Jeep Creep: Wrangler Air Intake Kits, Rear Axle Swap, Adding Larger Tires and More

May. 19, 2015 By Jim Brightly, KF7SCT

In your Jeep Creep questions, please list your first and last names, your hometown, and your state/province/country, so that we can publish that information here. If you donít provide this information, we may not be able to publish your question and answer. Donít forget to be as complete as possible with the description of your Jeep and its problems, too. Send your Jeep questions to editor@off-road.com, Attn: Jeep Creep.

Previous Jeep Creep Columns
April 2015

March 2015

February 2015

No Jeep recalls from NHTSA this month.

Air Intake
I want to change the air filter set-up on my 4.0L TJ. Iím looking for more air flow and maybe a cold air intake. Can you recommend something?
Richard Lake
Casa Grande, AZ

Yep, Richard, there are several different manufacturers from which you can choose. K&N has a kit, or you could go with a Volant kit such as the one in the photo. This kit includes everything youíll need to relocate the filter (formed tube, hose connections, etc.).


1993 Wrangler
I recently bought my first Jeep. It is a Ď93 Wrangler with the 2.5L and manual transmission. It has a 2-1/2-inch lift with 31x10.50 BFG ATK tires on Pacer rims. The Jeep is in great shape, no frame rust, etc. I plan to use it as a daily driver with some light trail riding, nothing serious at all. With the larger tires I feel it really needs deeper gears to perform similarly to the way it did from the factory. I plan on using 4.56:1 gears in the stock axles with a master rebuild kit to replace all the bearings. A Jeep guy I know said the axle in the rear is junk and would not recommend regearing it, but recommended replacing it entirely. I understand if I plan to do heavy wheeling, it isnít the best, but it has lasted this long (141,000 miles) without any issues. I donít think I need to change it out completely, but what do you suggest? Also, do you believe 4.56 is a good ratio for how I use my Jeep? I may eventually go up to 32- or 33-inch tires but nothing larger.
David M. Moye
Dublin, VA

Your YJ has a Dana 35 C-clip with a 27-spline differential with 1.18-inch diameter shafts and 2.62-inch axle tubes. Since it has lasted for nearly 150,000 milesóand youíre going to rebuild it with new bearings, seals, etc.óIíd stick with it. You already have 4.10:1 gears so you wonít have to change out the carrier, and your overdrive will be very compatible with the 4.56:1 gears, especially when you replace the tires with a set of 32- or 33-inch tires. I like 4.56 gearsóI had them in my CJ7 and Iíve installed them in the í05 Rubicon Unlimited Iím currently buildingóand they wonít overstress the Dana 30 front differential.


Hard-Starting YJ
I have a Ď95 YJ 4.0 HO. When I go to start, it will just turn over. After I stop turning over the starter, the auto shutdown (I believe) will start clicking. After a few minutes it will stop and fire briefly before doing it again. HELP! New symptoms! After a few hours of tinkering and checking, I found that the fuel pump is making the same clicking noise and I am not getting fuel even to the filter. When I disconnect the pump I just hear the relays clicking, both the auto shutdown and the fuel relay. I replaced the pump last year, so not sure, ECU maybe?
Doug C.
Pittsford, VT

The problem sounds simpler than an ECU. I believe itís simply a clogged fuel line. Disconnect the fuel line from the filter on the tank side. If fuel doesnít flow out of the tube, have someone blow into the gas tank from the filler hose. Fuel should spray out. If not, youíll have to clean the entire fuel system, starting at the tank.


JK Tires
I have an all black 2013 Jeep Wrangler Sport Unlimited with an automatic transmission. Can I install bigger tires on it? How tall? Will anything else have to be changed?
Eric Wientraub
El Toro, CA

Eric, the 2013 Rubicon Unlimited is equipped with 32-inch diameter tires, so your Sport should also accommodate 32-inch tires without modification. If you wish to go taller, youíll need to install a modest lift kit or adjust the steering stop. The steering stop is a nut-and-bolt assembly on both sides that is pre-set at the factory to stop the steering before the tires contact the Jeepís frame or fenders. Although the nut is welded to the bolt so that you canít adjust the steering to be sharper unless you replace the bolt. However, you can add a washer or two or another nut to stop the wheels earlier.

