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87' Project... Confused about the right axle - Need Help!


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Hey guys, thanks for any help in advance!

 

So I currently have a stock 87 4x4 MJ with a 2.5 and currently a 4 spd manual I picked up for $50... needless to say I have plans for my jeep and they don't involve any lifting other than the tire size.

 

I've been poking around google trying to research what axle's I should go with for my project and am not really getting anywhere. On one forum I read the stock D30 and D35 will handle 31's, on another 33's, and on occasion I've found some guys saying they've been running 35's with 3 out of 5 not having any major problems. Most have said to swap to a D44 or to avoid premature breakage to run D60's.

 

My plan is to run 36's or 37's on 16 inch wheels swap in a 4.0 and hopefully bump it up to around 300hp and swap in either a 5 or 6 speed manual transmission ( no I haven't put much thought into this portion yet and how it pertains to fitting into the vehicle in reality ). I have no desire to lift my truck - instead I'm going to pull out the fenders and/or cut where necessary to make clearance and install bypass shocks since I read somewhere they dominate the offroad racing world... or something like that; point being they're supposed to be badass performance shocks.

 

My jeep will be running blacktop, mountain roads which consist of pavement; gravel; 3-4 inch rock; river rock; clay; various grasses as well as tree branches and various sizes of potholes as most of you know. I live in oregon, and honestly if you leave the pavement or gravel roads you find a lot of clay beneath the grass. I'm not much of a rock climber but my brother likes to be a trail crawler and we end up racing once we hit the gravel roads - and in some places I do end up airborne. I also intend to bring my truck to the local mud races. To sum up - I'm a fairly abusive driver probably 70% of the time and value good acceleration. I currently am running 225/75/15's and for being pretty worn out the 2.5 with the 4 spd is pretty quick and has never left me stranded... which is something I value especially when help is an hour away. 

 

Like I said, everything I've read says go with a D44  and for 37's people have recommended the D60 to avoid the breakage of heavy use. But since none of the information I found was very relevant to my plans I decided to seek more direct help and am totally lost about which axles to put under my truck for my intended uses and driving style since both can vary from mild to highly aggressive. And I don't know if this helps but I also want disc brakes on the rear end.

 

Again thank you for any help in advance!

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First off, good luck squeezing that much tire with no lift. I don't think you would have any fender or bedside when you got done. If you are wheeling it too hard/much the D30 may hold up. The easiest swap for the rear IMO is a Ford 8.8 from a late 90s explorer. 31 spline axles and disc brakes, just need a few parts to make them work properly. However, depending on money you could step up to a 44 or 60 but then you either have to look into narrowing them or run them full width. In the end it comes down to how much you want to pay. Anything can be done with $$

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Sounds like you have cool ideas but unfortunately not all of them will work. For the front axle a D30 may be able to survive under the front with 37" tires if you stick to pavement or gravel roads but if you start doing any type of wheeling it is a ticking time bomb. A D44 really isn't much of an upgrade over a D30 because in most cases they run the same size u-joint as a D30. As for a D60 front axle, its not going to happen at stock height. The massive pumpkin (and truss needed for mounting it) is not going want to share space with your oil pan. In the rear the stock D35 is weak. A lot of people get away with running 31-33" tires on the street with a D35 but you have to drive like you have a D35. I have seen a D35 snap a shaft pulling out of a parking lot with stock tires. You can fit pretty much any axle you want under the rear. The 8.8 is a popular and easy swap for the rear due to the matching bolt pattern like Dunnc1991 said but 37" tires is even pushing the limits of an 8.8. As for 37" tires on stock height? Unless you plan on running the tires outside the wheel wells with really offset rims or only going in a straight line I think you are going to run into issues trying to make turns with 37"s. 

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You won't read anything that's relevant to your plans, because IMHO your plans are totally unrealistic. The MJ doesn't have a frame in the front, it has a unibody. You start running that size tires and jumping it over rocks, and you'll destroy the unibody in about a week. There's a reason the Baja trucks and prerunners all use vehicles that have separate frames -- they can reinforce the frame and/or tie a cage into it for stiffening.

 

By the time you get done, you won't have anything that's ever recognizable as a Comancge, so why are you gong to destroy a truck that's no longer being made? Sell the MJ now, and go buy a Ranger, S-10, Colorado, or Dakota. Or, better yet, a full-size pickup.

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So, you are looking to sink at least $7K into a $50 truck.....did I read that correctly?

 

It's a $400 truck, I picked up the 4 spd with TC for $50... but still, yes - I love my truck.

 

 

You won't read anything that's relevant to your plans, because IMHO your plans are totally unrealistic. The MJ doesn't have a frame in the front, it has a unibody. You start running that size tires and jumping it over rocks, and you'll destroy the unibody in about a week. There's a reason the Baja trucks and prerunners all use vehicles that have separate frames -- they can reinforce the frame and/or tie a cage into it for stiffening.

 

By the time you get done, you won't have anything that's ever recognizable as a Comancge, so why are you gong to destroy a truck that's no longer being made? Sell the MJ now, and go buy a Ranger, S-10, Colorado, or Dakota. Or, better yet, a full-size pickup.

 

It's mostly happened when I find steep hill crests and we're doing 50+mph, being airborne isn't something I try to do, like you said because it's a unibody as well as destroying various suspension parts but things happen. And I know it's not totally realistic, I'm rolling with an idea that sounded awesome to me and am gradually putting it into perspective. 

