Supra Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
980 Posts
Discussion Starter #1
It looks pretty thin through the inspection plates. Only had it for 5k miles and have never been to the track.

AFR is solid and the car is holding boost but the clutch seems to be slipping, grabbing, slipping, grabbing, etc...at high rpm and boost. Not fully slipping yet. Of course I could have another problem.

 

·
looking for another Supra
Joined
·
1,890 Posts
are you exceedind the capacity of that clutch possily? i never went to the track but mine did the same thing. i pulled the clutch off and my disk was torn like a virgin.
 

·
Supra Owner Since 1996
Joined
·
2,723 Posts
How much power are you putting down?
 

·
Cheifbootknocka
Joined
·
1,944 Posts
From the pix it looks fine to me, thats just how thin they are.
 

·
Cheifbootknocka
Joined
·
1,944 Posts
house_of_senate said:
:scratch: looks good in the picture...
Yea the two pictures posted above. You can see the clutch disc thickness, thats how you gauge how much life is left.
 

·
Registered
Joined
·
980 Posts
Discussion Starter #8
I'm running a T78 at 25psi on a 114/93 mix (mostly 114) at a 11.3 AFR. I'm guessing it's seeing no more then 600ft-lbs?

Here's whats happening:

In the higher gears (3rd-4th) at full boost, the rpms sound like RRRRRRRrrrrrrrrRRRRRRRRRrrrrrrrr. Kind of like the clutch is slipping, grabbing, slipping, grabbing. Basically, the rpms *sound* like they're varying instead of increasing steadily. The car doesn't seem to be losing power that I can tell.

I'm confused. This is strange. Ever since I took my 300lb brother-in-law for a ride it's been doing it. lol Maybe he stepped on the ECU cover and knocked something out of wack? A wire or something?

I probably need to log a run using the MAP ECU and verify a steady increase in rpms and that boost is in fact holding fine.
 

·
Registered
Joined
·
980 Posts
Discussion Starter #9 (Edited)
TooJayZee said:
Yea the two pictures posted above. You can see the clutch disc thickness, thats how you gauge how much life is left.
Yeah, it looks thinner towards the middle of the disk pad if you look closely. I actually really hope the clutch is fine. Thats the only thing I needed some help with. All the other APU work I did on my own. I'd have to take it to someone and hand them my key and walk away. And I haven't done that and don't want to. Tommy Bahn came to my house in Houston and put in the one in the pics.

Thanks!
 

·
Registered
Joined
·
980 Posts
Discussion Starter #10
Just got an email form Dave at Spec:

That is right about the limit of the old st4. We just upgraded our Supra
TT
plates to 3200 in the last 30 days or so, which makes our tq capacities much
higher. But the old unit was rated about 650 whp, so you may be getting
some power slippage. It could also be some disc contamination that is
burning off and that's why it's intermittent. Most of the time if a clutch
is being overpowered it doesn't recover like that. It won't hurt to keep
driving it for a bit, but if it starts slipping a lot I would refrain, b/c
you don't want to get it too hot. What flywheel is it on?
If it becomes a power slippage, we can upgrade your plate to the new one or
you can go to a st3+ or 4+, all three of which will take you deep in the
700's to low 800 rear wheel tq. If we have to do that, we'll give you
credit towards the upgrade so your not having to buy a new unit.

David Norton
S.P.E.C., inc
 

·
Cheifbootknocka
Joined
·
1,944 Posts
StokerSix said:
Just got an email form Dave at Spec:

That is right about the limit of the old st4. We just upgraded our Supra
TT
plates to 3200 in the last 30 days or so, which makes our tq capacities much
higher. But the old unit was rated about 650 whp, so you may be getting
some power slippage. It could also be some disc contamination that is
burning off and that's why it's intermittent. Most of the time if a clutch
is being overpowered it doesn't recover like that. It won't hurt to keep
driving it for a bit, but if it starts slipping a lot I would refrain, b/c
you don't want to get it too hot. What flywheel is it on?
If it becomes a power slippage, we can upgrade your plate to the new one or
you can go to a st3+ or 4+, all three of which will take you deep in the
700's to low 800 rear wheel tq. If we have to do that, we'll give you
credit towards the upgrade so your not having to buy a new unit.

David Norton
S.P.E.C., inc
I said in my previous post that the thinkness determines life of the clutch. I would like to re-phrase that to say... thinkness tells how much pad is left. You could have a brand new clutch but if you are over powering it, it will slip.
Take Davids advice from SPEC and find out whats going on. You should get the car to a dyno to find out how much power your making. I cant belive you would only make -600ft lbs on a T78 with 25psi and race fuel. After re-reading this post, I think it may be possible that you are having some slippage.
 
1 - 12 of 12 Posts
Top