[DeTomaso] ZF gearbox extra cooling for Candy 2862

adin at frontier.net adin at frontier.net
Wed Jul 18 17:30:11 EDT 2007


Llyod told me the cooling pumps were driven off the rear - at some point.

NASCAR sources might be easier at this point in time.

david


Quoting JDeRyke at aol.com:

> Several of the original Gr-4s did have add-on trans coolers, judging from
> published photos. All used mechanically driven pumps- one by   
> vee-belt off the rt
> side inner u-joint adapter, the other off a stub-shaft driven by the  
>  mainshaft
> thru the rear cover. This may have been due to the unreliability of electric
> pumps 35 years ago. And remember there were two different ZF limited-slips;
> racers tried not to use the street version with LSD clutches 'cause   
> those units
> generate more heat. Instead, they used the earlier, cooler-running
> sprag-clutch type, and rebuilt it after each long race due to rapid   
> wear of the sprags.
> But before you rush out and buy a cooler, I suggest drilling & tapping a hole
> in the ZF case as close to the ring & pinion mesh as possible, for a 0-250 F
> temp sensor. Then try it in practice- if the lube you use does not rise above
> maybe 220F, you probably don't need a cooler. Non-synthetic diff lube is
> stable up to about 250F & synthetic a bit higher, then things start getting
> serious. I did this a few years ago, & the highways with 70W80   
> non-synthetic lube,
> our '72 at a constant 100 mph rises to barely 180 F and even that takes
> considerable time.
> Thicker 'racing' lubes will  heat more and cool off slower, and you'll
> probably need either a manual valve or an oil thermostat, 'cause the  
>  lube when cold
> is thick enough to shear most drive systems or blow out cooler tubes. I would
> not attempt to adapt some other type of cooler for differential lube- get a
> unit designed specifically for this stuff. In the U.S, NASCAR   
> builders run such
> a cooler only in the longer races- just more complication & chances of parts
> failure.
>
> If you do decide to add a cooler, note there are cast-in undrilled bosses
> inside the ZF cases that were designed for just such a system, from   
> back when the
> trans was used in the LeMans GT-40s with a smallblock engine. The passages
> exited on the rt side in the back, under the shifter cross-shaft   
> extension. I'd
> contact Lloyd Butfoy at <rbttrans.com>; he's likely more familiar than anyone
> else with this. The one example I've seen of an actual air-to-oil cooler was
> small- about 12"x 6", mounted alongside a real GT-40 gearbox on a bracket.
> Good luck, Patrick- J DeRyke
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