Transmission Choice M1009

[86m1028]

The 6L80 does have an additional overdrive but it is situated as 5th, not 6th.

Both 5th & 6th are over drives.

 

[sandcobra164]

Splitting hairs on my grammar but you are correct. 5th and 6th on a 6L80 are overdrive ratios. Thank You for the correction Sir!

 

[86m1028]

Splitting hairs on my grammar but you are correct. 5th and 6th on a 6L80 are overdrive ratios. Thank You for the correction Sir!

I read that a couple times before posting.
I'm the last one to be a "grammar cop" lol.
Just trying to figure out what you meant.

 

[Hal O'Peridol]

Rebuild the TH400. In a 1009 it is not a problem. I get 24 mpg on the highway with mine, stock.

 

[Chaski]

I recently bought a 1986 M1009 Blazer with only 40000 on it. Mechanically sound. Just replace both alternators and going to change the gasket for rear axle gear tomorrow, last person did horrible job and leaking like a siv....lol Plus transmission pan is leaking and was recently serviced before I bought it. That being said, I want to get a transmission with an overdrive. I have a bad right shoulder and arm, disabled vet here, so manual tranny a no go. I do not want a computer of the 4l80, want to keep the green beast simple. Any way of modifying the 3l80 to a non electronic 4l80??? even possible of just a pipe dream? I have to pay someone else and do not have tons of money, I need to install AC into it also, I am an old K( guy and have a PTSD Service Dog I am making the vehicle for us to go hunting in. Going to make a ZORT K9 Unit out of the M1009.

Cmon guys, help an old K9 guy out here with some good advice. Is there a good none electronic swap our of a civilian Blazer for 82-86 I could go try and get at a junkyard and have someone rebuild for me and install that is a four or five speed???

Thanks - Dwayne 'Big Dawg' Higgins

If you want an automatic with overdrive the 700R4 swap is easiest, and with a few upgrades is nearly impossible to destroy behind a 6.2 turbo or no turbo. Other positives are the overall length requires no driveshaft work. If you search for 700R4 on this forum you will find a ton of info. Only difficult part to find is the TV cable bracket for the diesel applications. It is a 4 speed transmission that was in millions of GM cars and pickups.

That being said I am with the others that an OD transmission is a waste of money with the stock 3.08:1 gearing in a M1009. The only positive I can think of is the first gear is a little lower in a 700R4 than a T400 or 4L80E, so your rig would be a little more snappy off the line and would net you a lower crawl ratio. Now if at sme point someone swapped ratios to 4.10, 4.56 or maybe even 3.73 with stock sized tires an OD transmission would make sense.

A leaking pan isn't uncommon, maybe try pulling what you have, & check the pan with a straight edge. You would most likely be leak free with a new gasket, and a little straightening of the pan you have. People often over torque the pan fasteners bending the pan flange and damaging the gasket.

 

[richingalveston]

unless you change the diff gearing, or put really small tires on it. A 1009 does not need an overdrive. It is nice to have one, only if you change the diff gears to match. The 6.2 does not like to be loaded at low rpms (below 1800)

with an overdrive, any version (700r4, gear vendor, 4l80e) 3.73 might be ok with stock tires. 4.10 would probably be best and work with up to 33 inch tires.

with my 4l80e. I am pushing my 4.56 with 39's. it would probably be better with 37's my rpms could be a little higher at highway speeds.
I am working on a turbo and the possible 6.5 swap so I hope to solve my HP problem first then see if I need a gear change.

 

[NovacaineFix]

Well if you're getting crazy stupid and money is of no issue, and especially if you don't care about the stockness of your truck, then I would go with a Lenco ST1200.

It adds a whole new level of cool factor to your truck with the 5 lever shifter sticking out of the floor. Might set you back about $4K plus installation and additional parts that are most likely needed, but you will have 1 hellava tranny.



But seriously, why not just rebuild the TH400? If you're looking to upgrade and go with a overdrive unit, or want to stick with an automatic, then the hard choice is either 4L80 or Gear Vendors. I would steer clear of the 700R4, but that's just my opinion. They can be made pretty tough, but overall, it's no TH400.

 

[Tinstar]

I would rebuild the 400
Easiest and cheapest option.
Agree with the power (lack of) of the 6.2, it wouldn't make sense with the gearing you have.

The 1009 goes down the road great in stock form. Unless your wanting to go the 85mph speed
limit in west Texas you will be fine.

I was getting 21-22 mpg in my M1009 (100% stock) before I put it in long term storage.

Rebuild
Save $$
Still cruise at 70
Get great Mpg's