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September 2008 4x4 Tech Questions - Techline

Posted in How To: Tech Qa on September 1, 2008 Comment (0)
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I am planning a project rig based on a Jeep Cherokee. Short term, I am thinking gears and 35-inch tires. Long term, I am thinking motor buildup, winch, lighting, Atlas transfer case, and so on. This rig will be mainly for camping, trails, and medium-difficulty wheeling with my family. Can you offer any advice on a year and trim package best suited for what I am trying to do? What additional modifications will I need to make in the short term to get the bigger tires on and perform? Does one year have a better motor/transmission/transfer case/axle setup than the others? I don't want to replace the axles, but would upgrade the shafts and so on if need be.

Brian Cracraft
Mesa, AZ

The XJ Cherokee makes for an excellent trail vehicle. You just might want to go to your back issues and read our Grand Cherokee "Project Ain't it Grand(er)" series, which dealt with the suspension, and front and rear axle upgrades. You can find these stories on our Web site at www.fourwheeler.com.

Yes the rear suspension is coils on the ZJ, versus leaves on the XJ, but the front is nearly identical. I would start out with a '97-'00 model, mainly because you didn't want to change out axles and you can get the high-pinion front and the Chrysler 8.25 rearend with the 29-spline rear axle. There were some '96s that also used the 29-spline axle over the earlier '91-'96 27-spline axles.

Starting in '97, there were some body improvements that were also worth having. We used the ARB locker up front, and over the last year it has worked just great, other than you really have to remember to unlock it when making a turn. Finding room to mount the air compressor under the hood is kind of a magic trick.

In all reality, I would suggest that you stick to 33-inch tires unless you plan to upgrade the front axle with the three-spline locker and 44-style axles such as Superior Axle & Gear sells. Even with 33s, it would be a good idea to do the upgrade. To make the 35s fit, you need some aftermarket fenderwell cut-out flares such as those from Rusty's Off Road or Bushwhacker.

The Chrysler 8.25 isn't as strong as the Ford 8.8 that we installed in project "Ain't it Grand(er)," but it should handle 33s without a problem, especially with an axleshaft upgrade. Again, 35s bring up the subject of strength, especially in the smallish Dana 30 front end. I think that if I were going to run 35s, I would want to use a 4.89:1 gear ratio, but this makes for a mighty small pinion gear and I would not recommend anything lower than a 4.56:1 ratio, strength-wise. I know (and am sure someone is going to write and tell me it's not a problem) there are people who are running these lower gears with 35s, but I don't like to break things and they will break in time with any serious four-wheeling.

Suspension-wise, I definitely recommend a long-arm suspension up front for any lift over 3.5 inches. The factory-length control arms are just way too short, and with the lift, the operating angle is such that with any bump, the wheels have to travel in a steep forward arc as they move upward, making for a terrible ride as well as putting more of a load on the subframe mounting locations. There are a lot of good long-arm kits available, with each having its own good points. I would also recommend using a full set of springs in the rear instead of just an Add-A-Leaf or lift blocks to gain the needed tire clearance. Again, it has a lot to do with ride quality.

An Atlas transfer case is an excellent choice, but the 231 with a slip-yoke eliminator kit and possibly an update to 241 planetary gears and drivechain also make for a good combination.

For engine performance modifications, two of my favorites for the 4.0 are a K&N air intake system and a set of Borla headers. I have used these on two different 4.0 XJs, and cannot get over the performance gains. I am sure that there are other intake and exhaust systems that work equally well.

I am looking into doing a budget build on a Wrangler or CJ. I am not particular on the year, just looking for cheap. I would prefer a five-speed six-cylinder. I would primarily use it for a fun weekend car and a little plowing in the winter. I was hoping to put in a rebuilt engine and transmission, Rhino-Line the interior, and add a mild lift. The toughest part of it all is I am considering using a Toyota drivetrain. What really concerns me about this is having to possibly put in a new computer and/or transfer case. I think that might get expensive. What do you think? What model year would you recommend, engine setup, and any other tips, as I am new to Jeeps?

Mike Gilman
Oak Grove, KY

By all means go with the Wrangler over the CJ. To start with, the suspension system is much better, and the frame is stiffer. Find a '91-or-later with the 4.0L fuel-injected six-cylinder and the AX15 transmission. The really weak link is the Dana 35 rear axle. If you don't use it hard, and limit the tire size to, say, 31 inches, then I have known the axleshafts to last well over 150,000 miles. With 33s and a bit of traction, the axleshafts are made of butter. If you decide you need a stronger rear axle, then keep your eye out for a disc-brake 8.8-inch rearend out of a Ford Explorer or a Jeep Dana 44 from a TJ to swap in.

