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July 2009 4x4 Truck Repair & Tech Questions - Nuts & Bolts

Posted in How To on July 1, 2009
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Confused? Email your questions about trucks, 4x4s, and off-roading tech using "Nuts, I'm confused" as the subject and include a picture (if it's applicable). Digital photos must measure no less than 1600 x 1200 pixels (or two megapixels) and be saved as a TIFF, an EPS, or a maximum-quality JPEG file. Also, I'll be checking the forums on our website (, and if I see a question that I think more of you might want to have answered, I'll print that as well. Otherwise drop it old-school style with the envelope addressed to the address below. Letters published in this magazine reflect the opinions of the writers, and we reserve the right to edit letters for clarity, brevity, or other purposes.

Write to:
Nuts & Bolts
4-Wheel & Off-Road
6420 Wilshire Blvd
Los Angeles, CA 90048-5515
fax 323.782.2704.

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Chilled Slush-Box
Question: I have a fullsize '89 Blazer 5.7L V-8 and 700R4 transmission. I bought a TorqFlo Super Cool transmission cooler (PN 911679) to install on it, and I am unsure which way I should install it. The directions show two ways of doing it. One is to install it in series with the radiator so that the transmission fluid still travels through the radiator as well as through the new cooler. The other way is to disconnect the lines from the radiator altogether and only have the fluid passing through the cooler. I am unsure which way would be the best for my truck.

I have heard of radiators going bad internally and allowing water and coolant to enter the transmission, turning the fluid into Pepto Bismol. I don't do any towing with my truck at this time, I am only putting on this cooler for a little extra protection for my tranny since I already replaced one, and, frankly, as expensive as it was to buy and find one, I don't want to have to do it again anytime soon. Any advice you can give me in this matter will be greatly appreciated.
Lou F.

Answer: If protecting your transmission is the goal, I'd say use both coolers. If your are nervous about the coolant leaking from the radiator to the transmission cooler that is built in the radiator, then have your radiator serviced or replaced. Many times the in-radiator trans fluid cooler is nothing more than a tube running through the tank of the radiator, so bypassing it won't make too much difference, but I say two coolers are better than one.

Run, Jimmy, Run
Question: I have an '85 GMC S-15 Jimmy that I have been working to turn into a decent wheeler. The original plan was to build it to run in a local fire department's Tough Truck event. The truck has been completely gutted except for the driver seat. The only real additions made to it are a hoop-style rollbar and a front stinger as well as a nice rattle-can paint job. Now that I've spent some time in, on, under, and around my truck, I'd like to try and beef it up a little and try to make it into a decent trail rig. Not something huge and extreme, just something capable of making its way through without breaking.

I've searched high and low and can't seem to find any aftermarket support for this style Jimmy/ Blazer. Am I condemned to fabricating all my own parts, or is help out there? Any ideas on the types of improvements would be great. I'm new to wheeling, and I'm not sure where to start.
David F.

Answer: There are actually many options for your S-15, also known as a Chevy S-10. If I could only have a few off-road performance parts I'd vote for a locking rear differential and better tires. Randy's Ring & Pinion (888.905.5021, offers quite a few different locking and limited-slip differentials for your GM 71/2-inch rearend, for between $400 and $600. But if you are really budget minded you could just weld up the spider gears, even though that's harder on axles and tires in the long run.

As for tires, your axles and front differential will not take excessively large tires for long, so I'd go up an inch or two from what you have, trim the fenders if they hit, and go have fun. Find the most aggressive tread you can if your trails have mud holes in them. Eventually you may want 1-ton axles, lower gears, and more power, but for now get some traction and go wheeling. Go with friends, and as parts break you'll figure out what to upgrade next.

Axle Answers
Question: I have a '90 Cherokee 4.0L, 4.10s, 33s, 8.8 out back, Dana 30 up front, and EZ lockers all around. I would love to upgrade front axleshafts. I know '98 and newer Cherokees have larger U-joints, but it's still a weak shaft. Chromoly would give me more strength, but the cost is high enough that if I go that route and still break a shaft my wife may just kill me.

