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July 2008 4x4 Truck Tech Questions - Techline

Posted in How To: Tech Qa on July 1, 2008 Comment (0)
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Address your correspondence to:
Techline
Four Wheeler
6420 Wilshire Blvd.
Los Angeles, CA 90048.

All letters become the property of Four Wheeler, and we reserve the right to edit them for length, accuracy, and clarity. The editorial department also can be reached through the Web site at www.four wheeler.com. Due to the volume of mail, electronic and otherwise, we cannot respond to every reader, but we do read everything.

Wants External Slave Cylinder For Ford
Question: I have a '95 Ford F-150 with a Mazda five-speed transmission (with a solid bellhousing) that is four-wheel drive. The trans has an internal slave cylinder for the clutch. I would like to know if anyone makes a kit to put the slave cylinder on the outside of the transmission so you don't have to drop the trans every year to replace the slave cylinder.
Mike Driggers
Grover, SC

Answer: Yep, it should last a lot longer than one year. Ford has issued a couple of service bulletins on this due to past problems. In fact, they have a revised slave cylinder which has a new dust shield and upgraded lip seal to help prevent leakage of hydraulic fluid from the interior seal (PN F87Z-7A508-AA).

Could it be that you're buying your cylinder from a local discount auto parts store and that their supplier has never updated the design?

There is also the possibility that you're not bleeding the system properly. I believe the proper revised bleeding instructions come with the cylinder if you get it from Ford. If not, ask the parts guy if he can print you out a copy of Article No. 93-12-19. The procedure is quite extensive-a lot more than just opening the bleed valve and letting fluid flow.

Cherokee 2.8L Swap Options
Question: I'm in possession of an '86 Jeep Cherokee Laredo with the 2.8L and three-speed auto. My questions are concerning a possible engine swap. Other than the 4.0L, knowing it will probably mean swapping out the entire front end, what other options might I have? Maybe an engine from another vehicle besides a Jeep, and which ones?

My local used parts suppliers all offer the 4.0 but with an extensive list of items that I would have to gather from various other vehicles. No engine would be complete. And the used sales lots want about as much as it would take me to transform my machine.

My intentions for this machine are a daily driver and some light 'wheeling in the foothills around Las Vegas, with an occasional trip to Moab or the like to explore some of the beginner trails. I'm looking at a 3.5- to 4.5-inch lift with slip-yoke eliminator, shafts, and 31- or 32-inch tires.
Robert K.
via fourwheeler.com

Answer: Let me tell you right off the start that selling the Jeep and buying one with a 4.0 in it will place you money ahead. My guess is that you didn't factor in the time involved. Also, don't forget you're going to have to swap out the wiring harness as well as the computer. I also would never consider buying a motor that was not complete. It's a crap shoot as to just how well the motor ran before the accident that placed it in the salvage yard. It would be very frustrating to make the swap and then find that the motor had a terrible knock or smoked badly. By trading up, at least you know what you're getting because you can drive the vehicle and actually check the motor out.

As far as an engine from another vehicle, I have seen some Chevy 4.3L V-6s installed that came out quite nicely. These incorporated the trans as well as the transfer case from the donor vehicle. Again, remember you're going to need the wiring harness and computer to match the new engine.

Bronco Disc-Swap Alternative
Question: I was just reading "Wants Bronco Disc Brakes on the Cheap" (Techline, Apr. '08). I agree that the master cylinder has to be changed, but for the Ford purists (which I am not), you can do the disc-brake swap without the use of Chevy parts. I have a Dana 44 out of a '71 Bronco under my '94 S-10, and to achieve disc brakes I swapped everything from the ball joints out with a Dana 44 out of a '79 F-150.
Kenny Brown
via fourwheeler.comv

Answer: You're right. That is another way to do it, one I maybe should have mentioned. Like I said at the start of the second paragraph, "There are several ways you can do the front conversion." The nice thing about the early open-knuckle Dana 44s is that most of them have the same yoke spacing and offset, so parts are interchangeable. Doing it your way also gives the installer an easy option to replace the ball joints while doing the conversion. I am sure our readers will benefit from your solution.