When you say you want to use the Toyota drivetrain, do you mean engine, transmission, and transfer case along with the front and rear axles? Well, the Toyota components are pretty darn strong, but to go to all that much work to install them would be, well, a heck of a lot of work. Yes, you would need a new computer and wiring harness to make the swap, and then would the Jeep still be emissions-legal in your state? If that is the way you're going, then I suggest you buy a pre-'91 as it would be easier to get around most emissions issues.

I have a '95 Dodge Ram 1500 two-wheel-drive with a 360 V-8. I was in an accident where I rear-ended someone, with most of the damage occurring to my vehicle on the driver side. Now, with the wheel at center, and turning to the right, it will go to the lock, but from center turning to the left, it only goes half to three quarters of a turn. I have replaced the steering gearbox, replaced the passenger pitman arm, had the drag link and tie rods checked to see if they were bent. I need help to fix my truck. Does anyone have any idea what could be wrong?

Chris Wallen
New London, OH

That's a tough question to answer without really looking at all the steering components. My first-and in reality, only-thoughts I have are that you do not have the steering gear in the steering box centered. I suggest that you pull the drag link off the pitman arm and then turn the steering wheel all the way until it stops in one direction. Mark the steering wheel with a piece of tape in alignment with a fixed object. Now turn the wheel in the opposite direction, counting the turns it takes. Divide this number in half, and then turn the wheel back to this number. This will place the steering box gears within their center.

The steering wheel's crossbars may or may not be centered. If they are not, remove the coupler from the splined input shaft of the steering box and reinstall it with the wheel in a centered position.

There may be a flat spot on the steering box's input shaft. If so, this flat spot should be facing upward; if not, turn it so it is before connecting the coupler. My guess is that you're going to now have to change the adjustable length of the drag link so it properly lines up with the pitman arm.

I have a '92 YJ with the 4.0L, five-speed, 1-inch body lift, and 31-inch tires. It is a commuter vehicle but I love it. The Jeep is going through clutch master cylinders like crazy, they leak at the stem in the cab side of the firewall at the pedal connection. I have tried O'Reilly's, Napa, and Chrysler replacement parts, but what is the trick? Replacing and rebleeding every 8 to 10 months gets real old.

I bought this Jeep two years ago with 200,000 miles on it. I have rebuilt the engine, brakes, transmission, and transfer case. I replaced the clutch and slave when leaking, and sealed it. About all that is left is paint and interior and this thing will be "like" new, but this clutch master cylinder is driving me nuts. I'm on the third one since an engine and trans overhaul maybe 6,000 miles ago. Is there an update or some trick? Let me know, please.

Heath Edwards
Edmond, OK

I am not sure if I have a solution or not. I checked for any factory TSBs on the subject and came up with none on the master cylinder. I checked a factory service manual to see if I was missing something that you might have inadvertently done.

I assume that you are not trying to rebuild the master cylinder with some kind of a kit. If so, you're really out of luck as the aluminum cylinder doesn't hone properly. I was also under the impression that one could not just buy the master cylinder from Jeep but had to also buy the slave and the connecting hose, and that is about $200, the last time I looked.

Where you say it is leaking is just about the only place that it can leak any fluid out. My best guess is that the pushrod is not attached to the clutch arm in the proper location. When you depress the clutch, the pushrod may be at too much of an angle and is putting some side load on the piston, causing the cup to not seal properly. Could it be that someone, for some reason or another, changed out the clutch-pedal assembly for something different, or that the Jeep originally had an automatic trans and was converted to a manual and the wrong clutch-pedal assembly was installed?

I suggest you take a close look at the pushrod, and make sure when the clutch pedal is pushed in, the rod pushes straight into the piston and not on an angle. If it does go in on an angle, then I suggest that you redrill the mounting hole on the clutch arm so that it pushes straight in.

I like to look at off-highway vehicles, be it a super-trick rockcrawler or an average trail rig, as there is always something interesting on them. Lots of times I get some really good ideas to pass on to readers of this column. However, this month, I want to pass on some "bad" things that I commonly see.

