Clutch and throttle cable adjustment?

[97GSTspyder]

Just two general questions that I've been forgetting to ask...

1. What is the *proper* way to adjust the clutch? I've been told not to go under the dash and mess with the master cylinder rod. Why is this? And what is the other way?

2. The accelerator cable...Where exactly do you adjust it at? Mine needs adjusted because my car idles at approx. 1500...If i adjust the idle, it drops to about 1200 before i can't adjust the idle anymore, so the cable must need adjusted...Where exactly is the screw (or whatever) for the cable adjustment?

Thanks for any help...

[kjewer1]

1) The adjustment at the pedal is ONLY to set the amount of travel you get at the master cylinder, and how far back the rod comes. If the rod doesnt pull back far enough out of the master, it wont "uncover" the bleed port that lets excess pressure out of the clutch line. What happens is you are pumping it up like a bb gun everytime you use the clutch. You'll feel the pedal harden up after some usage, then it will begin to keep a preload on the clutch (and thrust bearing!!!!). So you are risking your clutch, TOB, and motor. Now the right way to adjust this is so you get maximum travel, without pumping it up. It should have been set from the factory, but if you have messed with it (and I think we all have) it might be time to set it correctly. Just screw it out (longer) 1 full turn at a time until it starts to pump up, that go back a full turn. Now, you can use this to adjust the engagement point as long as you are screwing it IN (shorter). All you are doing is lessing available travel.

The rest of how the clutch works, like the engagement point, etc, is set by the step height cut into the flywheel (.610 for stock, ACT, and most other clutches) and the thickness of the disk. Most machine shops wont realize that we really do need it at exaxtly 610, and just resurface it. I had to try a few shops before I found the guy I list on my main web page. When I brought in the flywheel first thing he said was "what step height do you need it cut to?" We have a winner!!

If you find that you arent getting enough travel, especially with heavy clutches, a washer behind the ball stud (throw-out fork pivot) will move the fork closer to the clutch, giving you more travel. In fact I shim the ball stud on every tranny now. You can always remove some travel at the pedal if its hitting the side of the hole in the tranny (where the fork sticks out for the slave rod).

Obviously no amount of adjusting will make up for a piss poor bleed job. Get 2 or 3 people and do it right. Get a stainless line and bypass that POS accumulator. Its always full of shyte waterlogged fluid that never comes out when you bleed. Remove the restrictor in the slave as well. Then bleed properly, with the car level. JAcking it up on only one side can create air pockets that you will never get out. Ask me how I know.

2) Throttle cable adjustment is 10 times easier than the clutch The sheath of the cable is bolted to the back of the intake manifold, two 10mm bolts through its braket. The holes in the bracket are slotted. There is your adjustment. Now, the key is to get the throttle fully closed at idle, and fully open at WOT. There is EXACTLY enough travel in the cable to achieve this, no extra. So if you are off just a little you will not be getting what you want at one end of the range. COmbine that with the fact that the cable shrinks when it warms up, and you have a big pain in the ass on your hands. Again, ask me how I know

There are several ways to adjsut it. I have tried them all. I now use a method that I came up with that will garanatee the best adjsutment, only crappy part is you need two people (or a brick ).

MAke sure the car is warm, so the cable is at its normal length when heated. Loosen the two 10mm bolts on the cable bracket. HAve a friend (or a brick) hold the gas pedal floored (with a bit of pressure, many poeple try to drive it through the floorboard when racing, account for that here and reduce the risk of a broken TB). Pull on the cable, sliding that bracket towards the drivers side, until the throttle body is wide open against its stop. Now tighten those bolts, without slacking on that cable. Maybe 3 poeple is a better idea. So now "gas pedal floored" and "TB plate open to the hard stop" correlate as well as they are ever going to. This gives you MAXIMUM SLACK left in the cable when you are off the gas, reducing the chance that your idle will go up when the motor warms up. Many idle problems that show up when the car is WARM are because of this cable being too tight.

The right thing to do next is to verify that the TPS is adjusted correctly. If the TPS was last adjsuted while the throttle cable was NOT correctly adjusted, it will be off. In my case, I just hook up the logger and verify that I get 0% at idle and 100% floored. SOmetimes you can't get enough travel STILL to get 100%, in that case its better to get 0 at idle, and let it be what it will at WOT. Here's why. The ECU knows when to go into closed loop idle speed control based on the throttle closed switch. The 1g actually uses a switch on the throttle plate (the single wire switch sticking up on the firewall side of the TB) while the 2g has it incorporated into the TPS. Thats why the 2g TPS has 4 wires and the 1g has 3 by the way. It needs to be 1% or less typically for it to tell the ECU the throttle is closed. The ECU doesnt care where WOT is. Anything over 90% is considered WOT by the ECU. And no adjustments are really made based on throttle position, its primary function is for the accelerator pump simulation (carburator guys will know what this is). Fuel delivery is based on several factors, TPS is not one of them. So adjust it for 0% closed. You can also use hte AFC for this, but the AFCs throttle position display may not match what the ECU sees. And the ECU is what we care about here. There is also a procedure using a multimeter, but that still doesnt really tell you what the ECU Sees. But its in the factory manual and is a perfectly acceptable way to set it.

The throttle itself will function properly becuase of the badass adjustment method I suggested, and that what really matters, but the TPS is what you often have to fudge (I can never get 100% at wot with idle at 0% on my car)

Hope that helps!

[pro3racer]

From reading that, it sounds like the throttle adjustment is for a non-cruise control car. Since on a cruise car, theres 2(3) cables.

[97GSTspyder]

wow thanks for the excellent reply. i'll try doing that later today after i assemble a leak tester and test my car for leaks...hmm wonder how many leaks my car has lol

[kjewer1]

Adjustment with CC is the exact same. You should never have to touch the adjustments at the CC junction box. But you are right, I tossed that bullshit years ago. And for whats its worth all 2g turbo cars came with cruise.