I need help :(

[Newcomer12b]

I just recently started getting into mudding, and last time I was home on leave I picked up a 78 CJ7 . The guy I bought it from did a few mods to it and I'm wanting to do some of my own. The only thing is I have never built a mudder before and I have no idea what I'm doing. I have some ideas of what I would like to do, but I don't know where to start! Right now I'm just looking at putting 37" tires on it but I've been told going with bigger than 33" tires I will have to do a lot of modifications to it. Any information would be much appreciated!!

 

[Old Dog]

Right now I'm just looking at putting 37" tires on it but I've been told going with bigger than 33" tires I will have to do a lot of modifications to it. Any information would be much appreciated!!

To do good in the mud you will need good horse power (think V8) to spin the tires
that means you will need better axles than you have stock now. Also
to fit 37's you will either need to trim the wheelwells or have a really
tall lift to keep them from rubbing.
You should hang out at the local mud hole and see what other people
are running to get some ideas.

 

[IOPort51]

for a start, check into one piece axles for the rear axle, locking differentials for both ends,four inch lift, at least 4.XX ring and pinions both ends and 33" super swampers. That should pretty much use up your disposable income for the next 2 or three years and supply hours and hours of entertainment.
:ww:from the Republic of Texas and good luck on the path to enlightenment.

 

[Newcomer12b]

I've got about $10,000 I can put into it. It has a lift right now. I think 37's might fit under it. I need to get ahold of the guy I got it from and find out exactly what he's done to it. It has 33 Super swampers on it right now. I just wanted to go a little bigger because of where I've been taking it.

 

[jasonmark1993]

What engine did it come with?

Depending on how serious you want to get a decent AMC 304 should work.

Beef up a Dana 44 with some lower gears; same with the front. Dana 30 ?

Expect to spend a couple grand doing that; if you want bigger axles altogether (like a Dana 60 rear and 44 front) plan on spending 5-6K just on that.

Your going to have to get custom driveshafts if you really want 37" tires.

I've never run tires that big but I'd use a combo of a decent lift and trimming the body and getting some aftermarket front fenders from Bluetorch. You can really get into it with lots of lift when you have to change steering components, brake lines, etc.

I'd start with the engine and work your way back. Lift and tires last.

 

[rr41mag]

I have 35's with a 4" suspension lift and 1" body lift and they have plaenty of room. Start by putting a header on that will give you a little bit more power.

 

[TeamRush]

You are headed for a number of problems you will need to solve...

37" rubber will require a substantial lift,
Lifts over about 3" REQUIRE a dropped pitman arm on the steering box unless you want issues with steering, which is never good.

The biggest thing that comes to mind is the axles under your particular year of Jeep...
Dana 30 front and AMC20 rear aren't the sturdiest axles to start with,
And when you start talking about large tires (Seriously over leveraging the axles) they usually don't live long...

I would look into finding a set of WIDER axles also.

TALLER rubber gives you ground clearance,
WIDER axles gives you turn clearance for some steering.

Most people just think about clearing the fender tops,
But you have to be able to STEER those 37" tires also, and they will usually get into the frame long before you hit the factory steering stops...

Full width axles out of an earlier Full Size Jeep (FSJ) will give you FULL SIZE Dana 44 axles front and rear,
And they will give you stability side to side,
And they will give you steering room for really tall tires.

Since every manufacturer used Dana 44 axles in the front at one time or another, there are TOP STEER knuckles out there, which gets your steering linkage up and out of the worst of the mud.

Scout axles used a Dana 44 center section, but they used the small Dana 30 tubes, axles, U Joints and steering knuckles...
So if you consider a switch to Scout axles, it's always better to go to a full size Dana 44 rather than a Scout Dana 44 if you intend to run really tall tires.

Outboarding the spring mounts, Mounts for the spring ends moved outside the frame instead of under the frame, allows you to accomplish two things,
You can lower the center of gravity by moving the spring mounts UP the frame,
And you can fit full width axles without a lot of custom machining to the housings/tubes that costs a lot of money.

If you play 'Mix & Match' with axles (requiring a regear, which you will have to do with lockers anyway),
The axles from under a J-20 truck have a heavy duty version of a Dana 44 in the front,
MUCH stronger than an older, lighter duty Dana 44 from under a wagon with a Dana 44 in the rear.

Some of the earlier J-20 trucks had a D-60 in the rear,
Some had an AMC20 in the rear, so be aware of that.
I don't much worry about a front axle coming with disc brakes or drum brakes since I usually use Chevy or Dodge steering knuckles with high steer,
And about all those came with disc brakes, so I swipe the entire steering knuckle, spindle, brakes, ect.

A D-60 in the rear hangs down quite a ways,
So one alternative to keep your ground clearance is a heavy duty Dana 44 up front,
And a Ford 9" in the rear.
Ford 9" gives you a LOT of extra ground clearance in the rear, comparable to the Dana 44 , and it's VERY STRONG if you get the large tub/bearing version out from under a Ford Pickup.

Ford Pickup 9" rear diffs are VERY tough, and since every racer around the country runs them, they are VERY EASY to get axles and custom hardware for, like disc brakes and high pinion differential center sections.

Ford 9" rears are VERY easy to narrow and weld on, and they grow on trees for cheap.

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Lockers are an issue, so make sure you get a SELECTABLE locker for the front.
It's very hard to turn with both axles locked solid, so a selectable in the front will allow you to unlock to make turns MUCH easier and require a lot less steering effort.

Large tires like 35" up are hard to turn, especially in mud or up against a rock or tree,
All that extra stress is transferred to the steering box and frame,
So a heavy duty steering box BRACKET & BRACE is a very good idea!

When guys run large tires and actually wheel the vehicle hard, they always wind up doing one of two things, (or both),
They knock the bottom bearing out of the steering box,
And/Or they crack the frame where the steering box attaches to the frame.

A heavy duty steering box bracket is a real good idea,
And if you find an FSJ, swipe that VARIABLE RATE steering box with heavier bearings and internals and mount that in your CJ.

--------------------------

Gears are something you don't want to do twice...
So when you get to looking around at the gear sets, go deeper than you think you will need.
Better to error on the side of being able to turn the tires than to breaking drive line parts...