[DeTomaso] Transmission viewing hole cover

Jeff Cobb jeffcobb1 at me.com
Sun Jun 10 15:23:37 EDT 2012


> How many other cars do you know of that have such a venting scheme on their 
> bellhousings?   I can't think of a single one....
> 
> Mike

Hello group,

Interesting clutch temp thread.
For the last 120 years or so a driver would talk about his clutch problems on a few primary levels:
It slips, it overheats and it chatters. With slip and chattering creating heat. The clutch only makes rotation shaft motion or heat.
So nearly all clutch problems create unwanted heat which then creates more slippage. Heat causes surfaces gassing of the fabric matrix which inhibits correct friction.
The flywheel and pressure plate do try to provide the thermal absorption required for friction operation of the clutch. 
Heat is the enemy that damages the friction surface and puts undo stress onto oil seals only inches away.
Not many cars are on the streets today have the high horsepower and mid engine transmission like the Pantera.
Only a handful of cars have the torque and hp like the Pantera so the clutch temp comparisons are difficult. 
A new Lambo and Ferrari owner would be so happy if they could get 34,000 miles out of their clutch, which is caused by software that slips the clutch too much, again a heat issue. 
Also considering that clutch friction weave surfaces have developed so greatly since the early 70's that the temp problem has lessened immensely. 

 I am at work today and went over and checked out some cars in my shop. The 06 and later BMW M5, Viper, Lambo Espada and Murci, Ghibli, Bora, Mustang Cobra stick shifts have vents. Automatics have the same problems so the Ford C6 has upper vent slits,  Benz-Jag-BMW ZF's have vents covered with plastic screens and these mentioned trans have stood the test of time since the early 70's. Chevys do not and have always has trans damage due to temp.

I have torque convertors in my shop out of 50 and 60's Mercedes today that I just looked at that have 30 mm or so tall cooling fins built into them for a turbine cooling flow function. These are all low powered cars. An overheated {ballooned} convertor will most likely burn/wear out the thrust bearings faster than a clutch car. It would seem reasonable that a high performance clutch should have an air flow pump mounted or duct so positive air pressure would enter the clutch housing and help out. Hell, you could use an exhaust generated venturi suction tube to remove unwanted heat and dust as the drag cars due to venting the crankcase.

The clutch like the brake needs cooling air for proper operation even if your speeds are not,
Cooling might be important at 200 mph on the Mulsanne....
Mike. 

Hope this has helped.
Jeff Cobb

Jeff Cobb Auto Works
1316 South Acadian Thruway
Baton Rouge
Louisiana, 70806
www.liveoakconcours.org
Concours, April 12-14, 2013
Work  225-343-7525
Fax     225-343-7550
zumzum at cox.net
jeffcobb1 at me.com				

On Jun 10, 2012, at 12:26 PM, MikeLDrew at aol.com wrote:

> In a message dated 6/10/12 7 16 31, sdlgibson at sbcglobal.net writes:
> 
> Is it possible that the spinning clutch assembly act as an "impeller" so 
>> to speak and draws in cooler air to aid in cooling?  Some of the older 
>> units have 2 ports and maybe this acts as an intake and exhaust.  Just some 
>> food for thought. 
>> 
> The holes are to vent heat out, not draw cool air in....
> 
> How many other cars do you know of that have such a venting scheme on their 
> bellhousings?   I can't think of a single one....
> 
> Mike
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