Brake Master Cylinders

[mark030358]

Gents,
Can you get larger bored master cylinders for the Elan. I am having trouble getting mine to operate properley. Two pumps and the pedal is solid, the first pump travels too far. The pedal is not spongey as if air entrapment.

I have NO air, no disc run out, all pads and discs are new. I have a newmaster cylinder, servo, front and rear calipers (which are not loose) and I have no fluid leaks.

My thoughts are that I am not moving enough oil, hence can I get a larger bored master cylinder and where from?

cheers
Mark

ps any thoughts

[rgh0]

Mark

There is still something wrong with your system as plenty of systems have been built that dont need a new larger master cylinder. Dont know what, but you must still be missing something. Are ALL your system components original and either new or in good condtion, have any been modified in any way, have the pads been bedded in.

A common problem is with excessive pull back of the pistons into the calipers due to changes in detail design of replacement pistons and seals over the years. A similar problem can occur with excessive pull back of the floating piston in the booster. Careful observation and measurement of caliper piston movement on application and release of presusre can help diagnose these sorts of problems

Rohan

[types26/36]

Mark,
Try to isolate were the additional movement is coming from, you can try clamping the flexible brake hoses one at a time and checking the pedal travel each time,if by the time you have clamped all 4 hoses the pedal has still excessive travel then the movement is somewere in the master cyl or lines up to the hose's, if you find it improves with one particular hose then your problem is related to that caliper or hose.
There are clamps made for clamping brake hoses but if you are CAREFUL you can do it with vice grips or small "G"clamps.
Brian.

[nigelfletcher]

Hi, I agree with everything Brian has said, but in addition if you've replaced the front calipers check that you've put them on the right way round. I didn't and spent ages trying to work out why I had a spongy pedal - only to feel rather stupid when my friend pointed out the bleed nipple should be at the top....

[gjz30075]

<!--QuoteBegin-mark030358+May 31 2005, 03:59 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (mark030358 @ May 31 2005, 03:59 AM)</td></tr><tr><td id='QUOTE'><!--QuoteEBegin-->
My thoughts are that I am not moving enough oil, hence can I get a larger bored master cylinder and where from?

[/quote]
Actually, I believe that is the opposite, ie, a smaller bore would move more fluid. A larger bore cylinder will move less but will take more effort.

As Rohan suggested, unless you have a bum MC, you still have something wrong in the system.

And I'd start with Brian's suggestion of clamping off the lines one at a time to determine which corner might be giving the problem.

Greg Z.
'72 Sprint.

[mark030358]

Gents,
Re clamping the lines. I have steel ones not rubber ones. Possible to clamp these without damagine them?

cheers
Mark

[flyinggellyfish]

I also have braided brake lines and had a pedal that required 2 pushes to get a good pedal . I removed the pads and moved all the pistons right back in and put wood blocks in the place of pads which prevented any piston movement . With this done I managed to bleed more air from the system then before . Pedal is now harder and even more with the braided hoses .

Rick

[djmoncado]

It is very important to bleed the brakes in the correct order. I had the same problem until I realized I bled them in the wrong order. the correct order is (for North American) driver rear, pass rear, pass front, driver front. Basically you go from longest run to shortest run.
Dean
69 Elan +2

[type36lotus]

And a set of eze-bleeds makes life real easy and bleeding the brakes quick one person job.