Lotus Elan

New Lines NO Brakes

PostPost by: Greg Foster » Mon Jun 18, 2018 10:09 pm

The old lines on my 67 SS elan were getting rusty and I noticed a seep from one of the SS braided lines at the front wheels. The engine was out so I decided to tidy things up.... Brakes were working fine before I replaced the lines. Care was taken to blow the swarf out of the lines prior to installing them as I manufactured the compression flairs. All the unions were cleaned and new fittings used, new ss hoses installed and a vacuum bleeder was used to draw new fluid from the master cylinder. The master cylinder is a dual circuit system with no brake booster.
I pumped a quart of fluid through the system but cannot build pressure at the pedal. The car has been sitting for about a month in dry storage while the lines were open and fluid removed while I replace parts in my spare time. The lines were still on the Master cylinder as I started from the back of the car installing new as I moved to the front. Since I can't build pressure I cant check for major leaks.....
My feeling is the master cylinder is in need of a good prime OR rebuild. When looking in the resivoir fill spout, you can see fluid coming back up when releasing the pedal while it is being pumped.
The whole system was about 30 years old since the lines were replaced. I rebuilt the calipers around 10 years ago and everything was working fine then. Guess stuff gets old...... Greg
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PostPost by: Greg Foster » Mon Jun 18, 2018 10:17 pm

Another picture of the install
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PostPost by: Greg Foster » Mon Jun 18, 2018 10:22 pm

Come to think of it, I probably went through the M.C. back then....
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PostPost by: Bigbaldybloke » Tue Jun 19, 2018 12:51 am

Sounds like the seals or valve in the master cylinder, have you tried putting air pressure on the reservoir to push fluid through rather than sucking it from the calipers? Might just get things working, but if the seals are all 10 years or so old, they are about due replacement all round really. What fluid are you using, is it the same as original?
Change is inevitable, except from a vending machine!
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PostPost by: Greg Foster » Tue Jun 19, 2018 1:14 am

It is interesting, the coincidence of replacing the lines and failure of the M.C.... I was going to try pressure as a test to see if I could wake up the unit. Another option may be bench bleeding but if I am that far I will put in new seals.
The brake fluid Ive been using for all my hydraulic cylinders is Valvoline Synthetic DOT 3- 4, been using this for many years with no complaints.
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PostPost by: nmauduit » Tue Jun 19, 2018 8:46 am

Greg Foster wrote:It is interesting, the coincidence of replacing the lines and failure of the M.C....


If the return valve is stuck opened somehow (I've had that in the past, due to a hair-like filament of slave piston seal torn out by the "mechanics" who had rebuilt the MC without break grease), you may be able to se some fluid motion when pressing the pedal, a bit like for fluid return. If not it's likely you still have air in the system: you may want to purge with the calipers off to position them more favorably. you may also purge the car at an angle to help with bubble displacement, depending on your installation.

good luck !
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PostPost by: Frogelan » Tue Jun 19, 2018 9:09 am

Greg

It's not rocket science, there is a leak somewhere.

If we assume that there is not a ruptured or loose pipe somewhere, then you should be looking at the seals.

As a general remark on old car it is good policy to change the master cylinder seals in any case every 3 years (clutch and brake). This also allows you to check on the wear on the piston.

If your master cylinder is also rather old (over 5 years), then IMHO, you should change it as a safety measure. Might I suggest you also look for one made by reputable folks as there are some extremely cheap copies being made!

This particularly important on an Elan, as the car cannot be slowed using the original handbrake...

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PostPost by: Greg Foster » Tue Jun 19, 2018 10:13 am

I will be removing the master cylinder....almost there anyway. It isn't worth taking a chance on safety. Do it and enjoy good working mechanicals for a long time!
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PostPost by: Citromike » Wed Jun 20, 2018 7:15 pm

Here's an idea.

I always loosen the fitting for the line coming out of the M/C and have someone else press the pedal down and hold it, and tighten the line. Then step vigorously on the pedal a few times and then loosen and repeat over and over til you get only fluid and not air. You'd be surprised how much air comes out.

Good luck and good pedal

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PostPost by: Chancer » Wed Jun 20, 2018 9:15 pm

Frogelan wrote:Greg



If your master cylinder is also rather old (over 5 years), then IMHO, you should change it as a safety measure. Might I suggest you also look for one made by reputable folks as there are some extremely cheap copies being made!

Andrew


Forgive my flippancy Andrew but where exactly do you think you are going to find a mythical reputable manufacturer making OE quality master cylinders in such small volumes in this modern world?

I'm afraid all the old very sensible advice like yours above goes out the window these days when the original 50 year old parts on your vehicle are far more likely to be of decent quality than any newly manufactured replacements.

There are of course decent small volume companies reconditioning brake cylinders but they are only as good as the seals that they have available to them and probably dont have much faith in.

To the OP try a pressurised Eezi-bleeder.
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PostPost by: Chancer » Wed Jun 20, 2018 9:24 pm

Citromike wrote:Here's an idea.

I always loosen the fitting for the line coming out of the M/C and have someone else press the pedal down and hold it, and tighten the line. Then step vigorously on the pedal a few times and then loosen and repeat over and over til you get only fluid and not air. You'd be surprised how much air comes out.

Good luck and good pedal

Mike


The brakes on my 500000kms Skoda always felt a little unreassuring, I changed the 17 year old fluid last year even though it passed all the boiling point tests (still running all the original cylinders and rubbers), Mytyvac bled the system thoroughly but it felt there was still air somewhere although the pedal was probably no less firm than before the fluid change, my neighbours newer model had much better brake feel.

I thought maybe there was a special procedure for bleeding the ABS and when googling I discovered that the master cylinder has 2 bleed nipples, one for each brake circuit :shock:

I did not have anyone to help me bleed them and my eezi-bleed and Mytyvac was in another country so I just slackened them one at a time and waited till fluid weeped out of them from gravity, there can only have been a tiny volue of air if any that preceeded the fluid coming out but the brake pedal is rock solid now, better than it ever has been.

The air cant have got in when I bled the brakes because we always kept the reservoir topped up so it must have been there since some previous work on the brakes or always there and gradually made its way up to the master cylinder, I was amazed at the difference.
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PostPost by: Greg Foster » Mon Jul 09, 2018 8:44 am

So to follow up,
Yesterday afternoon, a friend and I went to the garage to work on bleeding the brakes and getting them to work. It ended up that air was still in the line for the rear circuit. I learned a good lesson in that even though 99% of the time vacuum bleeding will do the job, that 1% still exists where you need someone to physically sit and pump the pedal. With a pedal pusher and vacuum bleeder we re-bled the lines and now have excellent brake pressure.
I reviewed my notes of work done to the car and found the system calipers and master cylinder were rebuilt when I went through the systems....10 years! where did the time go?
Thanks for all of your help and suggestions.
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