Tell me I'm crazy :-)

[dubya]

I'm thinking aobut switching out my th350 to a 5speed. It's on my '72 4x4, with a sbc 400. I haven't picked up any of the parts, so I can be talked out of it. Anyone esle done this?
W

[mrein3]

Originally Posted by dubya

I'm thinking aobut switching out my th350 to a 5speed. It's on my '72 4x4, with a sbc 400. I haven't picked up any of the parts, so I can be talked out of it. Anyone esle done this?
W

If you are doing this to save money, do some math.
The OD of the 5-speed will give you approximately 30% savings in fuel costs if you don't do a lot of stop and go driving.

The cost to install a 5-speed in a 72 4x4 with a th350 STARTS at $2250. (There is a NV4500/NP205 over on the parts board right now).

So lets say you get 10mpg now like most '72 4x4s with a small block. 30% better mileage is 13mpg.

So if you drive your truck 12,000 miles a year you got 1200 gallons with the th350. At $2.099/gallon you got $2518.80 in gas.

Those same 12,000 miles with a very optimistic 30% increase in mileage with the NV4500 you'll need 923.08 gallons. At $2.099/gallon you spent $1937.53 in gas.

A $581.27 savings in gas. It would take 3.87 years just to pay for the tranny and transfer case. If you drive it twice as much cut the payback in half. If you drive half as much double the payback time.

Don't forget you got to deal with the hydraulic clutch, drive shaft lenghts, and probably a couple of other things I don't know about.

If you're considering this swap because you like to shift gears it may be worth it to you. If you're just looking for an OD gear, look at a 700r4 swap. With the Advanced Adapters output shaft that 700 will bolt to the transfer case adapter you already have from the factory.

[vtblazer]

Kinda depends on your motivation...

As posted above, gas saving's or wanting to shift gears.

Or a third option...wanting highway drivability!!! Then YES!

Cruising on the interstate @ 2400 is SO much nicer than 3500/4000.

It's not a cheap swap but it will definetly save your motor alot of RPM's.

[chevy_fatman]

You asked for it: you're crazy....


















The posts above are informative, they're right if you go with new stuff, good used parts are cheaper, I know that you can put a 5 speed in a 2wd for under 1 G, but what do I know, just my $.0002
besides these truck have been around for 30+ years, I'm sure they'll be around 30 more, so cheap or pricey, go for it.

[Jim_PA]

No, but I can't wait to do it. I'll be starting with a super t-10 4 speed since I already have most of the stuff to do that (except a clutch and shifter), then I'll probably go to a Tremec or T-56. I would prefer 10 times over to drive a manual trans over an auto.

[special-K]

It`s a good idea.There`s alot more to it on a 4wd than a 2wd.Advantages are fuel economy,driving comfort at hiway speeds,longitivity to the motor,less harmonic vibration,and you don`t have to run lame gears so you don`t kill the off roadability or haling values.The more of a "package" you can find,the better.A complete donor vehicle is best.Hydraulic linkage is easy to deal with since it`s just a length of hose from master cylinder to slave cylinder.