Blown 400 And Six-Speed For Suburban?
Question: I have a '93 Chevy Suburban 1500 4x4 with a 350 V-8. The engine has 180,000 miles on it and is very tired. This summer I plan to replace the engine with a Roots-blown 400. This is pretty straightforward. However, I would also like to get rid of the Slush-O-Matic and install a six-speed manual. I know I will need a donor clutch-pedal assembly and a compatible bellhousing as well as a new driveshaft. Can you point me in the right direction for a good donor vehicle? What tranny should I run that will bolt to the small-block and transfer case?

Would it be better/easier to find a five-speed setup versus the six-speed? Are there any axle upgrades that would handle the power of the blown 400?
Stephen G. Dant
via fourwheeler.com

Answer: Chevy has used the ZFS6-650 six-speed transmission from 2001 in some applications both with gas and diesel engines. I believe that you will need the gas version, and there are not a lot of them around, especially those hooked to a transfer case which you will also need. It will be an expensive transmission. Maybe a better choice would be the NV4500 five-speed as there are a lot of those around.

A 1500-series Suburban may not be the right choice, axle-wise, for a Roots-blown 400-inch motor. That much torque and horsepower will make a lot of little pieces of metal out of the front and rear axles. I would suggest a Dana 60 swap up front and a 3/4- to 1-ton Corporate 12-bolt for the rear. The rear changeover is pretty straight forward, but the front will require a major suspension change. Cage Off Road (www.cageoffroad.com) and Off Road Unlimited (www.offroadunlimited.com) are two companies that come to mind that offer solid-axle conversion kits. There is a lot of information on the Internet if you do a search on "Chevy solid-axle conversions."

In reality, you would be better off finding a nice earlier 1-ton solid-axle Suburban as a platform to start out with. Some of these even had big-blocks in them, which would be a better engine for four-wheeling than a 400 with a blower, as that combination tends to have little low-end torque as well as overheating problems.

How To Measure Backspacing
Question: I have an '89 S-10 Blazer 4x4 that I want to put new rims on. I was going the cheap way and getting some steel wheels from Cragar, the 397 series in a 15x8 size. The only problem is that I don't know how to calculate the backspacing. I would like the tires to stick out from under the vehicle a little bit, but not too much. Can you help me figure out the spacing I would need so I can get the correct rims?
Kody Moran
via fourwheeler.com

Answer: I have seen all sorts of so-called trick ways to figure the correct backspacing, and nothing beats trial and error. No, I don't mean you have to buy or borrow a lot of wheels and tires, but that would be the best way to do it. First off, why do you want the tires to stick out the fender? For one, the tires will throw trash over the sides of the truck, and second, in most states it is illegal. But perhaps you plan on running some type of aftermarket fender flare.

From the mechanical aspect of it, the less the backspacing (more tire sticking out), the more load on wheel bearings and suspension components. Plus, you can interfere with what is referred to as "scrub radius." Basically, the suspension is designed so that the tire will pivot off the center of the tire. More or less backspacing, and even a wider rim, will change the pivot point and cause the tire to "scrub" when turning. Usually it's no big deal other than a bit more tire wear.

Keep in mind that the 8-inch wheel with stock backspacing will also move the center of the tire outward about an inch (half the distance of the additional width of the new rims versus the old rims). You didn't say if you were going to use your present tire or go to a larger tire. A wider/taller tire will not only bulge out more to the outside but to the inside also. This may or may not cause more contact with the frame or fender opening. If you're keeping your present tires and just adding the wider rims and you have no tire-to-body contact, then most likely the stock backspacing is what you want to use.

Backspacing can easily be measured by placing a straight edge against the rim flange, and using a tape or ruler, measuring from the mounting surface of the wheel to the low side of the straight edge. It's important that your straight edge only makes contact with the rim and does not rest against the tire.

Ranger 4WD Snaps, Crackles & Pops
Question: I have a '94 Ranger 4x4 that is totally stock. When I have it in four-wheel drive and go to turn, the front end snaps and pops. Also, the front wheels feel like they are trying to fight each other. Also, when I first put it in four-wheel drive, it makes a popping and cracking noise when I start out.
Rodney Hostrander
Lock Haven, PA

Answer: There are a couple of things that could be wrong with your front end. My first guess is that there is a problem with the automatic hub-locking system. Ford had a lot of problems starting around 1990 with these hubs. The problem could be anywhere from broken internal parts to the wrong lubricant used.