1 Excessive U-bolt length: Most spring-under-axle vehicles, such as CJs and TJs, have their U-bolts over the top of the axle pointed downward past the springs and through a bottom plate. Nuts are used to tighten the U-bolts to hold the leaf-spring pack up against the axle. The excessive amount of U-bolt length past the nut is not only a great rock catcher, but you take the chance of it actually breaking the U-bolt when it does catch on an obstacle. Cut the excess off! Even at that, you still have the nuts hanging down. There are several aftermarket companies that make skidplates for these nuts, but these reduce ground clearance. Your better choice is some special spring plates with wings off to each side that move the nuts up above the bottom of the spring.

2 No bumpstops or improper-length bumpstops: Bumpstops are there for a number of reasons. They keep steering components such as the tie rod or drag link from contacting the frame; the differential housing or driveshaft from hitting the engine; and, best of all, they act as an extra cushion when the axle reaches its limit of upper travel. One of the fastest ways to destroy a leaf-spring pack is to let a positive arch go into a negative arch. The same thing goes for shocks-they should never bottom out their stroke before a bumpstop is fully compressed. I've actually heard people say something like, "Oh, my springs are so stiff, they never flex that much." Well, I'm glad I'm not riding in that vehicle.

3 Shackle angle: This fits right in with springs, as the spring shackle should always be pointed at a slight angle in the direction it moves when compressed. I've seen mistake made time and time again, especially on Jeeps with front-axle shackle reversals. With the shackle pointed forward at a normal ride height, axle drop is limited, plus there is some loss of ride quality.

4 Axle shims!: Before I get off springs, let's talk a bit about using shims to correct pinion angle. I have nothing against shims, as often they are a necessity. What I don't like are those thin, cheap cast-aluminum ones that just sit over the spring center bolt. Maybe these are OK on a passenger car, but not on a rig that sees trail use. Springs flex, U-bolts stretch, and that shim cracks and falls out. Now you wonder why your rig is handling so terrible. Oh, look! The axle is flopping around. Same kind of thing happens when the shim is too thick and the spring center bolt now won't fit into the locating hole on the axle pad.

5 Rollcages: Those who build rollcages to cover the front seats but let their rear-seat passengers (usually their kids!) hang out in the open. Spreader bars between the front and rear hoops that have a compression bend in them and/or are not out to the far edge. Mounting plates that only have washers on the underside of the body on the hold-down bolts. Joints that lack gusset plates.

6 Missing lug nuts: Come on, guys, the manufacturer put X number of lug nuts on a wheel for a reason. Missing one of five lug nuts means 20 percent less center support. There are only two ways a lug stud is going to fail. Both are from improper torquing of the lug nut. Overtorquing stretches the stud past its point of elasticity, and undertorquing doesn't stretch the stud enough to retain the nut.

7 Poor welds: Poor welds not only don't look good, they generally aren't good. You have to be a really good welder of heavily V-notch rollbar tubing to get a safe quality weld with a flux-coated 110 wire-feed machine. On a rollbar, you're trusting your life to the quality of that weld. I hate to see welds that look like chicken crap or those that were heavily ground down in an attempt to clean them up. If you're not sure about the quality of your welding, let a pro do it instead.

8 Winch cable: Bird-nested winch cables are not good. When a pull is put on them, they kink, flatten, and pinch the cable strands. This definitely causes weak spots at these points. When I see this, I really question just how safe is that person's winch cable.

9 High-mounted equipment: OK, there is no room for the spare tire inside the vehicle, or that ice chest, so where do you mount it? Up on the roof rack? Wrong? Most roof racks were never designed for a 100- to 150-pound tire and wheel, or a 50-pound chunk of ice and ice chest. Not only that, but think what it's doing to the vehicle's center of gravity. Modified 4x4s are tipsy enough on their own. You don't need the extra leverage of additional high-mounted weight.

10 Loose items: Or even improperly mounted items like Hi-Lift jacks or ice chests held in place with rubber tarp straps. Would you want someone to toss a camera or hard water bottle at you from 3 feet? Not really, but what happens to those items in a rollover?

11 OK, I went over 10: People who hit the highway after a trail ride and don't take a few moments to take a look under and around their rigs for any trail damage that just may develop into a bad consequence at 65 mph.

Address your correspondence to: Techline Four Wheeler, 6420 Wilshire Blvd., Los Angeles, CA 90048. All letters become the property of Four Wheeler, and we reserve the right to edit them for length, accuracy, and clarity. The editorial department also can be reached through the Web site at www.four wheeler.com. Due to the volume of mail, electronic and otherwise, we cannot respond to every reader, but we do read everything.

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