6 lug rear end options

[yossarian19]

I am certain this has been covered at great length but my google skills are failing me.
I'm basically coming up with
*Full size Jeep Dana 44
*Early 60's 12 bolt / Dana 44 & later K10 / 4WD 12 bolts
*GMT-400 era 8.5" 10 bolts (which do, in fact, fit but only *just*)
*Toyota Tundra or T100 rear axle? Don't know the width but I know they are 6 lug, some have lockers & many have disc brakes.
My truck needs a posi and there's nothing available for the OE rear end. Are any of the above listed axles convincingly better than another? Anything I'm missing here?

[SCHRUMGMC]

I'm debating on what to put in my rear end as well. I'd like to go highway speeds when the truck is restored

[yossarian19]

With an overdrive trans the 3.90 ratio isn't as big a deal as you'd think. On gravel roads or during enthusiastic throttle use, though, the lack of a positraction is a deal breaker for me. Makes a good one-sided smoke screen when I floor it but I'd rather it hooked.

[joedoh]

chevy colorados gmc canyon are 3:42 (in 2wd) opt 3.73 (I think all 4x4 are 3.73)and have the same 6 lug pattern. the hub bore is larger than the 88-present fullsize but is the same size as the original, and the widths are good too, 61" wide wms to wms for the 2wd and 63" for the 4x4. its a 8.5 rear, and g80 locker was optional on all forms. some had disc brakes, but dont let that be the decider, discs on the rear are pretty much for show.

a good rule of thumb for rpm and gears is that each gear change is worth about 300 rpm. so if a truck with overdrive has 4.10 gears and turns 2600 rpm at 65mph, a 3.90 will turn 2300, a 3.73 will turn 2000, a 3.42 1700, a 3.23 1400, a 3.08 1100, etc. this is not exact, but, holding tire size constant, its a good gauge to figure out what you want to do.

so for example a truck without overdrive turning 3500 rpm at 65mph with a 4.10, by installing 3.08 gears you can expect a 1500 rpm difference at 65 and 2000 rpm will be the engine speed at 65. there are only so many gear sets based on the combination of pinion to ring teeth.

[1project2many]

Toyota 4X4 "pickup" or "Hilux" from the mid '90s is an option. The four cylinder trucks with stock tires have 4.10 gears and trucks with 31's from the factory have 4.56 gears. A little searching will net a differential from a V6, 2wd, or older truck with the correct dimensions and numerically lower gears. I was able to easily find 3.73's for my '92 Yota.

[yossarian19]

I did a little google searching for the Colorado rear end. It seems like a pretty appealing option but I wasn't sure about the hub register; it would necessitate new wheels / tires right off the bat.
It turns out the Colorado rear isn't a straightforward 10 bolt.
When GM split off it's axle division into AAM (and started selling running gear to Dodge, amongst others), somewhere around then, they developed the Powerlite 800 derivative of the 10-bolt. It uses an aluminum center section and an 8" ring gear. I'd bet it's "enough" for my old truck but I think I'm going for a full-size Jeep Dana 44, which my same-old wheels & tires will fit onto and which is more of a known quantity to me.

[yossarian19]

Add-on
The Colorado is rated to 3500 lb-ft of torque. So, 300 ft-lbs at the crank * 3.06 (first gear ratio in a 4L60e) * 3.73 (axle gear ratio) makes 3424 ft-lbs of torque. So, the 4.8 liter Vortec is pretty much maxing out a Colorado rear end (assuming 3.73 ratio. 3.42 ratio gets you to 3140 ft-lbs, a little more headroom there)
Axle weight rating is 3200 lbs. My truck is 3900 lbs with gas in the tank and me in the seat. Assuming 60/40 distribution (pretty typical for a truck) the rear axle has about 1,600 lbs on it empty. That leaves pretty decent headroom for load, though I wouldn't want to have anything in the bed + a trailer.
So... just due to the torque rating the axle is a good fit where you are keeping a mild 289 or I6 but probably not for anything stouter than a crate 350.

[SKFengineer]

Yoss, I totally understand where you are coming from regarding the capacity values of the Colorado truck rear end but I would say offer it's still a good option. There are many parts available to upgrade that rear and I've seen these trucks piled high with crap in the back and they just keep taking a beating.

[yossarian19]

Yeah... Muddying the waters a bit further, I see that the Dana 44 is rated at 3,500 lbs weight & 3,460 output torque. So, just a tad-bit beefier than the Colorado axle. It's really going to come down to price to get either one under the vehicle, posi-equipped & with disc brakes. I can't find any information to compare an 8.5 10 bolt or 12 bolt truck axle with regards to torque / weight ratings.

