Landspeed rear end gear efficiency

[Doug Odom]

Landspeed rear end gears. Trying to find out if there has been a real back to back test of the efficiency of the different types of rear end gears. Quick change, Ford 9", Mopar 8 3/4", GM 8 1/2" etc. Everyone has a SWAG but I would like to see real data. The used NASCAR gears I get have had a ton of work done on them. I understand that a lot of that info is private but I still can ask how much measurable good does it do?

[SpeedZealot]

quite a bit. I have seen a 9" lose 3-5% over a 12bolt. Even More over a stocker 7 5/8 fbody rear. Keith prolly has this data. He has run an 8.5 9" and quick change.

[JeffMcKC]

I know the trick set up was a 12 bolt drop in in a 9 inch housing but I here they are high maint.

[SpiderGearsMan]

how about fwd ? the old physics about pulling vs pushing and all that

[CTX-SLPR]

Without equal length halfshafts its going to torque steer baddly. Best bet is probably one of the weird GM longitudenal setups like the Tornado, Eldorado, and 79-85 Riviera.

[std]

The closer to the center of the ring gear the pinion is, the less power is lost. Generally speaking.

The drawback is that the smaller the pinion is the less durable it is.

[KeithTurk]

I know exactly what Doug is trying to do here... and frankly I know there are folks out there with rear end and transmission dyno's... but they are mostly used to run the stuff in.... and to test it's efficency.. I don't know of any back to back or same standard testing...

Sorry Doug... wish I could help...

Keith ( I'd bet a call to Jim at Tex racing would get you somewhere though )

[Freiburger]

We did this at CC some time ago: Dana 60 vs 12-bolt vs 9-inch. I'd need to look it up and see, but I think the difference was hardly anything, at least at the power levels that were tested. And I think that's critical. For example, a 9-inch may eat more power than a Dana 44 at low power levels, but what happens when the weaker housing starts to deflect?

[Scott Liggett]

Sounds like a test made for the F-bombs 1000 hp.

[Huskinhano]

I recall a few years back in Muscle Mustangs & Fast Fords they tested a set of 8.8 ring gears before and after being polished with the Micronite system that made a substancual reduction in friction. IIRC there was something like a 10 hp gain on a chassis dyno. Don't hold me to that though, I could be wrong but that's the number that I seem to recall. BTW, isn't the 8.8 Ford axle very similar to the Chevy 12 bolt, even to the point of sharing some of the same bearings???

[revolutionary]

I remember that Mikronite test and it was pretty interesting as the polished gear made more HP but as I recall it also built more heat. Kind of wierd.

[JeffMcKC]

more surface contact, less room for oil, and more heat made from more surface contact

[dieselgeek]

too bad "Papa" Jon Huber doesn't get online much. He'd rule this thread!! those guys are so into mechanical efficiency, it's crazy. For anyone into offshore powerboating, he's the guy who redesigned the Mercury Marine "Velvet Drive" to be more efficient, take big HP, etc. The "Huber Marine" gearbox is an important upgrade if you're running a mercruiser sterndrive with big power... anyways, he's nuts about rear end, trans, efficiency. The guy can go on for hours and has good data to back it up...

[JeffMcKC]

I think you can make up a lot by using ceramic bearings$$$$$$$