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July 2010 Techline

Posted in How To: Tech Qa on July 1, 2010
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Where To Write
Address all correspondence to: Techline Four Wheeler, 831 S. Douglas St., El Segundo, CA 90245. You can also reach us by e-mail at; be sure to type the words "Tech Line" in the subject line. All submissions 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 Due to the volume of mail, electronic and otherwise, we cannot respond to every reader, but we do read everything.

Lifted GM IFS Truck Steering Clunks
I own a '93 3/4-ton Duramax pickup with a lift kit (not sure of the brand, as I bought the truck used with it already installed), and 36-inch tires. The truck handles really badly, wants to wander down the highway a lot, and seems to have a lot of steering play. I had the tires rebalanced and the frontend checked. The shop told me that the idler arms were worn out as well as the steering shafts. I get a "clunk" that I can both feel and hear when I turn the steering wheel. The shop told me that unless I took the tires and lift kit off the new factory steering components would also wear out soon. I see lots of truck with tires this big, so do all of them handle badly, or is there an aftermarket fix?
Mark Hakle

Don't despair, there is a solution. Yes, the bigger tires will cause early wear to all of the steering components, so it would be a good idea to also look at the tie-rod ends. The idler arms have always been a problem with the Chevy trucks once they went to IFS, and not just on lifted trucks. Several aftermarket suspension companies offer a heavy-duty idler arm. From your local auto parts you can order some Moog arms that are considerably strong than the factory units ( For some really heavy-duty versions, check out the ones offered by Super Steer (888/898-3281,

As to the steering shaft, that also seems to be a problem. Chevy has a couple of Technical Service Bulletins on this problem under Numbers 00-02-35-003N and 03-02-36-002. Borgeson ( has a new heavy-duty steering shaft with new U-joints (p/n SKU: 000937) that is far superior to the Chevy shaft, and it's a direct replacement.

Allison HD Tranny for Older GMC?
I have an '88 GMC 3500 dualie with the 454 V-8. Can I bolt on an Allison 1000 transmission to my big-block? Any information would be awesome.
S. Al-Marri
Doha, Qatar

Yes, you can, but it will be an expensive swap. The Allison 1000 is rated to handle up to 620 lb-ft of torque. Initially, it was a five-speed transmission, but a new "Generation 4" 1000 was introduced in 2005 that added a sixth gear at the very top of the ratio ladder, making it a double-overdrive like heavier-duty Allison transmissions. For the 2006 model year, manual gear selection was introduced. This feature gives the driver greater control over the transmission, enhancing operation when more engine braking or less frequent shifting is desired.

The transmission has its own electric controller that also talks with the engine's control module, which presents a real problem when trying to interface it with that of the gas motor. However, there is a solution. Performance Automatic Transmission Center (888/201-2066, ) offers a stand-alone controller and wiring harness for the five-speed version that costs about $1,600. For others reading this, they also make adapters to hook this transmission or any GM transmission to both Cummins and Ford Power Stroke engines. There is also a company called Destroked (303/945-7570, that offers an electric controller as well as special Cummins adapters.

Ford 8.8 Swap for TJ Dana 35
I was reading the "How Big a Tire For Stock TJ Axles" question in the Mar. '10 issue. I have a 1997 TJ with the 2.5L engine, five-speed manual, Dana 35 rear, and 136,765 miles on it. I've been told that a Ford 8.8-inch will fit in my Jeep. I would like to know what has to be done to do this. I can get an 8.8 with 4.11:1 gears in it for $75, and it has the posi-lock. The early Explorers had leaf springs, and the newer models have coils, I think. Would the newer axle fit better than the older version?

I know that my TJ (with 2-inch lift and 31-inch tires) is a good daily driver. I get about 21 mpg just in daily driving as long as you stay under 60 mph. I do use Fourth gear more than I should, but I live in western Pennsylvania and we have some hills.
Ted Kent
Western PA

It's good that you're considering swapping out the rear axle for the 8.8, as it is a very good choice, especially for the price. Grab it while you can. The Dana 35, even with the low-horsepower four-cylinder, is a real liability on the trail, as it will break!

