Plus 2 Brakes locking on

PostPost by: gwiz22 » Sat Oct 29, 2005 7:19 am

The brakes on my +2 occasionally lock on for a few seconds when braking, then release themselves. I have just purchased this car which although extensively restored in the early 90s has had very little use recently. I think it is the servo at fault. I have read the post in the technical section of LotusElan.net and that confirms my suspicions regarding the servo but mentions Girling technical documents G.149/2 and G.283H. Does any one have a copy of these or have experienced this locking on problem? I believe the servo is a Lockhead unit not a Girling as these were no longer available at the time of the restoration. Can anything be done to the servo or does it have to be replaced? Many thanks :?:
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PostPost by: worzel » Sat Oct 29, 2005 1:15 pm

Hi

It's probably the air valve located in the top of the servo under the air filter.

I haven't read the club technical bulletins but I imagine their content is along the lines of fitting a small spring on the outside of the nylon valve so that one end sits on the valve and the other is comprtessed by the snap on cover that fits on the outside over the filter.

This is after making sure the small piston in the "workings" of the servo is free. You can do this by removing the snap on cover and the air valve and under it you'll find a large plate held on by 3 cross-headed screws- leave this plate in place and look down the small centre hole- the piston is directly underneath- it's about 5/16 th in diameter.

Have a helper press the brake and see if the piston moves- if it doesn't you might have a problem- try tapping with a small drift- if you're very careful you could remove the piston and clean it up and replace it without having to bleed the brakes- but this is not workshop practice.

My own car developed this fault about 18 months after fitting a new servo- I fitted a spring and it's been fine for the past 20 years or so.

Cause of the fault- probably water finding its way in- I don't know about plus 2's but on 2 seaters the servo is nicely placed to catch water so I made a plastic cover to fit over the top.

Hope this helps.

John
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PostPost by: Foxie » Sat Oct 29, 2005 9:33 pm

The problem of the brakes locking on can also be caused by the piston in the master cylinder not retracting fully, due to insufficient free travel or a sticking pedal shaft. This prevents the release valve in the master cylinder from opening and relieving the pressure. You can get extra clearance by shimming the master cylinder mounting lugs.

Sean Murray
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PostPost by: elansprint » Sun Oct 30, 2005 12:22 pm

I had the same problem on the sprint it was exciting when you had braked hard. The car had been standing for 15 yrs & i had rebuilt the calipers so they were not sticking & it was the master cylinder that was the problem

regards

Ian
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PostPost by: gwiz22 » Sun Oct 30, 2005 9:37 pm

Thanks for all your responses. I will check master cylinder as well as this had no occured to me.

John, I though it was a lockhead servo but after some further investigations, I think it might be a Girling but it does not look like the pictures in the workshop manual. This one has the large cylidrical chamber as in all servos and the addition of a fyling saucer looking component approx 3.5 inches in diameter, with 5 screws around its edge, and attached to the thin part containing the piston, and also connected to the back of the servo by a rubber tube. Was this the type of servo you were describing?
I have a picture of it but cannot see how to attach it to these posts.

Once again many thanks to you and the other respondees.

Regards
Graham :?:
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PostPost by: theelanman » Mon Oct 31, 2005 1:41 pm

mine was the servo......
the car was fine and working well.....then it started sticking the brakes on for a couple of seconds after you'd take your foot off the pedal.....anyway I was directed to the master cylinder played with it....no improvement....
about a week later coming to a roundabout at about 80mph went for the brake...erm foot went to the floor.....parp!!!!!
anyway made it over the roundabout and got it home much later that day when the traffic had dispersed......anyway when it went to the garage it turned out that the seals etc had all collapsed in the girling servo......
changed it over to a lockheed servo and not had a problem since!!!
just another option!!
cheers
G
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PostPost by: elansprint71 » Mon Oct 31, 2005 5:18 pm

... it is not unknown for the flexible brake pipes to look OK from the outside but to become swollen on the inside- so swollen in fact that the brake will not release, either temporarily, or at all.
It makes sense, if you don't know how old these items are, to replace them as a matter of course.

Cheers,
Pete.
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PostPost by: berni29 » Tue Nov 01, 2005 2:47 am

I have had this as has Si 130/5 up the road from me. Servo in both cases. He fixed his with a new spring that someone from this forum sent him. I fixed mine by cleaning the servo filter and around that area. My brakes used to lock on completely. His was the slow to release.
Zetec+ 2 under const, also 130S. And another 130S for complete restoration. Previously Racing green +2s with green tints. Yellow +2 and a couple of others, all missed. Great to be back 04/11/2021 although its all starting to get a bit out of control.
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PostPost by: tdafforn » Tue Nov 01, 2005 9:44 am

For the Lockheed servo, the spring definately works V. Well.
Thats what I used.
Spring was about 2 cm diameter and 2cm length, it wasn't very springy but works fine
Cheers
Tim
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PostPost by: theelanman » Tue Nov 01, 2005 10:42 am

if you ask john.p.clegg nicely he may send you a spring for the cost of a beer......think he bought a job lot of these springs for the lockheed servo....although he has given quite a bit of it to guys on here......
cheers
G :P
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PostPost by: tdafforn » Tue Nov 01, 2005 3:51 pm

Hi Gareth...
Thats why I didn't mention it, as I think I have already passed a number of guys his way...
Mind you he could probably drink his way around the world with all the drinks he has been promised!"
Cheers
Tim
PS hope to really by him one at stoneleigh
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