My streetable autocross / road racer MJ build.....

[YELLAHEEP]

When envisioning the build for this project, I'd hoped to find an'89 - '90 2wd 5spd Eliminator truck as a base. Pretty few and far between out in this part of the country (In the eastern states they're plentiful but all I'd found were VERY used, beaten and rusty..... and shipping them was $$$) but the idea was that it'd already have the AX15 and a D44 and buckets......

This truck wasn't exactly what I'd hoped to find specifically, but this is a real solid truck to build on. Short of the D44..... it's almost an Eliminator..... so here we go.

'88 MJ short bed, 4x4, 5spd, non-A/C truck. Absolutely rust free. 270K miles.
-Rebuilt 4.0 with unknown miles since rebuilt was installed 2 owners ago.
-Late model AX15 with external slave bell housing swapped in with new clutch.
-Runs and drives beautifully.
-Bonus: this truck already has the bucket seat interior and full gauge cluster. Also nice newer tires, a custom off road rear bumper and bed mounted tire carrier I can use for other projects or sell.

Biggest mental hurdle with this truck was coming to terms that I'd have to remove the 4x4 parts. What helped me with that hurdle was a ComancheClub member in Pueblo who's an even bigger parts hoarder than I am, was willing to sell me all the bits I need to go 2wd. So, next week I'll be hauling off to Pueblo to get these things.

The bigger challenge will be the suspension. Ideally it'd be great if I could source the parts to duplicate the SCCA trucks the Archer Brothers used for their trucks - custom front coils and fiberglass mono-leaf rears. Dunno how successful I'll be in coming up with those or items similar. Rumor has it that certain years of the Astro van used similar fiberglass mono-leaf rears that are the right length...... For now, I have several sets of off-road front coils that I can cut down to see if they provide the stiffness and drop I'm looking for up front. The rear may just see the removal of the overload leaf and one additional leaf from the middle. :dunno:

The 2wd front axle will get outfitted with WJ knuckles and brakes. I have 16" wheels already to clear those brakes. I'll have to see if the WJ steering will work with the lowered suspension..... may end up going to a simple heim setup for steering and track bar.

Rear axle thoughts: Since I won't have D44, I can do one of two other builds....
-Keep the D35 and do the Liberty rear disc swap
-Get an Explorer 8.8 with the discs.

The 8.8 might be a bit on the heavy side but I wonder how a D35 would stand up to all the throttle work and up/down shifting abuse........ I believe the Archer trucks used D44's but those trucks were running the 2.5 4cyl engine........

I'll put a cage in it, move the fuel tank and battery into the bed and use a YJ Hurst shifter for the trans.

Anyway........ the truck:

I'm using their photos as the truck is currently filthy and frozen.....

John and Brad were so concerned with the upkeep of this truck that when they went to replace the doors (had minor rust along the bottom from rotten window seals) they held out until they found red doors..... and got lucky to find another Pioneer so the doors even had the stripes!

The rear bumper may look familiar to some of you....... It's a Custom 4x4 Fab rear bumper for the '97-'01 XJ and it fits the truck perfectly. John and Brad made custom brackets to mount it up but it looks like it's made for it!

 

[YELLAHEEP]

The wheels / tires for the truck:

245/50/16 Firestone Firehawk SVX

 

[Fred]

Why two wheel drive? I'd put in a 242 for full time. As I recall, the MJ is even more tail happy than the XJ, having front wheels pulling helps in a drift. What will you be saving in weight? Maybe 200#? Get rid of the bumpers, the console and the passenger seat.

I can't claim to be an expert, I've just been sliding around corners in a variety of drives for a long time(probably should add, without hitting anything . My best drifter was the Datsun 1600, with a perfect 50/50 weight distribution and rear wheel drive. The WJ with the 242 was great in the snow, the XJ slides real nice on dirt roads in 4WD.

I get the 2WD thing, if the truck came that way, I'd go with it. But since you have 4WD anyway, why not use it.

.02

 

[eflores]

im with Fred 242 or eff it 249

 

[lesslimited]

I'd guess the 2wd thing might be an SCCA rule. If not, 242 for sure. Best thing I did on my 94, lets me go through and launch out of turns much faster, in any road conditions.

