Axle swap or not

[carter262]

So I have been doing a lot of research and am trying to make a decision.

First I have a 1984 M1009 stock configuration.

I am trying to decide what to do about my axles. I really do not like to 3:08 gearing. I am eventually gong to a 3" lift and 33" tires but I first got to get the axles figured out.

I was first thinking of re-gearing. 3:73 or 4:10. The last time I re-geared a vehicle, CJ 7, I believe it ran me around $1500. I'm not sure what it would cost now. For that price I though I could swap in a new set of axles out of a CUCV truck. So far I have been able to find a rear axle only for $450, but it would still have to be re-geared. I would also still have to find a front axle.

So to swap out I would have to change out the spring perches, new plates for the U-blots, re-gear, shorten the drive shaft (possibly), hybrid u joint, beak lines, and so on just for the rear. The front is supposed to bolt in but I'm not sure about pitman arm and sway bar. I would end up with a lot stronger axle with a Detroit locker instead of the gov lok.

I am not sure what swapping both axles out would end up costing though. I looks like It could get pretty high not counting buying the axles.

So I need your opinions, is it really worth the work to swap out the axles. I use My M1009 as a daily driver and some towing (utility trailer and camper a couple times a year). I do not really go 4-wheeling anymore but to go off road sometimes. In fields and for camping. Would it be more economical to just re-gear the 10 bolts it came with. How safe are they really. Do I have to worry about the C clip holding the axle in breaking and the axle falling out. Do you think it would be a waste of effort to swap in new axles since I am not a hard core trail rider? If you would like to share the cost of your swaps I am interested in hearing.

Thanks

 

[cucvmule]

Upgrade to three quarter axels or one ton would be great for off road but not for the occasional trip into the unknown.

Plenty of upgrade parts for better dependability, but try a different gear setup. Three seventy threes are a good compromise, even with larger tires. If you get off the hard road you can low lock the transfer case and have plenty of grunt in difficult terrain. And also always get you some spare axles, parts for when you need you got.

If you get a little aggressive, mud pits, getting a little air then you would want to get the heavier axle setup.

I believe the Gov-Lock has a bad reputation because it is used for more than normal use, if there is such a thing. I have used the Gov-Lock in Truck and Suburbans, which is a heavy vehicle and was surprised at the abuse that it can take, but will fail if really abused.

There are other carriers that will upgrade the axle and make it more dependable. There are axle shafts and propeller shafts with better u-joints that also upgrade axles.

All depends on budget and mechanical skills. If you can remove original axles or find an extra set and upgrade with new parts then you have replacement set when something goes south. But if you just occasionally get your feet muddy then go with simple mods.

 

[olly hondro]

The CUCV 1008 pickup axles, like I have on my Blazer, are geared 4.56. With 37s the engine is working hard at 60 MPH. So, with the smaller 33s you are planning, yes, I agree 3.73 would be a good choice.

 

[Rustyshackelford]

I thought this through for a long time on my m1009 a couple years ago. I decided that the m1009 10 bolts will cost more money than it’s worth once you take out all the bad parts and install upgraded stuff.
I upgraded to m1008 axles and it was worth every cent and all the hard work I put into it.

 

[Chaski]

Here is how my axle swap went...
Rear...
Craigslist Open 14 bolt $175
New gears $250
New Detroit locker $500
Bearing kit $130
New u-bolt style yoke $90
New slave cylinders, shoes and hardware $160
New hub bearings and seals $130

Front...
Craigslist GM Dana 60 dually $800
New SRW hubs and rotors $380
New Gears $275
Bearing kit $170
Hub bearings & seals $140
kingpin kits $100

New u-bolts $60

One trillion hours of my labor
$180 eBay Case spreader
$300 new inch pound dial type torque wrench
$300 new “clamshell” bearing puller (worth every penny)

Be sure to get the OEM passenger side spring plate off of whatever the donor vehicle is. It is different than what you have and you need it if you want to run a sway bar.

