Javelin Hydro Mechnical brakes

Robin Fairservice · Post by **Robin Fairservice** » Thu Jul 23, 2009 7:09 pm

I saw Keith's reference to the 3mm clearance, but I have that. I tried to slacken off the high pressure hose from the MC to see if air or fluid would come out, but when I pushed on the brake pedal it was rock hard! I looked back at the hose and I had accidentaly kinked it. This suggests that the seals are OK.

By the way did you mean MC when you said MS?

Keith Andrews · Post by **Keith Andrews** » Thu Jul 23, 2009 9:16 pm

that we spotted the problem - the problem was that the master cylinder piston was not going fully back

This is a very common issue with 1st gen camaros when updating MC /brakes from drum to disc or introducing power brake units
The pin that goes into the back of the mc is the wrong length, eith to long or to short.
To find out if it is the issue the mc bolts are loosened off the rod and distance into the MC are measured, there should be about a 1 to 2 mm clearance....this related to the amount of pedal free play before moving the MC piston.
The amount of leverage on the pedal would be different in the jowett.
Too much play means the piston will not move its full travel
Too little or no play means the pston will not fully return, which usually results in the brakes not unbinding..drag or locking the wheels.

Both of these creates issues when bleeding and not being able to get all the air out.
Generally we bench bleed the MC before intalling.
If the brake cicuit has a proportining valve , depending on how it works, this can cause issues if vaccuum or pressure bleeding.
Ie on the camaro one can pressure bleed the front brakes, but not vac bleed because the prortiong valve closes that cicuit and cant the rear (Presuure)without activating the button on the side of the valve that sits over the diff.

Robin Fairservice · Post by **Robin Fairservice** » Fri Jul 24, 2009 12:54 am

I have been lying under the car whilst my wife pushes the brake pedal up & down. My hopes are dashed as the piston road seems to be moving in and out as far as it can. There is a clearance at the front yoke, which I have tried to measure and it seems to be 3/32" as per the book. If there wasn't any clearance then I would say that the piston rod is not travelling back as far as it should.

I have ordered a Gunson's Pressure Bleeder, and may be that will get all of the air out. We tried some more bleeding as well, and got some foam out of the right hand brake bleeder, and the pedal is a bit better.

Post by **Forumadmin** » Sun Jul 26, 2009 10:17 am

How slowly does it take to go fully down?
If it is less than two seconds I suggest it is something very wrong, such as wrong seal or wrong assembly or air in the cylinder. Until you get all the air out you will not have brakes.

The Gunson bleeder only helps if you do not have assistance. Now the wife is trained ask her to push slowly, taking 30 secs to fully depress. Getting foam is not what you want, large bubbles are better.

You could also disconnect hose and allow to flow under gravity, keeping the reservoir topped up. May pay to take the MC off and fill on the bench and check basic operation.

Keith Andrews · Post by **Keith Andrews** » Sun Jul 26, 2009 10:29 pm

Are u pumping when u bleed?
If so if any air is in the system getts foamed up
have a person in the car..
Start at the bleeder farthest way from the MC.
press the pedel, open the bleed, hold the pedal down, close the bleed.
And repeat
Do NOT allow the MC to MT out.
If u do Start again.

roger young · Post by **roger young** » Mon Jul 27, 2009 8:48 am

quote [Start at the bleeder farthest way from the MC.]

I was taught to always start at the bleed nearest to the master cylinder and work back so that any air in the system is worked back and you are not bleeding past any pipes that might have air in them

Robin Fairservice · Post by **Robin Fairservice** » Mon Jul 27, 2009 5:02 pm

Thinking about which wheel is furthest from the MC made me realise that they are both the same distance as far as the piping is concerned. There is a common pipe from the MC to a Tee in the centre of the car, and from there the lines to each wheel are the same length.

As mine is a left hand drive car, I was assuming that the right hand wheel was the farthest. Now I realise that is irrelevant.

Keith Andrews · Post by **Keith Andrews** » Mon Jul 27, 2009 8:58 pm

The farthest on a left hook is the right rear and visa versa on the right hook.

Post by **Forumadmin** » Mon Jul 27, 2009 11:03 pm

Having just fitted the brake pipes in the great SC rebuild, I can assure you that the closest to the MC is the driver's side front wheel and farthest is the passenger side rear wheel.

