:

http://www.justoffbase.co.uk/Brake-Clut ... aley-VS820

The root problem I was having, especially on the rear calipers, was that the bleed nipple threads are not airtight, even when loosened only slightly. (Rotoflexible made the same comment a couple of days ago.) You can go some way to sealing them, but if just pumping at the pedal there always seems to be a risk of air being drawn in when you release the pedal. Also, the bleed systems that suck the fluid through from the bleed nipple are prone to drawing air in through the threads as well. The pressurised bleed systems like the one above don't have this problem, and also don't have the problem of having to top up continuously. It will force fluid through even when the system has been completely drained.

Still, I must have put 5 litres of fluid through before I was happy with it. Next time I do it I will try a lot harder to seal the threads on the nipples before starting because it really shouldn't be that hard.

Paddy

[andyelan]

I've had the same problem Paddy. I finished up using the technique:- Open bleed nipple, Press Pedal, Close bleed nipple, lift pedal.

It's a real pain and obviously a two man job (one man, one wife) but it does work. Requires perseverance though.

[GrUmPyBoDgEr]

I've had the same problem Paddy. I finished up using the technique:- Open bleed nipple, Press Pedal, Close bleed nipple, lift pedal.

It's a real pain and obviously a two man job (one man, one wife) but it does work. Requires perseverance though.

Yes that's the way my Dad taught me how to do it & I've always followed that procedure without any problems.
Only at the start of the process where mostly air is is coming through is when I don't take the precaution of tightening the nipple.
!/2 Liter of fresh fluid does the job.
Cheers
John

P.S. S4SE with servo removed.

[crannyr]

I have had similar frustrations with brake bleed on several Elans. The one recomendation I found in an early post was to wedge the brake pedal on with a weight or board and let it sit overnight. I am not sure why it works (I am guessing it slowly purgess air thru the master cylinder vent) but it works very well.

[richardcox_lotus]

This last point I've seen mentioned before - Air getting trapped in the master cylinder - takes an age for it it be expelled - but placing a brick / piece of wood on the pedal & leaving overnight seems to help.

[AussieJohn]

I think the pedal jammed down with wood fixes the brakes sometimes because it sets the caliper piston seals so they dont move so far from the discs when the brakes are off. I dont think any air can bleed out because the valve in the bottom of the master cylinder is closed when the brakes are operated.

[Tonyw]

Hi all,
I am not sure why such a simple brake system causes so much of a problem but I have tried on many occaisions all of the remedies stated on this thread. From experiance disc brakes with twin pistons times four take a fair bit of pushing out from such a small and relatively short stroke master cylinder if you can imagine what displacement is required on a fresh system i.e. all pistons need to be pushed out to reach the disc, all pistons will have nice new seals that retract well (8) if the pads are new they may not be mating up very well at first so the poor old master cylinder may be having a bit of a hard time. Vacuum bleeding is probaly just as good as pressure bleeding but you really need to know if you have all of the air out, i suggest you fit some clear plastic tube (tight to snug fit) over each bleed nipple starting with the one furthest from the master cylinder, put the end of the clear tube in a small container making sure the end of the tube is submerged in brake fluid, open the bleed nipple and pump the brake pedal slowly and observe to see if there is still air coming out, once you have pumped and no air appears to be coming out tighten that bleed nipple and do the rest. If you are concerned that the up stroke of the master cylinder may draw air in from the bleed nipple thread for the last couple of down strokes close the thread for the up stroke if you get my meaning. I have similar problems with my rice burners you have my sympathy.

Tony

[mct340]

I've found that bench bleeding the new master cyl. makes all the difference.

Jury-rig two clear lines from the ports that loop back into the full reservoir and pump the piston until the bubbles stop. Block the ports and replace the unit. Fit the lines and bleed as normal.

You will need to find a couple of nipple fittings to screw into the ports. Earl's or Aeroquip.

I suppose you could do this while the master is mounted in the car.....good luck.