[DeTomaso] Clutch Slave Cylinder "Bell Crank"

[Joseph F. Byrd, Jr.]

Working with old hydraulic controls with pistons and levers,  the first setting rule of thumb was "Perpendicular at mid stoke"
Thus the angle at end of strokes would be equal and opposite.

As stated, as the angle differs from perpendicular, the amount of rotation is lossed and force to rotate goes up

Now, the actual setting at midstoke is difficult, you can take half the stroke and the arm length and calculate the angle at the ends 
That little trick allowed me to set levers and links when no oil was available to stroke the pistons, when others said they had to wait for oil

Joe

-----Original Message-----
From: DeTomaso [mailto:detomaso-bounces at server.detomasolist.com] On Behalf Of Mike Drew via DeTomaso
Sent: Thursday, January 21, 2021 12:28 PM
To: Frank Lisi
Cc: detomaso at server.detomasolist.com
Subject: Re: [DeTomaso] Clutch Slave Cylinder "Bell Crank"

Frank,

It’s not a simple question to answer but the concept is simple enough. 

The lever translates linear (in-and-out) motion of the pushrod to rotational motion. The rate of movement ‘gearing’ is therefore not constant—it is 1:1 when the arm is perpendicular to the pushrod, and something less than that any other time, dropping completely to zero when the arm is parallel to the pushrod. 

Thus I would suggest that having them perpendicular to one another when the pushrod is halfway extended would be the most efficient. 

Something else to be concerned about is the fact that the bolt head on the arm’s crank can strike the gearbox case if it’s not in the right position and there is enough hydraulic pressure available that it can actually shatter the case. There is a TSB somewhere that addresses this too, I think by advocating judicious grinding of the case in the affected area (that might be an old POCA tech article I’m remembering, and not an actual TSB?)

Mike

Sent from my iPad

> On Jan 21, 2021, at 09:09, Frank Lisi <fjlisi at mediacombb.net> wrote:
> 
>    Hi All,
> 
> 
>   My question - can anyone provide guidance on the correct position of
>   the bell crank (according to the TSB article 88 it is called the
>   release lever on the cross shaft, it is part 7515 throw out bearing
>   lever)?
> 
> 
>   I needed to replace the slave cylinder and wanted to make sure that I
>   set it up correctly.  I read all that I found on setting up the slave
>   cylinder, but have not found any clear description on the bell crank's
>   correct position with reference to the slave cylinder.  I set the push
>   rod to the length as indicated in article 88, however I am not sure
>   that the lever is in the correct position.
> 
> 
>   Unfortunately I do not know the manufacturer or specification of the
>   clutch, I have not changed it since I purchased the car and it appears
>   to be in good working order.
> 
> 
>   Any guidance is greatly apricated.
> 
> 
>   Frank Lisi
> 
>   #06228
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