Mj Rock Truggy Questions

[Matt S.]

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

[VegasAnthony]

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...

[Matt S.]

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!

[woody]

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

[Matt S.]

You think portal outers are over kill on a 60 or 9"????

[woody]

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.

[4ward]

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.

[Flowers]

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

[Matt S.]

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

[C-ROK]

105" to 107" is an excellent choice Matt :)

See you this weekend?

[BrettM]

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

[Matt S.]

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

[BrettM]

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
http://www.pirate4x4.com/forum/attachment.php?s=&postid=530116

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.

[CRASH]

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

[Goatman]

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

[rockwerks]

Well its a start
http://us.f1.yahoofs.com/users/c4df20a2/bc/My+Photos/truck+building/__hr_new+rock+crawler+003.jpg?BCj8NF_APGZgOUUS

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

[BrettM]

Originally posted by xjnation
Well its a start
http://us.f1.yahoofs.com/users/c4df20a2/bc/My+Photos/truck+building/__hr_new+rock+crawler+003.jpg?BCj8NF_APGZgOUUS

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!

[Pete M]

I love my fullwidth axles and would never go back!
http://pic5.picturetrail.com/VOL91/512063/2243189/27115370.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!

[4ward]

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

[Pete M]

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

[Matt S.]

Richard, I agree with the motor. I will probly be doind just that because there is NO other motor that has the low end power and RELIABILITY that is has. As well as the AW4. From what i can remember, you have the RENIX motor correct? Well, I just sold my jeep and it had the RENIX, the engine bay makes me uncomforable and could cause a problem with the tubing work that i HOPE will be done.

NO, i do not have the truck already. And I WONT be buying one until I finish my schooling here in Phoenix. But I plan on getting my entire designing done with math and all. Then begin wiht buying the pieces to build. I have a TON of time for this.

Basically, If you were to cut everything from the firewall forward off and everything from behind the cab off, thats what i am looking into. So I want to have a semi-prerunner body styled LOOK built for rockcrawling. I am thinking that if i can build a full chassis and incorperate the body into it, this would be very benificial for CA laws and such. And because I DO want to drive it on the street to wherever I need to go, I have to pass CA emissions and all that.

Full width 60's are probly what will end up under it because of parts availabilty and reliability. And with at least 38s, probly 40s, shaving is going to greatly help to keep up with the smaller axles.

For the lightwieght ideas, where i get concerned is WHERE the wieght is going to sit. If it is mostly tubular, most of the sprung wieght WILL be in front of the cab. Somehow i have to figure into the design wieghts to creat a blanced vehicle wieght, so the suspension will work much easier, and HOPEFULLY be balanced as well.


THANKS
MATT

[4ward]

Put your battery, radiator, tools, spares, etc. in the back. Unless you plan on doing completely flat rockcrawling, the weight bias seems to be a lot better with it towards the front. Just don't tell Tiny that ;)

Sean

[Pete M]

Since you're in the "planning" stage, don't rule out the Unimog axles just yet. The Volvo portals are the ones that are rare. Unimog axles aren't really that hard to find and are reasonably cheap. (yes, they can be found in junkyards, but I recommend getting someone else to track one down for you ;-) Check out:
http://www.rockymountainmoggers.com/links.html#forsale
and scroll down (way down) to see lots of different companies that carry parts. Heck, they still make Unimogs and sell 'em in this country!
The stock 404 'Mog wears 37" tires (with an ungodly tow rating) and has a coil suspension already, so it's plenty strong and already has link mounting points and coil buckets. The only complication may be the torque-tube length, but even then, if you're starting from scatch you can easily design around it. I'm pretty sure there are companys that make torque-tube eliminators too. And with all that gear reduction, you can even get a 2.5L (another torque-biased motor) to help keep the front weight down. Besides, you'd have to shave the bottom *half* of the Dana60 off to even approach the ground clearance of the portal!
(I don't mean to be argumentative, I just want to see this Comanche *trounce* the other guys, not just keep up! ;-)
Oh, and I once saw fiberglass bedsides for the Comanche on the web. You might want to try an internet search for that.
Jeep on!
--Pete

[Matt S.]

(I don't mean to be argumentative, I just want to see this Comanche *trounce* the other guys, not just keep up! ;-)

That is SOO great Pete. You may have just helped me name the project.

Sean, so a 50/50 wieght distribution is not THEE most optimal way to design? Maybe a thred should be started on actual weight Distribution. This is why I am planning now. Do you think that a rear mounted radiator is going to sufficiently cool? I suppose i could then use a freakin HUGE radiator and big CFM fan(s) right?:eek: :eek:


The only complication may be the torque-tube length, but even then, if you're starting from scatch you can easily design around it. I'm pretty sure there are companys that make torque-tube eliminators too.

