2G Clutch Drag Test - [Video]

[Artago]

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Built race trans with 500km (310mi), SBC SS-TZ clutch w/ new pressure plate. Stock re-surfaced flywheel 10k ago. Replaced master and slave 20k ago.

Slave was bleed a week ago but I will double check.
Master rod is backed out. Relief port is not blocked and fork returns normally.
I will try to re-adjust.

Is this a small, medium, or large amount of drag?

 

[Artago]

Reserved

 

[Tiki2777]

I would remove the limiter to start with, you need to test for drag past that, but from my experience that's not a ton of drag, but its still there. You need to make sure the hydraulic system is bled properly, and from there: is the pivot ball new? and did you actually check the step height for the flywheel?

 

[donniekak]

Any amount of clutch drag is unacceptable. If that is the Kevlar disk, it seems that most of them do this.

 

[oneslowwdsm]

Any amount of clutch drag is unacceptable. If that is the Kevlar disk, it seems that most of them do this.

Yes as well as mis-matching clutch and flywheels. For example I have a Clutch Masters flywheel with an ACT clutch and pressure plate. I have a little bit more movement than the OP at 6-7K rpm. (Adjusted perfectly with new slave, master, fork, pivot, and TOB) While so many people tell me it is 'unacceptable' I have been on this setup for 8k hard miles and I have zero problems shifiting at close to 8k RPM as well as perfect low end shifting and engagement.

 

[donniekak]

It's unacceptable because a clutch system isn't designed to almost completely release. People are amazed at the speed of shifting, and the shift feel when the clutch is adjusted for no drag.

 

[Tiki2777]

Yes as well as mis-matching clutch and flywheels. For example I have a Clutch Masters flywheel with an ACT clutch and pressure plate. I have a little bit more movement than the OP at 6-7K rpm. (Adjusted perfectly with new slave, master, fork, pivot, and TOB) While so many people tell me it is 'unacceptable' I have been on this setup for 8k hard miles and I have zero problems shifiting at close to 8k RPM as well as perfect low end shifting and engagement.

Yes you may be right but your transmission will have serious wear (and/ or damage) if you continue to drive with it dragging. Please do yourself the favor now and fix that, I've had perfectly good transmissions that I thought shifted well taken apart to find damage all across the board, because my clutch SLIGHTLY dragged. my .02

 

[oneslowwdsm]

Yes you may be right but your transmission will have serious wear (and/ or damage) if you continue to drive with it dragging. Please do yourself the favor now and fix that, I've had perfectly good transmissions that I thought shifted well taken apart to find damage all across the board, because my clutch SLIGHTLY dragged. my .02

Well after the new clutch setup I was pulling my hair trying everything to get it to stop dragging until I gave up and chalked it up to the problem being mis-matched clutch setup. I'm not pulling my trans again until something blows. I need a built trans anyway

 

[oneslowwdsm]

My shifting and engagement is crap. I did a core swap for a built trans from Jack. This unit has about 300 miles on it. I took it off the road until I fix this (driving a Subbie as my daily)

Well there is obviously an issue then. Maybe the transmission itself or possibly the flywheel has more ware than you think.

http://www.roadraceengineering.com/clutchandflywheeltech.htm

This article can help if you havent read it already.

 

[bling5tatus]

After watching the videos, that is definitely clutch drag.... no matter how slight it may be. You're basically slipping the ever living piss out of the clutch when it does that. It creates heat spots and likely glazes the disk.... not to mention wears the pressure plate and flywheel in a non-standard fashion.

 

[twicks69]

What is the measured distance of slave cylinder travel? What is the placement orientation of the clutch fork in the inspection window? Is the clutch fork new or reused? Pivot ball new or reused? Replaced hydraulics 20K ago; with new OEM or parts store units? If you fully depress the clutch pedal and hold it, what is happening at the slave cylinder for travel as well as if it is returning while still depressed?

 

[97_4g63t]

I had the same clutch and I couldn't get it to quit dragging. I eventually got tired of it and got an act. No problem since.

 

[Artago]

Master is leaking (and clicking). Ordering a new one. Will update when installed.

 

[Artago]

Update: I rebuilt the master. Bled the clutch. Engagement point is perfect. Tested for drag with the car up on blocks. Doesn't drag at 5000 RPM at all. 3rd gear is still grinding on the road. FML

 

[bastarddsm]

So one thing I've noticed, ACT tells me that there clutched are designed to release with stock amounts of TOB travel. They are liars. I put togther a clutch flywheel and ACT street disc on the bench released them with a bolt and bearing through the middle.

Stock 1g turbo FWD pp needs .195" to release the disc, and .385" to get a reccomended .060" airgap.

ACT2600 old style with thick fingers needed .230 and .424 respictively,

ACT2900 new style was .250, and a touch over .443"

quartermaster has a max release bearing travel of about 0.170"

Obviously the ACT needs a lot more TOB travel, I'm sure the SBC PP needs more than stock too.

On a 1g at best you can have 1" of slave cylinder travel. Ratio of master to slave is .69:1 Meaning at best you get .69" of slave travel. But it's not 100% efficient, so your really probably down at about .5" Lastly, TOB fork is about .625:1 So with stock shit at best you have about .3125" of TOB travel. See the problem?

Finally if you rev high like I do, the fingers will move outward due to centripital force, and push the throw-out bearing back, probably as much as .050 - .100". ACT says it can't happen, but it sure does, I have a log of it happning. ( position sensor on my clutch) Now we are down to bareley enough to release a stock cluch.

I can also say that a worn pivot ball, fork and shimming the pivot ball will have little to no effect on release. The only way it could have an effect is if the geometry of the system was way off. An example would be if the clutch fork was 45* to the trans instead of close to parallel like it is.