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My '88 Mj Streetable Autocross / Road Racer Build


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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..... :D

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!

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Ugh..... The NAXJA folks are trying to talk me into keeping it 4x4 (go figure)....

 

They're suggesting swapping in a 242 t case and the low pinion D30 with CV's from a WJ.......

 

I dunno how I'd get the suspension low and not have contact issues between the D30 and engine mount bracket and/or oil pan.....

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Ugh..... The NAXJA folks are trying to talk me into keeping it 4x4 (go figure)....

 

They're suggesting swapping in a 242 t case and the low pinion D30 with CV's from a WJ.......

 

I dunno how I'd get the suspension low and not have contact issues between the D30 and engine mount bracket and/or oil pan.....

While it would be really cool that oil pan is a problem. PseudoSport's build shows just how much trouble it was with a 2WD axle beam.

 

Those look like some nice wide tires. :D

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  • 2 weeks later...

Thanks for the link to PseudoSport's build!  I forgot about it.  Good info I can use on mine.

 

 

Yesterday, I got word that a junk yard that I frequent just got in a '91 MJ.  I work graveyard shift, but hauled out there after my 15 hr shift to go see what I could snatch from it.   Turns out, the info was bad....... it was the same '91 I'd scuttled 4 weeks earlier.....

 

But it wasn't a total lost trip out there.  Found a 2wd '98 ZJ (pretty rare around these parts) that also had a D35 with NEW brakes and rotors on all 4 corners!  I snatched the front brake parts for another rig, then took the front unit bearings with the stub shafts.  I'll need the stubs when I build a 2wd front axle with WJ big brakes.  I then grabbed the rear disc set up with brake lines and e-brake cables.  I've got another decent MJ D35 that I can put these on to swap under the race MJ when I get to that point.  I decided against putting in an 8.8 for now as I believe most racing rules don't allow wheel spacers... and if the Archer Brothers ran D35's........ no reason I shouldn't.  :thumbsup:

 

 

 

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  • 2 weeks later...

Cool build, I'd go with the 2wd setup for the weight savings alone. 

 

Here is a shot of the XJ-R's front axle to give you an idea of how much space there is. We did clearance the front axle but the suspension bottoms out before the axle would have hit the pan.

 

Jeep_XJ-R_Grassroots_Motorsports_Challen

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Thanks for the pic!  I'll have a 2wd axle pulled here shortly and my intention is to get it cut and sectioned in similar fashion.  Then get the WJ brakes/knuckles set up.  Put it in all at once.

 

Any thoughts on eliminating the OEM track bar and steering in favor of a simple straight tube set up with heims?  Seems the lower that axle gets, there's quite a few steering component clearance concerns..... everything is all bunched up close together and the track bar really doesn't need that bend and outward bow.

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Suspension components defiantly gets bunched up but it’s not too bad. It’s even tighter when you try to run turbo plumbing through it, lol. Since nothing has been hitting we have left things alone. Our logic was that if anything breaks we can find stock parts pretty easy then upgrade if needed. A straight tube set up should work and simplify things.

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why don't you rub it in? :yes:

 

:D I could've said...

 

... I'm sitting on GENUINE ARCHER SPRINGS...

 

Any plans on what you're doing for the cage yet? Really curious if you're going to match the SCCA trucks or something else. For that matter, are you keeping things in the cab or do you have plans for going through the rear window?

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Yeah the cage design is something I'm not yet set on. SCCA rules seem fairly simple. Not a fan of a plexi rear window ....... But going through the cab seems a bit daunting as well. I have an idea to make the top of the cage in a "U" shape where the two ends go through the upper cab corners and become the down bars into the bed. The rest would be easy enough.

 

Not sure if I'll go through the dash or drop the "A" pillar tubes down in front of the dash.

 

All this is a little ways down the road still.

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  • 2 weeks later...

Picked up seats for the race MJ.

New in the box 2009 Drag Pak Challenger seats. The guy immediately went with aluminum racing seats for his Challenger. These are flip-forward too. :thumbup:

 

 

 


This is the guy's car....... Awesome. Runs 10.7's.

Image Not Found

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  • 1 month later...
Got some progress on the race MJ.

 

About 2.5" drop up front by cutting 2 coils from the OEM springs.  Added stiff shocks front and rear as well.  Unfortunately I couldn't find any long u-bolts to get the rear done.

 

Front done with rear at stock height and 235 75 15 tires:

 


 

Rear with the race wheels:

 


 

What I cut out:

 


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Dropped the rear.  3" block for now.  I may play with removing the overload leaves and the mid-leaves to see how it sets and go with a 1.5"-2" block this summer.  I've learned that the rear sway bar from a ZR1 Blazer, the stock links from a WJ and XJ rear link brackets makes a sweet setup.  So I plan to get that fabbed up, then I'll play with the leaf packs & blocks.

 


 


 


 

I'm probably gonna have to shorten that load sensor valve rod...... lol.

 


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The stance looks very good to me!

 

Any chance you could snap a picture of the front suspension/steering/etc like you did for the rear? My mind wants to see what kind of clearances there are.

 

Yeah it's tight in there, particularly on the drivers side. It's bump-stopped to keep the UCA from hitting the motor mount bracket. The trackbar bracket is an inch or so from the diff.

 

The D30 and all that OEM steering and stuff will be tossed in favor of a 2wd axle, rod ends and DOM links.

 

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