New 88 MJ owner questions

[Junder28]

Hey ok so I just picked up an 88 MJ  5speed long bed 4x4 with 130k on the clock. I picked this right up to be a hunting truck. There Are a few things that I’m fixing currently like the speedo just broke the fuel gauge doesn’t work and the e-brake cable broke. Outside of that I’m this thing is in great shape and runs awesome. The main concern is I need tires real bad and I’m debating on getting a 4.5” full lift kit from Rustys off-road and run 33” tires or go 3” and 31s. I will ride on the road here and there but it’s mainly for off-road. If I want to go 33s should I consider getting a stronger rear axle and better gearing? If I can get away with not doing that for a while that would save me a ton of $. What has been y’all’s experience? Will I hate it on 33s without better gearing and a stronger rear axle or will it be tolerable? Also just as a note I am hunting pretty hilly property. Thanks for any and all feedback.

[Dzimm]

For hunting you'll hate lifting a deer into the lifted truck.  It's not fun to do alone but still doable.

 

I've got the Rusty's 4.5" kit on mine, rides better than the worm out stock suspension for sure.

 

Find out for sure what rear axle you have, you can tell by the diff cover.  Most likely it will be a Dana 35 but they did rarely come with a Dana 44.  If you have the D35 you'll want to upgrade no matter what since you'll be off-road.  Easiest swap would be a C8.25 from a 97+ XJ.  If you want disk brakes you can do Ford 8.8 or liberty C8.25.  I've done the XJ and Libby C8.25 myself and it's quite easy, cut off all brackets, weld on new perches and bolt it back up.  

 

[JMO413]

If it's all factory your probably at 3.07 for a gear ratio. You will definitely want to change that to 4.10 or so. Unless your a kick one your rear axle will be a Dana 35. You will want to swap it out if you're planning on wheeling 33's. Chrysler 8 1/4 or ford 8.8 are the most common swaps.

[Junder28]

So yea it’s got the Dana 35 it looks like. Is it really that weak of an axle? Could I run 31-32” tires without needing to replace the rear axle right away? What’s the limit of that axle? I do believe it’s 3.07 gearing. It needs tires now but I kinda want to start somewhere o can build off of rather than do it all at once. So could the Dana 35 handle 31-32s for a while until I can switch to a let’s say Chrysler 8.25 and then I can loom at doing 4.10 gears and maybe a locker?

[Dzimm]

It's up to you but I'd recommend not changing the tires.  The D35 is a light duty truck axle.  They are just fine at street driving and mild off-road with stock tires but as soon as you change tires, especially bigger tires off-road, it'll be likely to break.  I've also heard stories of guys with stock tires on a street only truck have that axle break.  Just not worth the risk IMO.  Some guys have also had success running bigger tires on it so it may just come down to luck.

 

If you are going to lift the truck, I'd recommend doing tires last anyway.  You may not like the look of the 31s/32s once lifted and want 33s.  You also may run into rubbing issues with it at stock height and bigger tires, I can't remember the biggest tire you can go without rubbing.  I personally still run stock tires on my lifted MJ because I ran out of money and it was still DD duty up until recently.

[Junder28]

Ok so if that’s the case do you have any helpful search tools to find out how difficult the 8.25 swap is? If I swap the 8.25 should I try and find a matching Dana 30 so the gears match? Is it as simple as bolt for bolt or is there a lot of modification?

[Pete M]

what size tires do you have now?  a 3" lift and 31s will likely suit you just fine. 

 

car-part.com can help you find junkyard parts.    the site only lists by part number not compatibility and any year XJ dana 30 will bolt in, so be sure to look for various years.  95+ will have the bigger Ujoints. 

 

4.10s can be found in Liberty 8.25s and explorer 8.8s.  some simple welding is required either way since you'll need new perches put on in the MJ location. 

 

33s only have 1" more ground clearance than 31s and a 4.5" lift only lifts it 1.5" higher than a 3".  but the bigger things bring more headaches and costs.

 

rocker guards and bumpers are worth their weight in gold.  don't forget about solid recovery locations like tow hooks or a hitch.

 

can you share a photo of your leafs?  it almost looks like you've got a later metric ton pack with the double overloads. 

 

don't get ahead of yourself and spend any cash until you're comfortable with the plan forward.   there's a TON of info on the CC.  lots of it in the link in my sig and in this thread:

 

 

[Junder28]

Super helpful response! Man I think I’m contemplating 3” and 31s now just to save money and headache. I bet it will be plenty capable at that height. I looked up the vin and build info and it has the one ton package but it does not have the Dana 44 which sucks. If I’m using this as a hunting rig I don’t want it super difficult t put dead animals or gear in the back either. 

[Junder28]

Could I do the 3” lift and tires first since I need tires bad before I work on an axle swap?

[JMO413]

I am running 31's on a Dana 35, so yes you can do it. Not saying it's the best idea but it will work. I drove mine with the 3.07's for a couple years. First is super long and fifth is pointless. 

 

If I was building another one or mine again I would make a needs/wants list. Changing suspension, axles, gear ratio, etc adds up each time. Slap some cheap 235/75/15 on it and drive it for a while. See what you can live without and also what you want. It will save you a ton to do everything else just once. IMHO

[Pete M]

1 hour ago, Junder28 said:

Super helpful response! Man I think I’m contemplating 3” and 31s now just to save money and headache. I bet it will be plenty capable at that height. I looked up the vin and build info and it has the one ton package but it does not have the Dana 44 which sucks. If I’m using this as a hunting rig I don’t want it super difficult t put dead animals or gear in the back either. 