Yes, the front wheels would feel like that they are "fighting each other" as one hub locks, and the other unlocks. I suggest that you check with your Ford dealer service department as there are several different technical service bulletins out on this problem. Ford does offer a kit to update and repair these hubs.

There also could be the chance that the axle universal joints have a considerable amount of wear in them and need to be replaced.

Tire Fitment And Regear For Silverado
Question: I'm writing because I need help finding what tire/wheel combo can work for me. I drive an '05 Chevy Silverado Z-71 (with the G80 and Autotrac), mainly stock. I did crank up the front end to fit some 285/70R17 Pro Comp A/Ts, but I fell victim to a slashing and need new rubber. Will a 17x9 wheel work on my truck with some 305/70R17 Wrangler MT/Rs? I plan on doing a 3-inch body lift before I mount these. Would I need anything more than that for them to fit? (I saw the "2005 Chevy Silvy Back 2 Basics" articles too, which gives me hope with the wheels).

Also, what about regearing? My stock gearing is 3.42:1. Would it be a good idea to change that at all (I didn't change it for the 285s)? I saw a kit for 4.56:1s, but that may be too much. What do you guys think? Not now, but eventually I plan on towing some small stuff (and it would be nice to not be a dog off the line). I'm not really too concerned with gas mileage, either.
Michael Chachakis
Port Jefferson Station, NY

Answer: Just off hand, I don't see any reason why they would not fit with the 3-inch body lift, as I believe the Z/71 package sits the truck a bit higher than your average pickup. However, you most likely will have some body contact under full wheel compression, and may need to do some slight trimming on the fenders. I will have to assume that the backspacing on the wheels you plan to use will allow for full turning without any frame contact. The overall height of the proposed tire is just under 34 inches. The 285s are about 32.75 inches.

The 3.42:1 gearing definitely will make the truck seem way underpowered, especially if you plan to tow with it. Yes, the 4.56:1s would greatly enhance the overall performance, either just driving or with a towed load. You may have to buy one of the computer reprogramming systems to correct for speedometer error and to improve the transmission's shift points. Superlift (www.superlift.com) has what they call a "true speed sensor calibrator" that will take care of this.

Direct Bolt-Ups For 4x2 Cherokee?
Question: I have a '96 Jeep Cherokee Classic with the 4.0L H.O. engine. It is two-wheel drive, but I would like to make it four-wheel drive. I was wondering if it is as simple as getting a new front axle, driveshaft, and transmission with a transfer case. I was also wondering if there are bolt-on transfer cases that could go with the existing transmission, or if I would have to go with a new one that is ready for four-wheel drive.
Tyler Jenner
via fourwheeler.com

Answer: You got it-everything is a direct bolt-up. I would go with a matched trans/transfer case already put together to make things a bit easier. In all reality, I think that it just might be a lot more time and cost effective if you sold your present ride and just bought a factory-built 4x4. Then again, if you found a great deal on a rollover that only sustained body damage and the drivetrain was unhurt, it might be the way to go.

I think that your first steps would be to find out just how much your Cherokee is worth, then price out all the component parts necessary to complete the swap. Then figure out the amount of time that it is going to take you to make the swap and just about double it. My guess is that you will be looking to do a trade instead of all the work.

Here is another way to look at this project. The rear end in your XJ is most likely a problem-prone Dana 35, being that it came as a two-wheel-drive. It could be a Chrysler 8.25, which is a bit better, but not by much. How about using some Dana 44 axles such as those sold by several of our advertisers such as 4 Wheel Drive Hardware (www.4wd.com)? These axles are designed for the '97-'06 TJ Rubicons and are almost a bolt-in for your XJ with some rear-axle mounting changes. Yes, you will have to add brakes and steering knuckles to these, but you get lockers and quality aftermarket axleshafts. The overall price is a lot cheaper than you would expect.

Another thing to check into would be present-day Rubicon axles directly from your local Jeep dealer. Believe it or not, these axles are available at a very reasonable cost. In fact, this just may be the way I would go if I had to build "Project Ain't It Grand-er" again. The negative to this is that the bolt pattern has been changed, but then again, if you're building up your XJ from a two-wheel-drive, then I am sure new wheels and tires are on your change list.

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