It is a big project, and kind of expensive. Other catch is the axles are HEAVY, and your ride will suffer a bit. It is a huge amount of unsprung weight. Just the combined weight of the axles is about 900 pounds. Don’t expect it to ride like a new SUV.

I’d do it again in a heartbeat.... but it may be a bit excessive for 33” tires...

 

[Ilikemtb999]

I had 33” tires with stock axles for quite a while off-roading and daily driving and never once had an issue. My original plan was to find a semi-float 14 bolt in 6 lug and then re gear the front to match whatever I got for the rear. It’s half the headache and can reuse your wheels. You get a beefier center section and axles than the 10 bolt. The front 10 bolt will take you pretty far off-road with the enemic 6.2.

I ended up finding a whole parts truck for a grand so ended up going Dana 60/14 bolt with disc brakes and 35” tires. It was costly.

 

[nyoffroad]

It is what it is, if your not off roading and beating on it why change it? If you had a set of gears or better yet axles just sitting around then I can understand it. For the average daily driver with a few hunting/camping trips its strong enough.

 

[Kaiser67M715]

They used the 10 bolt in the heavy 3/4(8,900lb GVWR) with 8 lugs, knuckles in was all the same, spindle and brakes changed. IMO plenty strong for road and some decent off roading.

The downside to the rear axles is the semi float, both for 14 and 10 bolts. If anything I would upgrade the rear to the 14 semi-float as a minimum. Full float would likely require a matching wheel stud pattern for front. You do lose quite a bit of ground clearance the bigger the axle.

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[someoldmoose]

I M H O, The "stock" axles in your truck are more than stout enough for 33" tires. If the units are in good shape and the only problem is the ratio, changing ring & pinions is the way to go. For what you'll pay for Corporate 14 bolts you can change the r & p AND add a traction improver ( prefer Detroit or ARB for the back but the ARB is expensive and requires extra "stuff" ). I rarely recommend any traction improver in the front of a street driven vehicle but if one is desired a limited slip unit with manual hubs is the way to go unless you are going Hardcore off-roading where you might be on three ( or two, or one ) wheel at some point. If you're concerned about bending the tubes, add a truss. Saw somebody mentioned a sway bar for the rear. I do not recommend unless you add disconnectable end links or your articulation will suffer ( I even put them on the front of mine ). One other point, if you are upping the wheel and tire weight, please, upgrade your brakes. At MINIMUM the best pads you can afford with NEW rotors. Best suggestion, drilled and slotted rotors and TRUCK pads. Not a lot you can do with the rear brakes except use the best shoes you can afford and NEW hardware EVERY time you change shoes. You can change the rears to discs but that is expensive too and in M H O not really necessary. Hope you get where you wanna be.

 

[nyoffroad]

Another option yet to be mentioned is keep the 308 axles and change out the TH400 to a TH700r4 or 460LE, both will give you a lower 1st gear to get the bigger tires rolling AND an overdrive to keep them rolling at 70+mph. May be cheaper too depending on what you can do and the cost of a donor tranny.

 

[someoldmoose]

Great idea although I'd do the 700R4. No electronics.

 

[carter262]

Thanks for all the input and ideas.

I would prefer to do the full axle swap, but it appears to be more cost effective and for my use not necessary to just keep the axles I have. Plus I have another set sitting around if I need parts in the future.
So now I need to decide on either 3.73 or 4.10. I what a lower gearing for towing the camper (around 3500lbs). 3.08 does fine going down the highway to the beach, but really really sucks in the mountains.

So my M1009 is stock. I will be going to 33" tires to help with the top end speeds. I try not to do over 65 even now with it stock. Other than changing the tire size and gearing I'm leaving the rest of the drive train stock.

