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October 2011 Your Jeep - Tech Questions

Posted in How To on October 1, 2011
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Libby Locked
I have a 2WD ’06 Jeep Liberty Renegade, with the 3.73 rear end and auto transmission. I would like to put a locker in it. I use it for some off-road use during hunting seasons on some nasty muddy roads. Can you suggest what would be best for my application? The Jeep has the ESP system in it as well as ABS brakes. Does this change anything?
Allan W.
Via jpmagazine.com

I believe your rear axle should be a 29-spline Chrysler 8.25. I like the 8.25: It’s a durable axle with a good overall design when not overtaxed. There are several lockers manufactured for this axle, including the Detroit Locker and several drop-in “lunchbox” locker types like Lock-Rite, Aussie Locker, and so on. The downside with these automatic lockers is harsh engagement and degraded on-road handling. You’ll get a lot of feedback through the steering wheel as you let on/off the gas around corners.

Your best bet for not giving up your on-road civility would be an ARB Air Locker. The downside is they’re expensive and require a source of onboard air, such as ARB’s compressor. The ARB will be fully locked (spool) when engaged, but open when not. Your Liberty will drive and handle just like stock when the locker is unlocked.

Another good choice would be a limited slip. There are several available for the Chrysler 8.25 such as the factory Trac-Lock (weak perfor-mance), the Auburn Limited Slip (good unit but requires case grinding for clearance during install and special lube with friction modifier…has clutches that can wear and degrade in performance over time), and the Eaton Truetrac. Of all these limited slips it’s the Truetrac I’d personally recommend.

The Truetrac will cost you roughly less than half the price of the ARB Air Locker. It has excellent on-road manners, is 100 percent gear-driven (requires no special fluid and has no clutches to wear), and of-fers excellent off-road traction. I often use a Truetrac over a locker in many of my dual-purpose on/off road rigs.

The ESP or ABS function won’t be hampered. The limited-slip won’t cause either system to freak out. The Truetrac will just limit rear wheelspin, allowing the ESP to hold off activation longer. Once you reach the traction limits of the Truetrac, the ESP will kick in.

Steer Clear
I am in the middle of swapping a late ’70s Scout Dana 44 into my ’77 CJ-5 and have a few questions about the steering. I’ve already taken care of outboarding the springs to accommodate the spring pads on the axle housing and had the knuckles turned for the caster issue, but I have been searching around on the web and it seems that the steering arms on the outers are going to give me problems. My original plan was to run a well built Z-bar drag link, but I heard the steering box would need moved forward 4 inches. I don’t want to get into that crap so my next plan is a high-steer setup (which was in the plan for the future anywho).

However, I need to get this done for the Carlisle All Trucks event in August. It seems everybody has their different ways of mixing and matching Ford and Chevy parts to get the flat top outers and keep the 5-on-5½-inch bolt pattern. All my Scout Dana 44 outer pieces are new (bearings, seals, rotors, calipers, pads, hubs, and so on), so I would like to use what I already have. What are my options? Who sells a here-is-everything-you-need-kit so I can get my Jeep together before the truck show? I imagine I’ll be out $500-$600, but if I had to buy all new everything again, plus get the outers machined, drilled, and tapped, I’ll probably be in the same ballpark. I don’t know which way to go and I’m running out of time, so any insight would be greatly appreciated.
Greg Sloan
Pittsburgh, PA

Reid Racing (reidracing.biz) makes or used to make a right-hand knuckle under part number D44001SR for the Scout axle. It has a flat, machined top for use with a standard crossover-steer arm and ac-cepted all the stock Scout spindle/brake/hub components. I didn’t find it on the company’s website, so perhaps it’s been discontinued. If so, hit up Google and start looking for vendors that may still have one in stock.

For a crossover-steer arm check out Parts Mike (partsmike.com). The company can set you up with the correct steering arm for tire and spring clearance once you provide a couple measurements. If you run a steering arm that’s flat or doesn’t have the correct angle you could run into tie rod end-to-tire interference or your drag link could hit your spring pack. Parts Mike would also be the place to set you up with the parts to do your crossover steering setup if the search for that Reid knuckle turns up snake eyes.

Pump Problems
I have an ’84 CJ-7 with a transplanted ’90 GM 5.7L engine. I am having a problem with it getting hot at highway speeds. I’m hoping maybe you know something I can do that I haven’t thought of. Here are some particulars:

1. Fiberglass body and one-piece front end
2. Aluminum radiator with 16-inch Spal fan (wired correctly)
3. New engine I rebuilt it myself, 180-degree thermostat
4. Runs 185-190 degrees idling
5. New water pump

The only thing I can think of is its not getting air thru the engine compartment. Any ideas?
Rick Mace
Westfield, IA

I’d first verify you’ve got the correct water pump on there. Some pumps meant for serpentine systems spin backwards. They’re called “reverse rotation” pumps, not to be confused with “reverse flow” pumps that came on the LT1 and LS1 engines. At higher engine speeds the impeller will cause cavitation and won’t move any coolant. If you’re using an older V-belt pump with a serpentine pulley setup or a serpentine pump with a V-belt setup this could be your problem.

