professionalpyroman

Hi there,

I'm going through my drivetrain and trying to settle on a setup for my 89 TII. I am rebuilding a new-to-me transmission because I bought it used and want to have new bearings, synchros, and piece of mind. The clutch I currently have in it is slipping and I know has been baked, because I'm the one who baked it a few years ago. It's a long story and had to be done to make it home (lost all but 4th gear when countershaft trans bearing blew up).

Anyway, I'm trying to size a clutch kit for daily driving that would hopefully be the only one I put in this car. I've tried to calculate the required load the clutch would need to handle but I haven't found guidance that I'm fully trusting.

The method I have tried is by calculating horsepower (rx7.com), and then trying to calculate the torque based on the horsepower. I don't have a good reference RPM to use as a base point which makes both of these sort of useless when making torque estimations. You guys have more experience with this, so I figured you would know what would be a good fit.

This problem is kinda similar to YoKramer's in a previous post.

My setup is a very mild streetport S5 with 750cc injectors, and a BNR stage 2. I have a 255lph fuel pump, and a racing beat 3" exhaust. Stock intercooler. I am going to upgrade to a haltech computer when I go to install everything, so the ecu will be new as well.

The clutch I am looking at getting is the Exedy Stage 1 HD. People seem to like it on here quite a bit. It will probably be pretty stiff. Is this clutch overkill for this setup? What sort of safety factor should I plan for on clutch strength?

Thanks a bunch guys

jjwalker

If it helps, torque and horsepower are always the same 5252rpm

YoKramer

Im on a very similar setup to you, street port, 720 primaries, 1000 secondaries, BNR Stage 3, and already on a Haltech RE. What was in the car when I got it was an Exedy, not sure if it was the standard or HD but either way it doesnt stand up to higher RPM full throttle. 1st gear it will hold fine to redline but 2nd and 3rd it starts to slip around 4500, not much but enough that you are about 10mph lower than you should be at the top of 2nd and a bit more at the top of 3rd. That is all on wastegate at a peak of 12.8lbs, I plan on setting up the boost controller to open at 14lbs so I dont think even the HD will be enough with it only having ~60 lbs more capacity than the non HD. I ordered the ACT Z65-XTSS (also recommended by Rotary Evolution) which is good to 440 ft-lbs which will be more than Ill ever need.

Z65-XTSS // Advanced Clutch Technology

KompressorLOgic

iTrader: (6)

the stage 1 hd sounds like it should be a good match for your setup, and work well for the street since they are still a full face organic disk.


I'm somewhere around 350-400 hp with a exedy stage 2 with HD pressure plate,( its a 3 puck sprung clutch) and while it feels "streetable" to me, and I drive it in traffic sometimes even I could see most people not wanting something that grabby for street driving. as when it gets hot it really bites.

RotaryEvolution

iTrader: (30)

i never recommend pucks for street driving, even if yours is semi manageable it doesn't mean the same clutch in someone else's car won't be super grabby and annoying as hell to try and work.

i could picture getting stuck in heavy traffic and getting aggro as hell.

KompressorLOgic

iTrader: (6)

ive found I could slip the 3 puck( I had the same clutch on my old t2) but it make a crazy whiring sound, which sounds like its tring to tear the flywheel apart or something... id agree do not do this on a daily.

another thing is I run this on a stock flywheel, which is quite heavy, which makes a big difference as well... I'm not fond of light flywheels on dd cars either. my old s5 vert had one and it sucked taking off from a stop in it.

professionalpyroman

Appreciate the input fellas.

I did some more looking and made a couple phone calls. I think I'm gonna go with the next pressure plate down, the ACT Z65-HDSS.

It's pretty much the same tier as the Exedy S1 HD, but with about 20 more lbs of torque capacity. Should provide a decent buffer as far as strength.

You guys seem to like ACT really well, so I'll differ to your knowledge and try this one out

RotaryEvolution

iTrader: (30)

honestly, i don't ever recall having an ACT clutch slip, i have had just about every other brand slip though. Spec was by far the worst clutch, don't give them your money or you will be disappointed.

YoKramer

So far Im loving the ACT in mine. Got it in Friday and gave it a little break in and its holding fantastically. Chirps going into 3rd now. Has the same pedal feel as the Exedy that came out, and engagement is smooth yet immediate and definitely holds all the way through the RPM range now.

professionalpyroman

Awesome. Got mine ordered today. Not gonna put it in until I put new bearings and synchros into my spare transmission. Then the one I'm using will be up for sale. Its pretty good. 3rd gear synchro is starting to slip in the one I have installed but everything else is still great.

I appreciate the help guys. Hopefully this will be the conclusion to driveline work. I ordered a full set of Mazda synchros on the advice that aftermarket ones in the kits were junk. Do you guys know if I need to lap them in or not? Last I checked, they were ribbed on the inside instead of a flat bearing face. The bearing kits on ebay looked legit though as they had Nachi bearings in it and those were what I pulled out of the spare transmission.

Wife didn't necessarily appreciate me going around the house singing "It's beginning to look a lot like Christmas..." when I got the UPS shipping notice...

RotaryEvolution

iTrader: (30)

new synchros are supposed to have sharp ribs, the reason the old ones don't is because they are worn. think of them like tread on a tire.

professionalpyroman

Appreciated. That should cover all of my bases