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July 2013 Techline

Jeep Jumping
Ali Mansour
| Brand Manager, 4WD & Sport Utility
Posted July 1, 2013
Photographers: Four Wheeler Archives

Your Tech Questions Answered

80 Where?
What vehicles did the Dana 80 come under?
Name withheld
Via Email

According to my research the Dana 80 rear was available under the following vehicles:

’94-’02 Dodge ¾- and 1-ton trucks

’88-to-present Ford F-350 and F-450 trucks (primarily dual-rear wheel)

’92-to-present GM motorhomes and commercial vehicles (primarily dual-rear wheel)

ZJ Carrier
I’m looking for a rear bumper and swing-out tire carrier for my ’96 Jeep Grand Cherokee. Do you know of any companies that offer any? I would prefer an aluminum carrier to keep the weight down, but I guess beggars can’t be choosers.
David Wainwright
Via Email

Proto Fab (www.protofab4x4.com), Kevin’s Off-Road (www.kevinsoffroad.com), Rock Hard 4x4 (www.rockhard4x4.com), and Hanson Off-Road (www.hansonoffroad.com) all offer swing-out tire carrier rear bumpers for your application, though none are aluminum.

Timing Chain
I have a ’09 GMC Yukon with the stock 5.3L and it just rolled 100,000 miles. I want to make sure that it lasts a long time. On my Honda Accord I drove in college I was told I needed to replace the timing belt at 100,000 miles. I looked in the factory manual and couldn’t find the suggested service interval for my Yukon’s timing chain. My local mechanic said that most of the newer trucks timing chains are good for the life of the engine and not to worry about it. Is this true?
Bill Claudel
Via Email

It’s not unrealistic to think that the chain could be good for the life of the engine. Much of how long an engine and its assorted internals will last has to do with service and wear. Most engine techs I spoke with feel as though 200,000 miles would be the most that they would be comfortable putting on a stock chain. With that being said, it’s not uncommon to see a 5.3L with well over 200,000 miles on it with all stock internals.

I personally know of one very used, and sometimes abused, 5.3L ’00 Chevy 1500 on 40s with over 265,000 miles, that’s still on the stock chain and running strong. If it sounds like there is slop or noise, you should definitely replace the chain. Otherwise, so long as you keep the truck well maintained and serviced, it should last for the bearing (internal) life of the engine.

No Lift Tires
It is time for me to buy new tires for my Jeep Wrangler JK and I want something larger and more aggressive than my stock tires. What is the largest tire I can run without installing a lift? I currently have 255/75R17. I have been told I can go as large as 285/70R17 on the stock rim, but have heard mixed reviews on whether I will need spacers. Can you shed some light on this for me?
Christian Collins
Via Email

If you are trying to avoid modifying the Jeep with any type of lift, trimming, or wheel spacers, a 285/70R17 or 33x10.50 will likely be the biggest tire you can go with. Even with this slight upgrade in tire size, it’s possible to have some minor interference. Tire variances and types, such as mud-terrains versus all-terrains, can be the difference between a slight rub and zero interference.

Consumer Reports?
I was seriously considering purchasing a Jeep Wrangler Unlimited until I read in Consumer Reports that the Jeep Wrangler Unlimited was one of the worst vehicles that they had tested in years. I do not understand this. We are a Jeep family and currently have four Jeeps. Are the individuals doing testing for Consumer Reports a bunch of sissies or is there a legitimate problem? I am a big fan of your magazine and would like your take on the issue.
Frank W. Green
Snail Mail

I believe you are referring to Consumer Reports’ “The Worst Cars of 2012.” I saw that review as well. Their said evaluation is “based on our more than 50 tests conducted at our 327-acre facility.” While I am not privy to all of the ins and outs of their test, it appears that the same testing basis is used throughout. I take this to mean that a Honda CRV is on the same point scale as a Jeep Wrangler Rubicon. That sends a red flag to me right there.

I understand that the target audience for the Jeep Wrangler Unlimited is much larger than those only looking to modify it and take it off-road. But, I have a hard time buying that a person looking at a Wrangler is comparing the MPG and performance ratings to a Honda CRV, which doesn’t even have a two-speed transfer case. While I will say that their test has some validity, it doesn’t evaluate the Jeep in the way our reader, or we, would.

For example, our Four Wheeler of the Year competition evaluates the vehicles on- and off-road performance with a detailed rating and review of where the said vehicle excels and falters. If a rig is horrible in the rocks, but great on the highway, that’s fine, we will let you know. There just has to be a certain level of legitimate testing for a vehicle that’s intended to go off-road and I believe that’s part of the problem with Consumer Reports’ points scale and testing.

You say you have four Jeeps. My guess is that you purchased them first for the off-road capabilities, with the understanding that one or all may not handle the same as say a Honda CRV or Ford Explorer. Where you and I understand that having a rugged off-road vehicle with live axles and a multilink suspension means a little trade-off here and there, some do not. More so to the point, the test that other magazines subject their test vehicles to often focus on things that are not as important to us.

Sure, the 3.8L engine in the ’07-’11 Wrangler models is a little on the sluggish side, but the 3.6L took care of that issue. I am not going to say that the Jeep Wrangler Unlimited is perfect, but I think it’s absurd to call it the worst of anything. The simple fact is there currently isn’t another factory-produced SUV that can outperform it off-road. Stock for stock, it’s simply at the top of the class.

I would gladly recommend an Unlimited to you or anyone else for that matter. Ultimately, the Jeep Wrangler Unlimited opened the Wrangler to those unfamiliar with the roots and capabilities of the machine. ESC (electronic stability control) has even allowed the dealerships to offer Moparized editions with lift kits, larger tires, and bumpers. If you want to buy a new fridge or dryer, Consumer Reports isn’t a bad place to look. If you want to know about SUVs and trucks, please continue to check us out.

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