Here are some numbers I have ran; do they seem right?
Stock; 31" tires; 3:08 gearing (all based off 3rd gear)
35mph 55mph 65mph
1234 1940 2469 (RPMS)

33" tires; 3:73 gearing (all basted off 3rd gear)
35mph 55mph 65mph
1404 2207 2608 (RPMS)

33" tires; 4:10 gearing (all basted off 3rd gear)
35mph 55mph 65mph
1544 2426 2867 (RPMS)

In my mind 4:10 would tow better, I just don't know how much better. Is the RPMs in acceptable ranges safe ranges?

 

[Kaiser67M715]

With 4:10 I feel your pushing it with 65mph

My 6.5 turbo, sm 465, 3.42 gears and 31" tires (actual road diameter 29.5") will do 55mph at 2200 rpms, and it likes when I get up to 65 at times, which is around 2600rpms. MPG really drops after that though.

I would opt for 3.73 with 33" tires.

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[carter262]

Update:

So I ended up regearing instead of axel swap. Insides of Axel's look great and due to the cost and work and fact I don't get crazy off road I decided it was the best option for now

I ended up with 4:10. I kept going back and forth with the decision but due to towing the camper I opted for the lower gear. I also got new 33"s put on the next day.

I pulled the the reducer off the transfer case and put in a gray 44 tooth speedo gear. Now speedometer reads 55 mph and I am actually at 60 mph. So only 5 mph off. I can live with that. It cruises good at 60 mph. I probably want push it over that.

Next lift. I wanted a 3", but the guy at the shop I deal with has a 4" rough country lift (front leaf springs & blocks in the rear) I can get for $250. Not the exact set up I wanted but I don't think I can pass up on the price, that is if it fits. He said it was for the suburban same year range and would fit my m1009. I need to confirm that before any money is exchanged. We will see.

Thanks for the help!

 

[someoldmoose]

If you can get a 4" lift for $250 AND it's a complete kit, JUMP on it ( $100 an inch for solid axles is the "standard" ). It will fit. All solid axle K trucks used the same springs just with different numbers of plies for the GVW. A 1/2, 3/4 ton setup is identical. The 1 ton added another leaf and "helper" springs. All other components were the same. Easy, peasy, lemon squeezy !

 

[Ilikemtb999]

I find 4” and 33” tires to be way too tall but I guess it’s all in personal tastes. I thought my 2” lift with 33” was too tall so I swapped to 35” tall tires.


also chances are that rough country kit will ride harsh compared to springs from tuff country (who also makes their stuff in the USA). Check out the spring rates between companies in this chart

https://ck5.com/forums/resources/spring-rate-table.14/

 

[doci869]

The CUCV 1008 pickup axles, like I have on my Blazer, are geared 4.56. With 37s the engine is working hard at 60 MPH. So, with the smaller 33s you are planning, yes, I agree 3.73 would be a good choice.

So are you saying the 37's are too much for the gear ratio? I ask because I have the CUCV Blazer and just got my hands on the truck with 4.56 geared axles. I was thinking of doing the swap as the truck is kinda hashed out. Reeks of mouse urine! And they had a bale lifting hydraulic bed on it that they took off leaving no box so just cab and chassis right now. I was thinking of 35 in tires for my build as this is my current all around rig, hunting, mudding ect. and I figured that would be a good pairing so I still have power and can go over 55 mph. TIA

 

[98G]

So are you saying the 37's are too much for the gear ratio? I ask because I have the CUCV Blazer and just got my hands on the truck with 4.56 geared axles. I was thinking of doing the swap as the truck is kinda hashed out. Reeks of mouse urine! And they had a bale lifting hydraulic bed on it that they took off leaving no box so just cab and chassis right now. I was thinking of 35 in tires for my build as this is my current all around rig, hunting, mudding ect. and I figured that would be a good pairing so I still have power and can go over 55 mph. TIA

I interpret what he's saying as even with 37's the rpms are high at 60mph.

4.56's and 37's should be a good combination. 4.56's and 35's may result in too high of rpms st hwy speed, depending on your tolerance for rpm and just how much you drive interstate.

Personally I'd go with the 37's if they clear in your application.