Lotus Elan

Exchanging the brake servo

PostPost by: Pistacchio sprint 72 » Wed Aug 21, 2013 5:06 pm

Hello,

My car suffer from a sticky breaking annoying feeling. When i release the brake pedal, you can feel the car is still breaking.

I got told by reading the forum it could be cured by cleaning and lubing the small piston inside the servo. I got scared by the process so i went for a straight swap.

Got a new servo from Steve and installed it today.

Easy job. Now i need to bleed the brakes but i am not sure how to do it!

Can i just work at the servo level or do i need to go down to the calipers bleeding screws?
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PostPost by: billwill » Wed Aug 21, 2013 6:01 pm

You will need to bleed the brakes at the disk calipers, not at the servo, and you will probably need to do all four.

If you are going to do it on your own, I strongly suggest that you get hold of a bleeding tube tool that has a valve in it. Something like this
http://www.ebay.com/itm/One-Man-Brake-B ... 25&vxp=mtr
though that one is on USA EBay, you should find something similar nearer. The valve stops it sucking air or old fluid back into the caliper when you release the pedal.

Though you can get clever gajets to automatically top up the master cylinder reservoir, I found most of those a waste of time, all you need on an Elan is an ordinary kitchen-type plastic funnel and a bit of plastic pipe to extend it so that you can poke it into the reservoir through the gaps near the carburettors.

Remember that brake fluid will act like paint-stripper if you get it on your paintwork so take care not to spill any.

Since your car is new to you (I think) you might as well change all the brake fluid so that you can be sure it is not old. get about litre.

So what you will be doing is filling the reservoir then going to each caliper in turn, attach the tube and put the free end into an old glass jar, loosen the bleed screw 1/4 to a 1/2 turn. Go to the cabin and press the brake pedal all the way down about 5 times. Look in the reservoir to make sure there is still some fluid in it, then go look at your jar. Fill up reservoir & repeat until you have about 250 cc in the jar. With that amount you can be pretty sure that you have blown any bubbles of air out, but you can ask a helper to watch the jar while you pump if you have one handy :) Tighten the bleed screw, not too tight, (only about 10 ft pds ) that's about a kilo pull on a 20 cm spanner. Then remove the bleed tube and repeat the process for the other 3 wheels.


Here are some links to general descriptions and videos of bleeding brakes.
https://www.google.com/search?client=ub ... tf-8&gl=uk
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PostPost by: collins_dan » Wed Aug 21, 2013 6:12 pm

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PostPost by: mbell » Wed Aug 21, 2013 6:22 pm

You should start at the wheel with the longest run of brake pipe, on my car that is the rear left wheel. So once that has clear fluids the other lines shouldn't take too much effort.

On my car I'd do them in the order, rear left, rear right, front left, front right. It's a lot easier if you car find someone to pump the pedal. Hopping in and out of a lotus isn't the quickest/easiest thing to do, even for me at my relatively small number of years/experience.
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PostPost by: Pistacchio sprint 72 » Wed Aug 21, 2013 6:39 pm

Thanks guys! Someone show me the look of a bleed screw please?! :mrgreen:

Oh yeah and its location on the caliper...
Last edited by Pistacchio sprint 72 on Wed Aug 21, 2013 7:36 pm, edited 1 time in total.
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PostPost by: Pistacchio sprint 72 » Wed Aug 21, 2013 6:41 pm

I have a small girling tank and a bigger one... The level in the big one is low...
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PostPost by: pharriso » Wed Aug 21, 2013 7:24 pm

Pistacchio sprint 72 wrote:I have a small girling tank and a bigger one... The level in the big one is low...


Larger Girling cylinder = brakes ; smaller = clutch master cylinder

Cedric, remind me, is your car LHD or RHD?
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PostPost by: Pistacchio sprint 72 » Wed Aug 21, 2013 7:25 pm

Another question! Engine on so the servo gets the vaccum it needs or engine off?

Car is rhd
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PostPost by: Pistacchio sprint 72 » Wed Aug 21, 2013 7:35 pm

Do you have to screw back the girling cap before pressing the brake pedal?
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PostPost by: pharriso » Wed Aug 21, 2013 7:45 pm

Pistacchio sprint 72 wrote:Do you have to screw back the girling cap before pressing the brake pedal?


If you are asking do I need to put the master cylinder cap back on before pressing the brake pedal? - then no.
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PostPost by: Pistacchio sprint 72 » Wed Aug 21, 2013 7:48 pm

Ok! Thanks
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PostPost by: mbell » Wed Aug 21, 2013 9:40 pm

Pistacchio sprint 72 wrote:Thanks guys! Someone show me the look of a bleed screw please?! :mrgreen:

Oh yeah and its location on the caliper...


It's the thing with the rubber cap on it (hopefully). Be very careful with the spanner/wrench you used as they tend to be seized it and you can round the bleed nipple easily. tray to use the correct sized 6 side hex spanner. Then you in for a lot more fun.

(Picture is pre-refubishment of my calipers...)
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PostPost by: pharriso » Wed Aug 21, 2013 9:57 pm

I have circled the bleeder in MBELL's picture:
IMG_1145.jpg and


I really hope that yours are not as rusty as these! Give the bleed nipples a good soak in wd40 or other rust penetrant before you try to open them, You are screwed if the bleeder shears off in the caliper
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PostPost by: billwill » Wed Aug 21, 2013 11:31 pm

You can see the bleed screw, top left on this picture.

Image

As mentioned above, it looks a bit like a bolt, but with a small nozzle sticking out of the top of it.
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PostPost by: billwill » Wed Aug 21, 2013 11:35 pm

pharriso wrote:I have circled the bleeder in MBELL's picture:
IMG_1145.jpg


I really hope that yours are not as rusty as these! Give the bleed nipples a good soak in wd40 or other rust penetrant before you try to open them, You are screwed if the bleeder shears off in the caliper


Not quite screwed...I sheared one of mine off earlier this year, but Classicar Automotive were able to get the busted bleed screw out by cutting it out carefully with a milling machine.

My photo above is what it looked like when they returned it. ...Immaculate.
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