[Supras] New clutch slipping, shifting problem?

Wed Feb 27 16:46:35 CST 2008

It's a Southbend unit. Toyota PP with new diaphragm so should be any
difference there. Perhaps the disk is thicker as I don't recall the FW
being thicker. I'll try bleeding the system again, it feels similar to
when the slave was bad at one time and leaked although it's not loosing
fluid this time around. Engages very smoothly but has to be pressed
further to allow gear selection and disengagement.

-----Original Message-----
From: cthommes at adelphia.net [mailto:cthommes at adelphia.net] 
Sent: Wednesday, February 27, 2008 5:43 PM
To: Walker, Brian (Rich. Dist)
Cc: Supras at supras.com; Jeff Mohler
Subject: RE: [Supras] New clutch slipping, shifting problem?

I think a clutch could fully engage if the disk was in backwards, the
disk hub binds against the fw center (perhaps the bolts) and the PP
still engages the disk fully.  It seems like this would make a buncha
noise though.  I dunno, I've never put a car together this way to
verify.  :)

No, the release point is not really adjustable.  Pressure is irrelevant,
because (barring leaks) pedal motion will cause the same ratio of motion
in the slave cyl thus the fork, thus the plate.  Unless the plate
diaphragm is so substantially different than original that it requires
much more clutch fork throw to move the plate... doesn't seem likely.

If materials were substantially thicker (in the plate, FW surface, or
disk) the release point could be much lower.

But it strikes me that to have to go all the way to the floor for
complete disengagement points to a problem.  What clutch is this again?

-Craig

---- "Walker wrote: 
> I don't think there's a problem with the setup, the disk is certainly 
> in place correctly (I wouldn't fully engage otherwise would it?)
> 
> A ran a lap after the one where slipping occurred and made sure to 
> shift smoothly. Went even further into the revs and it was solid (as 
> solid as a 20 y/o engine can be) so I'm guessing this occurred from 
> the slipping between 1st/2nd.
> As for Geoff's comment, he knows a whole lot more about racing than me

> but this was time trials so a good start does come into play (fastest
> lap) but I try never to launch the car anyway since breaking pieces 
> isn't worth a couple 10ths. I think it was a combo of getting used to 
> the new FW and engagement point and shifting while the tires were 
> spinning and not gripping.
> 
> How about the engagement point, I don't believe this is adjustable.
> Seems like it wouldn't change unless the heavier plate takes more 
> movement (hyd. press) from the pedal to operate? Like I said, it has 
> to be almost to the floor now so it's thrown me off a little.
> 
> Thanks,
> Brian
> 
> -----Original Message-----
> From: cthommes at adelphia.net [mailto:cthommes at adelphia.net]
> Sent: Wednesday, February 27, 2008 5:21 PM
> To: Jeff Mohler
> Cc: Supras at supras.com; Walker, Brian (Rich. Dist)
> Subject: Re: [Supras] New clutch slipping, shifting problem?
> 
> Besides Jeff's expected "I know more about racing than you" reply, 
> perhaps you're actually looking for an answer to your question?
> 
> I hate to say it but it sounds like something in the clutch broke.  
> The lower disengagement point coupled with the slipping leads me to 
> believe that there's something wedged or cocked somehow between the PP

> and flywheel.  I had similar symptoms when a puck pad broke free from 
> one of it's rivets in an RPS clutch.
> 
> I also had similar symptoms when a hub spring broke out of a clutch 
> disk in an old Integra I had.
> 
> Might be able to get the car in the air and see something through the 
> inspection plates without too much hassle?
> 
> OOOOoooohhhhhh.... or perhaps you have the disk backwards on the input

> shaft?  This would also make all these things happen.  That'd suck...
> 
> -Craig
> 
> ---- Jeff Mohler <speedtoys.racing at gmail.com> wrote: 
> > Dude, nobody EVER won a race from a stop.
> > 
> > We dont do many standing-stop starts, because it breaks so much
stuff.
> >   Clutches, diffys, transmissions...everyone's on race rubber that 
> > wont give so easy also.
> > 
> > if youre faster than someone..you'll catch em in a lap no matter
what.
> > 
> > On Wed, Feb 27, 2008 at 1:36 PM, Walker, Brian (Rich. Dist) 
> > <Brian.Walker2 at vdot.virginia.gov> wrote:
> > >
> > >
> > > Didn't put much, I think it was due to a poor shift at the 
> > > beginning
> 
> > > of the lap. I wasn't sure if that would allow it to slip but 
> > > evidently it can. I'll be trying it out under full sessions next 
> > > month (these were time trial laps from a stop) and will try to
> smooth out the shifts by then.
> > >
> > > Btw, does the press. plate normally change the engagement point
> drastically?
> > > The pedal has to be depressed almost to the floor now and we've 
> > > bled
> 
> > > it a couple of times.
> > > Thanks,
> > > Brian
> > >
> > >  ________________________________
> > >  From: Dave Koos [mailto:dave at azsupras.com]
> > > Sent: Wednesday, February 27, 2008 3:51 PM
> > > To: Jeff Mohler; Walker, Brian (Rich. Dist)
> > > Cc: Supras at supras.com
> > >
> > >
> > > Subject: Re: [Supras] New clutch slipping, shifting problem?
> > >
> > >
> > >
> > >
> > > You didn't put too much grease on the input shaft of the trans, 
> > > did
> you?!?!
> > >
> > > BTDT!! :-O
> > >
> > > Dave  92T & 86 P-type
> > > Mesa, AZ
> > > http://www.azsupras.com/suprattop.htm
> > > http://www.azsupras.com
> > >
> > >
> > > ----- Original Message -----
> > > From: Jeff Mohler
> > > To: Walker, Brian (Rich. Dist)
> > > Cc: Supras at supras.com
> > > Sent: Wednesday, February 27, 2008 9:30 AM
> > > Subject: Re: [Supras] New clutch slipping, shifting problem?
> > >
> > > Could have glazed in the bad earlier shift...doesnt have much time

> > > on it either.
> > >
> > > It SHOULD work itself out...over time.
> > >
> > > If it doesnt..its nothing that 200grit sandpaper can work out, but

> > > we all know what that would take to do.
> > >
> > > On Wed, Feb 27, 2008 at 8:22 AM, Walker, Brian (Rich. Dist) 
> > > <Brian.Walker2 at vdot.virginia.gov> wrote:
> > > > I put about 700 miles on my new clutch (kevlar) and FW (AL.) 
> > > > before a  time trial this weekend. During one lap it started 
> > > > slipping very  noticably in 3rd so I let off, applied throttle 
> > > > again it was again  slipping, much more than the stock unit ever

> > > > had. Earlier in this lap I  had made a poor shift to 2nd where I

> > > > mistakenly slipped it a fair  amount, could this be the reason 
> > > > it was slipping in 3rd and 4th? I know  I'm not making the 460
ft-lb.
> 
> > > > the clutch is rated for (I'd guess I'm in  the 320-340 hp range 
> > > > with similar torque)  I was under the impression that the clutch

> > > > will not slip once engaged  unless it's TQ rating is exceeded, 
> > > > will poor engagement between shifts
> > > >  (ie: excessive heat) cause it to slip prior to this?
> > > >
> > > >  Thanks,
> > > >  Brian W
> > > >
> > > >
> > > >
> > > >  _______________________________________________
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> > > >  Supras at supras.com
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> > > >
> > >
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> > 
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