Yes, you have to cut off the leaf spring mounts and add new mounts to convert it over to the coils that your TJ has. Mountain Off Road Enterprises (877/533-7229, has all the parts you need to make the conversion. Part number 98700 includes all the necessary brackets; part number 221379 is the special yoke adapter; and part number EB4 is the proper emergency-brake cable.

You will find that the rearend is about 11/2 inches narrower than your present setup. You can leave it like that, or install some longer lug studs and some Baer spacers, both of which are available through Summit Racing ( The spacers are pretty cool as they center on the raised ring on the center of the axleshaft.

Oh, and if you're still not sure you want to make the conversion, try Googling something like "8.8 Jeep conversion," and you will find more information than you will ever need on the subject.

Chevy TPMS Won't Recalibrate for Replacement Tires
I have a question about the tire pressure monitoring system in my 2007 Chevrolet 2500HD. I had my local Chevrolet dealer install new wheels and BFG All-Terrain T/A tires (305/70R17s) on my truck. As part of the package, they installed new tire pressure sensors in my new wheels (to the tune of $50 per wheel). The problem is that my TPMS light is always on because I run my new tires at 60 to 65 psi, and the sensors need 70+ psi to turn the dash light off (apparently set for a recommended minimum pressure for the OE tires). I assumed that the new tire pressure sensors would or could be recalibrated for my new tires, but the service rep and parts person are saying there is no way to adjust the pressure at which the light comes on. After some discussion, they agreed to refund my $200 for the sensors. My question is whether you know of a way to recalibrate the sensors, or are there any manufacturers of aftermarket sensors that would work for pressures in the 60- to 65psi range? Any help is appreciated.
Jeff Morris
Redding, CA

The way I understand it from reading the factory service manual, you should be able to get the tire pressure sensors to "re-learn" various pressure settings. The procedure is quite involved, and way too long to print here, but hopefully you should be able to get your dealer to print it out for you if they are nice guys. However, it also takes a special Tire Pressure Monitor Diagnostic Tool (p/n J-46079) in order to do the necessary calibration. I have no idea what the tool costs, but it just might be cheaper to have the dealer do the work instead of buying the tool and only using it once. Then again, there is always the "black electrical tape over the light" method.

Wants Scout Diesel-to-Cherkoee Swap
I have a 1980 Scout II diesel four-speed that I bought new and ran until the body fell off. I have been storing this vehicle hoping that someday I would "get around" to going through the truck and installing a fiberglass body kit.

Current economic conditions and parts availability have me thinking I'm not going to be able to do the Scout the way I wanted to. So as a form of project triage, I have considered pulling the SD-33T engine (doing my engine mods) and setting it into a Cherokee or other Jeep product of similar size and weight (as the Scout II) that had an inline-six engine.

This is where you come in. Since I have basically been anti-Jeep my whole life (nothing personal), I have no Jeep knowledge.

What years of the Cherokee might be the most suitable for the transplant? What will bolt to the SD-33T? My goal is to make a neat, safe, semi-emissions legal, long-lasting, fuel efficient, simple daily driver with an overdrive, lockout hubs, four-wheel disc brakes, 15-inch wheels, easily available parts, and at the same time not create an overly expensive fiasco.
A.D. Nachbar
Wilton, CT

My opinion is that it is not a very practical swap for several reasons. The Jeep Six is about 29 inches tall from oilpan to the air filter housing, and the length is about 25 inches from fan mount to bellhousing mounting flange. Now go measure your diesel. My tape says the height is 32 inches and the length is 36 inches. I am going to assume that you have already peeked under the hood of a Cherokee. Already have problems, right? Even if you modified the bulkhead that supported the radiator, and moved the radiator in front and against the grille, you're still going to be a bit short on room without modifying the firewall. My guess is that the stock radiator would also be marginal. Here is the next problem: the AMC engine weighs in at about 500 pounds. Got any idea what the diesel you want to swap in weighs? My sources say some where between 780 and 800 pounds. That's about the same weight as the IH 392. Wow! Three hundred more pounds on the front axle. It's no wonder that Scouts came with heavy-tubed Dana 44 axles. I think that the extra 300 pounds might not be compatible with the Dana 30 front end. Plus, you would have to go to heavier springs to compensate for the additional weight.