Fan Belt Routing
I want to be a member of your forum, but can't find where to sign up. I have an Ď85 Jeep CJ7, and I need help figuring out the belt diagram. I have no AC, and no idler pulleys, but I do have two belts, and they both came off it yesterday. It's my only means of transportation.
Julie Musial

You failed to tell me what engine your Jeep has, but Iím guessing itís the 4.2L straight six. Iím including a fan belt diagram. If you ignore the belts for the air conditioner (and idler) and air pump, I believe the two belts left are what your engineís belts should look like. And hereís a link to the forums, Julie: http://forums.off-road.com.


Rubicon Lockers
I know my 2005 Rubicon has lockers in both axles but for some reason the front doesnít appear to be working. When I hit the lockersí switch the rear lockerís light clicks in after a moment and stays lit. But the front lockerís light flashes on and off and I canít tell the difference in the steering like I used to. Does this mean the front locker isnít working? How do I fix it?
Chase Williams
Renton, VA

The lockers are activated by low-pressure air when you flip the switch. Each locker is equipped with its own air pump, which are mounted on the same cross member that supports the Jeepís transfer case. They sit just behind the transfer case on the driverís side. Several things could cause the locker to quit: blown fuse, bad air pump, leaking air hose, and/or a loose or disconnected wire. Before testing the air pump, you need to make sure the locker itself is still good. Use very low pressureóless than 8 psióon the differentialís input hose. With both front tires off the ground, rotate a tire. If the opposite tire rotates in the same direction, the locker is working. Next step is to make sure the air hose is connected properly and is not leaking. Lastly, make sure the air pump is working and pumping sufficient air. If the air pump is not working, check its fuse. If the fuse is good, make sure the wiring to the air pump is good.


Error Code 36
In a question in a previous column, a Jeeper asked about the OB1 error code 36, which involved the air switch solenoid. My Ď96 XJ 4.0L is running good (for the most part) and it is an occasional driver for me. I try to drive it once a week just to keep it in good running condition. Last week I was driving home from work and tried to pass someone on the highway at about 65 mph. My Jeep chugged and slowed down and wouldnít go above 35 mph. I pulled over to the side of the road and decided to chug along to the next exit and limp home at 35 on the back roads. Moments later, after turning off the highway, it came back to life and I turned around got back on the highway and went 75 all the way home. The CEL is reading only the fault code 36 and I canít find anything on how to replace this or test it or anything. What is it and how do I fix it? Itís driving me crazy that I canít figure it out.
Jordan W.

For multiport fuel injection cars, such as your Cherokee, a code 36 is triggered when the air switching solenoid circuit is open or shorted. This happens when the ECU doesnít sense near 0VDC or 12VDC when the solenoid is turned on or off. When code 36 is thrown the power limited light will not be lit and the system does not enter limp mode. The possible reasons are poor wiring or connection. Check the wiring and connections from the logic module to the solenoids. Clean and re-grease the connectors with dielectric grease. The solenoids are located in the right-front fender in a cluster of up to four solenoids. If a signal from the harness to the solenoid measures 12VDC when the solenoid is off, the solenoid will need to be repaired or replaced.

I have a request of all the readers out there. Send us your questions. For some reason the questions have fallen off, and I know we havenít answered all your Jeep technical questions. There are no dumb questions; only unasked questions. Send them in and try to stump us.óJim Brightly

As usual, each month, Iím shouting out a huge THANK YOU to Paul Schupp at Rock Lizard 4x4 in Kingman, Arizona, for his invaluable assistance in answering many of the Jeep Creep questions.

Send your Jeep questions to editor@off-road.com, Attn: Jeep Creep.

Previous Jeep Creep Columns
April 2015

March 2015

February 2015


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