Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - 4WD transfer case in a 2WD vehicle for low ratio?

stillsearching · 08-26-2012, 12:42 AM

I had kind of a dumbsmart idea while responding in another thread... maybe not 100% right on since this is ecomodder not performance modder but its for an mpg-aware hot rod and there's lots of smart people here so here goes.. it's for an eventually proposed hot rod type project i'd like to do I wanted it to get good mileage when on the highway (the super low RPM big engine thread is related to this, i'd like to get 30mpg with 500cid) but be capable of accelerating fast on the weekend drag strip. And to do it without an excessive budget. (cheapness is more expensive then absolute weight savings I mean)

So I was thinking, why not use one of those 4x4 transfer cases behind the transmission? Turn the 2.29 highway gears (even higher in overdrive) into a 4.56 or lower when in "4Lo", except there's no 4WD going on, just the range selection, unless there's some danger having a nonconnected part of the shaft just capped off by a metal tube or something covering it. It would act like a two speed axle. Maybe even parts could be stripped to use just the range selector ignoring the transfer case function entirely and saving more weight? (having never torn one apart i've no clue how hard it would be to stick it inline and fabricate up a lever to actuate it, or whether it's normally integrated into the case but I thought some 70's transfer case modifications used "double range boxes" so I assume some of them have a detachable unit you could use in this fashion)

Sure you can do the same thing with a modern six speed transmission, like the 6L80 going from 4.03:1 first gears to 0.67 overdrive or something about that. Price one out sometime. :P

This is a little clunky, adds weight, but all I would care is that it works. Is there any reason it wouldn't? Could maybe a 4x4'er more familiar with how the transfer cases even hook up under there comment on the feasibility of this?

PS - there's a secondary mileage related issue in that this could also solve my tow vehicle problem. Stick this in the Caprice, keep the 2.29 highway ratio, yet use it for 7000lbs towing unless there's a reason it cant run highway speeds in "4lo" to just one axle.

08-26-2012, 12:42 AM	#1 (permalink)
stillsearching EcoModding Apprentice Join Date: Dec 2011 Location: Minnesota Posts: 201 Thanks: 45 Thanked 8 Times in 7 Posts	4WD transfer case in a 2WD vehicle for low ratio? I had kind of a dumbsmart idea while responding in another thread... maybe not 100% right on since this is ecomodder not performance modder but its for an mpg-aware hot rod and there's lots of smart people here so here goes.. it's for an eventually proposed hot rod type project i'd like to do I wanted it to get good mileage when on the highway (the super low RPM big engine thread is related to this, i'd like to get 30mpg with 500cid) but be capable of accelerating fast on the weekend drag strip. And to do it without an excessive budget. (cheapness is more expensive then absolute weight savings I mean) So I was thinking, why not use one of those 4x4 transfer cases behind the transmission? Turn the 2.29 highway gears (even higher in overdrive) into a 4.56 or lower when in "4Lo", except there's no 4WD going on, just the range selection, unless there's some danger having a nonconnected part of the shaft just capped off by a metal tube or something covering it. It would act like a two speed axle. Maybe even parts could be stripped to use just the range selector ignoring the transfer case function entirely and saving more weight? (having never torn one apart i've no clue how hard it would be to stick it inline and fabricate up a lever to actuate it, or whether it's normally integrated into the case but I thought some 70's transfer case modifications used "double range boxes" so I assume some of them have a detachable unit you could use in this fashion) Sure you can do the same thing with a modern six speed transmission, like the 6L80 going from 4.03:1 first gears to 0.67 overdrive or something about that. Price one out sometime. :P This is a little clunky, adds weight, but all I would care is that it works. Is there any reason it wouldn't? Could maybe a 4x4'er more familiar with how the transfer cases even hook up under there comment on the feasibility of this? PS - there's a secondary mileage related issue in that this could also solve my tow vehicle problem. Stick this in the Caprice, keep the 2.29 highway ratio, yet use it for 7000lbs towing unless there's a reason it cant run highway speeds in "4lo" to just one axle.