700r4 or TH400 with gear splitter?

[kwmech]

In my opinion, 700s should NEVER be considered in a truck for any type of work. It is a passenger car transmission. The very last thing I would do is put one behind a big block. I've had enough trouble with them behind small blocks, special drums, vette servos, shift kits heavy duty this and that...they just don't last long term when asked to anything heavy duty, such as towing. Go with a Gear Vendor or a 4L80e. I am converting my Suburban from a 700 to a 4L80 and I have a gear vendor in my 69 flat bed. Flat bed has a built big block and the suburban is a stock 350 tbi soon to be a 400 next year if money allows

[sweetk30]

as said big block engines are for WORK not mileage .

and a good cheep way to optimize fuel mileage is a simple gauge like this .

you will be amazed how much you can gain by watching this little guy . not saying you will get a ton but it will improve .

[Tom]

Originally Posted by kwmech

In my opinion, 700s should NEVER be considered in a truck for any type of work. It is a passenger car transmission.

No its actually very much a truck transmission. Cars used the 200-4R except for full sized caprices.

Originally Posted by 95 S_Trucker

You don't buy a truck with a big block for mileage. You buy it to haul/tow.

That's a terrible statement. Just because you buy something to work doesn't mean you can't or shouldn't maximize its efficiancy where possible. And I know this may sound crazy, but some people buy big blocks for fun, not work. Not too many 48yr old trucks being put to real world, daily business type work these days.

[kwmech]

Originally Posted by Tom

No its actually very much a truck transmission. Cars used the 200-4R except for full sized caprices.

Whatever they're still junk in my book. I've wasted a quite a few grand on 3-4 700s, only to have them either break, slip, not shift correctly etc. All built by professional "700 experts"

[Greasey Harley]

What mileage are you averaging right now?
What would you consider an acceptable increase in MPG?
How much are you willing to spend, to achieve this increase?
What speed are you trying to run, and what RPM are you running at that speed?
What gears do you have?
How tall are your tires?
Is this a 1/2 ton, 3/4, 1 ton?
2wd, I assume?
What Carburetor or FI system are you running?
Points or HEI
Is this thing properly tuned?
Are you sure you need OD?
Would taller gears and/or some tuning get you close enough?
A properly tuned 454 will twist some pretty tall gears.

Keep your expectations low. It ain't EVER gonna get great mileage.

[57NAPCO]

Originally Posted by Tom

And I know this may sound crazy, but some people buy big blocks for fun, not work. Not too many 48yr old trucks being put to real world, daily business type work these days.

I just like em, all four of em

[andyh1956]

A question to ask when considering a GV is "Can the gears be split PROGRESSIVLY"?
I've asked this question lots & GV dances around the answer.
Yes it will "Split" the gears, but if it won't split them "PROGRESSIVLY" then all you're adding is an OD box that will go from direct to OD & back again.
Also remember that the GV box is very small & uses it's own lube reservoir, not the trans lube & there's no way to cool it.
Not bashing GV units but it's a lot of $$$ to spend & not know the answers.

[DieselSJ]

Originally Posted by andyh1956

A question to ask when considering a GV is "Can the gears be split PROGRESSIVLY"?
I've asked this question lots & GV dances around the answer.
Yes it will "Split" the gears, but if it won't split them "PROGRESSIVLY" then all you're adding is an OD box that will go from direct to OD & back again.
Also remember that the GV box is very small & uses it's own lube reservoir, not the trans lube & there's no way to cool it.
Not bashing GV units but it's a lot of $$$ to spend & not know the answers.

If you are asking if it will do this...

1st
1st OD
2nd
2nd OD
3rd
3rd OD

It won't do that in automatic mode, but it is fully capable of doing that with manual control.

If that isn't what you mean, then please explain "progressively".

[andyh1956]

Originally Posted by DieselSJ

If you are asking if it will do this...

1st
1st OD
2nd
2nd OD
3rd
3rd OD

It won't do that in automatic mode, but it is fully capable of doing that with manual control.

If that isn't what you mean, then please explain "progressively".

DieselSJ that's xactly what I was talking about. Some transmissions & splitter boxes aint compatable ratio wise. Having said that, ALL my experience is with Class 8 truck equipment, not the GV splitter, although I did drive a truck once with a Doug Nash Under drive in it but it was an auto trans.
Have you owned / driven a GV w/ a std trans & shifted it progressively? Sure be interested to know how they perform!

[DieselSJ]

Originally Posted by andyh1956

DieselSJ that's xactly what I was talking about. Some transmissions & splitter boxes aint compatable ratio wise. Having said that, ALL my experience is with Class 8 truck equipment, not the GV splitter, although I did drive a truck once with a Doug Nash Under drive in it but it was an auto trans.
Have you owned / driven a GV w/ a std trans & shifted it progressively? Sure be interested to know how they perform!

Yes, we had a shop truck with a NV4500 and a GV. The NV has some fairly large splits so the GV worked very well with that trans. Drove that truck fully loaded towing an enclosed trailer with a race car with a full set of spare parts and tools from the shop in San Diego out to Colorado Springs. We had the manual switch for the GV mounted on the gear shift so it was easy to shift both units at the same time.

If you are concerned about the split ratios, it is easy enough to figure out what the splits would be if you know the ratios in your transmission.