700r4 for a 456 geared 1009

[rsh4364]

Found a low miles 700r4 for an 85 k5 th350 locally fairly cheap. I will have trans rebuilt. Do I want to replace output shaft on transmission or the input shaft on the factory transfer case?

 

[Chaski]

Found a low miles 700r4 for an 85 k5 th350 locally fairly cheap. I will have trans rebuilt. Do I want to replace output shaft on transmission or the input shaft on the factory transfer case?

Cheaper to swap the input in the NP208. You can buy a new 27 spline input for under $100... or get a use one much cheaper.

 

[rsh4364]

Thanks that is what I was thinking, now trying to decide on final gear ratio.

 

[Recovry4x4]

Thanks that is what I was thinking, now trying to decide on final gear ratio.

Thought it had 4.56 gears. Considering a swap?

 

[corelokt]

I went through 3 700r4s before going to a 4l80.
If you go the 700r4 way, I have a TV cable and bracket.

 

[The FLU farm]

Thanks that is what I was thinking, now trying to decide on final gear ratio.

A 700R4 and 4.10 gears worked really well for me. That was with 35-inch tires and a turbo, though.
It's probably best to do the math and decide on the gear ratio based on your usage and preferences.
As for a 700R4 holding up, if built correctly and with the right parts they can be built to take upwards of 500 ft. lbs., so it's really only a matter of how much of a safety cushion you want, and how much you want to spend. I had $2,500 in mine, in parts alone.

 

[rsh4364]

Thought it had 4.56 gears. Considering a swap?

Yes, the 1009 is my daily driver and I drive 100 miles plus per day for work. I am thinking 4.10 gears, that would give me a 2.87 final drive ratio.I normally drive 65mph so my rpms in od would be around 1915 rpms which should give me around 20 mpg.

 

[rsh4364]

I went through 3 700r4s before going to a 4l80.
If you go the 700r4 way, I have a TV cable and bracket.

I would definitely be interested in the bracket and cable.That would be one less thing I have to search for. PM me with what you need for it. Thanks.

 

[Chaski]

What size tires you going for?

 

[rsh4364]

Right now I run 33x12.5x15 at 32.8",but ultimately want 295x75x16,which are 33.4".

 

[rsh4364]

Every 1" of tire height only reduces rpms by 50-60 rpms.

 

[someoldmoose]

4.10's are just right for 33 - 35 inch diameter. Shorter gears would only be needed if towing heavy or hardcore off-roading regularly. You will find the first gear in the 700 much nicer also. Have them use the upgraded sprags when you have it rebuilt. I ran an '86 behind a 500 h.p. 350 for 2 decades with zero problems. Change the fluid as recommended and it should outlast the rest of the truck.

 

[The FLU farm]

Every 1" of tire height only reduces rpms by 50-60 rpms.

I think the simplest way to look at it is with percentage. For example, a 5% increase in tire height (static loaded radius to be more precise) gives 5% lower rpm.
Same with gears. 10% taller gears gives 10% less rpm.

 

[Lonnie]

I ran a 700R4 behind a built 427 w 4.56 gears & 35" tires. It was a good combination that I would not hesitate to do again.With all the 4L65E & 70 parts out there now you can build an upgraded 700 rather easily for less than a 4L80E that will hold decent power.

 

[Chaski]

I run 4.88's with 37" tires, it is a perfect combo for me and the terrain I drive on. With 34" tires I would probably go with 4.56, but I live in a mountainous area.

With your 700R4 your builder probably has his own recipe... But if you are looking for parts suggestions I would go with a Sonnax "smart shell" sunshell. It is beefier and has a Torrington bearing that eliminates thrust load on the planetary gears.

Put a .470" or .500" boost valve "V8" or Corvette sized servo in it, go with a better clutch pack, especially 3-4.

Last thing is the use of a Transgo shift kit. They have the "bootstrap" TV system that is supposed to eliminate the chance of screwing up your transmission if your TV cable breaks or isn't adjusted correctly. Fair warning, it is a totally different animal to set up the TV cable with one of the kits installed, you actually run the cable with 2-5 clicks of slack in it which you would never do otherwise.

I enjoy my 700r4. Rebuilt it at home about 3 years ago and have put 10,000 miles on it, and it gets me around on the trail and the highway.