Converting a CJ-7 to rock crawler - JeepForum.com

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post #1 of 16 Old 10-02-2013, 12:13 PM Thread Starter
PcolaJeeper
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Converting a CJ-7 to rock crawler

Hey group,

would love to get your opinions on a few things. First maybe some quick back ground. I have owned a few jeeps, love to go off-roading, most of my experience is in the Gulf Coast south. (woods, mud, trails, washouts, etc .. but no real 'rock / mountain')

I own a '79 CJ-7, AMC 304 rebuilt, 3" lift (32's), w/ turbo automatic transmission just installed and an '83, stock 6 cyl engine/ 5-speed transmission (less than 50,000 original miles), 4" lift (33's). (neither jeep has anything extra done to axle's, etc)

So far I've gone with the idea, when something breaks, fix it better, until then, keep riding.

My friend takes a yearly trip to CO, rides/camps out. The trails are pretty isolated and feels that some haven't been ridden on since their last trip. It's mountain, hard rock trails and sometimes you have to deal with small boulders/large rocks in the 2' - 3' size. I want to start making these trips with him. (I'll trailer my jeep up)

He's into the newer jeeps (currently has a 4 door Rubicon, I'm into the older CJ-7's. I love the CJ look and feel.

If you're willing to spend enough money, I realize any jeep can be outfitted for any environment. I don't have that type of money, but I do have some money put aside for play.

My question .... Being that I want to expand my off-roading, should I consider buying something newly used with the 'rubicon' suspension/axle upgrades? Or is it practical to 'upgrade' my CJ? If I switch to Dana 44's, S.o.A. conversion, upgrade transfer case, re-gear axle, add lockers, etc (ton of things I don't know enough about) would I even be able to match a stock rubicon?

Very interested in hearing your thoughts. Thanks

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post #2 of 16 Old 10-02-2013, 12:38 PM
Renegade82
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That's a tough question to answer. Jeeps generally weren't made for rock crawling but can be adapted. The early wranglers weren't either but their later models were better suited when they switched to coil spring / track bar type suspensions. That being said, you can adapt that type of suspension to a Jeep as well, it just takes a bit more fabrication but both a Jeep or a Wrangler would need to use an aftermarket suspension so that kind of a wash as far as money goes. If it's primarily a trail rig you could still use the leaf spring setup but do a spring over axle conversion which will allow more wheel travel. And that's a big part of a "crawler" is suspension travel and articulation. Beyond that it's about using a beefier axle which is generally an aftermarket item to either rig so the cost is again a wash.
As to your question about matching a stock wrangler rubicon packaged rig, to a modified Jeep. Easily! Most of the rubicon crawlers you see are highly modified as well.

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post #3 of 16 Old 10-02-2013, 12:42 PM Thread Starter
PcolaJeeper
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Thanks Renegade ... If it's a 'wash', then I rather put more upgrades into my CJ!
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post #4 of 16 Old 10-02-2013, 12:49 PM
Spieg8
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Being that you already have a CJ, I'd think it much cheaper to modify what you have than to buy a whole new Rubi (even a Rubicon will need some modifications to hit the more difficult trails... lift, tires, body armor, rock sliders, etc...). Probably never going to get a leaf spring suspension to flex as well as a coil spring setup, but they can still do pretty well. You can of course put coils on a CJ if you want to go to that extent (some kits are even better than what you'd get on a Rubicon).

Another thing to think about - Fuel injection is a real nice thing to have on a rock crawler (they will run smooth at most any angle, and don't mind being bounced around a lot). This is an area where the newer motors have an advantage. If you currently have a carbureted motor, you might want to think about an upgrade to TBI or MPFI.
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post #5 of 16 Old 10-02-2013, 01:00 PM
dg6772
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As to the fuel injection, most tbi's are adapted from the G.M. tbi. It isn't very expensive to salvage a system from a early 90 G.M. mine cost 35.00 with the computer and all sensors

Dave in Muskegon
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post #6 of 16 Old 10-02-2013, 01:21 PM Thread Starter
PcolaJeeper
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Thanks guys .. Fuel injection was something I meant to bring up. neither jeep has fuel injection and I was worried about it




Quote:
Originally Posted by dg6772 View Post
As to the fuel injection, most tbi's are adapted from the G.M. tbi. It isn't very expensive to salvage a system from a early 90 G.M. mine cost 35.00 with the computer and all sensors

Dave in Muskegon
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post #7 of 16 Old 10-02-2013, 01:26 PM
CJuncky
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There are a ton of trails you can do in Colo with out a lot if any mods to a CJ. my current 5 has a 2 in lift with 33's. I do now have lockers in the stock diffs but don't use them hardly at all. Low gearing is nice but not a must for a lot of trails. Best advice I can give is get a couple of books on Colo trails, check the rating, pick a few trails rated for what you have, do them, and mod as needed for the harder trails.

