Transmission Swap

[motormayhem]

Ok well I just finished up my d44/14 bolt FF install in the m1009. The rear now has 4.1's instead of the 3.08 stuff and I can really tell the difference. I am running 36" tires, but the motor really seems to get going at 50 and I am a little hesitant to take it up to 65 for highway driving. Anyway my th400 got cooked running 3.08's and 35" tires so I am in the market for a transmission. I figure while I am going to have to spend $$ on a tranny I should get something with an overdrive. So far from what I have read the GM stuff is a 700r4 or a nv4500. I am fine with a manual and if it is not to much work would prefer not to have to worry about large tires and hot transmissions. How difficult is it going to be if I can find a 90's 6.5 turbo truck for a doner to fit the 4500 in the m1009? I am looking for something that is more or less a bolt in job where I dont need to get adapters and special mounts and such. Also can I run a np208 on the 4500 or will I need to get new driveshafts and such for a different t-case. As for the 700r4 that uses a lockup torque converted correct? If I use that will I be able to use a 208 and keep my driveshafts? Any info on what my options are and what I will be looking to buy would be great.

 

[scrambled]

The 700r4 swap is much easier to do. The 700r4 and the 400 are about the same length. Driveshafts won't need to be changed. You can get the TV cable and kickdown brackets from a boneyard civvy blazer, truck, or burb with the 6.2 and 700r4.

 

[motormayhem]

How reliable is the 700r4 going to be. I am worried about frying the auto as my previous experience with the 400 was not good (dies after 10,000 miles) but I also was new to wheeling and when I got the truck it had 35's 3.08s and not tranny cooler so...

 

[dstang97]

700's are junk. There is not one good thing about them. Your 400 should have gone way past 10000 miles. someone rebuilt it wrong or something. they can take tons of abuse.

 

[Recovry4x4]

700's are junk. There is not one good thing about them. Your 400 should have gone way past 10000 miles. someone rebuilt it wrong or something. they can take tons of abuse.

I've had several and with a decent rebuild using quality parts, you can easily get tons of miles out of them. The 6.2 hardly has enough power to hurt them and the 3.06 1st gear really helps. It's not a 400 turbo by any means but it will survive most folks uses. Before I get a bunch of crap, I know how to break parts so you can't say I'm not working mine. I've got one being readied for my M1008.
You will find as many opinions on them as you will find trannys.

 

[dstang97]

Mine cracked in half with the weight of the 208 on it. Ever sinces that day I've hated them. There is a reason why they did not have 700r4 in 3/4 and 1 ton trucks, But if it works for you I wish you the best luck.

 

[tm america]

the weight of a 208 wont break a 700 case they come with them. a bad front u joint on the rear shaft will break any case 350,400 700 4l80e,any of them the harmonics and whipping effect will crack the bell housing really quick . also bad mounts will do that to .700 is not a durable trans they only put them behind a deisel for a couple years . a 400 will hold up to around 500 hp even in stock form. i have 400s that i have built that are in cars running 6.80et in the 1/4 and hold up anything over 450hp and a 700 isnt gonna do to good.if you want od i would go with a 4l80e it will hold up and give you od

 

[skark_burmer]

i love my 700 and i beat the snot out of it. Yeah its starting to slip now but before i got it the guy pulled a 3 horse trailer and put 280k miles on it before he sold it to me. I am running 33's.

but yeah, your 400 should have lasted till the cows come home, unless you overheated it, thats a quick way to kill any auto.

If you are going to go auto what about a 4L80e? You'll have to do a manual shift kit in it, or buy a $1000 shift controller. Just a thought.

 

[skateabrock]

after your tranny swap I would highly recomend some new gear sets. Try for atleast 4.56 maybe even 4.88. Your truck will love you for it. Pick up some YUKON gear sets and maybe a rear locker too. PS if you have a gov-lok in the rear rip it out and throw it away before it blows up, haha.

4Lo.com :: Gear Ratio & Tire Size Chart

 

[tm america]

chart is usefeul thanks skateabrock

 

[Recovry4x4]

TM, are you sure about the 700 6.2 combo only used for a couple of years? I had an 84 C-10 with the 6.2 and 700R4 from the factory and I now have a 91 V1500 burb with the 6.2 700 combo. Unless these were the couple of years but I also had an 87 blazer with the same combo.

 

[POOR WHITE BOY]

The 700r4 /6.2 combo was available for 6 or 7 years. Also they put the 700r4 in many 3/4 ton trucks - 84 thru 87 light 3/4 ton models had a 700r4 - the heavy duty 3/4 ton models had a turbo 400 and ran on regular gas thru 86

 

[tm america]

sorry i meant in heavy duty trucks. only a few years they ran a 700 in a 1 ton with a 6.2 .the military did things they stopped doing in the civy world. but there are always exceptions as you can order some crazy stuff that isnt in the option list.

 

[acmunro]

The 700r4 was first available the same year the 6.2 was first available 1982.
I had (2) 1982 K-10's with the 6.2 700r4 combo. I would go with something heavier duty than the 700r4. I am gathering info to do the 4L80e swap. Good luck on whatever you choose.

 

[Recovry4x4]

The 700r4 was first available the same year the 6.2 was first available 1982.
I had (2) 1982 K-10's with the 6.2 700r4 combo. I would go with something heavier duty than the 700r4. I am gathering info to do the 4L80e swap. Good luck on whatever you choose.

Devilman96 just put the 4L80E in his M1009.