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Clutch Pressure Plate Force


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I had a thought regarding slipping new-ish clutches, complained about particularly on EA82(t)s:

 

How many people that have slipping problems have a stiff clutch pedal? I had taken it for granted that Subaru clutches were stiff to operate until my recent purchase of an XT. The XT has a pedal force similar to Datsuns and Toyotas that I have driven, which are very light (1/4 the effort of my twagons).

 

Is the difference in stiffness because of cable/actuator friction/binding? If so, this works both ways: It will reduce the clamping force of the pressure plate because it is equivalent to someone "riding" the clutch pedal.

 

Just a thought...

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yeah i have seen high pedals and stiff cluthes from over tightened clutch cables. this stresses the cable and wears on teh pressure plate, over extending it

 

my rule of thumb is to adjust the cable just till it takes the slack out, but not enough to pull back on the fork. the you can adjust the nut a few turns to set your pedal, but no more!

 

i hat ehigh pedals as i like to keep my foot rested on the floor, heel on floor clutch with my toe. a high pedal i would have to hover my leg in the air, very awkward.

 

the clutch should engage no sooner than you start to release the padal

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I'm not talking about cable adjustment. I am referring to excess "stiction" in the cable, possibly contributed to by poor routing of the cable.

 

I am assuming that the pressure plate clamping force (spring rate) in the XT is roughly equivalent to that of my 82 wagon, my 87-and-up twagons, and my 88 SPFI. If the PPs are reoughly the same, and the release arm and its pivot (lever ratio) is the same, and the pedal-box geometry is roughly the same, then the pedal effort should also be roughly the same... not different by a factor of 4x of so.

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I'm not talking about cable adjustment. I am referring to excess "stiction" in the cable, possibly contributed to by poor routing of the cable.

 

I am assuming that the pressure plate clamping force (spring rate) in the XT is roughly equivalent to that of my 82 wagon, my 87-and-up twagons, and my 88 SPFI. If the PPs are reoughly the same, and the release arm and its pivot (lever ratio) is the same, and the pedal-box geometry is roughly the same, then the pedal effort should also be roughly the same... not different by a factor of 4x of so.

If the ratios are the same and the presure plate has the same springs. Then there must be something causing the extra drag. Ether the cable or the pivot points.
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Bump

 

Folks, what I am looking for here is your personal experience with burned clutches and how stiff your clutch pedal is/was.

 

The Datsuns and Toyotas that I have driven with equivalent horsepower (and usually much more low-end torque) than my EA82Ts, have much lighter pedal force than all my subes except my XT, and I have never had clutch issues with them. My 510's clutch isn't significantly different in size (IIRC, been 15 years since I changed its clutch :-p ), has far more torque, and a light clutch pedal...

 

So what gives? Is a binding cable at the root of some of the clutch problems that many gripe about?

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