Lotus Elan

Brake Bleeding Problem

PostPost by: elanman3 » Fri May 21, 2004 4:30 pm

Has anyone had problems bleeding brakes on a +2S 130? I've rebuilt all 4 calipers with new pistons and seals, fitted a new master cylinder, bled them with an Eeesybleed kit, I?ve no leaks to be seen, and still they're soft. Two / three pumps of the peddle before I have any peddle pressure, engine on or off. I?ve done the bleeding as per the manual, started at the furthest caliper and ending at the nearest caliper. Everything indicates air in the system but the fluid coming out of the calipers is free of air bubbles!

Does anyone have any brake bleeding tips that I can try over the weekend. I?ve ordered a servo repair kit that I?ll fit next week but after that I?ll have totally run out ideas.

I?m looking for inspiration can anyone help?

Colin
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PostPost by: elansprint71 » Fri May 21, 2004 10:36 pm

Colin,
I have just changed the chassis on my Sprint and in the process also binned the servo and fitted +2 front brakes; the only original parts that I re-used were the rear calipers. I have come to the conclusion that minute air bubbles stick to the surfaces of new pipes etc, and the only way to get ris of the soft pedal is to keep on bleeding the system at weekly intervals. I am now very close to having a firm pedal on the first press!

Pete
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PostPost by: jopalm » Sat May 22, 2004 7:03 am

Did you bench-bleed the MC? Typically air trapped here cannot be bled through the bleed nipples at the calipers. Reason being the fluid outlet(s) on the MC are not located at the "high part" of the cylinder and any air here is trapped.

Best bet would be to get the MC absolutely level so that any air will collect at the tipping valve. Then *very short* strokes (~ 1/8 - 1/4 inch) of the MC piston should allow a pea sized bubble back into the fluid reservoir. Repeat as needed. Also might help to rotate MC through several degrees back-and-forth then re-level.
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PostPost by: JACKJABBA » Sat May 22, 2004 8:03 am

Colin
I have also just fitted a new master cylinder and have still got the same problem as you. I have bleeded the brakes as per the manual and then started again after the first go. They are getting firmer but not what is expected of this system.

I dont fancy taking the throttle box back out again, but will loosen it off so that I can try Jopalm's idea.
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PostPost by: nebogipfel » Sat May 22, 2004 1:15 pm

An old trade dodge which I've been told works but I have never actually tried is to leave the car overnight with pressure on the pedal (prop the pedal with something). In the morning you should have a solid pedal .............might be worth a try.

More high tech but perhaps not better? :) would be one of the vacuum bleeding devices.

Sometimes just letting things settle for a few days and then gently bleeding the old fashioned way does the trick.
John

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PostPost by: JACKJABBA » Sun May 23, 2004 9:47 am

I tried the old trade dodge.

Left the car overnight with a sledge hammer wedged onto the brake pedal. Removed it this morning and hey presto the pedal is now rock solid. :)

Top tip, Thanks to nebogipfel.

Regards Jack.
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PostPost by: nebogipfel » Sun May 23, 2004 6:58 pm

You are welcome :)
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PostPost by: gjz30075 » Mon May 24, 2004 12:07 pm

John, I wonder if that'll work for the clutch, too. It's a bugger to get to that bleed screw! Interestingly enough, new technology on hydraulic clutch operation is the concentric slave/throwout bearing with only one line going to it. It's bled the same way, ie, fill the system, keep the cap off overnight and, viola, a solid clutch pedal in the morning.

Greg Z.
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PostPost by: elanman3 » Mon May 24, 2004 1:12 pm

Took all the suggestions and tried as many as possible.

1) Pete?s suggestion of micro bubbles is probably right. After bleeding one of the wheels I held the glass bottle up to the sun and there were millions (well thousands) of micro bubbles in the fluid. So I didn?t re-use that fluid. No point adding bubbles to the system. I used fresh fluid each time I bled a wheel. I also jacked the back end of the car higher than the front hoping that it would help the bubbles flow to the calipers.

2) Jopalm?s suggestion of wiggling the master cylinder also sounded good so I undid the mounting bolts and gave the M/C a good shaking, back / forwards and left / right. I think that helped :D as a lot of air came out on the next bleed and there was definitely pedal pressure from then on.

3) I think my big problem was that when I was using the EeezyBleed kit I was relying on the system pressure to push all the air out. This time I pressurised the system, opened the bled screw and then ran around the car and started pumping the pedal until the EeezyBleed reservoir was almost empty. About a pint of fluid was pumped through the system at each wheel. That definitely helped a lot. I?m now getting reasonable pedal pressure.
If you buy an EeezyBleed Kit, beware none of the reservoir caps that come with the kit fit the clutch or brake master cylinders on the Elan. You have three options a) buy a universal cap from EeezyBleed, B) make you own, c) buy caps from Christopher Neil. On the whole the kit makes single handed brake and clutch bleeding a doddle.

4) I didn?t see John?s suggestion until today (Monday) so I?ll try that tonight. Here?s hoping that I get the same results as Jack.

5) Following that I?ll be going through JACKJABBA?s weekly / bi-weekly bleeding program.

Like I said, ?all I needed was some inspiration and a little help from some friends?. I hope we all learned a few things from this. I know I did. Thanks again for all your help and suggestions.

Colin
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PostPost by: type26owner » Mon May 24, 2004 1:17 pm

Don't know the +2 braking system but I've had several cars that absolutely required 'bench_bleeding'. On other cars it seems it's not really all that necessary. Forget that assembly step and you may suffer. Painful lessons are the well learned ones for me. Lots of info on the web.
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PostPost by: elanman3 » Tue May 25, 2004 12:08 pm

I'm showing my ignorance here but how do you go about bench-bleeding?

Colin
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PostPost by: type26owner » Tue May 25, 2004 2:57 pm

Colin,
Like I already suggested do a web search on 'bench bleeding'. Might include the brand name of the servo thingie to get any exact instructions. Whenever I purchase a new master cylinder I always buy the bench bleeding kit for it too since they are only a few dollars. So cheap it's not worth cleaning it up and storing it until next time. Consider it just part of the cost of a well done brake job. However it can make the bleeding process go a heck of a lot easier and most importantly less stressful. This is best practice stuff and well documented in many places so if you don't want to suffer while Lotusing then take the time to read up BEFOREHAND. I do when I need to work on something I'm not up to speed on. :)
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