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Location:
Terrigal
Registered:
May 2002
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Odd clutch problem
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Mon, 16 May 2005 04:32
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Hi all, i've got a bit of a strange clutch problem thats got me baffled.
If I drive normally clutch is fine, it engauges around half way up the pedal travel.
If I drive fast, eg. accelerating quickly, then change gear. The clutch pedal has no pressure in it and it bites right on the floor.
Any ideas on this one? Me thinks the 28 is just too damn fast and the G forces stop the clutch working  haha j/k..
This problem first became apparent at the drags awhile back when selecting 3rd gear there was no clutch pressure on the pedal at all.
Now started noticing it more often. At wakefield a few weeks back it was happening now and then out of corners and stuff.
Maybe just needs a bleed?
Cheers
Joel
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Location:
Newcastle
Registered:
July 2003
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Re: Odd clutch problem
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Mon, 16 May 2005 05:32
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is it a hydraulic clutch system ? if so im guessnig you have old crappy fluid in there. once it is getting *HOT* it is forming bubbles reducing its effectivness. this is generally casued by water in the fluid as it has a significantly lower boiling point then clutch fluid. flush the system out and see how you go.
adittionaly assuming you have no moisture in the system once the fluid has boiled and then re-liquified then its boiling temperature will be reduced, hence bringing the problem on earlier.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Odd clutch problem
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Mon, 16 May 2005 06:21
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there's little reason for CLUTCH hyd fluid to boil.. unless it is far far too close to the exhaust or similar..
what is clearance to hot stuff?
by driving normally and quickly, i'm assuming you mean the rate at which you press the pedal?
might be good insurance to renew the whole systems fluid, and if it happens again, start looking at lines.. maybe a fast pump is causing a nasty bubble in one of the lines?
perhaps the master and slave to see if there are any piston sealing issues?
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Location:
Brisbane
Registered:
May 2002
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Re: Odd clutch problem
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Mon, 16 May 2005 06:27
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My guess would be dodgy seals in the M/C.
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Location:
Terrigal
Registered:
May 2002
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Re: Odd clutch problem
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Mon, 16 May 2005 06:28
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Sorry I meant not how fast you press the clutch pedal, but actually how fast the car is accelerating.
If I slowly let the revs climb up and change gear its fine, at whatever the RPM is.
But if I take off as quick as I can and change gear, there is no pressure on the pedal.
It is hyd clutch. The line does run quite close to the dump pipe but I have it sheilded in some special wrap stuff and its a braided line also. It doesn't touch or anything.
The clutch master and slave are around 1 - 2 years old..
I will try replacing all the fluid and see what happens.
I just find it interesting the problem is caused by how fast the car accelerates. Its probably not possible, but its almost like the fluid is getting pushed away or something.
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Location:
Land of Oz
Registered:
June 2004
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Re: Odd clutch problem
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Mon, 16 May 2005 06:32
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Hi,
Interesting topic.
My clutch seems fine, but the gear changing is a little clunky. Down changing to 3rd gear can cause the odd snarl of gears. If I do the downchange slowly then its okay. Also, the faster I am going when I downchange to 3rd the more chance of the gears crunching.
I am assuming this is a clutch problem due to the clunkyness (for want of a better word) when changing up the gears.
Actually, I'm hoping its a clutch issue 'cos I can't get bits for my gearbox and I've only ever seen one (P51) for sale.. and that was a few years ago. I was told by Toyota that these clutches are not adjustable?
seeyuzzz
river
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Odd clutch problem
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Mon, 16 May 2005 06:34
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you don't have very low levels of fluid in the reservoir?
could be allowing the inlet to become uncovered between changes... so the first 1 or 2 are ok, but then by the third change, you are starting to suck some air into the lines?
there should be no acceleration effetc on the slave afaik.. only the MC fluid level moves around....
weird....
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Location:
Forster NSW
Registered:
September 2004
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Re: Odd clutch problem
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Mon, 16 May 2005 11:28
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I'm with norbie in thinking it's the MC seals.