Now we have transmission/transfer case problems. Okay, you can bolt up a Chrysler 727 automatic to the diesel-that is, if you can find the special adapter ring that goes between the transmission and the engine. My understanding is that there were only about 1,500 of these ever made. Okay, you don't have to use an auto trans if the Jeep you decide to use came with a manual. However, there are no adapters to the IH bellhousing. Part of the problem is that International used a very long-input transmission shaft, longer than anyone else's. So you're pretty much stuck with using the IH transmission-like their version of the T-18 or T-19. All you have to do is fabricate some clutch linkage. There is a company called Jesco (209/537-5057) that has a lot to do with the Nissan diesels, and they may have a transmission/transfer case solution.

What do you do about the transfer case? Nothing wrong with the Dana 300 that you have-in fact, it's a really nice unit. Well, there's nothing wrong with it other than the front driveshaft comes out the passenger side and the Jeep differential is on the driver's side. Two ways to solve the problem. Order up one of those "flip kits" that will flip the 300 so it's upside down and puts the front output on the correct side. Or, perhaps better yet, you could cut all the suspension brackets off the Jeep Dana 30 and weld them onto the Dana 44 that you have left over from your Scout. I am not really sure how the front axle will clear the steering components, but that can all be worked out with a bit of blood, sweat, and tears. While you're at it, you might as well swap in the rear axle, so you will have a matching bolt pattern for the wheels.

Still want to do this? I sure wouldn't.

Forklift Steering Pros & Cons
I will soon be installing power steering in my '71 Bronco. I have heard in the past that hydraulic steering from a forklift is the cheapest and more powerful than regular power steering. Is this true? If so, what kind of forklift do I need to look for? How hard is it to install? Is it too much power for my Dana 44 on 35-inch tires? I don't want to destroy something that I will need if it doesn't work.
Willie Suter

Forklift-type steering, and variations of it, have been used on some specialized "rock buggies." Instead of a steering box mounted to the frame in a conventional way, a special hydraulic valve is attached to the steering wheel's shaft. When the wheel is turned, hydraulic fluid from a pump is directed from this valve to a ram mounted to a bellcrank that in turn moves the wheels in the proper direction. Sometimes, two rams are used and are connected directly to the steering knuckle arms. It takes a lot of specialized fabrication and some knowledge of hydraulic system functions to make it work properly. Yes, it works quite well at slow speeds, but on the highway at speed, the handling is-well, kind of scary. While I am sure that some people have made it work properly, it is not something that I would recommend swapping over to.

There are a lot of better ways to improve your steering system. For instance, several companies such as PSC ( offer modifications to your steering box or can sell you a complete rebuilt steering box with special ports tapped off of it that will allow an auxiliary hydraulic ram to be mounted to the steering tie-rods that will provide additional power assist. This type of a system works quite well both off and on the highway.

Wiring Diagram for Wrangler YJ?
I have an '89 Jeep Wrangler that I need a wiring diagram for. The motor caught on fire and burnt all the wires under the hood. I am trying to find a diagram that shows where all the wires go from the fuse panel that runs through the firewall under the hood. I know the fuse panel has a grid system, and I need something to show me how to read the grid. I have tried the dealers around me, but no one can seem to help. Any diagrams or info on where to go to get a diagram would be greatly appreciated.
Josh Gammill
Chattanooga, OK

I spent quite a bit of time trying to find a solution to your problem without much luck. You have some pretty poor Jeep dealers if they can't help you out by pulling out one of their factory service books and letting you copy down the information. I found quite a few companies that made replacement wiring harness for Jeeps, but not a one had a harness for an '89; most stopped much earlier. Painless Performance Products (817/244-6212, has a harness that may work for you (PN 10106).

You might also want to search places like eBay or Craigslist for a factory service manual. Then I went to my problem solver, a company called All Data ( For 25 bucks, you can have access to one vehicle for (I believe) one full year. When I mean access, I mean access to a factory service manual as well as factory recall information and factory technical bulletins. I guess if you want to spend the time, ink, and paper, you could print out the complete manual or just portions that you may need for future reference.