[joedoh]

Originally Posted by yossarian19

but I wasn't sure about the hub register; it would necessitate new wheels / tires right off the bat.

not unless you are currently running factory wheels with the newer chevy truck centerbore size. the colorado centerbore is the larger one of the earlier chevy trucks all the way back to the 40s. its also the common centerbore size of all import trucks and just about every aftermarket wheel ever made. seems no one in the aftermarket ever agreed with chevy making the fullsizse centerbore smaller so they make the wheels with larger holes and on chevys you buy plastic hubcentric rings.


the colorado mini spare is a great spare to carry around with a stock axled AD truck because the fullsize spares dont fit the AD centerbore.

also, I have owned 3 colorados and not one of them was as svelte as 3200 lbs. I think my s10 standard cab was more than 3200 lbs. I know my crew cab was over 4k lbs curb weight, and had a 242lb ft 3.7 liter. get what you want, but you would really have to be at max payload to have a problem, those axles are pretty stout. dont forget the 7.625 came with a locking carrier behind the 3500 lb firebirds.

[Coupeguy2001]

Aren't Jeeps' lug pattern 5 on 5 , not 5 on 4.75?

[1project2many]

Some of the older full size Jeep Cherokees and pickups used six lug axles. They're pretty uncommon in this part of the country but I'm betting they're all over once you get out of the rust belt.



http://www.fourwheeler.com/how-to/tr...rd-axle-guide/

[yossarian19]

Another option I stumbled on - the 9.5" ring gear semi-float 14 bolt. It's 65" (2wd) or 67" (4wd) wide but very stout, available 3.73 / posi, and pretty common / cheap.
I had a line on a Dana 44 from a Wagoneer (6 lug) for $100 but starting to re-think that. By the time I add a posi & brakes (it has no brakes on it) I'm coming up on the price of intact axles which don't require any work on them.
Sigh.
Driving myself a little nuts, here.

[Coupeguy2001]

Why are you trying to keep the 6 lugs?
Do you have special wheels?
If you are going to keep it stock looking, aren't you going to cover the wheel centers with hub caps? why not use 5 lug disc conversion on the front and 5 lug rear?
I have a 57 3200, and I enjoy the 5 lug 17" wheels.

[whitedog76]

Chevy Colorados came with 8" and 8.6" rearends. Either one is more than up to the task of an AD truck. Chevy Trailblazers have 8" and 8.6 rears, but only a 6x6 bolt pattern. My 04 has a 5400 lb GVWR, so there is plenty of payload capacity.

Nissan rearends are another option, but they are crazy expensive at the salvage yards even though they are just modified Dana 44's.

[yossarian19]

I'm going six lug because I already have money sunk into the front end, which I kept six lug, and I already have six lug wheels.
If it were in the budget at this point, I'd go with the Dakota IFS kit, put the 8 lug rotors on it, then a disc swapped G80 14 bolt in back using the C10 coil setup, run 16x8 Wheel Vintiques #12 wheels painted white and baby-moon hubcaps.
Instead, I'm saving for a house with a proper garage & scheming how to get a posi rear into this thing as cheaply as possible. So, no new bolt pattern.

[1project2many]

The least expensive option may be an 8.5" GM axle and a scrounged posi. Finding a built 5 lug axle then drilling out your own 6 bolt pattern is an option as well. For cheap, there's always the Lincoln posi...

[roger55]

I've got a '65 GMC pickup rear axle in my '57. It's a Dana 44.

Since it was already in the truck when I bought it, I rebuilt it and used it for my restomod.
I put a new Trac-Loc (posi) and 3.54 gears. Perfect for the TPI/700R4 drivetrain it put in it.

I modified the backing plates in order for them to accept stock-type e-brake cables. New brake drums aren't available anymore for these but I was able to get a pair of new Waggoneer drums to fit perfect after a little machine shop work. The center hole needed enlarging and the lug holes need to be drilled out to 9/16" to fit the shoulders of the GMC axle lugs.

Since the stock wheels on the front of this truck wouldn't clear my disc brakes, I opted for a set of 16" Wheel Vintiques smoothies.

[yossarian19]

WOW.
I really like your truck. That is just about exactly my end-goal with my own truck, appearance wise. Very very nice. Love the green & white!

[SKFengineer]

Yoss,

Maybe you already have but if you like Roger's truck take the time to read his built thread over at the tri-five site. It's the best 115 pages next to your own build thread.

[roger55]

Thanks for the compliments guys!

Yoss, I built this truck for my wife and she made the final decisions on the colors.
The white is an off-white called Wimbledon White and I got that paint from Summit.

If you are really considering green, take a look at the interior color my wife chose. So many people have told me things like "Ya know I never would have thought to put a light brown like that with green but now that I see yours, I really like it together". Some might call it a dark tan but the color is called Fawn Brown.

I will be going through your build thread tonight. I had not seen it before. I spend most of my time on trifive.com.