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SpeedBleeders causing premature Master Cylinder Failure?

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Originally posted by POWERED by HONDA:
My brother sent this to me to find out if it is true or not. I find it HARD to believe that SpeedBleeders (let alone the pump and hold technique) can cause such failures. Can anyone shed some light on this? I don't believe it for one second... but here it is.
http://forums.audiworld.com/a4/msgs/1128980.phtml

Thanks in advance.


Sounds like crap to me but I've e-mailed the link to speedbleeders to get the "official" response.

------------------
Andrew Henderson
The NSX Model List Page

"We have long acknowledged that enthusiasm for things automotive is a sure
sign of emotional instability if not outright dementia"
- Brock Yates
 
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Guys,

I have to say I do not think this is crap. The master cylinder piston will stop at a certain position in the bore normally. When you bleed IF you push the brake pedal to the floor you pass that position. That position inside the bore usually has a buildup of dirt/comtaminates. There is potential that this dirt, once the seal passes through it, can cause the seal to get damaged or deteriorate/leak.

I was made aware of this about three years ago at an NSXCA event, in a discussion with a very competent NSX mechanic out here in the east. He recommended that when you bleed ONLY push the brake pedal about half way down, similiar to the position it would stop in, if the system was closed.

Anyway this theory all made sense to me, so when I bleed brakes I only push the pedal half way down. I would say that depending on how clean you keep your brake fluid/system, this will be more or less of a possibility.

I DO NOT think that has anything to do with SpeedBleeders though. I personally use a "roaming" speedbleeder, since I have a piece of brake line with a one way check valve at one end. I connect it to the bleeder, open it up, jump in the car and start pumping. When I am done, I get out, close the bleeder and move on to the next wheel.

I always have a firm pedal when I am done, and I can track the car for two days and things are fine.

My $02,

LarryB
 
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Woodwork tells us to place a piece of wood between the pedal and the bulkhead when bleeding brakes. This is good advice on any car. A small piece of 2 x 4 works fine for me.
 
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Originally posted by Soichiro:
Woodwork tells us to place a piece of wood

That's fitting...
biggrin.gif
 
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I have had speed bleeders for 10 years and have had no master cylinder problems or replacement. I know people recommend not going full stroke when you bleed but if your master cylinder can not take its full travel without a problem then I think it should be replaced.
 
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What Larry B said... saw this problem on a number of Porsches. On some the seal on the piston caught on a lip or debris at the end of the stroke and actually flipped the seal over.

Just caught that this thread is over 10 years old!
 
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