Since it doesn’t overheat when idling, I doubt it’s something like a thermostat issue, head gasket, or that your coolant passages in the block are restricted or fully blocked. If it’s the correct water pump and you don’t have obviously huge obstructions in front of the grille such as off-road lights, a winch, or other stuff, then move on to creating some improved airflow out of the engine compartment. I don’t know if it would be safe since I haven’t actually seen your setup, but if there’s a way to shim the front clip upwards a bit so there’s a ¾-1-inch gap between the front clip and body tub you could take it for a testdrive and see if the problem still persists. Do that only if the clip is secure and won’t go flying off or open.

Peugeot Punchout
I have an ’87 Wrangler with a Peugeot five-speed and I believe an NP207 transfer case. The Jeep has 250,000 miles on it, has been coast-to-coast twice and we use it now to pull a 4,000-pound trailer in the mud! It has served very well, but the transmission is about to go out, and the last time I had it in the mud the 4x4 worked on the way in but not on the way out. Luckily there was a 450J dozer handy to pull me out.

I would like to know what transmission and transfer case would bolt up to my 258 without modification. I want a newer five-speed and an NP231. I also have a ’76 CJ-5 with a 350 Chevy and a T-18 with lots of custom stuff, so I really want the ’87 to use stock parts.
Dismas Schmelzer
Bremen, Ohio

Wow, that’s a lot of abuse. I can’t believe it held up that long.

The AX15 and NV3550 are both the same length (within about ¼-inch—not enough to cause an issue) as the Peugeot BA10/5 transmission in your YJ. That means pretty much any AX-15 or NV3550 five-speed from a junkyard Wrangler (YJ or TJ) will work for you. You’ll be able to use all factory parts.

Don’t forget that Jeep crossed over from the older, more problematic internal throwout bearing to an external slave cylinder in ’94, so if you get a ’93-earlier bellhousing it will be for the internal throwout design. I’d look for a ’94-up unit with the better external slave setup.

Depending on how cheap you are, you could use the donor Wrangler bellhousing, transmission, slave cylinder, and clutch master (although you could adapt your current clutch master with a hose kit from Advance Adapters) and reuse your 258 flywheel and pressure plate. Grab a clutch disc for your AX15 or NV3550 and a new pilot bushing (older ’88-’91 AX15s have a 19/32-inch pilot tip, ’92-’99 AX15 and ’00-up NV3550 have ¾-inch pilot tip). Also, if your NP207 is in good shape you can simply bolt it to the back of your new five-speed. The BA 10/5 came with either 21- or 23-spline output shaft, but your six-cylinder YJ should most likely be a 23-spline output, which would match the AX15 or NV3550. The NP207 is not a bad T-case, actually.

Rubi Runnin’
I have a TJ Rubicon and want to put 33x12.50s on my factory wheels. I would obviously have a lift but I’m concerned about the tires and wheels. Would these tires be too wide for my stock wheels? Would I need spacers or wheels with more offset to clear at full steering lock?
Kyle Rossi
Killeen, TX

The factory Jeep Rubicon wheels are 16x8 and will easily accept up to a 35-inch diameter (315/75R16) tire. However, you may find the need to slightly turn out the steering stops on the front axle to keep the 33-inch tires from hitting the control arms. The tires will also rub on the rear coil buckets so you should probably consider a wheel swap or some spacers to gain clearance for the 33s.

Drum Brake Car-b-Que
I’ve got a ’75 CJ-5 that I’ve been building. Everything is brand new, but the braking sucked. So after reading your magazine and doing a lot of research, I decided to swap the front axle over to disc brakes. I did this a little over a year ago. Well, life happened and I never really got to drive the Jeep after the conversion other than a little bit around the neighborhood. I finally got to take it out the other day and didn’t make it that far. I kept smelling something so I pulled over and the rear driver-side drum was smoking like a barbeque. The passenger-side drum was extremely hot as well. I let everything cool down and limped the Jeep home. The guy who installed the discs and I pulled everything apart in the back and couldn’t find anything wrong.

Do I need to get a different proportioning valve? If so, which one do I get? I reused the stock one because the place I got the brake kit from (and the guy who helped install my kit plus 10 or 15 other kits on different Jeeps) said it would be fine.
Allen Calahan
Via email

If you kept the stock master cylinder and didn’t change anything in the rear brakes, theoretically there’s no reason they should suddenly start smoking. Normally after brake conversions if something like this happens it’s due to a brake rod with improper length, but your brake pedal, rod, and master weren’t messed with, so let’s move on.

When you do a disc conversion using the stock master cylinder you need to remove the brake line for the front at the master and pull the residual pressure spring and check ball. Then put it the line back. That will prevent the front disc brakes from dragging. However, simply putting front disc brakes on your vehicle shouldn’t have changed anything that would keep the rears from staying engaged. Did the guy who put your front discs on change anything? Add another in-line residual pressure valve or proportioning valve of some kind? If not, the problem most likely lies in the original drum brake hardware.

It sounds like your rear brakes were either adjusted too far out, are staying engaged after the pedal is depressed, or possibly were pulled apart and not put back together correctly and the E-brake actuation is staying engaged as you drive. Also, there are two different shoe sizes in the rear brakes: a shorter one and a longer one. The shorter shoe should face towards the front of the vehicle. The longer shoe faces the rear bumper. Running them backwards will make the brakes drag and/or limit the energy when the brakes do engage.

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Got a tech question you’re just itching to get answered? Send it on in to Jp magazine, Your Jeep, 831 S. Douglas St., El Segundo, CA 90245, or email christian.hazel@jpmagazine.com.

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