[DeTomaso] Wrong Slave? Re: Clutch woes in Asa's garage

[Julian Kift]

Mike,

 

This is all good stuff, collectively we are getting closer to resolution I'm sure, but I have a problem with the fact the hydraulic volume dictates the slave piston travel, not the rod. In a normal system what you say on rod length is absolutely true because too short and the slave hits the stop (snap ring) but in Asa Jay's case he has no snap ring to stop the piston coming right out the slave, so I don't think he is getting the travel (fluid volume) in the first place.

 

Julian
 
> From: MikeLDrew at aol.com
> Date: Mon, 7 Sep 2009 01:09:03 -0400
> To: asajay at asajay.com; detomaso at realbig.com
> Subject: Re: [DeTomaso] Wrong Slave?   Re:  Clutch woes in Asa's garage
> 
> 
> In a message dated 9/6/09 21 43 12, asajay at asajay.com writes:
> 
> 
> > With no adjustment to the
> > pushrod (i.e. short as possible), the spring pressure on the piston now
> > pushes the pushrod against the lever arm to the point the throw out is
> > -still- against the pressure plate fingers.  Even with the system bled
> > of air. 
> > 
> >>>Of course--that's normal. What else would you expect?
> 
> 
> > So I'm thinking to myself, this is never going to change. 
> > 
> 
> Not until you adjust the pushrod length to the PROPER length, instead of 
> just arbitrarily making it as short as possible, which is what it sounds like 
> you've done.
> 
> More information is coming forth in each post, and it appears that you are 
> manufacturing your own problem. Before I thought you had a hardware issue, 
> but now it's quite likely that it's simply an adjustment issue, if what you 
> wrote above is true.
> 
> As I said before, you need to adjust the pushrod length so that the piston 
> is almost completely retracted in the bore, and the fingers of the clutch 
> arm are just barely touching the throwout bearing. Then, when you apply the 
> external spring, it compresses the piston just that much more, and lifts the 
> fingers of the clutch arm just barely off the throwout bearing.
> 
> If you are just blindly shortening the pushrod as far as it will go, 
> effectively what you're likely doing is pulling the piston out of the bore almost 
> all the way (assuming the fingers of the clutch fork are on the throwout 
> bearing). This leaves almost no room for the hydraulics to do their work.
> 
> Alternately, with the pushrod too short, if you have the external spring in 
> place and it's of the proper strength (strong enough to easily overcome the 
> spring in the slave cylinder), then the piston will be retracted in the 
> bore, and the clutch fork will be miles from the throwout bearing. 
> Application of the clutch pedal will result in tons of movement through free space 
> (and a very light pedal), before the fingers finally touch, you get a little 
> bit of clutch release, and then the master runs out of steam and you're stuck.
> 
> So. Adjust the pushrod to the proper length, with the parameters 
> mentioned above. Install the external spring. Depressing the pedal then should 
> result in sufficient movement to release the clutch.
> 
> You have never described the feel of the clutch pedal. What you should 
> have is about 1/2 inch of relatively light resistance (which is simply the 
> external spring on the master, and perhaps the spring on the pedal if it's 
> still functional), then much heavier resistance as the fingers of the clutch arm 
> touch the throwout bearing, and the clutch starts to disengage.
> 
> If you don't have that, it's wrong, and that adjustment is entirely in the 
> slave cylinder pushrod length and/or positioning of the arm on the shaft.
> 
> Please don't make me fly up there. I *almost* flew to Spokane today to 
> try to sort things out in person...but resposibilities forced me to fly home 
> instead.....
> 
> Mike
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