Lotus Elan

Sudden Brake Failure

PostPost by: Elanintheforest » Thu Jun 09, 2011 6:16 pm

I was moving my Elan last week after its winter slumbers, and everything was working fine. After a couple of hours, I came to put the car away, and hit the brake?.it was absolutely solid, with no brake !! When I say solid, it?s like pressing against a brick wall, absolutely no movement.

I?m sure it can only be the piston has somehow seized in the master cylinder, but can?t imagine how. To go from working perfectly one minute to rock solid the next, I guess it has somehow wedged itself in the bore?but again, I can?t imagine how!!

Has anybody come across this before? The car is about to have a full hydraulics overhaul, so it doesn?t matter. But it?s a sobering thought that this can happen!

Mark
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PostPost by: paddy » Thu Jun 09, 2011 7:30 pm

Are you sure it's not the push rod that's dislodged somehow so it's not pushing on the piston?

I had an issue with a master cylinder (which was new) where the circlip could pop out, which would mean that the push rod could come out of the front of the cylinder, or get stuck half in and half out. A bit alarming for a new part :(

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PostPost by: RichC » Thu Jun 09, 2011 7:48 pm

.....or the pivot mechanism locking somehow? I heard they were prone to wear, but could this contribute to locking up somehow?
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PostPost by: p.faurie » Thu Jun 09, 2011 10:20 pm

Hi Mark i had the same happen to me on my +2 it was my servo [lockheed type] the hydrolic piston? must have stuck.I by passed the servo and its been ok since ,and quite frankly the brakes seem fine without assistance from the srevo,hope this helps regards phil
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PostPost by: MickG » Thu Jun 09, 2011 11:11 pm

I had the same thing happen many many years ago after attempting to overhaul the Lockheed servo. The pedal just went solid and I had to resort to removing the vacuum pipe and blanking it off with an old spark plug just to get me home. Went and bought a new servo which solved the problem.
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PostPost by: reb53 » Fri Jun 10, 2011 5:54 am

Had it on the clutch master when the internal coil spring broke and jammed the piston solid.

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PostPost by: Elanintheforest » Fri Jun 10, 2011 8:02 am

Thanks guys
I really didn't think it could be the servo as the pedal is so hard...literally not a millimetre of movement! But it does have a Lockheed servo. It's a strange sensation when driving along and pushing something solid and unyielding instead of the brake...the car seems to accelerate!

Mark
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PostPost by: gerrym » Fri Jun 10, 2011 8:26 am

Mark, bypass the hydraulic lines to/from servo and then retest the system.

It might convince you to junk the servo on a permanent basis?

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PostPost by: Mazzini » Fri Jun 10, 2011 10:46 am

It's a modern replacement servo, but I suppose that doesn't count for much, it could be twenty years old.
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PostPost by: elj221c » Fri Jun 10, 2011 11:15 am

p.faurie wrote:Hi Mark i had the same happen to me on my +2 it was my servo [lockheed type] the hydrolic piston? must have stuck.I by passed the servo and its been ok since ,and quite frankly the brakes seem fine without assistance from the srevo.


Mark,
Same for me too. I've never used a servo since. When I took the thing appart it was full of petrol which I assume made all the seals rot. Yes, the pedal was 'rock' hard.

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PostPost by: Mazzini » Fri Jun 10, 2011 9:43 pm

Mark, the easiest thing would be to sell the car, it would be much less expensive than fixing it :lol: :lol: :lol:
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PostPost by: Tonyw » Sat Jun 11, 2011 6:37 am

Mark,

I have had exactly the same problem and it was the servo/booster piston seized, I never thought it would be possible for the pedal to be so hard I cracked of the hydraulic to the booster and could get fluid out but not from the booster bleed nipple, pulled it apart put it a kit and away we went again.

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PostPost by: Elanintheforest » Sat Jun 11, 2011 7:00 am

Well Tony, I just did the same thing...opened up the input pipe to the servo, and sure enough the pedal went down. I'd heard of Lockheed Servos locking the brakes on, but not locking them off before! One thing is for sure, there won't be any Lockheed rubbish on my cars in the future! The servo isn't very old, and even though the car has been off the road for nearly 5 years, it's run up and driven around every month or so.

Scarry!

As for selling the car Louis, send a blank cheque and it's yours. I'll fill in the numbers, and you can trust me to be quite reasonable :D

Mark
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PostPost by: Tonyw » Mon Jun 13, 2011 2:25 pm

Mark,

try not to be so hard on Lockheed my experience was with a PBR booster and I have had both problems leaking fluid into the vacuum chamber and a solid lock up.

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PostPost by: alexblack13 » Mon Jun 13, 2011 4:37 pm

Elanintheforest wrote:
As for selling the car Louis, send a blank cheque and it's yours. I'll fill in the numbers, and you can trust me to be quite reasonable :D

Mark


:lol: :lol: :lol: ...Nice one mark! let me know if it works...

Good to hear you found the brake problem. Bloody scary!

C U Soon..

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