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S Chassis Technical discussion related to the S Chassis such as the S12, S13, S14, and S15.


 
 
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Old 12-28-2009, 12:43 PM   #1
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Ultimate clutch pedal thread

Please note that this is just my experience. It is not the only way to get things done. Please feel free to share your own experience and recommendations.
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I've been inundated with so many clutch pedal questions asking about the same thing.

First, you need to remove the clutch damper from the hydraulic system: Clutch Line Modification - Removing Damper Loop - zeroyon.com

The damper serves no purpose other than making the clutch pedal feel numb and impossible to bleed by hand. Everyone should bypass the damper.

Instead of trying to bend the stock line, I recommend a braided clutch line straight from the master cylinder to the slave cylinder. There are many brands and they all are essentially the same thing. Just pick one.

Before bleeding, you should adjust the clutch pedal to get maximum travel. This will help you pressurize the line.

Open up the CL section in the FSM and look at the pedal diagram.

On US cars, at the bottom of the clutch pedal travel is a small switch. This is your clutch interlock switch.

You should also bypass the clutch interlock switch: http://zilvia.net/f/tech-talk/106125...-56k-warn.html

At the top of the clutch pedal is either a stopper bolt (base model with no cruise control) or an ASCD cancel switch (cruise control). This limits the height of the pedal travel off of the floor. Remove this bolt/switch for now.

NOTE: The ASCD cancel switch activates when you move the clutch pedal away from its top position. This kicks off the cruise so the engine doesn't overrev.


If you look in the CL section, there is a page showing you how to adjust the clutch pedal. Look at the pushrod. You want the pushrod to be as far out away from the driver as possible.

Start by unlocking the locknut on the pushrod. Then you can twist the pushrod with your hand or a tool. You want to unscrew the pushrod so there is as little sticking out of the threaded hole towards the driver as possible.

Don't unscrew the pushrod too much or the rod will come out of the hole completely.

As you back out the pushrod, you will notice that the pedal height will rise above the floor. Pull the pedal up by hand and you'll see.

I usually back the pushrod out until the pedal hits the backstop and cannot go any more. There's no point in backing the pushrod beyond this point because the pedal won't come up any more (the pedal is already stuck on the backstop).

You can leave the locknut loose for now until final adjustment.

Now you can start bleeding the clutch like normal. You'll notice that the clutch pedal has a lot more travel than it usually does, but that's ok.

TIP: When bleeding the braided line, you can pump the pedal several times to pressurize the line and hold the pedal down. Have someone quickly unbolt the line at the master cylinder and quickly close the fitting. You will feel some air escape and fluid will go into the line.

You then bleed at the slave bleeder bolt. It should only take a few pumps to fully pressurize the line compared to the stock setup with the damper.

When finished bleeding, test drive and chek the engagement point "friction zone" off of the floor.

If you still can't shift with the pushrod backed out all the way off and maximum pedal height, something is wrong. Either you have some internal problems, or your clutch master cylinder has the wrong ratio for your setup.

Guys with LS-series/V8 swaps must swap out the stock clutch master for something with a bigger bore like 3/4". There is no way to push enough fluid with the stock pedal travel and 5/8" bore. You either need more pedal travel or more bore.

Once you're sure the clutch can be disengaged, you can shift smoothly without grinding, no creeping in gear, and you can slip the clutch at a stop sign, then you can adjust your engagement point off the floor.

You progressively screw the pushrod into the pedal about 1 turn at a time. You'll see that the pedal height will come down.

Take your stopper bolt or ASCD cancel switch and install it where you removed it. You want to set the bolt/switch so that the clutch pedal barely touches it at the top of the pedal travel.

Take out and test your engagement point. If you're not satisfied, srew the pushrod in another turn, set the bolt/switch, and test drive. Repeat until you're satisifed.

After a while your engagement point will change due to clutch wear so you will have to readjust periodically.


The most imporant thing are:

1) Make sure that the clutch master cylinder pushrod can retract completely. This will take pressure away from the hydraulic system. If you set the stopper bolt/ASCD switch too high, the pedal won't retract completely and it will be like riding the clutch pedal all the time. Not good for your clutch system.

2) Make sure the clutch can disengage completely when the pedal is pushed all the way to the floor. Test all gears. You should be able to shift smoothly with the clutch pedal all the way down.

3) All you guys with cruise, make sure that the pedal is contacting the cancel switch at the top of the pedal travel. Otherwise your cruise won't work. Adjust your ASCD switch until the switch is pushed in by the pedal at the top of its travel. As you push the pedal down, the pedal will come off the switch and cancel cruise.

If the pedal doesn't push the switch down, the car will think that you're always riding the clutch pedal and automatically cancels cruise.

Test for creeping. Select a gear and hold the pedal down. The car should not creep. Check all gears.

If you set the pushrod too high, you won't have enough pedal travel to completely disengage the clutch disc. Every time you shift you will hear a crunch. It's like not pushing the pedal down completely when shifting.


Let me know if you have questions or criticism.
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