 

 

did you add the vin to the registry yet? 

https://comancheclub.com/forum/28-comanche-registry/

[Pete M]

1 hour ago, Junder28 said:

Could I do the 3” lift and tires first since I need tires bad before I work on an axle swap?

 

yes, absolutely.  but I'd like to see your leafpacks first.   

[Junder28]

So I forgot to mention it already has 31s on it but it’s stock height. So they run at full turn but other than that seem ok. I want clearance more than anything for where I’m taking it but i think from some of the other threads I’ve been reading this thing should be pretty cable at 3” and 31s. Recovery and protection being paramount. Then if I decide to add beefier axle I can look at different gears and maybe a locker... I’ll take pictures of the springs this week. It’s parked at a shop right now

[Dzimm]

I'm guessing they probably rub on the lower control arms.  If that's the case, you can swap the bent lower control arms from IIRC a WJ to get the clearance. 

 

If you want ease and cheaper then just go with the 97+ XJ C8.25.  to swap you'll just cut off the perches and shock mounts, weld on new perches in the MJ locations, then attach your brake lines and you are done.  The only part you've got to be really careful about is getting the pinion angle correct.  Plenty of threads here for this swap for more details.  You'll also have the old axle to get measurements off of for the mounting location.  If you don't have a welder that can weld the thicker tube, find someone who does.  You'd be surprised how easy it is to trade a case of beer for a quick weld job.

Id just recommend again that the axle be towards the top of the list, if not the top.  Reason I say that is if you do break out in the woods you'll need decent recovery points to get your truck out.  You can spend the money on bumpers, winch, and recovery points, or you can spend it on the axles to drastically reduce the chances of breaking in the first place.

 

You can get the axle from most any yard for $200 or less (I payed $100 for my XJ C8.25).  Add another $30-$50 for perches and factor in new brakes.  You may be able to get a bundle price if you buy the front and rear axle together.  For less than $400-$500 tops you should be able to get matching ratio front and rear XJ axles, new perches, and new brakes. 

 

Better yet, find a 97+ XJ someone is selling for cheap and part it out to get your axles and make money from the other parts to fund your truck parts.

[Pete M]

another option is 3.73 geared dana 30 from a ZJ matched with a 3.73 8.25 from a Libby.  both are pretty common in the 'yards. 

 

be sure to also start researching the dual booster swap.   

 

WJ arms are the same length as the MJ arms and can work for up to 3" of lift.  they are way better built and a good upgrade.  combine that with 3" coils and shocks and longer brake lines.  there is some adjustment in the lower control arm rear mounts for alignment purposes.

[Junder28]

How difficult is it to swap in an liberty Axle or the ZJ front? Is it a bunch of modifications or would it be similar to the XJ 8.25? Just cut of the old perches and weld in the MJ perches?

[Pete M]

there is more to cut off on the liberty axle since it's a link suspension, but after that you can weld on the new perches to make it an MJ axle.   check out Dzimm's build thread.  he put one in his race truck.   

 

the ZJ will bolt-in.  

 

[Dzimm]

10 hours ago, Junder28 said:

How difficult is it to swap in an liberty Axle or the ZJ front? Is it a bunch of modifications or would it be similar to the XJ 8.25? Just cut of the old perches and weld in the MJ perches?

The Libby axle install itself is the same as the XJ.  The difference is the brakes.  With the XJ drums you just hook your E-brake and brake lines up and go.  No changes needed.  I don't think it's been mentioned yet but you will need a new driveshaft or to have yours cut down a bit with the new axle as the diffs are slightly longer.  I lucked out and found a premade shaft online that was the correct length for my 92 and at a good price.

 

With a Libby axle, you need to find a brake distribution block from a ZJ that had rear disk brakes.  You cannot reuse the stock MJ dist block because it was designed for drum brakes and won't work properly with the Libby's disks.  You'd also absolutely want to do the dual diaphragm brake booster as well.  You also need to buy a conversion u-joint to fit your stock driveshaft yoke to the diff yoke as the Libby uses bigger u-joints.  If you have a new driveshaft made you can have the rear of it made with the bigger yoke. Then you have to figure out how to adapt your E-brake cable to work with the disk setup, which I haven't done yet so can't really answer to.  

 

I'd recommend to go with the XJ axle if you want an easy swap.  If you want the extra braking power, then go Libby. 

 

For reference later, for an XJ axle look for a 97-01 XJ, for the Libby look for an early first gen 02-03 era and make sure it has the yoke and not the flange on the input. 

[MiNi Beast]

ummm

[Pete M]

1 hour ago, Dzimm said:

for the Libby look for an early first gen 02-03 era and make sure it has the yoke and not the flange on the input. 

 

02 will have drums, but can easily be converted to disks. 

[Junder28]

Ok so i think i have decided for ease and less headache i would be happy with a 97-up XJ 8.25 3.55 swap with a  matching dana 30 in front. It seems like the cleanest and easiest way to get a better rear end. But just to clarify if i do the swap i will also need to either have my driveshaft cut down or buy a shorter one? 

[omega_rugal]

1 hour ago, Junder28 said:

i will also need to either have my driveshaft cut down or buy a shorter one?

 

your choice

[Junder28]

How do i know the length i will need? DO i have to install the new axle and measure?

[Pete M]

you'll need 1inch shorter than right now because the snout of all the upgrade axles is about 1inch longer than a dana 35. 

[Dzimm]

11 hours ago, Junder28 said:

How do i know the length i will need? DO i have to install the new axle and measure?

 

7 hours ago, Pete M said:

you'll need 1inch shorter than right now because the snout of all the upgrade axles is about 1inch longer than a dana 35. 

Pete hit it on the nose (snout ).  It's right around an inch of difference for the C8.25.  Typically you would want to measure after install but you can go with an inch and be plenty good.