Eco Boost Owners - Anyone using a Tow Tune?

carringb wrote:

Ford also stuck (still is actually) a 9.75" ring gear in the E350 vans with the diesel or the V10. It holds up just fine for anyone staying below 20,000 GCWR, and at stock to moderately boosted HP. I'm not aware of any special treatments they do to the material. I suspect the full-synthetic gear oil specified is the main reason they can rate a small rear end so high.

Bryan,

I think you are right.

I suppose that is what it must be, synthetics. I know that raising the pinion height reduces tooth contact (and strength), thus friction, and that is why Ford went from the tough old 9" to the GM-like 8.8". And chain drive front wheel drive is more efficient than spur gear drives which are more efficient than hypoid gears. But, in rear wheel drive, I can't imagine what else would reduce hypoid gear friction unless the synthetics help a great deal.

In this regard, I've heard there is very little frictional difference (syn is just slightly better) between modern straight petroleum oils and synthetic and I tend to believe that in spite of predictable product hype. But I understand there is a significant improvement in synthetic heat tolerance between the oils, which is why synthetics were originally developed for jet turbines. I suppose that Ford (and others) may now be getting away with smaller, more efficient gears with no fear of lubrication heat break-down and subsequent gear failure.

Lending credence to this perspective would be Fords original(?) use of synthetics in the 10.5"-gear Excursion, and then later(?), the F-250's. I think I saw an early review saying that Ford expected the special Ex synthetic to be a lifetime axle lube; i.e. a car-like extended service benefit. Also, GM quit adding oil coolers to the Corvette, but spec'd Mobil 1 synthetic, or the equivalent as a suitable replacement. OEM's don't do anything they don't have to do.

I know, that in the '60's, some NASCAR cars ran a yoke-driven power steering pump to cool the differential lube, which was, and I believe still is, the sturdy Ford 9". Besides the flex resistant extra 3rd pinion bearing, the low-mounted-pinion 9" engages more teeth for strength. At todays speeds I wondered if NASCAR ran synthetic, perhaps instead of cooling, so I tried to google it. I didn't have a lot of luck pinning NASCAR to synthetics, but I did find out why gear oil stinks. See the short article under the Boundary Lubrication paragraph.

Thanks,
Wes
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