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Your Jeep Tech Questions September 2015

Posted in How To: Tech Qa on July 30, 2015
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Best Loaded Lift

I have enjoyed Jp for years. I just bought my second Jeep. I was tired of getting beat up by my old YJ. At 65 years old, I'm ready for some comfort. The new Jeep is a '04 Wrangler with 125,000 miles on it. It has 31-inch tires, a winch, and a hardtop. The suspension needs help. The frontend is sagging, and there is not enough clearance for the 31s. I was thinking about a 2 to 21⁄2-inch lift. I'm happy with 31s but I may go to 32-inch tires eventually. I have been looking at the ARB Old Man Emu (OME) lifts. Most lift kits seem to come in inches of lift. OME gives you options such as winch, hardtop, gear, and so on. This is an all-purpose Jeep. We live on small ranch, so it's a ranch Jeep and a drive-to-town Jeep, and every summer we spend month or so in Colorado. I plan on adding roof rack for a kayak. I also carry lots of gear to Colorado. At some point I will likely add a towbar so it can be towed to Colorado. I'm looking to get room for 31s with good ride and not a bunch of changes to the drivetrain.
Wayne Rossi
Austin, Texas

Given the hardtop, winch, and the variety of hauling tasks that the Jeep performs, I think you're on the right track with the ARB (arbusa.com) OME 2-inch lift kit. I would recommend the OME Heavy Kit (PN OMETJHKS). Two inches is about as far as you want to go without installing a slip-yoke eliminator kit and CV rear driveshaft. The lift will easily clear 31-inch tires. The 32s can be made to fit with the proper wheel selection. The OME Heavy Kit suspension will ride a little firmer than the standard suspension kit when the Jeep is unloaded, but the suspension won't sag as much when loaded up for trips.

Increase Tow Capacity

I own a '09 Jeep Wrangler Rubicon Unlimited and was wondering if there is any way of increasing the tow capacity. I'm of retirement age now and was thinking of getting a 16-foot self-contained trailer, but the Unlimited will not (or is not rated) to tow anything that is over the 3,500-pound range.
Doug Schaffernoth
Via email

Unfortunately, there really is no reasonable and safe way of increasing the tow capacity of your Wrangler Rubicon Unlimited. There are many factors that are taken into consideration when the tow capacity is derived by the manufacturer. This includes power, drivetrain longevity, suspension, frame strength, braking, stability, cooling capacity, and more. If a self-contained travel-trailer is in your future, you might want to consider a Jeep that is designed to haul heavier loads, such as the Grand Cherokee. The Grand has a tow capacity of up to 7,400 pounds, depending on the options you select.

No Lift Shock Input

I own a '12 Jeep Wrangler Unlimited Arctic, and I am looking for tests of aftermarket shocks on non-lifted Wranglers. I am currently using a set of Bilstein shocks, but they don't seem to help handling much. Have you ever tested Fox and/or King shocks on a non-lifted Wrangler JK?

Also, I have been told that the exhaust manifold is integral with the heads and that no headers exist for the '12 model. Is that true? I have supercharged my 3.6L V-6 with the Magnuson supercharger and a Squires Performance tune, and it runs great! I subscribe to your magazine because you say you are for "All Jeeps," yet I haven't found any articles on non-lifted Jeeps. Please keep those of us in mind that don't go rockclimbing or mud diving. I rarely drive on a dirt or gravel road, but I do drive and corner faster than most.
Ronald Corte
Via email

Fortunately, many of the same suspension principles and components we cover for lifted Jeeps can be easily applied to non-lifted Jeeps. Everyone has a different driving style and ride preference. It sounds like you prefer a slightly firmer and sportier suspension. You have a couple of options to help make your Jeep a better corner carver. Your aftermarket Bilstein (bilstein.com) shocks can be rebuilt, revalved, and tuned for more performance and a firmer ride. Unfortunately, your particular model shocks cannot be revalved at home. You have to ship them back to Bilstein.

Fox (ridefox.com) doesn't offer a bolt-in off-the-shelf shock that fits a non-lifted JK. The minimum lift is 11⁄2 inches. That's not to say that Fox can't build you a custom shock. The company probably can, but you would have to call Fox directly. If you go this route, I highly recommend adding the DSC reservoirs to your order. The DSC knobs give you the ability to externally adjust the low and high speed compression valving. You'll be able to tune in the ride and handling that you want. This is probably the most ideal solution, although it will not be an inexpensive one.

King Shocks (kingshocks.com) offers bolt-in OEM Performance Series shocks that fit Jeep JK Wranglers with 0-2 inches of lift. I would recommend the 21⁄2-inch-diameter remote-reservoir shocks with the compression adjuster. Like the Fox shocks, they will be total overkill for your application, but they will give you the firmer ride you are looking for along with some adjustability.

You might want to also look into the ARB (arbusa.com) Old Man Emu BP-51 shocks. There is a JK application being developed, and it should be available by the time you read this. The BP-51 shocks are internal bypass shocks with compression and rebound adjustability. Again, they will be total overkill for your application, but they will provide the adjustability and sporty handling you are looking for.

It's true that the exhaust manifold structure is built into the heads of the 3.6L Wrangler Pentastar V-6. This design helps eliminate exhaust leaks at the manifolds. There is no need for a header. To increase performance, you could remove the heads and have them ported, though.