 

[eflores]

I did a 242 swap on my 5.9 zj..... so much win

 

[YELLAHEEP]

As sexy as an all-wheel drive MJ road racer sounds..... The complications in making it all reliable and durable would DOUBLE the build budget.

Ya gotta figure the 242 or 249 in race conditions is gonna get stupid-hot, so some sort of oil pump and cooler would need to be fabbed up. And what's the durability of the viscous coupler going to be under sticky tire race conditions?

The front axle would need to be a later model low pinion with the Grand Cherokee booted CV's I'd imagine so..... A complete WJ axle?

Lowering the suspension is gonna be necessary to improve the COG ...... The D30 pumpkin doesnt allow for much of that..... Lots of motor mount bracket and oil pan conflicts. The plan for the 2wd axle is to shorten the UCA mounts an inch or so, and lower the LCA brackets the same. This relieves some upper area conflicts and restores some control arm angles.

How about the power loss to move that extra drivetrain on the stock 4.0?

IDK...... 2wd just sounds like more fun and less hassle.

 

[O-Gauge Steamer]

IMO, for the purpose of this build, 2WD is the preferred option. The beam axle can be sectioned out in the middle to allow the front suspension to be dropped. Pan clearance and all that stuff. Doing the rear is a spring under conversion. Spring under will give a better COG and provides better control, overall, of the axle. Plus, it makes installing traction bars much easier.

This will be a fun project.

Needs a compressor installed though...

Not A/C, the other type.

 

[eflores]

you're over thinking the awd thing Troy
good fluid in the t case make it a 242 and grab a zj. Axle if you want lp and cv shafts

 

[eflores]

if a healthy built 360 with ME behind the wheel couldn't kill a 242/lp30/44a On 31s your six cylinders On 28s won't either

 

[WB9YZU]

We can't find MJs in that kind of condition around here

As far as the Autocross/Road race thing. It's an interesting project. Obviously your never expecting to run in ""Stock Class"" :laugh3:

Running AWD is hard on components in Autocross, esp parking lot AutoX. So many tight turns really gives the VC something to heat up about.

Since the weight reduction, suspension mods, and wheel change will throw you very deep into modified class, I would scrap the idea of the full tread tires and opt for a set of Dunlap Direzza (s). I believe you will thank yourself for the move from a ""Summer Performance" tire in the middle of the pack to a "Summer Performance" tire at the upper edge of the performance range.

Can't wait to see where you take this, should be a cool ride

-Ron

 

[jeepfreak1020]

You picked that dam one up to?!?? Lol

 

[SolarBell]

Re: Re: My streetable autocross / road racer MJ build.....

IMO, for the purpose of this build, 2WD is the preferred option. The beam axle can be sectioned out in the middle to allow the front suspension to be dropped. Pan clearance and all that stuff. Doing the rear is a spring under conversion. Spring under will give a better COG and provides better control, overall, of the axle. Plus, it makes installing traction bars much easier.

This will be a fun project.

Needs a compressor installed though...

Not A/C, the other type.

X10!

 

[Fred]

Um, the MJ is spring under stock.

 

[adrenalinepirate]

I would run the 8.8 due to the yoke flange on a 35 and a stick I have torn up from burn outs and braking the ring.That was on 235 tires. 8.8 would also have a limited slip. Even if you kept sua I think it would be a better candidate. Also I would keep it 2wd. You know my rig was 2wd auto and it was fun to drive and lighter. I could only imagine how much fun a 2wd stick would be able stick the tires down.

 

[YELLAHEEP]

Yeah, I'm pretty committed to the 2wd part of this build, given my intentions for it.

I agree that the tires I have for this aren't optimal, but for $100 for that set of 4 tires AND wheels, I wasn't complaining. I'll have fun tearing them up while I learn and trouble shoot the truck.

I also agree that a compressor would be pretty cool, but not for the expense. I have a bored throttle body, spacer and intend to do a home brew CAI through the driver's fender like I had on my blue '97 XJ. Probably an exhaust header as well. Exhaust will be only a cat and then it'll exit out of the pass. side bed panel ahead of the rear wheel.

 

[papasmurf]

Are you going to swap out the renix system?

 

[YELLAHEEP]

Are you going to swap out the renix system?

In favor of?

 

[papasmurf]

A Hemi! :laugh3:

 

[YELLAHEEP]

No. .........Unless I decide to try my hand at the 1320's.

Hmmmmm........... :laugh: