What transmission does my 1009 have?

[TexAndy]

I just got my 1009 from Minot with the transmission in the back. It's "bad" according to the yellow grease pencil diagnosis written on it.

Well, I showed it to a friend and he said "that's a 700r4." He seemed pretty sure.

I thought they were all TH-400s? What's the deal?

What are my options?

If it's a 700r4, I'd prefer to replace it with a TH-400, but I don't know if the torque converter and transfer case will work with it or if I'll have to replace those as well.

 

[4bogginchevys]

is the tranny pan square or odd shaped, and does it have a modulator?

 

[TexAndy]

I cannot say at the moment . I flat towed it over to a friend's house who has a big automotive lift.

Don't even know what a modulator is.

 

[Sgt Hulka]

Well, I'd be very surprised if it was a 700R4. I doubt the military would do such a modification. Possible perhaps, but not likely. It is not a trivial thing at all. There is another possibility that somehow a 700R4 got tossed into the back, but that seems unlikely also. Modulator is a metallic cone-ish looking thing about 3-4inches in diameter on the side of the tranny. Kinda looks like a vacuum advance on a distributor, which is pretty much what it is... You'll be able to identify it even from crude drawings or photos on the internet. They don't look very similar in detail...

 

[kassim503]

http://www.nastyz28.com/pictures/transpan.gif


If you dont feel like looking, you could always just put it in drive and see if it has 3 or 4 speeds (700r4 being the latter)

 

[TexAndy]

Thanks for the info, I'll post pics tomorrow.

 

[Keith_J]

Check the oil pan.

THM400:


pan_thm400.gif



700R4

pan_thm700r4.gif

If you indeed have a 700R4, salvage yard for a trade.

 

[jbingvtx]

The 700r4 is very expensive and unreliable and the th400 is less expensive and tough. I would look for a th400 for your Blazer. The last time I shopped for a 700r4 the best price I could find was $1200 for a used one. I found it more cost effective to buy another truck with a 5 speed manual to make one truck that would move under its own power.

 

[reloader64]

TexAndy, if this turns out to be a 700R4, I would like to talk to you about buying it. I disagree with jbingvtx, I think the 700s are very good transmissions. They got a bad reputation because of the early models, which were poorly designed. If you have a later model (1987 to 1989), these have been upgraded. The early models can also be upgraded by a good transmission man. They will cost more to overhaul than a TH400, but if you want the overdrive gear, it is well worth it.

Scott

 

[jimm1009]

You have a civy transmission called the TH400 but the CUCV series trucks had a GM modification performed during manufacture that redesignated them as THM400. The M standards from military and what it means is that there are more bands in the THM over the TH series. I have heard that the number is two but have never confirmed that.
About 15 years ago a GM engineer told me that number of bands was increased to provide more durability.
I don't have the break down of a TH400 or I could post it next to the THM for all to view.
Your filter is the and the pan is the same as a TH tranny.

jimm1009

 

[POOR WHITE BOY]

More bands ? Lol

 

[TexAndy]

ok chamfer off one corner and a small fillet and a large fillet on two of the others. Looks like a TH-400 to me...

 

[4bogginchevys]

I see a modulator....400

 

[3dubs]

Sorry the M in THM400 has nothing to do with military. Turbo Hydra-matic. It is also called the Turbo-Hydramatic. That is where it came from TH, THM is just where the hyphen is placed. When you order a rebuild kit it does not matter if you ask for a THM400 or TH400 rebuild kit you will get the same kit. I have never rebuilt a tranny but was told the TH400 is the easiest one to rebuild and the one to learn on. If you have the cash you can pay to get it rebuilt. But if you have a friend with a lift you most likely have a place to work on it. I would get the kit and download the Tech Manuals from this site and do it myself. Either way it should not be that big of a deal the tranny is very common. Good luck.

 

[The PIG Smith]

You have a civy transmission called the TH400 but the CUCV series trucks had a GM modification performed during manufacture that redesignated them as THM400. The M standards from military and what it means is that there are more bands in the THM over the TH series. I have heard that the number is two but have never confirmed that.
About 15 years ago a GM engineer told me that number of bands was increased to provide more durability.
I don't have the break down of a TH400 or I could post it next to the THM for all to view.
Your filter is the and the pan is the same as a TH tranny.

jimm1009

Very Correct.
However, most high performance TH400 rebuild kits includes these extra bands.
Kits with extra bands has been common practice for many years.
There is no doubt in my mind that a civilian 400 can built much stronger than a stock THM400.
If I were looking for a killer 400, run over to the www.4BTSwaps.com forum and pickup a cheap TH475 from a G30 'chip wagon'
These will be 2WD, but with the output shaft of the THM400 and the uber strong TH475 parts, this would be awesome tranny for your CUCV.

 

[TexAndy]

I ordered the "definitive" book on how to do the rebuild as recommended by a few people around here. Should get here sometime between the 25th and the 10th of next month. Amazon slowboat shipping.

I was thinking more along the lines of buying a used junkyard take-off and installing it to make it immediately road-worthy and then rebuilding this one in my spare time. I believe in having spares of everything.

 

[POOR WHITE BOY]

Th 475 has straight cut gears and a regular th400 has helicar cut gears. The th475 is much stronger with these gears however you cannot downshift . We use kevlar bands in my sled pulling truck -

 

[skark_burmer]

straight cut gears? I bet that sounds cool.
I might need to find me one of these...

 

[POOR WHITE BOY]

Th475 is very noisey.