[DeTomaso] ZF Cooling

MikeLDrew at aol.com MikeLDrew at aol.com
Wed Jul 18 12:28:50 EDT 2007


In a message dated 7/18/07 8:51:32 AM, kenn_green at yahoo.com writes:


> I think the GT40 switched to a 4 speed transaxle built using components 
> from a Ford 4 speed because they couldn't make the ZFs last 24 hours.  
> 
>>>Well, more accurately, they didn't *think* the ZF was up to the task of 
withstanding the massive torque generated by the 427 Le Mans motor.   They had 
already been bitten badly by the failure of the Colotti gearboxes (which were 
abject pieces of crap) and didn't want to take any chances.   Unfortunately, 
their first foray with the home-grown four-speed was a disaster too.

> Here is some info:
>   
>   http://www.gt40s.com/faq/engines_and_transaxles_toner.html
>   
>   I'm not sure of the sequence of events, but I thought Ford ended up using 
> the 427 with the 4 speed to win?  Kinda funny, it sounds like the NASCAR 
> engine and gears beat Ferrari?  Good ole pushrod V8, LOL  Can anyone comment on 
> what was the winning combination(s) at LeMans?
> 
Unfortunately, for the 1965 race Ford was literally throwing the cars 
together in a desparate attempt to have them ready, and the two 427-powered cars were 
a bit lashed together (one had never even run when it arrived at the race!)   
They tried a number of different aerodynamic solutions, and photos show the 
car's appearance changing, sometimes radically, every day leading up to the 
start of the race itself.

They proved to be the fastest cars ever run at Le Mans to date, but both cars 
were out by the seventh hour, irononically both felled by gearbox failures!   
In their haste to get the cars ready, somebody forgot to heat-treat the gears 
in the T44 four-speed transaxles (which were built by Kar-Kraft using Ford 
Toploader four-speed gears and a custom differential).   And the four 
289-powered cars all conked out; three suffered blown head gaskets (which was also a 
common failure in later years), and one suffered a highly unusual ZF failure.

By 1966, they had their act together, and the 427/four-speed cars swept the 
race, finishing 1-2-3.   Interestingly, all the remaining 11 GT40s entered 
failed to finish for a variety of reasons.   In 1967, the Mk IVs finished 1st and 
4th, and the other eight GT40s either crashed or blew up.

By 1968, the big-block cars had been outlawed, Ford Motor Company had quit 
racing at Le Mans, leaving it to privateers, who (to many people's surprise) 
managed to still carry the day, winning in '68 and again in '69 with cars powered 
by 302s (and a few with 289s) and ZF gearboxes.

Although today many GT40s on the vintage race circuit have been retrofitted 
with gearbox cooling systems, from what I can see they weren't used much (if at 
all) in period.   The Mk II (427) cars had two massive oil coolers, one on 
each side of the engine.   I *believe* they were both used to cool engine oil, 
but I'm not sure about that, and the left one *might* have been used for the 
gearbox.

Finally, regarding Patrick's dilemma--before modifying anything, I would 
first instrument the car, and measure gearbox oil temperature.   If the gearbox 
oil gets too hot in testing, *then* you can undertake the non-trivial job of 
introducing a cooling system into the car.

Mike


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