clutch adjustment

[normanh]

Hi all,

should the fork/thrust bearing be under any pressure without pressing the pedal?


Oh well, done it again!

[Dan]

In my case only contact pressure is applied (And the self adjuster on the Sierra pedal box takes care of that) ~ (I don't use the hydrolics)

Dan ~ http://homepage.ntlworld.com/danny.mann/

[snowyrm2000]

hi. dont know specifics. i am new to the cobra scene, however, as a general rule, you should have about 1 inch of travel before the clutch starts to operate. if you dont get any better advice, try it.

[wilf]

Hmmm - that does not translate into 1" of gap between the release bearing and the thrust surface!

I was told to set mine up with 1/16th to 1/8th gap as above. You will find that in a hydraulic system, the natural tendancy is for the self-adjusting nature of the hydraulics is to close up that gap anyway, thus leading to light contact between the release bearing and the cover plate at all times.

I fitted a spring to pull my release arm all the way back - I didn't fancy that release bearing spinning all the time, lightly loaded or no.

I am fairly sure that some clutch release bearings are designed to remain in (light) contact with the thrust surface of the pressure plate, and some are not, don't ask me which are which. Probably Drag Star (see Custom Car mag) Russ will know.

(BTW Russ - nice grin in that picture!)

[Aivar]

Hi all,

sorry for putting my question under this thread but it's quite related to this subject.
I'm running Sierra pedal box and Ford mustang T5 transmission in my Sumo. Got a problem with clutch operation (activation) - stroke of the clutch fork or pedal seems to be too short to be able to shift gears smoothly. Actually it's almost impossible to shift in 1 gear with engine running standing at place. I have to stop engine, put in 1 gear, start the engine again with pedal pressed down, however car start to move slowly after engine started.
Sierra pedal box has a kind of auto-adjustment mechanism (using quadrant), I tried placing spacer between cable end and bellhousing but this didn't give any effect. Clutch mechanism itself and clutch disk condition (thickness like new) looks ok.


Any suggestions how to overcome the problem? New bigger handmade pedal quadrant to lengthen the stroke?

Thanks.

Aivar

[nbracken]

Hi Norman, my advice was the same as Wilf details in his response. Should be 1/16" to 1/8" free play - I have a Tremec to Chevy combination using the Repower bellhousing set up with hydrolic activation through custom pedal box (came with the kit). Works great.

[russell_ram]

Like Wilf says, thrust bearings normally always run 'in light contact' with the clutch release springs - independant of whether it's a cable or hydraulic system. Any gap would result in 'lost motion' at the pedal before anything happened. Our problem in Cobras (and anything else were you mix components from different vehicles/manufacturers) is that of lever ratios, and on a hydraulic system bore sizes. OE manufacturers spend a lot of time getting pedal loads, lever ratios, release travel right - then we mix all the components up and still expect it to work!

If you need more release arm travel, then make the release arm shorter or increase the ratio of the pedal (effectively moving the master cyl/cable attachment away from the pedal pivot). Nett result is more travel at the release bearing BUT heavier pedal load.

Russ

NB I was grinning because I'd just won a big shiney trophy from Custom Car which I consider to be a huge endorsement of my build quality - has anyone checked out the quality of some of the show hot rods these days, in many cases far, far ahead of where the kit car industry is = big grin entirely justified.

[STEVE G]

Russ
Got your e-mail today.Sump not arrived yet tho.Hopefully tommorrow.
Question conected to above.
Just got new thrust bearing. Its made of plastic and seems to bit a looser fit than the old cast one.Also at present I cant get the fork to fit as the pins holding the two sliding blocks do not have enough gap between them.
I've been told this is the only bearing available and to grind the ends on the pins . Hows this sound to you?
Steve

[breskit]

Aivar,

There is a white quadrant avialavle for the Sierra pedal box, as opposed to a yellow one which seems more common. The white quadrant gives a little more movement on the clutch cable and for my RV8 box, gave me enough clearance to change gear with the engine running.

Perviously I had the same symptons as you have described.

Regards,
Tony B
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http://homepage.ntlworld.com/tony.breski