Ditching the TH400 for a NV4500

[JCampbell]

After burning up the TH400 in my '77 1-ton and having the Sub sidelined w/ a mysterious issue w/ it's TH400, I'm seriously considering swapping all my rigs over to NV4500 trannys. I'm going to use the '77 1-ton as the guinea pig seeing as how it's currently just a bare frame on the side of the house and if all goes well there, I'll move onto converting the Sub.

What I'm looking for is hints, tips, tricks and advice from those who've done such a swap. Things to look for, specific/desirable tranny years/serial numbers, possible fitment issues, floor modifications, crossmember relocation, etc.

Thanks in advance.

[gchemist]

You can all the conversion parts here: http://www.nv4500.com/

[JCampbell]

Cool. Thanks.

[JCampbell]

Really? No one has any info on this swap?

[hatt]

The more I looked at all the info on the NV4500 the better my SM465 looked. You can install higher rear end gears to replace the OD if that was the main reason for the NV4500.

[jltait]

J....
Here is what I know, I have not done the swap but I have a tranny and have been doing the research for some time.
There are several types of gm nv4500's transmissions with variations in 1st/reverse gear ratios, external vs. internal slave cylinders, and variation in synchronized reverse. The link with the various differences: http://www.nv4500.com/newsdesk_info....newsdesk_id/30
I will try to keep this simple the Earl,Early variant has a lower 1st/reverse gear ratio and a GM specific transmission to bell bolt pattern, in other words only a gm bell from 92-94?(see link) will work with that transmission and has an external slave but mounts on the passenger side. I think this is fine for a 2wd square body but will interfere with 4x4 front drive shaft with anything less than 6" of suspension lift. Then there is a nv4500 with the later bell to transmission bolt pattern (same pattern as other OEM's (Dodge))that also has the external slave and in the same location as the '92-'94?. This was a very short run maybe '95 model only iirc, check the link. Then there was the internal slave type that had the shared bell to tranny bolt pattern but with and internal slave.
The ealiest model will work but you are stuck with the slave on passenger side, probably not an issue for a 2wd but def. problem for a 4x4 with less than 6" lift.
The next model has some options, since it shares the bell to tranny bolt pattern with a dodge an advance adapters adapter plate can be used along with a dodge(light duty gas engine) 1 1/8" input shaft to bolt up an sm465 bell housing with the matching index diameter. The dodge input shaft is use to take it is 1" longer and offsets the 1" thickness the adapter plate adds to the dimension from the face of the transmission to the bell housing/engine mating surface. This allows the use of factory hydraulic sm465 parts for a sqare body or iirc even the old style mechanical clutch setup for a square body, again observing the correct bell index diameter.
The 3rd option (the one I am using) is the later '96?..'97 up internal slave bell housing. It has the "common" bell to tranny bolt pattern and uses and internal slave. This provides a very clean install but on the downside requires the removal of the tranny to replace a blown slave that would be readily accessible without removal on the other options. The hangup with these are the special fitting used on the slave that are not compatible with old square body hydraulics. Luckily Russell makes an adapter (others may as well) so an AN -3 hose can be adapted to the slave.
Square body master cylinder are supposed to work with either of the gm slave either external or internal from my research, otherwise a willwood brand .75 bore slave should do the job nicely(these are what Keisler ships with its t56 6 speeds that use the same type internal slave) and are about $50 mail order. I am probably going to use a factory unit.
Sqare body flywheels, Clutch pressure plates, and disks are supposed to work with any options listed above. Correct for the transmission release bearing is required.
Keep in mind gm 2wd tranny's do no have a mechanical speedometer connection.
Hope this helps and keep in mind this is researched data and I cannot swear to its accuracy. I will be doing mine in sept/oct and will try to take pictures and do a complete write up on it .
let me know if you have other questions.
JLT....

[Rpratt]

I have done it to my truck and it is very easy. Mine is 4x4 with the external slave. I drove it for a couple months without a lift and never had a clearance problem with the front driveshaft hitting the slave cylinder, but if you offroad your truck, you will need a lift. I now have a 4" lift and it is more clearance than I will ever need.

Crossmembers, bolts, driveshaft are all the same. You will have to come up with some hydraulic pedals from a square body, master and slave cylinders, compression fittings and brake lines to connect the two. The floor hump is going to be too small from your automatic trans, so you will either have to replace the hump with one from a stick, or fab one yourself.

This is a very easy swap, don't overthink it. The only thing I am unsatisfied with on my truck is the carpet..... the carpet for a stick shift will put the hole in the wrong spot, so I bought carpet for an automatic 2wd, the trans hump for the stick/4wd is so much higher, the carpet doesn't fit right. If I were in your position, I think keeping the automatic hump in place and building a housing for the shifter would be the best solution.

[D13]

Originally Posted by Rpratt

You will have to come up with some hydraulic pedals from a square body, master and slave cylinders, compression fittings and brake lines to connect the two.

If you have an auto trans you will need the pedal set including the bracket, right? But will the hydraulic pedal fit on the earlier mechanical bracket? Obviously the pedal and link are different and the slave would have to be positioned and mounted. But I can find the brackets for the mechanical clutch pretty easy, all the mud guys want the hydraulic pedal sets so they're becoming somewhat scarce here. I found the pedal and hydraulics from a guy going auto, but not the bracket as it was easier for him to keep his brake set up.

IIRC per Keith seymour the manual trans and/or 4wd got the taller hump.

[D13]

durn double posting!

[jltait]

Rpratt,
Do you know if the Crew cabs have different floor pans auto/manual or are they the same. For some reason I was thinking the Crews had a common floor pan but I am not sure.
JLT

[Rpratt]

I don't KNOW the answer, but I just got rid of a crew cab with an auto and without looking for the difference, it certainly looked like a smaller hump than the manual trans hump.