My first step would probably be trying new fluid... before looking into rebuilding (or getting a new) the master cylinder.
| river wrote on Mon, 16 May 2005 16:32 |
Hi,
Interesting topic.
My clutch seems fine, but the gear changing is a little clunky. Down changing to 3rd gear can cause the odd snarl of gears. If I do the downchange slowly then its okay. Also, the faster I am going when I downchange to 3rd the more chance of the gears crunching.
I am assuming this is a clutch problem due to the clunkyness (for want of a better word) when changing up the gears.
Actually, I'm hoping its a clutch issue 'cos I can't get bits for my gearbox and I've only ever seen one (P51) for sale.. and that was a few years ago. I was told by Toyota that these clutches are not adjustable?
seeyuzzz
river
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If it's only down shifting from 4th to 3rd that gives you crunching, it's most likely a syncro. How's the 3rd to 2nd? It's usually the one to crunch when down shifting. There's always double clutching...
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Location:
tallahassee FL usOFa
Registered:
May 2002
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Re: Odd clutch problem
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Mon, 16 May 2005 12:44
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excessive crank end float, or hydraulic.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Odd clutch problem
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Mon, 16 May 2005 15:21
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| allencr wrote on Mon, 16 May 2005 22:44 |
excessive crank end float
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ooh, thats not pretty... who was it that had horrible crank movement a while ago? on a supra?
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Location:
Terrigal
Registered:
May 2002
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Re: Odd clutch problem
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Mon, 16 May 2005 23:09
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Hmm crank end float.. Would that be caused from worn thrust bearings? Only replaced those recently..
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Location:
Land of Oz
Registered:
June 2004
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Re: Odd clutch problem
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Mon, 16 May 2005 23:13
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Hi,
| Dale_ta22 wrote on Mon, 16 May 2005 21:28 |
If it's only down shifting from 4th to 3rd that gives you crunching, it's most likely a syncro. How's the 3rd to 2nd? It's usually the one to crunch when down shifting. There's always double clutching...
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Down change from 3rd to 2nd is perfect. It's only from 4th to 3rd. I don't think my box has synchros, but bands. I just don't know enough about the P51 box and I've never seen a repair manual or anyhing like that for it. The few places I've taken it to just scratch their head and say "Sorry mate, never heard of it".
Toyota has a few spare parts but no spare bands. They said that it's possible to swap the band over (ie turn it back to front) and that may fix the issue, or get a new band engineered.
I'm not that keen to have the box pulled out without having some guarantee that someone can fix it. In the meantime I change gear slowly and use the brakes more than downchanging to keep it going as long as possible. Worse case I can put in a W50 and put the P51 aside until it can get fixed (if ever) - but I won't be doing that unless the box becomes undrivable, which, at the moment, is not the case (it's great except that downchange and a little clunky on all the upchanges). I was/am so hoping it would be the clutch.
seeyuzz
river
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Location:
Adelaide
Registered:
May 2002
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Location:
Land of Oz
Registered:
June 2004
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Re: Odd clutch problem
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Tue, 17 May 2005 00:26
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Hi,
| RobertoX wrote on Tue, 17 May 2005 09:50 |
Dont know what a porsche-syncro type is though 
Edit #2: Apparently they're a 'brake band type synchro'....
learnding is fun 
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Yes, that's the gearbox. Yeah, I dunno what a Porsche-syncro means also, nor what a "brake band type syncro" is. I'm learning too and it's is fun, but it'd be more fun if it was someone else's gearbox!
seeyuzz
river
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Location:
tallahassee FL usOFa
Registered:
May 2002
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Re: Odd clutch problem
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Tue, 17 May 2005 14:40
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porsche, Alfa & bmw (and probably others since the 70's)have a mickey mouse looking split ring & lever & weight on the synro hub,and that split ring is forced into/inside a taper on the gear when shifting. the lever & weight are supposed to help the split ring exert even more force(syncro action) at higher revs.
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