Rear End Cooler Plumbing Question

[James OLC]

I am trying to finalize the plumbing for my rear end cooler and, having received conflicting advice from a couple of manufacturers, would appreciate advice from those who may be experienced with similar setups. The car is being built primarily for ORR events and the One Lap and is utilizing a strange 9” housing with an aluminum center section and Black Gold differential. Packaging is slightly complicated as I am using a 3-link (Lateral Dynamics) setup and between the housing mount for the upper link and the cross-member where the Watt’s link is mounted space is at a premium. I am using a Tilton external pump (mounted on the output side of the cooler) and right now am considering having the pump thermostatically controlled.

The specific issue that I have not been able to get a clear answer to is regarding the “return” side of the cooler and whether it is preferable to have the cooled fluid directed towards the ring gear or towards the pinion side of the assembly.

I spoke to a respected NASCAR transmission/rear end supplier (who advocates internal pumps) and his advice was to direct the cooled oil straight onto the ring gear; their opinion is that this provides the maximum cooling benefit.

I also spoke to a respected rear end manufacturer who recommended directing the fluid toward the pinion bearing as they have observed what appeared to be a reduction in backlash when directed at the ring gear. They did include the caveat, however, that they have very limited experience with running external coolers (and road racing type applications in general, as their market tends to be directed towards drag racing).

DPI didn’t express a preference but deferred to the rear end manufacturers’ recommendations.

Here are the options that we are considering:

1. Top of the housing directed towards pinion gear side:





2. Still directed at toward the pinion side but on the “back” of the housing (at least as far “back” as the Watt’s link cross-member will allow:



3. Top side directed towards the ring gear side:





Any suggestions or options. Tech in general on external diff coolers seems to be limited so it nothing else perhaps we can shed some light on the topic.

[chicane]

Sell the Strange third member... and get the Williams unit. It will make plumbing and all else much easier.

Secondly... unless you are dealing with something mechanical... there is no way to reduce the back lash with the lube alone. You will only increase the amount of lube available for film pressure oiling. Which, will also improve its resistance to impact loading.

The Williams unit directs the return right between the two points in question... the ring and pinion mesh... and the pinion bearing support oil feed hole.

I know James... I'd hate to do it twice myself... but doing it right the first time around has been your mantra.