New clutch, have some issues.

[Toni]

Sweet, looks like my master kit is at my doorstep. Gonna tear this thing apart and start from scratch everywhere measuring specs etc. I actually want to see how much travel is possible in the slave to see where I am currently and how much it's capable of moving. I also called Southbend to see the spec of how far the pressure plate should be disengaging;I'm sure they have a spec. Should hopefully get some answers tonight. Hopefully, no more questions.

I also ordered a stainless line, might as well improve the feel while I'm at it (if it's not the original problem).

[Primus101]

Good luck on interpreting the FSM on the that clutch booster>MC rod adjustment....they leave it unclear as to the firewall thickness being taken into account. In the FSM, it appears that the booster is removed when measuring, dont know if thats just for illustrations or due to the tight room with the strut tower. They do show the two bolted together with the clearance shown, but unclear as to firewall skin? It shows the acceptable clearance variable of only .010", yes ten thou- My setup seemed to be working fine, so I just recorded the depth of the MC & if it changes with the rebuild kit, I know how much to change on the rod. If that clearance is way out on yours it could explain the extended pedal adjust rod.
I would also double check the bore size on the slave, IIRC the turbo is a smaller diameter than NA & may have been switched at some point.
Hope you sort it out-

[Toni]

Well have some updates. Took everything out and did all the measurements. Lots of room for error. Basically it ended up within spec. After doing the math they didn't account for the firewall and the gasket. I put the master on the vise and filled it up, obviously it starts leaking into the slave port. I move the piston in and it shuts off as expected. The travel distance is 2-3mm.

Alright. So then I think, screw this measurement crap, pedal play, etc blah blah. I put the master back in and left the slave port disconnected. I filled it up a bit and it was leaking into the port. I then put a stick between the pedal and my seat and moved it in maybe 1/2" and filled the master more and it stays. I slow move the seat back until it leaks out the slave. Now I know where I need to set the booster rod-> slave connection for my car to give me most throw without shutting off the valve. I imagine this is the most exact way for anyone to set their booster rod position.

Now, right now my pedal adjustment rod is at most throw possible. I'll adjust it so the valve shutoff is roughly halfway to give me future adjustment in both directions. I will run the same tests with the car on to provide vac to the booster to make sure it doesn't shut the valve. I measured the distance the slave traveled before doing all this so I'll see how much movement I gained. Also, my slave rubber line had no bubbles and nothing is leaking. I think my issue is a combination of a pressure plate that needs a lot of throw and my booster rod not giving me the most travel possible.

[Primus101]

Good work, It will be interesting to see if vacuum affects your theory. here's a decent cross section of the booster if it helps- from pg. 2-3 in the '93 3000gt technical information factory manual.



Did you confirm you have the AWD 11/16" slave & not the NA 3/4" slave?

[HellBringer]

southbend stage 3 endurance.

For what it it's worth, ALL of the newer (within the last 2 years) SB clutches are well known to have similar release issues on the Supra. It's either how their modifying the PP and/or the thickness of the disks. This is fairly well documented by several members on SF and measures have included shipping clutches back and forth several times to no avail. All eventually moved on to something else. A good friend of mine has a SB in his Supra and with the slave rod backed out as far as it will possibly go it will only disengage with the pedal on the stop, and that is with all of the mechanical travel you can possibly get in the system. The clutch has nice engagement and holds power, but is otherwise absolutely worthless so you can't bang gears with it.

[Toni]

Alright so I got this thing tuned for max possible throw. I gained 3/16-1/4" of throw on the slave and I know 100% that my valve is still open with the pedal out. I adjusted the booster rod so with my pedal adjustment set for max throw it still has the open valve. I am really good at removing the master/booster pedal assembly now lol. I took a few pics for a small write up and tips.

Hopefully this is it. I don't recall the pivot point of the clutch fork so I'm not sure how much movement I got on the release bearing. At this point my hydraulic system is maxed out to the most it's designed for. Anything else will point to an issue with the clutch fork, tob, clutch, or pp.

Good work, It will be interesting to see if vacuum affects your theory. here's a decent cross section of the booster if it helps- from pg. 2-3 in the '93 3000gt technical information factory manual.

Did you confirm you have the AWD 11/16" slave & not the NA 3/4" slave?

Thanks for the pic, my manual doesn't have that. After thinking about it vacuum won't affect anything because extra fluid can flow back when the car is off (at least once the vac runs dry). I have the AWD 11/16 slave.

For what it it's worth, ALL of the newer (within the last 2 years) SB clutches are well known to have similar release issues on the Supra. It's either how their modifying the PP and/or the thickness of the disks. This is fairly well documented by several members on SF and measures have included shipping clutches back and forth several times to no avail. All eventually moved on to something else. A good friend of mine has a SB in his Supra and with the slave rod backed out as far as it will possibly go it will only disengage with the pedal on the stop, and that is with all of the mechanical travel you can possibly get in the system. The clutch has nice engagement and holds power, but is otherwise absolutely worthless so you can't bang gears with it.

Hopefully that is not the case here. Definitely not something I wanted to hear. I do have another option and thats to get a new slave rod machined longer for more throw. I think it would have to be a two piece design that is adjustable after install otherwise getting it in would be hard if not impossible.

[stealthee]

Toni, as I stated prior DSM guys were known to shim their slave rods with washers to get more throw. It's something you could try just to get by if you needed to.

[Street_Chally73]

Which PP & clutch did you go with (SB for both)? I certainly don't want to have to deal with the headaches you're going through when I choose my next setup.

At least it sounds like you're making headway with this issue, but damn is that a lot of work! Hopefully you can get another rod made up or find some other alternative to get this all to work as you'd expect it to.


Sent from the garage

[Primus101]

You could probably just add washers or spacers between slave & bellhousing to bring the slave closer to the fork.

[Toni]

Toni, as I stated prior DSM guys were known to shim their slave rods with washers to get more throw. It's something you could try just to get by if you needed to.

Lol yup wasn't trying to steal your credit for the suggestion. After the booster adjustment and putting a washer behind the slave everything feels great. I went out and put on almost 100 miles today. Had a good route with a lot of stop and go then cool down.