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August 2011 Techline

Chevy Tahoe
Willie Worthy | Writer
Posted August 1, 2011

Tahoe Lift, Axles and Gears, Tradesman Van, and More!

Wants Lift for Tahoe, But Not New Driveshaft
Q I have a ’99 Chevy Tahoe 4x4, and the rear end has been eating up tires, so my question is what causes that?

The second question is, I’m looking to lift my Tahoe, but I don’t want to go any higher than a 4-inch lift. Everything that I find requires me to change the front driveshaft. Does anyone make a lift for mine that doesn’t require a driveshaft swap?
Kenny Bumpus

A There could be several reasons for loss of rubber on the rear tires. The most common is hard acceleration, which will cause more tire wear on the rear tires. Even if you don’t actually hear the tires squeal, rubber is being worn off because there will be some deformity of the tire’s tread when they are under load, which will result in a scuffing motion. A clutch-type locking differential that has the wrong gear lubricant in it can cause the clutches to stick and not properly release when going around a corner, again scuffing off rubber. Even excessive loads over the rear axle will cause the tires to flex more, resulting in more heat that increases tire wear. There could also be an alignment problem where the rear axle is slightly cocked with one side further forward that the other. This would show up as uneven wear across the tread’s face.

As to lifting the Tahoe, you’re right that the lift kit manufacturers recommend—and with the AutoTrac system, require—a new double cardan driveshaft. There is just way too much angularity on the single U-joint involved, and without the CV joint you will experience driveshaft vibrations. Plan on adding about another 450 bucks to the price of the lift kit. I believe that you may also have to do some custom exhaust work to adjust for clearances.

Swap Tips for ’70s Tradesman Van
Q I’m 17, and finally got to buy my grandma’s ’76 Dodge B200 Tradesman van with the 318ci V-8, TF 727 transmission and Chrysler 8.25-inch rear. I want to lift it a little bit (four to five inches), and four-wheel drive is a must. My fingers are numb from researching transfer cases so much, with little to show for it, so I figured I’d ask the god of four-wheeling.

From what I’ve read, I need a transfer case with a 23-spline output shaft and an eight-hole bolt circle to match my 727. I want a driver-side drop (the Dana 300 is not), heavy-duty, part-time transfer case that will bolt right up to the rear of my 727, or have a very low-priced adapter plate. I’ve seen a lot of Dodge vans with the NP203, but really nothing else. The 205 seemed like a good choice until I found out it’s a passenger-side drop too. Would a 208 work? Basically, I just want to know what year, make, and model year to look for.
Alex Goins

A You have quite an undertaking, so be sure you have the ability, the help, and the proper tools to complete this project before you even start turning a wrench. With a project like this, it’s really easy to take on more than what you can actually do.

Let’s start out with the transfer case. Instead of trying to adapt a transfer case to your present transmission, I suggest you search out the wrecking yards, Internet and newspaper ads for a complete Chrysler-style transmission and transfer case already mated together. It will most likely save you money in the long run and make just one more of the many tasks you’re going to have to do that much easier. Maybe it even would be a good time to buy a complete wrecked truck, and also use the front and rear axles from it. Not only will you have a matching drivetrain but a matching suspension too. Maybe you’re going to get lucky, and the transfer case mount/crossmember will be adaptable to your van’s frame. Otherwise, you will have to fabricate one. Yes, the Chrysler 8.25 is okay, but it would not be my choice for a van conversion.

I am not into vans, but I will assume that the van has a solid axle and leaf springs from the factory. You most likely will have to cut off the mounting pads on your new front axle and relocate them to the proper width for the current springs. Do some careful measurements before you buy the front axle, and make sure the distance between the front springs will allow the new drive axle to fit. It’s important to check this width as there may be some interference between the location where the spring has to mount and the differential housing. You might have to measure several axles to find one with the proper differential offset to allow mounting.

Keep in mind that it is important that the front and rear axle ratios match fairly close. Ratios such as 4.09:1 and 4.11:1 would be fine, while 3.92:1 and 4.11:1 would not be a proper match. Having the same wheel bolt pattern, front to rear, is also nice.

Steering may or may not be a problem. Whatever you do, don’t compromise on the steering system. Overkill on mounting the steering box and the rest of the components is the best idea.

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