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post #8 of 16 Old 10-02-2013, 01:54 PM
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Unless his Rubicon is radically modified, I don't think you'd have issues keeping up with him if you locked both axles and tossed 33's on. He's not crawling 2-3' boulders either, unless he's got a LOT of high zoot mods.

Matching a stock Rubicon isn't too hard. Their 31-32" tires are often too small for anything remotely serious, regardless of lockers and gearing. The low gearing is nice but not necessary in most places IMHO.

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post #9 of 16 Old 10-02-2013, 03:59 PM
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To add on to this discussion and noting that you mentioned increasing your offroad abilities, I must say that to do all the mods that have been listed above would be very costly. You could build a full blown rock buggy that will out perform my modified vehicles for the same price or less than the cost of modifying your CJ. All the upgrades you would be doing to the CJ or a newer Jeep would be done to a buggy and you would actually have more options and be able to build a rig that would out perform what a Jeep could do(limited travel without cutting body panels). I think that a decent vehicle setup with strong axels and lockers is capable beyond what most people realize. There are lots of trails in CO that your current Jeeps would do just fine on.

1981 CJ7 I6 258, NP435, Dana 300 Twin Sticks, AMC 20 & Dana 30 with Lockers, On board air, 33" X 12.50" tires
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post #10 of 16 Old 10-02-2013, 08:17 PM
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So here's the real question: How much money will you commit to spending?

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post #11 of 16 Old 10-03-2013, 02:54 AM
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Both your CJs will manage a lot of hard desert rocky trails with minimal further mods. Often technique, skill and strategy can outdo dollars on expensive kit. Before you hit the trail I suggest:

1. Service the vehicle, especially greasing.
2. Check the condition of U joints - easy to replace in the garage, less so on a mountainside
3. Check tyres and spare
4. Carry a farm jack, recovery gear, water, tyre pump, tyre repair kit, fan belts and a small tool kit.
5. Carry out a thorough check for worn parts and unfastened kit, like fuel tanks which are not strapped down and bushes which are shot.

None of this will blow the bank but should let you play with the other Jeeps and come home.

If you want to beef up the vehicle a rear locker is very useful, followed by a front locker and then a winch. They are all about getting you out of trouble that you maybe should not have got into.

Once you have blown your money on those items the sky is the limit.

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post #12 of 16 Old 10-03-2013, 03:44 AM
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Do you have low range with that Quadra-trac?

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post #13 of 16 Old 10-03-2013, 11:10 AM
Renegade82
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" I think that a decent vehicle setup with strong axels and lockers is capable beyond what most people realize. There are lots of trails in CO that your current Jeeps would do just fine on."

I agree. I wheeled all over SoCal trails with a fairly close to stock (11x15 tires & 3" of lift via shackles and add-a-leafs) and kept up pretty well. Going from stock tires to the 11x15 (32") Tru-Tracs made a huge improvement. I guess we need to know or see your buddies rig to get some comparison as to what you'd need, cause I'm picturing a heavily modded wrangler jk (since he can afford to trailer it out west every year, money probably isn't an issue). I think the guys here could suggest things that will have you following him just about anywhere. Knowing your rigs abilities is an important part in facing new trails. They didn't stop making Jeeps because it was lacking in off road capabilities. After all, they wrote the book and set the standard!

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post #14 of 16 Old 10-03-2013, 12:02 PM
Spieg8
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Just a quick note about Colorado trails. Here is a link to a site with a lot of details on specific trails;
http://www.traildamage.com/trails/index.php
Trails are rated for difficulty from 1-10. Generally speaking (very generally speaking), trails rated at about 5-6 or above will be best attempted with lockers and 35"+ tires if you want to be able to get past obstacles without stacking rocks and/or winching (8-10 will often require stacking/winching unless you drive a rock buggy).
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post #15 of 16 Old 10-03-2013, 12:03 PM
Krum81
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Most of my area is Rock and my CJ5 does 80% what most new vehicles do you got to know your limits.

DO you need d44? are you planning on running 35" or larger tires? Do you have heavy foot? If yes to any of those then you better upgrade axles.

IMO if a old cj has -

Good brakes
rear locker or power lock rear end
Well maintained Jeep
small lift and decent tires
Gears to allow torque to do the work

Bonus items would be

TBI - was a huge upgrade for me considering i live at 271ft and can be at 8000ft in 1 1/2 hrs
SOA at least front
D44 front and rear / or yota axles " cant believe i said it "
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