Keepin' it Cheap

I just picked up a super-clean '98 TJ Sport with a hardtop, 4.0L, five-speed manual transmission, limited-slip Dana 44 rearend, and 3.73 gears. My hard-wheeling days are not what they used to be. My dilemma is whether to do a 2-inch budget boost with adapted JK 255/75R17 tires and wheels (I work at a dealership so we have a few take offs laying around) or to step up to a 3-inch suspension lift and run 285/70R17 tires. One is 32 inches in diameter and the other is just shy of 33 inches. I'm trying to avoid doing a regear at this moment.
Eric Faley
Via email

If you decide to step up into the 3-inch lift, you'll also want to budget in a slip-yoke eliminator kit and CV rear driveshaft. It becomes pretty much mandatory at about 21⁄2 inches of lift. The driveline vibration from a 3-inch lift without the slip-yoke eliminator is enough to drive most people bonkers. The resulting vibration wears out the transfer case rear output seal and rear driveshaft prematurely, which can lead to transfer case failure. So, if a slip-yoke eliminator and CV rear driveshaft are off the table, go with the 2-inch budget boost. The 3.73 gears will be fine matched up with the 4.0L, manual transmission, and 32-inch tires.

Four-Link Query

I have a question concerning the installation of a rear four-link kit on a Jeep XJ Cherokee. If I was to install a rear four-link kit, will I be able to pull a loaded 8x10-foot utility trailer? I've searched the web, and I'm getting no answers. I like how much flex I would gain versus the leaf springs, but I still want to be able to pull the trailer. Any information will be appreciated.
Adam Carr
Via email

Switching to a four-link rear suspension won't necessarily make your XJ incapable of towing. Many vehicles with four-link rear suspensions tow trailers just fine, including the Jeep JK Wrangler and ZJ, WJ, and WK Grand Cherokees, among others. The key is in how you set up the suspension. When towing the trailer, you'll want to make sure you have a heavy rear sway bar to help control the suspension movement in corners and in windy conditions. You'll also want to use dual-rate springs or, better yet, coilover shocks with dual rate springs and compression adjusters. Properly selected and adjusted dual-rate springs will help keep the suspension from overly compressing under the tongue weight of the trailer, without killing your unloaded off-road performance. The compression adjusting feature will give you the ability to slow the movement the heavy trailer when it hits big bumps in the road and switch back to normal for a smooth on- and off-road ride when not towing. It might take some time to get the rear suspension tuned to work great in both scenarios, but it's totally doable.

Editor Trasborg adds: I did it with my TnT Customs rear four-link coil conversion. While they weren't happy I was beating the Jeep, it did fine. Squat was great. Torque steer nonexisting. The only issue was I killed the rear shocks super fast. A set of Rock Krawler RRD shocks fixed that issue, and afterward I had no problems.

Cranky Old Iron

I purchased this Willys Jeep for $500. The data plate is missing, but from what I was told, it's a '53 CJ-3A. It has a GM 350 V-8, a TH350 automatic transmission, and a Dana 18 transfer case with a Warn overdrive. The engine is a '72 model (block number 3970014). I have no idea what the year of the transmission is. I have four questions:

  1. There is not a single wire on this Jeep anywhere except for in the headlight area. What would be my best bet to rewire this Jeep with the engine and transmission combo mentioned above?
  2. The factory brakes were 9-inch drums. This Jeep has front and rear 11-inch drums, if I'm measuring correctly. I took OD measurements. The master cylinder is rusted out, and no hard lines are connected. What parts should I get to make the brakes work again?
  3. There are no spark plugs in the engine, and it has been sitting for one year, that I know of. I checked the oil and other than being overfilled, it looks clean. What steps should I take to get her running again after the wiring, brakes, and tune up has been done?
  4. I shifted the transmission by hand and it didn't feel like it was sticking. I flat towed it about 10 miles home with no problems. When I checked the transmission fluid, it was low and had what looked like dirt in it. No metal shavings though. What should I do about that?

Thanks for taking the time to read this, and keep up the great work!
David Sanchez
Via email

  1. Based on the body panels alone, your new-to-you Jeep looks like a CJ-3A, confirming what you have been told. The GM V-8 and TH350 are incredibly simple and don't require a complex wiring harness. If you understand automotive wiring, you can easily wire it yourself, or you can purchase a basic universal Jeep wiring harness from companies like Painless Performance (painlessperformance.com).
  2. The 11-inch drum brakes are a common upgrade on older Jeeps. The 9-inch drums are difficult to adjust and don't work all that well. The 11-inch drums are a great improvement. The good news is that you can use a stock master cylinder to feed the 11-inch drums. Omix-ADA (omix-ada.com) offers new factory master cylinders for almost all early model Jeeps. The 11-inch drums were usually pilfered from early FSJs or later model CJs. You'll have to match up the components to know exactly what they came from. There are likely many interchangeable parts so it should be an easy task.
  3. The removed spark plugs and fresh oil lead me to believe that someone at some point tried to get it running. The first step is to find out if you can turn the engine over by hand. If you can't, you may want to squirt a bit of ATF or spray lube into the cylinders to try to free up the pistons and rings. Let them soak a few days. The Jeep likely needs new points and a carb rebuild if nothing else is wrong with the engine. I would recommend draining and replacing the oil, even if it looks fresh, because you don't know the history. Once the wiring is done and you have fresh fuel in the float bowl, give it a crank.
  4. I would recommend you drain the transmission, try to hose it out as best you can with brake parts cleaner, and then refill it with fresh 80-90W gear oil. If it's exceptionally dirty, I might remove the transmission top cover and give it a really good scrubbing inside, washing the debris out the drain hole. Either way, once you get the Jeep running, you should drain and refill the transmission again after the first 100 miles or so, just to make sure it's clean. You can't always reach behind the internals of a tranny to get every bit of gunk out. Don't forget to check, flush, and refill the axles and transfer case as well.


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