Radiator Relocation Pros & Cons
I have a question about relocating my radiator to my bed. It seems that every time I go out wheeling, the first thing that happens is that I bury the front end right in a big mud hole. I can even hear the mechanical fan hitting the water. I always make it back out of these big mud holes, but it leads me to believe that having my radiator in the bed would be better than right up front.

I drive a '70 GMC 3/4-ton 4x4 with the 350/TH350/NP205 combo that was a longbed, but I did a custom shortbed conversion which only cost $350. If I put my radiator in the back, should I run a stock pump? How about an auxiliary pump? Could you refer me to a good source that knows this stuff?
Mr. Conyn

Mounting the radiator in the rear isn't going to be as easy as it first appears to be. The mounting system is going to have to be well engineered and one that will allow some radiator movement to prevent it from cracking any seams. You will need a very large electric fan for proper cooling and a properly designed shroud. A lot of off-road race trucks mount the radiator in the rear for both radiator protection as well as weight distribution. They also use some very expensive aluminum shrouding and duct work to get the air in as well as out. However, your stock engine doesn't have the heat exchange needs of a 600- to 800hp race motor, so you won't need to go quite as high-tech.

I spoke with Jack Wilson, the tech guy at Stewart Components ( The company makes some great high-volume mechanical pumps as well as inline electric booster pumps. He confirmed my thoughts that you must focus on maximizing coolant flow and/or velocity at all times. He feels that adding the inline booster pump is a must to help achieve this. Using the largest connections possible with the fewest bends and turns will help as well.

Whatever you do, don't try to run rubber hose the full length between the engine and radiator. For one thing, it causes way too much friction loss, and secondly, it will be subject to abrasion. Use only rubber hoses at the connections between the radiator and the supply lines. I would start out with the pump that you presently have and see what happens. You'll probably find that you will have overheating problems because there just isn't enough flow due to all the restrictions of the longer coolant travel and the friction loss involved. Stewart makes a really great electric pump that goes on the suction side of the radiator. This is a very quality pump made for racing, and while a bit on the expensive side, it will most likely outlast your truck.

Tech Letter Of The Month
Multi Generation Chevy
I am building a '55 Chevy 4x4 pickup. I used '76 Chevy running gear on the '55 frame. With the front axle mounted on the original springs, the knuckles are tilted forward (negative caster?). On the '76, they were tilted to the rear. Is this a problem? I know the OEMs use positive caster to aid in tracking and re-centering the steering, but the truck seems to drive alright. I have seen other trucks with the axle mounted this way. Did they cut and rotate the knuckle? Would you in this situation? I would rather not change the spring mounts, as I would have to lower the rear mount excessively.

I used a Nissan steering box ('80s Pathfinder) because it mounted the gears above the frame. It works okay, except when you're stopped-it will not turn at all until you start moving again. Is this a pressure problem? I'm using the Chevy steering pump. Any ideas/help will be greatly appreciated.
Dean Sandstrom
Puyallup, WA

The tilt of the steering knuckles is what is referred to as the caster angle. For the best handling, the top ball joint should be tilted to the rear of the vehicle or in a positive position. Caster angle usually is between zero and 8 degrees measured from vertical. With the negative caster angle you now have, I am really surprised that the truck goes down the highway in a straight line instead of like some well-used shopping cart.

You don't have to remount the springs to fix this. You can place special tapered shims between the spring pack and the housing mount to tilt the steering knuckles rearward. These shims are available from any suspension company. When doing this, keep in mind that the pinion yoke will be turned downward, so make sure you don't end up with the U-joint binding on full axle droop. In reality, the operating angle of both the axle yoke and the transfer case yoke should be within about two degrees.

As to your steering problem, yes, it sounds like lack of proper pressure and/or volume. This could be because the steering pump you're using is worn out, or that the pulley ratio is not correct and the pump at low engine speed is not turning fast enough to provide proper volume/pressure. Or the Chevy pump works at a lower volume/pressure than what the Nissan pump takes. Take a look at the West Texas Off Road website ( There you will find instructions for some simple modifications to your pump that can increase both volume and pressure.

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