alistairolsen
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posted on 17/11/10 at 01:38 PM |
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Recommend a brake fluid....
I went through a phase of buying Dot 5.1 fluid before deciding that Dot 4 was good enough in road cars if changed regularly. Using the car for odd
scatter rallies and stuff has however highlighted that even new Dot 4 isnt good enough.
This is whats in it just now (drained, flushed and filled 2 weeks ago):
http://www.uztexaco.com/cgi-bin/page1.cgi?p_lang=e&str=3&uprod=1120731987&upprod=1120731999&mtime=1120732097
I dont really want to make the leap to some of the really expensive "super dot 4" fluids like castrol SRF (49 quid a litre.....)
What is everyone using in their track cars and racers?
Cheers
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Stott
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posted on 17/11/10 at 01:55 PM |
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What's the matter with the fluid?
Could it be more of a lining issue? The cars I normally navigate in on night events use DOT 4 albeit with uprated pads and or discs and it's
never an issue.
ATB
Stott
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alistairolsen
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posted on 17/11/10 at 02:02 PM |
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I'm not sure. I was getting a long pedal when hot which was back to being normal (high up and solid) this morning.
Do pads not normally still feel the same, just stop stopping as well if that makes sense?
They werent dreadful but they lost a lot of feel when hot and since I need to swap out the flexis anyway I thought I'd ask
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RazMan
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posted on 17/11/10 at 02:05 PM |
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Sounds like you might have some moisture in the system - have you checked for leaks under pressure?
Comma DOT5.1 is my choice, mainly due to it's much higher boiling point - 40 degrees higher so much less likely to give problems in a hot
caliper
[Edited on 17-11-10 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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alistairolsen
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posted on 17/11/10 at 02:29 PM |
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Ive checked careful for any damp patches around unions and bleed nipples etc and nothing and as I say, the fluid was from two brand new bottles,
opened, poured in and bled.
I suspect the hottest point will be the rear drums tbh, calipers dont tend to be so bad.
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Stott
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posted on 17/11/10 at 02:47 PM |
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but what were the symptoms of brake failure? I've overheated my std pads a million more times that I've boiled my fluid.
Did the pedal hit the floor or did it feel ok but not stop you?
If it's the second option then uprated pads is the next course of action.
HTH
Stott
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alistairolsen
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posted on 17/11/10 at 03:05 PM |
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Nothing catastrophic, just went a bit soft and stopped pulling up as hard after 8-10 miles. I just know that given 30 miles of similar abuse they wont
cope.
Pads normally stop pulling up, but leave the pedal feeling normal dont they?
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adithorp
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posted on 17/11/10 at 03:37 PM |
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If you boil the fluid the gas that is given off is what causes the poor braking. The gas is not re-absorbed when the brakes cool, so they remain
spongy. What you've describing sounds like fading due to over heated pads.
What car, brakes and pads is this on?
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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alistairolsen
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posted on 17/11/10 at 04:55 PM |
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corsa, 256x20 disks, ate calipers and standard red mitex pads so the pads are probably suspect, but I never expected them to go spongey?
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Danozeman
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posted on 17/11/10 at 08:56 PM |
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quote:
corsa, 256x20 disks, ate calipers and standard red mitex pads so the pads are probably suspect, but I never expected them to go spongey?
Corsa brakes well most vauxhall brakes are always a bit spongey anyway. Sounds like you have a good bit of brake fade. Not the fluid boiling. As
said the air bubble created wouldnt just disappear. If the brakes disappear youl push harder on the pedal which will seem like its going down further
making it feel spongey.
Dan
Built the purple peril!! Let the modifications begin!!
http://www.eastangliankitcars.co.uk
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MikeRJ
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posted on 17/11/10 at 11:01 PM |
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You need to spend some money on decent pads - it's makes an unbelievable difference to the brakes coming from standard cheapo road pads.
Ferrodo DS2500 (or even DS3000 if you are getting them really hot) are pretty good, I know a few people that use these on road and stage rally cars.
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Paul TigerB6
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posted on 18/11/10 at 12:57 AM |
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Drained, flushed and filled 2 weeks ago - and nobody has suggested residual air requiring a re-bleed??? More likely than boiling new fluid surely??
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alistairolsen
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posted on 18/11/10 at 08:55 AM |
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Yeah Ive had decent pads in the past, just never attributed a spongey pedal to overheated pads. Will give them a go.
I dont think its residual air, i pumped the best part of 2 litres through with an easybleed and the pedal was fine for 2 weeks prior (and is again
now)
Ill swap some better pads in and give it a shot.
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RazMan
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posted on 18/11/10 at 09:27 AM |
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Incidentally, I have always had problems with the Eazibleed method and have always found SWMBO's foot far more reliable. I put it down to air
bubbles getting trapped in the master cylinder. These bubbles only seem to shift with the old school pedal pumping method.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Paul TigerB6
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posted on 18/11/10 at 09:26 PM |
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quote: Originally posted by alistairolsen
Yeah Ive had decent pads in the past, just never attributed a spongey pedal to overheated pads. Will give them a go.
I dont think its residual air, i pumped the best part of 2 litres through with an easybleed and the pedal was fine for 2 weeks prior (and is again
now)
I've also used an easybleed and as Razman says, they dont seem very efficient. I was bleeding the brakes on my first car repeatedly for whole
weekend using one and just couldnt get rid of the spongy pedal. I then borrowed a proper mechanical pump (several hundred pounds worth) from work and
within 10 mins had a really firm pedal.
I'd definitely suggest trying the "right leg" method first, and if not then consider taking it to a local garage with the proper
kit. Even rubbish pads shouldnt give you a spongy feeling pedal - they just wont stop you as fast.
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