Hey guys, first time poster here. I've got an 86 M1009 Blazer with the 6.2, th400, and np208. In the next few weeks it is getting a 14 bolt and 8 lug 10 bolt with 3.73 gears along with 36 12.5 16.5 humvee tires. This summer I plan on occasionally flat towing my cj7 which probably doesnt weigh too much over 4500. Right now I am running 36" bias swampers (which are going on the jeep once the axles are swapped for the truck). with the stock 3.08's and it is a real dog. I am hoping 3.73 gears will be enough, but what do you guys think? Here's some pics.... MallKrawlin
I would probably look for lower gears. From what I have gathered over at CK5, when it comes to gearing the 6.2 has more in common with a BBC than some of the later diesels. I would probably look for 4.10's. IMHO, the 3.73's are a little too high for that engine since it's not a real torquey power plant. WIth the gears aside, I think you could flat tow your Jeep without much fuss. I also have a K5 with 3/4ton running gear identical to what you plan on installing. I would feel safe with my braking power to pull a 4,500lbs Jeep, I was amazed at how much braking power those big 14BFF drums have over the whimpy 10bolts. BUT....you do have a hydro boost system as I have a vaccuum booster since my K5 is a gas version, this could effect the how well the larger drums work, or could make no difference at all vs. a vaccuum booster. I believe that with my 1/2t prop. valve I am actually getting more braking out of my rear than a stock 3/4t does, this may or may not be the same with your military version diesel K5. I used to pull this tandem flatbed all over the place back when I DD'd my K5 before my Ram. it worked suprisingly well for me, even with as much lift and bias tires. I even had that trailer loaded to 8K once or twice. I'm not saying K5's are good towing vehicles, but for what you plan on doing I think you'll be fine with the bigger brakes to stop it.
With the brakes that it has right now, it'll throw you through the windshield... The hydroboost will lock up the 36's in the front and in the back. With the 14 bolt, i'd imagine it could only get better. I ended up getting a set of axles with 3.37's for $175 and the 14 bolt has new brakes. I think I made out like a bandit. I think right now I'll run the 3.73's and see how they feel, if I feel the need to go up to 4.10's later down the road I probably will. Thanks for the advice. Nice lookin blazer RJF!
Those tires with 3.73 gears will still feel like you are dragging a dead elephant behind you. I always feel 4.10 is the minimum ratio if you are running anything over 33" tires. Then again I live in mountain country and dislike downshifting.
The truck will definitly pull your CJ around even with 36's and 3.73 but it won't win tow compititions or drag races. With the TH400 the 6.2L it won't be to terrible. It will keep the 6.2L revved up to a decent RPM range to keep power pumping while you are pulling. It would be alot worse if you kept the 3.08's but the 3.73's will give you a decent bump in the RPM range and power feel. Harley