 

As for other trucks, MJ's look cooler in general, there's not many around so there's that unique factor, plus I have it. I really don't want a full size because they're too wide and heavy for my taste - the sub compact category trucks have an easier time following random atv trails or random overgrown trails that haven't been used in forever. I have no intention of destroying it, but should it happen I'd rather it die in the hands of someone that cares about it.

 

 

here's my brothers MJ on 37s with a 6" lift,even with a 6" lift it took alot of cutting to make everything work without tons of bump stopping.

 

That is freaking amazing! Thank you for this picture, it helps a lot putting tire size into perspective.

 

 

First off, good luck squeezing that much tire with no lift. I don't think you would have any fender or bedside when you got done. If you are wheeling it too hard/much the D30 may hold up. The easiest swap for the rear IMO is a Ford 8.8 from a late 90s explorer. 31 spline axles and disc brakes, just need a few parts to make them work properly. However, depending on money you could step up to a 44 or 60 but then you either have to look into narrowing them or run them full width. In the end it comes down to how much you want to pay. Anything can be done with $$

 

36's or 37's were what sounded like they'd fill up the wheel wells good. I was fortunate enough to park next to a guy's TJ yesterday who's sitting on 35/11.5/15 I believe they were. Me sitting on 225/75/15 his tires came up to the top of the 1 inch flat side of my fender flares - after seeing that I'm thinking 35's will fill the wells like I want and after looking in there I think they'd fit perfectly with folding out the fenders and a little inner fender removal if necessary. 

 

My brother's father-in-law has a Bronco II that I believe had the 8.8 swapped under it, he said it was posi, but that's all the more I know. Well, $ is a barrier but depending on the pricing I'd rather go with what'll hold up better in the long run. That being said, would dropping down to a 35 make much of a difference on axle stress vs say a 37?

 

 

Sounds like you have cool ideas but unfortunately not all of them will work. For the front axle a D30 may be able to survive under the front with 37" tires if you stick to pavement or gravel roads but if you start doing any type of wheeling it is a ticking time bomb. A D44 really isn't much of an upgrade over a D30 because in most cases they run the same size u-joint as a D30. As for a D60 front axle, its not going to happen at stock height. The massive pumpkin (and truss needed for mounting it) is not going want to share space with your oil pan. In the rear the stock D35 is weak. A lot of people get away with running 31-33" tires on the street with a D35 but you have to drive like you have a D35. I have seen a D35 snap a shaft pulling out of a parking lot with stock tires. You can fit pretty much any axle you want under the rear. The 8.8 is a popular and easy swap for the rear due to the matching bolt pattern like Dunnc1991 said but 37" tires is even pushing the limits of an 8.8. As for 37" tires on stock height? Unless you plan on running the tires outside the wheel wells with really offset rims or only going in a straight line I think you are going to run into issues trying to make turns with 37"s. 

 

I had read about the D30 having an upgraded u-joint, does the D44 have the same option? Also, like I said in my last response to dunnc1991 I think a 35 will fit the bill for my plans more or less perfectly and I don't know how that would affect the axles. 

 

With the fenders I am wanting to pull them outward and up - for a lack of a better word, baja the fenders, to make the clearance room. And I am planning on finding a heavily offset wheel. I haven't had any problems up front but the back tires even on 225/75/15 I've rubbed the frame.

 

The main reason I am avoiding lifting it is because it's a unibody so everything sits lower than say an s-10; it has a lower center of gravity and can get away with more sideways abuse since it's not as top heavy. The guy I bought it from loved the truck for that very reason, he has a field and was slinging her around pretty good. So, lifting it would take a little of the fun factor out of my driving style.

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You need to ask yourself what you really want. Do you want a street truck that looks like a baja truck or a truck that you could actually use offroad? A stock D30 or D44 housing/knuckles are no going to handle being thrown around offroad with deep offset wheels and 37" tires very long. The bigger the tire the more stress you are putting on the axle, steering, suspension components. You might get away with it for a while but it is going to break eventually. You could build a D44 to hold up but you are talking lots of $$$. 

 

I know you want to stay low but stock height and 37" tires is not going to happen. The lowest Comanche I have seen with 37" tires and Baja fenders is the Zone Offroad Comanche and I think he was running around 5" of lift.

 

Here is his thread: http://comancheclub.com/topic/28780-project-mj-for-2011-ultimate-adventure-update-for-12-trip/

 

Give it a good read and see the amount of work you are talking about doing. 

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Here we go again....

 

Yep.

I will simplify what I want to know then...

 

What axles should I got with front end and rear end to handle 35's, 300 hp, and abuse?

D30 front open

D44, 8.8, 29 spline 8.25. Locker if you choose.

 

That's all you need. You'll be fine. Everybody wants to go big in the beginning. It's foolish. Put 3" of lift in the truck, cut fenders, run a wheel with 3.5" to 3.75BS and enjoy it. With a 6 cylinder, 4.56 or 4.88 will be good but you could live with 3.55s.

 

That is my recommendation for 35 inch tires. And always will be. I have run that combo more then once successfully on dedicated trail rigs and streetable jeeps.

 

But if it's a decent truck, buy a XJ to cut up.

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