Trans swap from T400 to Overdrive

[Edahall]

Originally Posted by DetroitDan

see, I've been told not to even consider a 700, and I've been told that the built ones are fine. Obviously I wouldn't two in OD, I didn't use OD towing when I had my 97 4l80e. I would love a 5 speed manual, but it looks like it would be even harder to get all the parts together and make everything work. Plus I dont know which trucks I can swap out of, which ones to avoid, I don't know much at all about hydraulic slaves. But I'd sure like to drive one. I wouldn't consider an sm465, hate those clunky trannies. It's really just a 3 speed anyway, so no improvement over the th400.
So, no thoughts on how much an overdrive auto can help with fuel? I have looked at Gear Vendors, but they won't save you enough to pay for it for years.
I really don't drive on the highway, and the towing is only pulling the camper a handful of times a year. Which is why the 400 is still in there. I even considered swapping the 454 for a 6.2. But diesel is so much higher now it wouldn't be worth it.

Maybe I should start looking at nv4500s... Oh, one other thing, I've got an NP205 transfer case and auto locking hubs. I would love to keep this case in it if I can.

700R4's work great behind a 500-600 hp light weight car for track use. But I've never see one hold up well towing 10,000 lbs for long distances. If anyone knows where I can buy a 700R4 that is capable of heavy duty towing and not fall apart in less than 70k miles let me know, I'm very interested. I would like to put one behind a 6BT Cummins for another project build.

The NV4500 would probably be the cheapest solution for getting O/D. Find one out of a Chevy 4x4 so it'll fit to your 454.

[beamn7]

Having built a fair share of automatics, here are my 2 cents:
1. THM-700R4 (4L60) built right is a good trans and can last a long time behind a smallblock with up to 450hp and towing no more than 5K lbs OUT of OD.
2. There is no such thing as a 4L80. They all have the "E" at the end and are all electronically controlled. 4L80E is also known as THM-R2 (4 = # of gears. L = longitudinal drive. 80 = series. E = electronic) Example: THM-400 was renamed 3L80 in the late 80's early 90's. 4T60E would be an electronically controlled 4 speed front wheel drive (T= transverse) 60 series.
3. 4L80E is based off the THM400 with the overdrive portion being based off the THM2004R. (2004R is stronger than 700R4)

I'm a fan of both transmissions but for some serious hauling / HP and Torque handling, I'd go with the 4L80E OR a NV4500. Always keep in mind that saying from the old Fram ads: "Pay me now or pay me later"

[78 Chevyrado]

When I was looking for 700r4 for my 78 C20, The trans places I went to asked what I wanted it to do, 400hp, 5200lbs truck tows 8k trailer from time to time, and I dont baby it (unless towing).

They said I need something like a stage 5 or so trans, all the goodies, just not the violent shift.

Also, in a C20 to not have to move the crossmember, to use a 700r4 you'll have to have the tail housing with the mount built into it, its off a 90's caprice police car, dont remember the PN. Otherwise you have to move the crossmember forward, and that will start moving it where the frame curves upward, which wont work.

To put in a 4l80e, the crossmember has to be moves backwards, which isnt a problem, but it may have clearance issues (I've heard) with low hump cab floors.

Here's a site with all the measurements. Look at the "C" measurements.
http://transmissiontechnologies.com/...surements.aspx

As far as the driveshaft, a local shop told me to go from a TH400 to a 700r4, to shorten the driveshaft and install a new front yoke was around $50. So the driveshaft part is pretty cheap and easy, relatively.

[Edahall]

Here's some information on how to go from Automatic --> NV4500
It's a 1st generation Dodge truck with NP205 transfer case so it would be very similar conversion for our trucks. The one difference would be to use an NV4500 out of a Chevy so that it bolts up to our engines. Other than that, it should be very similar.

http://www.dieselbombers.com/1st-gen...onversion.html

[wilkin250r]

I recall seeing a "Heavy-duty/Towing" transmission in a 700R4 configuration from TCI transmissions. It would be pricy, as you're obviously going to be paying more than junkyard prices. But I would imagine it comes with a warrenty.

[DetroitDan]

well now I'm leaning towards wanting to do an NV4500 conversion. I looked around on Craigslist, only found one Chevy nv4500 in my state or neighboring states, and the guy wants a grand for it. A little rich for my blood, I'd pay a few hundred for a used tranny, but not a thousand bucks. I'd rather find a whole truck for a donor, then scrap it and get some money back.
SO...can someone tell me what trucks would be an acceptable donor? I keep hearing Dodge had a lot of nv4500s, but then nothing else is going to bolt up. I'd like to have it as simple as possible ( because I am simple). I did see an early 90s Chevy parts truck with a 5 speed, but it was a half ton, and I didn't know if that was a 4500, or if the half tons had a different, wimpier tranny. I would really like to keep my existing transfer case if at all possible, but if I cant, then I cant.
How about length, is the 4500 longer or shorter than the th400? Can't do much without having to rebuild the front driveshaft, with the 6 inch lift I was told I'd have to lengthen it, but I didn't. It looks fine right now, but I'm sure it won't extend any further to reach if the standard is longer. Maybe the simplest thing would be to swap the trans and transfer together, along with it's crossmember, then just have two new driveshafts built. IDK.

[Rogier]

Robust solution, BUT try before you buy. I've driven one for a short period of time and I decided never to drive nv4500 again. That's why I've converted to 4l80e.

Good luck!
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[Edahall]

Originally Posted by DetroitDan

well now I'm leaning towards wanting to do an NV4500 conversion. I looked around on Craigslist, only found one Chevy nv4500 in my state or neighboring states, and the guy wants a grand for it. A little rich for my blood, I'd pay a few hundred for a used tranny, but not a thousand bucks. I'd rather find a whole truck for a donor, then scrap it and get some money back.
SO...can someone tell me what trucks would be an acceptable donor? I keep hearing Dodge had a lot of nv4500s, but then nothing else is going to bolt up. I'd like to have it as simple as possible ( because I am simple). I did see an early 90s Chevy parts truck with a 5 speed, but it was a half ton, and I didn't know if that was a 4500, or if the half tons had a different, wimpier tranny. I would really like to keep my existing transfer case if at all possible, but if I cant, then I cant.
How about length, is the 4500 longer or shorter than the th400? Can't do much without having to rebuild the front driveshaft, with the 6 inch lift I was told I'd have to lengthen it, but I didn't. It looks fine right now, but I'm sure it won't extend any further to reach if the standard is longer. Maybe the simplest thing would be to swap the trans and transfer together, along with it's crossmember, then just have two new driveshafts built. IDK.

Dodges also come with NV4500's but it won't fit a Chevy engine without adapters. T

NV4500 is shorter than a TH400.

$1000 is way too much for a used NV4500 unless it has been completely rebuilt. Sprags tend to go out on them and it'll grind shifting into 3rd gear.

The 1/2 ton Chevy trucks with manuals were probably NV3500's. Stay away from that transmission.

For a list of trucks that came with NV4500's, take a look here.

http://en.wikipedia.org/wiki/New_Ven...0_transmission

Hooking up the hydraulics for the clutch should be a lot easier than hoooking up all the mechanical linkages. You'll have to find a pedal assembly from a manual transmission truck.