??? Sorry, dont really know what your talking about :confused1
What is torque tube?

I know of one company who is making fiberglass front fenders and a hood, think it is Rusty. But havn't been able to find someone who makes a fiberglass bed skin. If that isnt ganna work out, could always do a flat bed or some trick thing back there.

One More subject for the geniouses out there. Can and Will a front 4 or 3 link non panhard bar front suspension be worked around the deep oil pan of the 4.0?? And if that is possible, throw a 404 into that equation!! Do you think that pinion wouldeven clear the motor and undercarriage stuff?? I could see pushing that front half of the jeep WAY forward. I guess in theory by doing that, you could also GREATLY affect the wieght distribution? Because if the cab of the jeep is more central, including the engine and whole body work, I can clear the huge snout of the 404 And help on wieght??

THANKS
MATT

[Pete M]

Hmmm, I guess I didn't really know what one was either. I thought the name referred to the huge pinion, but I did a quick search to find a picture and I've discovered that the "torque tube" is a really long extension coming off the differential that apparently hides the spinning driveshaft inside or something to that effect. Very interesting. :-) There's a pic on the right hand side:
http://www.killeraxles.com/html/mog__axles.html
And one of a conversion:
http://www.bc4x4.com/includes/thumbclickviewer.cfm?imagepath=http%3A%2F%2Fwww%2E bc4x4%2Ecom%2Ffv%2F2002%2Fhulk%2Fhulk%2D15%2Ejpg&caption=With%20the%20torque%20tube%20removed%20and %20the%20pinion%20shaft%20modified%2C%20the%20%27M og%20differential%20looks%20much%20more%20like%20a %20regular%20differential%2E&title=Hulk%21&sa=true
Then it doesn't matter, as you'll need to get the conversion kit either way. Here are some other sites I came across:
http://www.killeraxles.com (great site! Even has axle measurements on it!)
http://www.sorv.com/umcustom.html (has a conversion kit etc.)
http://www.exaxt.ca/ (deals in custom applications and other 'Mog axle stuff)
For the record, that Chevy on the Exact site was built by the man who’s truck I attribute with starting my obsession with Comanches. Rob Bryce! His Comanche was awesome! (I say was because he sold it, not because anything bad happened to it.) Here's the site about his Comanche:
http://www.bc4x4.com/ryeguy/ (scroll down and there's some links)
And some more info on the 'mogged Blazer:
http://www.bc4x4.com/fv/2002/hulk/
As to clearance up front, it will definitely be tight. (Another reason to build up a 2.5L! :-) Remember, you don't need tons of torque from the engine when your axles have 7-point-something gears in them. If you fall back on the D-60s, then I'd say 4.0L all the way. Plus the 4 banger will be easier to cool too.) With a custom built tube chassis, I'm sure it can happen. I know three and four links have been worked around the 4.0L. Do some internet searches and see if you can find some of the portaled trucks and buggies out there to see what they did. I'll let you know if I find anything interesting. I really like the idea of scooting the cab back a bit. If nothing else, I bet it'll look cool! :-)
I can't seem to find the fiberglass bedsides. :-( I know I saw them somewhere, but alas, they don't come up in my searches. Oh well, at least tube steel doesn't self-destruct when it touches rock. ;-)
Jeep on!
--Pete

[Matt S.]

Great links and information!! I had NO IDEA that 404s were so cheap!!!!! WOW. thats all i have to say. Deffinantly going to build around those, well i hope. Pete, remember that i am GOING to drive this on the road, whenever i get the chance. So unless that little 4 popper is charged, it wount do to well.

Another thing I can get some serious input on, if all of you arent bored, to PROPERLY begin my suspension design, I HAVE to decide on axles. If I go and design around portals, how does that suspension actions? Like the roll center of the whole vehicle, the anti-squat and anti-dive of the front and rear suspensions???

In my mind, if raising the SPRUNG wieght 5 inches, i can in theory get 5 inches of lift if STOCK suspension was used right? If that is right, then I will only need LESS than 4 inches of actual lift, if i am shooting for the lowest hieght with largest tire size. Maybe I am confusing my self on this. Maybe someone can clear me upon what EFFECTS that portals will have to how the suspensions works? If it does. Man I think I am lost now! :confused:

THANKS
MATT

[Pete M]

Yup, the further down the portals drop the wheel centerline, the less actual "lift" is needed. And don't forget that you don't need 44" tires with the portals. It'd be easier on all of your components if you design around like a 37" tire. You'd still have more clearance than 44inchers on a Dana 60.
In the July 03 edition, Petersen's 4whl ran an article (like last month or so) on how to design a rear four-link. I seem to remember that it listed a couple books at the end of it as references. If I can find it, I'll scan it for you. The house is extremely chaotic right now though (refinishing the floors), so you might want to check out the magazine rack at the store or you can order it as a back-issue at:
http://www.the-direct-source.com/Products.ASP?DEPT=53

