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Mj Rock Truggy Questions

Matt S.

NAXJA Forum User
Location
Fresno, CA
I am starting a MJ comanche project within a year and want to begin to design and buy all neccessary items for the rock truggy project. My only demand I am giving myself for the project is RELIABILTY and DURABILITY. Build it right the first time.

Here a few things that I would like opinions on that can help me choose which will work best. Explanations would be extremly helpful.

1. Engine/tranny choice

2. Axles : full width/portal/etc

3. Suspension choices

4. Tire size (west coast rocks)

Most important
5. Wieght goal W/O gear, gas, people, etc.

I hope this is open enough for some good ideas to show up, yet restricted enough to keep it helpful for me and many others

And if there is anything else that is needed to know, fell free to ask. But to clear it all up, i did MUCH searching and cant pinpoint what i need.

I am open to any and all opinions available. I know many people have many differnet other experiences, that is why I ask in such a BROAD spectrum. THANKS!

MATT
 
Umm whats wrong with the 4.0 I have seen big rigs with it climb awesome.

as far as the axle full width would be my choice.. a pair of dana 60's

detroit front and rear

long arms front and military leafs in the back...
 
I didnt say anything was wrong with the 4.0, a great motor. Just wanting to see some ideas that others have had and just not been able to do. Good start Anthony!
 
From whay I saw at Tellico this weekend, a 4.0 firing on 5 or 6 with gears to spin the tires works well. Whatever engine...as long as it stays running through the trail

If the one tickling the happy tounge wants to be noisy...big axles are Mmmmgood

Whenever I get back to my MJs, I think dual 60s are the way to go.

1/4 elliptic rear springs to lose the overhang on an MJ buggy thing... Nothing wrong with coils & 4 link up front IMHO
 
After wheeling this weekend in Tellico, I see that nothing is really overkill... A wound up 4.0 with stock tranny & T case can snap a FF60 shaft (38.5" TSL)and a 9" pinion shaft (36" TSL) so whatever axles you end up with, build them tough. Portals would be great to cure some of the diff snags we all had.

As for tires...the taller & tougher the better. I saw 37" MTRs and 36-38.5" TSLs work really well in Tellico (wet, slimy rocks) so I'd guess they be fine out west. I wouldn't mess with anything less than 35" for a truggy... and 40" or taller isn't overkill, as long as they have room for the suspension to cycle.
 
Portals are overkill on a 60. If you're going with a hybrid axle like that use a 9" or 44 center section. I hope you have lots and lots of money just to spend on axles. Personally, I'd go straight to 404's and not look back, Volvo's are too expensive and difficult to get parts for.

With a 404, you get an axle with the equivalent strength of a 70, 7.54:1 gearing (not good for a street rig unless you're running 53" tires), much improved ground clearance, cable locker, and a Benz emblem for your hood :) All this for less than $2000 for the pair of axles

Drawbacks of the 404- pinion snout is 19" long, gearing is too deep for a dual use vehicle, you'll have to setup a stout link suspension as the inherent design of a portal makes for nice torque induced link bending, disc brake conversions are ungodly expensive but not needed, wheel bolt pattern is funky and you'll need to run 17" rims at the minimum.

I don't live out west anymore, but I've wheeled all over and the bigger the tire size the better as long as you can keep the vehicle itself lower.
 
My MJ project has begun.



1. Engine/tranny choice

For now I'll run the stock 2.5, AX4 and 231. In the near future:Extremely modified 2.5, Auto and a NP205
The 4cyl. will decrease breakage thus increasing reliability

2. Axles : full width/portal/etc

Full width F-250. Rear 60 specs: shaved by ONETON, Welded by LINCOLN, 5:38's, disc conversion, and eventually a Detroit. Front 44 specs: ARB, gears,Warn shafts, 760's

3. Suspension choices

Front: coils, factory 4 link
Rear: Spring over for now, 1/4 elliptic as soon as Beezil and Sean work the bugs out of theirs.



4. Tire size (west coast rocks)

35 BFG Baja's
Walker Evans Beadlocks
If you have the cash...get Krawlers

Most important
5. Wieght goal W/O gear, gas, people, etc.

Minimal weight. I'll be hacking the floor out of the bed and floor boards and replacing with expanded metal. Lose the doors, all of the glass and hack the fenders as needed for around 6" of lift. When the 1/4 ellpiptic goes on I'll bob the bed to just in front of the most rearward point on the rear tire. Some weight will be replaced with the cage.

Good Luck

Flowers
 
Great input so far! Portals are for sure going to be out of my range. I would like to beable to run the 40" MTRs, but I would like to drive it on the street if i have to, or to go to a local run. I am not made of money, and am going to be trying to do as much myself as possible.

I am guessing that if i can run mostly fiberglass fenders, hood, etc over the tube work, i am going to beable to really lighten things up.

Oh! And I need to decide very soon on a WB so that i can begin the math and stuff. I am thinking at LEAST 105", but maybe those who experience JV, rubicon and the trails I am building for to chim in and hear what you all think on length.
THANKS
MATT
 
MOG axles could quite possibly be cheaper than any other axle combination to run 40s. You could still drive it to the trail, too. By my calculations, with a decent overdrive (AW4 or NV4500) you would be at just under 2800 rpms at 60 mph.

You could also do this with Rockwells, they can be had for under $1000 a pair. Properly shaved, they have the diff clearance of a D44.

You would spend about $4000 on a front 60. CTMs and Superior shafts alone are in the $2000 range
 
So after building just a front 60 alone I could be into a bigger axle? But is that better?? The rockwells are freakin HUGE, I am having a hard time seeing them fit under the motor with around 6" of lift. I guess if i did enough tube work it could fit. And 404s snouts are SO long. But maybe with the HP and Portals, that would not be an issue???