The pipes do not go down the centre of the car so left and right are different lengths.

The Javelin is virtually the same as the Jup. A left hand drive car may have less difference since the 4 way junction after the MC may be more central, although on the Jup it is positioned in the same place; but the opposite side.

The order in which you perform the bleeding is not critical but it is recommended that you start at the rear and do these two wheels first and then the front two. This will minimise the amount of potential cross-contamination between the new and old brake fluid.

But if the system is full of air then starting at the closest might be best since air compresses more than fluid it will expand back into the pipe that you have just filled. You will have to go around a few times to get all the bubbles out anyway. Always push slowly to give the surface tension time to coalesce the bubbles and collect the small ones up as the main bubble moves down the tube.

Tony Fearn · Post by **Tony Fearn** » Mon Jul 27, 2009 11:42 pm

Interestingly, after all these observations, when I went to the garage that services my Renault Scenic I asked about brake bleeding.

The mechanics said that gravity bleeds all the cylinders, usually!

I'm used to rod brakes, so make of it what you will.

Tony.

Tony Fearn · Post by **Tony Fearn** » Thu Jul 30, 2009 4:29 pm

I called in on Bob Mercer again this lunchtime and he'd been giving some more thought to the MC problem he had years ago.

He finished up writing to Lucas about the seal kits but was told that they no longer supplied kits but that the seals were available (in those days) singly and gave him a list of part numbers.

These numbers he had in his archive and I reproduce his little note below.

Bob wrote:-

JAVELIN MASTER CYLINDER HYDRO-MECHANICAL
One (1) seal ..... H1015 Outer seal
One (2) seal ..... H1483 Seal spreader
One (3) seal ..... H1145 Recuperating seal

JAVELIN MASTER CYLINDER FULLY-HYDRAULIC
One (1) seal ..... H1015 Outer seal
One (2) seal ..... H1483 Seal spreader
One (3) seal ..... H1016 Recuperating seal

NOTE:- Seals (1) are the same for both master cylinders
Seals (2) are the same for both master cylinders
Seals (3) are different for each master cylinder:-

H1145 rec. seal for hydro-mechanical
H1016 rec. seal for fully hydraulic

Bob recalls the moving of the spares from "down South" to "up North" and the fact that the two different recuperating seals that were stored separately in the stores down south were all thrown into the same box prior to transportation north!

Hope this is of some help.

Tony

Robin Fairservice · Post by **Robin Fairservice** » Tue Aug 04, 2009 3:55 am

Many thanks for the list of seal part numbers. Now if we could find out what the differences are, then I could see which ones I have.

Post by **Forumadmin** » Tue Aug 04, 2009 9:05 am

Neil Moore in NZ said via Leo Bolter that the recuperating seal inner lip is "too tight" on the shaft, so much so that it won't let the fluid return past it properly.

My fully hydraulic piston is 24.85mm .9785in, shaft 9.44mm .372in.
The recuperating seal when dry needs very light finger pressure to move it along piston. By contrast a worn seal just falls down!

The rubber seal is tight on the shaft needing much more force to move it.

Robin Fairservice · Post by **Robin Fairservice** » Thu Aug 13, 2009 8:10 pm

Finally I have brakes that work. It was suggested to me that I talk to a retired mechanic living in souther BC. It turned out that he had worked on Javelin's in the 1950's. I reviewed all that I had tried to do, and then he quizzed me about the front brakes. In the end he recommended that I dismantle the front brakes, and checke out the brake cylinders.
This I did and took both cylinders apart. Fortunately the seals looked good, but one cylinder did not look that good and there was dirt an gunk in it. I acquired a small honing tool and cleaned up both bores and put them back together. In putting the shoes back in place I looked carefully at the Girling drawings, but could not really see how the top spring was hooked to the shoes. Reading the text, and then looking at what I had, I realised that the two shoes had been joined by the spring, which was wrong. I reassembled them as per the book, and went back to trying to bleed the brakes. This was fairly easy and I now had a firm brake pedal. A road test confirmed that I had good working brakes, so I am now happy.

Many thanks to all those who tried to help. I guess that if any one had been able to come into my garage we would have solved this a long while ago.

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