Big Blue24
Comp Diesel Sponsor
I will come across as a salesmen if I tried to highlight every reason why I feel our 47/48re transmission is a better product, reader beware:
From the point of view of a 1000 to 1500HP daily driver application, let me highlight what is gained with 1 lube modification that we perform to benefit the overdrive brake clutch.
The overdrive brake clutch is engaged on the overdrive shift and is tasked with pulling the engine RPM down 74%. This means you are overcoming/holding both the full power of the engine and the rotational inertia of everything from the intermediate shaft forward: 20 lb intermediate shaft and gear-train, 10 lb input shaft, 75 lb converter, 15 lb flexplate, 130 lb crankshaft, 10 lb dampener, and every other spinning accessory component on the engine. On the dyno, a snappy overdrive shift spike on a 550 HP truck will usually peak around 750 HP. On a 1500 HP truck this is a spike to nearly 2000HP if the tires don't spin and the clutches actually hold.
The overdrive shift creates a tremendous amount of heat in the OD brake clutch pack on these 1000+ HP trucks. The solution has been to up the clutch count in this pack from 5 frictions and steels to 6 frictions and steels (great a 20% increase over stock) But we have 400% more power and 40% more RPM at the shift which equates to 77% more rotational inertia.
The factory lube to that pack comes from 2 small holes in the intermediate shaft which is sharing lube pressure with several other components. The factory lubrication is simply not enough on a truck at this power level. PDD (and Goerend is the only other brand I've seen) add a lube mod that sprays pressurized oil onto the overdrive brake clutch pack as a sort of "double" lubrication. This keeps the clutches cooler in all the other gears when they are not in use and are spinning/slipping in close tolerance so they start the overdrive shift as cool as possible. This extra lube also cushions the overdrive shift and helps reduce parts breakage as the shift engagement time is ever so slightly lengthened as the clutch pack has more oil to evacuate during the shift before it can fully lock up. The reduction in hard part shock loading and the increased overdrive brake clutch pack life is one small area that PDD (and any other builders that perform this lube mod) have a measurable benefit.
The opposing argument to this lube mod being a real benefit is how many 1000-1500 HP trucks run long enough between transmission maintenance/refresh to truly benefit from this lubrication mod? This is not the "weakest" link in most builds but eventually it shows up as all the other problem areas are addressed.