So with an engine, if the 4.0 was to be used, what is a good year? I want as little junk everywhere as possible.

Andy, was the NV4500 a direct bolt on?? I would like an auto, because of the convinience, but i like to have options.

I didnt know you could shave Rockwells that much, do you possibly have pictures of that??

Oh and Greg! I made sure to have ZERO plans this weekend. SO just tell me whats good for you.

THANKS!
MATT
 
Yes, Rockwells are HUGE, and it would take some creativity to fit them on a 6 inch lift, but they are wide enough, I would just go taller. As far as shaving them, check this out: http://www.pirate4x4.com/forum/showthread.php?s=&threadid=51753&highlight=shave+rockwell
attachment.php


The snout on a 404 is 19 inches, compared to the 10-12 inches of a D44. With the pinion so high, I don't think it would be a big problem, especially if you extend your wheelbase a little in the process. You also don't have to worry so much about control arm angles because there is 4.5 inches of lift built into the portal hubs.
 
I use an adaptor plate between the OEM bellhousing and the NV4500. A 231 or an Atlas bolts right up with no issues.

I use a 23 spline output NV4500 from a gas V-8 2500 series 1994 Dodge. The diesel and V-10's are 32 spline, and require the use of an NP241 with a 32 spline input. This is what Mistwolf runs, and he's pleased with it, from his reports.

CRASH
 
Matt, when you're talking about building on a budget, how can you beat the 4.0L and AW4 that's going to come in the truck? You just have to be patient and find an MJ with them, unless you already have an MJ with no motor, or one with a 4 cyl/4 spd. In CA, it's hard to swap engine years, so it's MUCH easier and cheaper to run whatever comes in the vehicle. Since the stock 4.0 L and trans are good choices, stick with them. No huge difference between year models on the 4.0, the '87-'90 are Renix controlled, and the '91-'92 are HO with Chrysler engine controls. The HO has a little more top end, low end is the same.

Do you already have the truck?

Are you going to build a total tube frame behind the cab? A short bed MJ is 113" wheelbase, and along bed is 119". Actually, these days, 113" could be real nice.

I think axle choice has a lot to do with budget, and what tire size you have to have. Full width axles have their disadvantages, but they are cheaper to build. Since reliability and durability are priorities, you'll need a D60 for the front (or the portals). In the rear, a custom 35 spline D60, a D70, a 14 bolt, or a 35 spline 9". Cheapest would probably be the 14 bolt. If you're going to get fiberglass fenders, you could cover the full width axles in the front, and you could build a light weight flat bed for the back if you want it to be a steet vehicle (I wouldn't build one that couldn't be driven to the trails, especially where you live).

Sounds like a fun project........I want to build one, too. :D
 
Well its a start
__hr_new+rock+crawler+003.jpg


whats going in it

88 4.0 with 77,000 miles
89 aw4 4x4 converted and rebuilt to 4x4
88 np231 with AA sye
4.1 KLUNE V
zuzu 44 rear from a 96 rodeo.
custom HP44 from a ford F150 cut to waggy size
custom flat bed
spring over
custom long arm front with black diamond coil overs
full cage tied to flat bed
racing seats with four point harnesses
misc. stuff
 
xjnation said:
Well its a start
__hr_new+rock+crawler+003.jpg


whats going in it

88 4.0 with 77,000 miles
89 aw4 4x4 converted and rebuilt to 4x4
88 np231 with AA sye
4.1 KLUNE V
zuzu 44 rear from a 96 rodeo.
custom HP44 from a ford F150 cut to waggy size
custom flat bed
spring over
custom long arm front with black diamond coil overs
full cage tied to flat bed
racing seats with four point harnesses
misc. stuff



That picture isn't showing up for me, even when I paste the URL. I'd love to see it, sounds sweet, try www.montypics.com

Long live the Comanche!
 
I love my fullwidth axles and would never go back!
27115370.jpg

Wider is better! :-D
I used axles from a 78 Bronco, but I don't plan on exposing them to anything bigger than 35s. (those are 33 inchers)
I've been checking out the Volvo portals, but that's WAY far in my future! I figure by the time I can afford them, the availibility problem will have subsided. The main reason I like them is the weight savings over Unimog axles (like *half* the tonnage). Either way, I personally wouldn't go through all the effort of fabrication for the poor groud clearance of a 60 (even with 40" tires), when I can have MORE clearance with Portals and smaller tires. Highway speeds may certainly be a concern for others, but I fitted a tow bar to the front of my truck. I'll never be wheeling alone anyway, right? :)
Jeep on!
--Pete
P.S. I sure hope all of you Comanche owners are saving a couple pics for the Comanche Yahoo group!
 
I'm not sure where you're getting your facts from but the last time I checked the volvo portals are well over 300 lbs. If they were that light, we'd all be running them over D44's.

60's are kinda pointless with anything less than 35's unless you've got the shaving cream out.

I can't wait to see Brian's creation, that thing sounds like it's gonna be kick a$$

Sean
 
I dug up my 4wheel mag and they say 320 lbs for the Volvo. More than a Dana 44 (~250#s), but less than the 500+ lbs for a Dana 60 or Unimog axle. (I said 'half' cause I was thinking the Unimogs were even heavier; my bad) Plus I can run a smaller tire on a portal axle to gain an even further weight advantage over the Dana 60. The article says there's a 5" clearance gain with the Volvo portal over a dana 44 (which would be even more when compared to the D60), so that's a 10" smaller tire I can run and still go over the same rock. It's a beautiful thang! :) Too bad they aren't cheap. But then again, one could spend a mighty big chunk of dough on aftermarket axle assemblies.
Jeep on!
--Pete
 
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