With the axle being that much closer to the "frame", it really isn't that hard to integrate a track/panhard bar into the equation. This rig at Killeraxles.com has one:
http://www.killeraxles.com/assets/images/Axle_Parts_036.xxl.jpg

Exxact can build unimog portals with a Dana44 or Ford 9inch center section. That would allow you to locate the front pinion more to the drivers side and maybe allow you to cut back on the gear ratio a bit. I'm clueless on details, but I'm sure they’d be happy to answer any questions.

And don't underestimate using leaf springs up front. There are lots of ways to get absolutely sick articulation out of leafs now-a-days and they are infinitely simpler to set-up and control (when building from scratch). Here's a couple examples I came across:
http://4wheeloffroad.com/featuredvehicles/92058/
http://www.twistedaxle.com/vehicles/vehicles/samurai.html
It's been done with great success! With the portals, it'd probably be best to do a spring-under to help control the wrap. Then again, if you build a good enough anti-wrap bar, I guess it doesn't really matter.

I think what I'm getting at is the need to do some real world research by tracking down rigs that use some of the components you're contemplating. Check out the rock crawling championship rigs especially. I know there are some running portals. Anything this complicated is bound to be a trial-and-error-fest and the cheapest way to learn is by learning from the mistakes of others! ;-) Find out what each builder likes and what problems they way be running into.

Jeep on!
--Pete

[BrettM]

-quote-
Exxact can build unimog portals with a Dana44 or Ford 9inch center section. That would allow you to locate the front pinion more to the drivers side and maybe allow you to cut back on the gear ratio a bit. I'm clueless on details, but I'm sure they’d be happy to answer any questions.
-quote-



That would be a sweet way to go! I'm pretty sure the 9inch goes down to 2.50 gears and the D44 down to 2.73. I'm also pretty sure the hubs give a 2:1 reduction, so you could run an overall axle ratio in the 5.**s, which would be perfect for 37s.

Search for "JR" and his "Fat City Bronco" on PBB, he has an awesome buggy with Mog/9inch hybrid axles.

[Matt S.]

Thanks for those sites and stuff. The main thing that is of my concern right now and is slowing down my thought process a huge amount, is what changes mathematically that the hub center line / axle center line do to all my measurments???

Ex: Soild axle on 40" tires. Hub AND axle center line are both the same. 4 link is built around the Axle center line, i think. SO it is faily simple to properly link a solid axle.
Now you seperate the Hub and Axle centerlines 5"s from each other, what happens? THis is boggeling my mind! :confused: I KNOW what tires i want to run. I KNOW that i wont need as much suspension lift. I KNOW how much frame clearance i want. What sucks about that is that to find how much suspension lift i need, in comparison with portal axles.

I keep trying to make myslef think as if i was working with a stock vehicle. If portals went under a STOCK XJ, you could fit 33s without trimming. Thats 5"s of vehicle lift, with 0" suspension. I guess what i am trying to get at is I dont want to be TALL. I want to sit the same height as a XJ with 35s and 6-7" lift. This is tough to figure out when dealing with 40 inch tires/ 5"s of hub "lift".

My brain hurts. I know how you feel Beez.

THINKING...................................OUCH!

MATT

[Matt S.]

Since this post has pretty much died.

I think I have figured out the situation.

If 40" tires are being used, your axle centerline is 20" from ground. Now add the 5" portal box to that and the HUB centerline is still 20"from ground, but the AXLE centerline is now 25" from ground. UNderstand so far?

So to MAKE the axle centerline 25" of the first example. You must run 50" tall tires. Hope this is right, if it sounds wrong please correct me.

Well, hopefully this has openedsome ideas into people here, and can help expand the XJ/MJ world!!!!

THANKS
MATT

[Pete M]

Certainly sounds plausible to me. But I don't have any experience running portals or designing four-links. Everything that I could come up with would only be conjecture and theory. You'll still need to ask those individuals who currently run portals or have designed suspension links around them. Have you contacted www.exaxt.ca yet? I bet they'd know or at least may be able to hook you up with some prior customers. Also, I'm dying to know how much it costs to convert the center section to a dana44 or 9inch. Please keep me posted on what you find.
Jeep on!
--Pete

P.S. When in doubt, just start a new thread. If a topic changes course, sometimes it's best to begin anew with a more specific title.

[Pete M]

I found a page that has some decent pics of the Rockcrusher.

http://www.4wdandsportutility.com/features/03044wd_crusher/

Jeep on!
--Pete