[DeTomaso] Techno Question: Adjustable Throw Out Bearing Experience

[Mike Drew]

Chuck,

There is a specific reason to use this in lieu of the stock setup. 

If you use a clutch whose finger height is different from the stock Pantera clutch, particularly if it’s shorter, the clutch fork will be too far away for optimal actuation movement. When viewed from the right side, let’s suppose that your short clutch with stock bearing has the clutch fork already at a 135-degree angle, pointing at 430 o’clock when it first touches the stock (short) throwout bearing. As it continues to rotate towards 90 degrees/3 o’clock, it has progressively less forward movement in relation to the linear displacement of the slave cylinder piston, and that reduces clutch motion. 

The adjustable throwout allows you to correct for this fundamental geometry error, by basically lengthening the bearing so that at rest, the fork is perhaps at 210 degrees/7 o’clock.  Depressing the pedal extends the slave piston and the fork rotates towards 160 degrees/5 o’clock. That maximizes the forward linear travel of the throwout bearing for a given amount of clutch fork rotation. 

Your job is to decide if you need this extra help or not. If your clutch has stock finger height, the stock setup should work fine. 

FWIW Lori’s Pantera has a McLeod diaphragm clutch from Pantera Performance Center. It uses the stock throwout bearing and works fine. However they used to advocate use of the adjustable bearing with this setup, something I didn’t learn until after it was installed and working great. Perhaps we just got lucky. 

Put your old stock clutch and new clutch face down on a flat surface and compare finger heights. If the new one is substantially shorter, an adjustable bearing is the way to go.  Presuming your old clutch is ‘correct’, by measuring the total thickness of the old bearing, and the difference in finger height between the old and new clutch, you can determine the thickness of spacers you need to add to the adjustable bearing to get you back in the ballpark.

Cheers!

Mike

Sent from my iPad

> On Sep 23, 2019, at 09:02, Charles Engles <cengles at cox.net> wrote:
> 
>  Dear Forum,
> 
> 
>                     Has anyone used the McLeod Adjustable Throw Out
>  Bearing?   Is it a direct replacement for the BCA 1625?   What are its
>  advantages over the ordinary common BCA1625?
> 
> 
>                                        Curious,  Chuck Engles
> 
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