Lotus Elan

Brake issues

PostPost by: l10tus » Mon Jul 06, 2015 11:11 pm

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Mmmmmm!

I looped out the Servo and tried the brakes - and found a great improvement !

Then, I took the servo (Girling Mk 11A) back to Classic car to be checked.

Sure enough, the smaller seal was cracked and needed replacing ( shelf life - 18 months max. As Recommended by classic car) - mine was 7 years old!

They were most helpful, I mean really accommodating.

Seals replaced and unit fully checked over - all seemed well.

However, once re-installed into my car, with the system well bled, I tried it round the block and well! To be honest couldn't feel any difference to using the system without the servo!!!

The vacuum is working ok, so now I wonder if it's worth taking it out of the system again, for good ?

It does now lock the wheels - if I choose to apply enough pressure, but it certainly doesn't feel like the power brakes on my everyday (modern) car?

Is this the best I can expect?

Not very impressed at all, also, although there doesn't seem to be excessive travel on the pedal, it seems slightly better to give a 'double pump' on the pedal to achieve a confident stop.

Am I expecting too much, or should it perform as good as modern cars do? - the car has only done 60 miles since rebuild.

Also (2), the pedal return seems to get slightly "bound up", if the clutch is depressed at the same time?
In fact the brakes hold on - until a toe under the pedal helps it back up to the top of the pedal's normal travel !

I've uploaded a picture of the return spring arrangement in the footwell, are the clutch and brake spring in the correct position?

Does the spring need to be replaced ?

should I use a stronger spring?

Does it always bind on the brake switch?

Replies appreciated!

Regards,
Phil.
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PostPost by: elansprint71 » Mon Jul 06, 2015 11:29 pm

Fitted +2 calipers and chucked out the servo years ago; did not change the master cylinder diameter- works great, however, it takes ages to really get all the air out of the system, particularly if all new pipes, etc have been fitted. Needs to be bled plenty of times before that hard pedal is restored.
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PostPost by: l10tus » Tue Jul 07, 2015 9:59 am

elansprint71, (or others)

Thanks for the reply.

I am told by Classic car that to test the servo, the pedal should be depressed, then start the car - and the pedal should sink once the engine is running and the vacuum built up?

Mine doesn't seem to sink ?

Any ideas?

Also, can you comment on pedal holding down ,once depressed?

Nightmare brakes !

Regards,
Phil.
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PostPost by: rgh0 » Tue Jul 07, 2015 10:26 am

The pedal should be substantially lighter with the servo inline and something like a modern car. I have run my Plus 2 with and without servo. With servo it is like a modern car and excessively light without it is just a little more heavy than my unassisted Elan. If I put in the smaller master cylinder it be the same as my Elan.

Sounds like you may still have a problem with you servo installation

cheers
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PostPost by: UAB807F » Tue Jul 07, 2015 3:49 pm

Phil,

In the days that I had a servo fitted I used the same check before every MoT. Press the pedal hard and as soon as the engine fires you can feel it move slightly but quite noticeable and instantly. There's no waiting for the engine to settle into idle, literally the first second of running and it moved.

The servo ratio isn't that high on the 2 seater Elan and the brakes never felt as light as, say, the wife's Audi, but you can tell when it's working.

If the pedal isn't sinking on start up then it won't pass the MoT. The easy things to check are the air line supply for leaks, after that I'm struggling on a rebuilt one. The Lockhead ones I've had used to have a habit with the valves sticking if not used for a few weeks, but I can't think of anything else on a rebuilt one.
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PostPost by: 661 » Tue Jul 07, 2015 9:43 pm

Do you still have a problem with the servo?
Personally I'd ditch it ( never thought I'd get rid of mine until I did!!)
Take time to bleed the system properly, and then do it again.
I've had my Elan since 86, the brakes are now the best they've ever been.
If you've been told the servo needs attention every 18 months what more incentive do you need?
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PostPost by: AHM » Wed Jul 08, 2015 7:40 am

I've only ever driven elans with the servo - When working they are fantastic! (for an old car).

If classiccar have checked out the servo you know it works.

so either you have a bad vacuum or a problem with the hydraulics.

Does the servo have a dedicated vacuum pipe - as original with the non return valve at the top of the steel section?

Do you have the hydraulic entry and exit the right way round?

Have you bled at least 1/4 litre of brake fluid through each calliper?

If the pedals bind check the position of the shaft support in front of the door. Remove the spring
oil the pedal pivot. If it isn't loose the shaft is misaligned. The standard spring is more than sufficient if you have everything correct. I don't think you have the standard spring which wouldn't bind on the switch.
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PostPost by: l10tus » Thu Jul 09, 2015 9:36 pm

Thanks for the replies Gents, much appreciated.

Rohan, I can't feel any difference in pressure from non- servo to system with servo, so I guess the servo's still not working.

I changed the white plastic servo pipe connector-non- return valve in the servo body for one that actually works ( the original one's Inards had been removed - I.e. no, non return valve), and checked the rubber grommet in the body, these seem to seal ok, but are quite a loose fit?

Replaced the rubber servo pipe.( but not with any sort of special "servo anti- collapse" pipe, though!) ??

Installed a new in-line non return valve at the manifold end ( so two non return valves working now - ( but very light pressure to operate them, so don't think it's too hard for the engine to overcome the resistance?)

Pipes connected up the correct way (I think?) - pipe nearest the diaphragm end of the servo, connects to the Brake master cylinder, the 'front' connection in the cylinder end goes to the 4 way brass connector ( then out to the calipers).

So just can't see why it's not working ?

Q: Must say, that the rubber elbo that connects the diaphragm to the steel 3/8" diameter tube and poppet valves on the servo casting, is a really loose fit, would this be a problem??

So 2 topics going on here !

Any chance someone can take a photo of their footwell springs for me?

The long spring on the left is for the brakes, do you think I've got the springs swapped about ( so in the wrong places?)

The brake (long spring) seems to bind on the brake light switch housing ( makes a rubbing/ tinkling sound when the brake pedal is depressed) - this can't be correct can it?????

Replies and photo's would be greatly appreciated !

Regards,
Phil.
Philip.

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PostPost by: AHM » Fri Jul 10, 2015 1:07 am

Both springs are like your clutch pedal spring

l10tus wrote:Installed a new in-line non return valve at the manifold end

Is it the correct way round? ie air going to the manifold
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PostPost by: rgh0 » Fri Jul 10, 2015 10:00 am

You need vacuum rated thick wall rubber hose in the line from the manifold to the servo. Normal rubber hose will collapse and seal itself off.

cheers
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PostPost by: l10tus » Fri Jul 10, 2015 10:13 pm

AHM, thanks for confirming the spring types.

Rohan, oh, ok, better get the correct rubber hose then !- any idea what I.D. I need?

Best regards,

Phil.
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PostPost by: Galwaylotus » Sat Jul 11, 2015 8:56 am

I have successfully used heavy reinforced rubber fuel hose for the vacuum system. I can't remember the I.D. but if you pull off one hose you should be able to measure the spigot diameter with a caliper.
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