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New MJ owner and have some ????

catmandu

NAXJA Forum User
Location
GA
Hello I am a previous XJ owner and have been a memmber on the board here a while under FireXJ but sold my XJ last year and have not been around in a while. I Just purchased a 88 MJ and need to get started on it. I need some manufac specs on it? It is a 88 comanche chief 4x4 SWB auto(in the floor) with a D35 in the rear, how can find out if it has trash loc?
I need all the intel I can get about these things so help me get started.
Where do I start? I want to do a spring over in the rear, how much lift will that give me? I just need it big enough to run 33's.
Do I need a SYE for that much? Engine is strong and runs great. I drove it home 6+ hrs yesterday and it gave me no problems whatsoever.
Should I change out the cooling system? I see alot of folks doing that
Also right now I have some vibes it feels in the rear drive line around 52mph and up. Need to diagnose and fix. Anybody got any lift parts mods or tires they want to sell? Just what what ever tech or mod info anyone has on them I would appreciate
Thanks
 
it doesn't matter if you have a trash loc in the rear or not, because the D35 is the first thing you need to get rid of anyway.

spring over: anywhere from 5-7 inches with stock packs, plenty of room for 33s

specs: 113 inch wheelbase, SUA rear, otherwise the same as an XJ of like year

No SYE needed, I'm at 8" now with my shortbed MJ and no problems, though you may want a YJ slip-yoke

cooling system is questionable, mine is still doing great with just a 3 core, but I don't expect it to last forever

lift parts: you don't need anything but steel and a welder for the rear (oh, and shocks), for the front, all parts apply same as an XJ, check the For Sale section of the board
 
Agreed with EVERYTHING above, 100% correct - the YJ yoke espically, I'm at 7.5" and my t-case was leaking till I swapped in a YJ yoke, exactly 1/4" longer than the MJ yoke, just enough to stop the leaking and provide more strength. Plus mine was free! No probs with my closed cooling system yet either.

Best of luck.
 
I did a SOA on my MJ and 4.5 coil springs in the front. I ended up adding a 1.75 BB to balance it out. You will need UCA and LCA too. I haven't done anything to the drive.
No SYE or slip-yoke. I did drop the T-case 1 inch.

enjoy!
 
If you want a super stable rig that fits 33's and don't mind doing a bit of sawsall work, I suggest running a longer shackle and a full length XJ AAL with the center hole redrilled to match the MJ packs. Couple this with 3" coils and a small spacer up front. This will be plenty of room for 33's. Remember, less is more!!
 
I've got an xj44 I'd sell ya lmao, but seriously these guys are right on the money with things. You'll learn alot of good info from them here. I'm running soa with and aal in back and 6" coils up front clearing 35s no prob. A little trimmin and you can easily go bigger.
 
Here's a letter I wrote for a fellow MJer last week. It might give you some ideas. (or if anyone sees any mistakes in the details, lemme know) The list was for a 2wd to 4wd conversion and a stick, but the important upgrades are the same.

-------------------------------------------
A Blueprint for 33s:

-MJ/XJ front axle
--non-CAD axles are preferred, but the CAD axles can easily be retrofitted with a 1-piece passenger-side axleshaft from later model Jeeps.
--95 1/2 and newer will have Dana 44 U-joints (297s) in them, but all older years will accept them as a bolt-in upgrade http://www.madxj.com/MADXJ/technical/technicalfiles/ARD30shafts297andSeals/D30shafts297andSeals.htm
--97 1/2+ are low-pinion are not desirable for that reason (and newer axles cost more than older axles anyway)
--99% of all front axles from a 2.5L equipped MJ/XJ will have 4.10 gears and are the same axles used in 4.0L Jeeps

-MJ/XJ front driveshaft
--Look for one with a CV joint at the t-case end. I thought they all had this, but apparently not.
--The ones on 2.5L Jeeps might be slightly shorter, so be sure to measure before you buy.

-Transmission
--AX-15 from 91-94 will bolt-in directly with no changes to the slave cylinder assembly
--95 and newer will have the more desirable external slave cylinder. Both units work fine, but the external will allow repairs to be done to it without dropping the transmission.
--95 and newer will also require the newer clutch assembly

-T-case
--it's best if you can find one still bolted to the AX-15, that way you'll know the spline counts are the same. Otherwise, stick with 91+ t-cases that came from behind 4.0Ls, as I'm not sure when exactly the change from 21 to 23 occurred in 2.5L equipped Jeeps. If you find one for a good price, you could always count the input shaft.
--a 23 spline MJ/XJ NP-231 will bolt right in
--a 23 spline MJ/XJ NP-242 should bolt right in and allow 4wd on dry pavement (not all that necessary in Florida ;-)
--be sure to grab the t-case linkage including the bracket that bolts to the underside of the Jeep
--A slip yoke eliminator is a wise investment

-Rear shaft choices:
--have your current one shortened to the proper length (will not work with SYE)
--find an MJ shaft from the junkyard that fits your application (this depends on the lift involved and this will not work with a SYE)
--have a new one made

-Rear axle
--Please do not put any money into your Dana 35 if you want to run 33"+ tires (just my opinion of course, lots of people do with varying degrees of success/failure)
--Ford 8.8 from behind a 95 and newer Ford Explorer equipped with a V8 (should have 4.10 gears, disk brakes, posi-traction, 5-on-4.5" bolt pattern, and be easy to find) You will need to weld on new spring perches, but that's necessary for all lift/axle configurations except keeping the MJ's current axle spring-under.
--Dana 44 from an MJ/XJ (drum brakes, requires regearing, may have posi but it'll be a really old posi that probably needs a rebuild, and can be tough to find)

-Lift
--at least 4.5" is needed to clear 33s (and that includes a lot of fender cutting up front)
--Extended bumpstops are your friends!
--you could always do a 3" lift with some aggressive 31s for now, then upgrade the lift later on. There's no need to go super-big right away. 33s only provide 1" more ground clearance than 31s, but bring a lot of complications with them.

This set-up will give you everything important (4.10 gears to help match your tires, Dana 44 U-joints up front, 31 spline axleshafts out back).
----------------------------------------

Jeep on!
--Pete

MJ Yahoo Group:
http://autos.groups.yahoo.com/group/jeepcomanche/
 
Pete & Nate pretty much nailed it down. I ran 33x12.5 with just a SOA rear and 3"+1.75" spacer up front with great results: (stock CAs, TB and steering at first, later with Rusty's steering and Adj. TB)

To tell if you have a track lock in there now, look for a tag on a cover bolt that says so first...if that isn't there, jack or hoist the rear so both tires are off the ground. Spin one and watch which direction the other one goes...if it goes the same way as you are spinning, it's a Track Lok. If the other tire spins in the opposite direction, you have either open diff or the TL is baked. Pulling the cover and looking for clutch packs out at the side gears is the sure-fire way to tell, but then ya are obliged to refresh the gear lube (+ friction modifier if it is a TL) and seal the cover.
 
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