My question is: If I get a set of donor shafts from, say, a full-width Dana 60, could I then have them cut and resplined to fit my 30? I know there would be a fairly high cost with this option (assuming it is doable), but in theory this would be the last set of shafts I would ever need. Does this make any sense, or am I looking at this all wrong?
Kevin T.

Answer: Resplining and stuffing a Dana 60 axle shaft in a Dana 30 housing and differential is like trying to tighten that little screw on your sunglasses with an impact gun. No only is it the wrong tool for the job, but it's also not going to fit and will likely break other parts. The Dana 30 is a small 1.16-inch 27-spline axleshaft, and the Dana 60 inner shafts are 11/2-inch 35-spline, meaning you'll need to cut the shafts down just to get them into the carrier-and then you'll likely have machined through the hardening of the axleshaft. Plus you're not going to be able to fit the Dana 60 joints and yokes inside the knuckle. Basically it's not a good idea.

Either swap in a 30-spline carrier like an ARB Air Locker and go to the bigger 30-spline chromoly axleshafts, or swap in a complete bigger axle like a Dana 44 or Dana 60. Either way, you'll need to hide it from your wife.

Blazin Trail-Shafts
Question: I have a '93 S-10 Blazer four-door. It has a 350 with a 700R4 and the stock 236c transfer case. I have an HP44 front and a 14-bolt rear. I just bought an HP60 for the front and thought while I'm at it I should beef up my front driveshaft. Does anyone make a 1350 or bigger yoke that will fit the front output of my transfer case? I want something stronger than those little baby U-joints that GM put in there, but I don't really want to get away from the pushbutton 4x4.

Answer: The NV236 transfer case is the same basic case as an NV233 part-time transfer case, except it has Autotrac or full-time four-wheel drive. When the Autotrac button is pushed, the Transfer Case Control Module (TCCM) locks the front axle, and monitors the front and rear transfer-case outputs for speed. When it sees the rear speed increase, it applies an internal clutch to lock the front driveshaft to the rear. Although it is not locked in, these cases always rotate the front driveshaft, even in 2WD.

The early version (like the one in your question) uses a front U-joint just like a NV231. Flanges from an NV231 will interchange, although sometimes the seal has to be changed. The production U-joint is a 1310 series. In 1997 the front output was changed to a male spline, and a CV was installed in the front driveshaft. These units need to use the flange developed by Diversified Creations (810.227.4777, to install a standard U-joint. Then you simply need a companion flange for your larger 1350 U-joint, and most driveshaft shops, such as Tom Woods Custom Drive Shafts (877.497.4238,, can supply this.

Toy trouble
Question: I have broken the motor mounts in my '85 Toyota truck. It has a 22RE, dual cases, and 5.29 gears. Are any better versions available?
Dustin G.

Answer: Funny you should ask. I recently had the same problem with my '86 Toyota mini-truck. I contacted the folks at Rockstomper ( and they sent me some of their fabricated mounts, which worked flawlessly while I was out wheeling. My truck has a late-model four-cylinder swapped in, but it uses the same style mount as a 22RE, but with a longer stud than normal for the aluminum engine brackets. Rockstomper has the motor mounts you are looking for.

'Cage Cube?
Question: I was wondering about the pros and cons of building a rollcage of square or rectangular tubing versus round tubing. I worked at Caterpillar, and all of their equipment uses square rollcages, and the prices seem much cheaper to do so. Any help would be appreciated.
Gregg P

Answer: The rule of rollcages is that it matters more how you build it than what you build it with. Square tube isn't a bad choice, but there are some issues with working with square tube. It is heavier for a given size since it actually has more surface. It's also harder to work with since you can't bend it as easily as round. However, square tube is a lot stronger if you're using it as a beam.

Anther problem is that there is a far greater range of material quality in round mechanical tubing than you find in square tube. They don't make DOM or 4130 square tube, or at least it's not anywhere near as easy to find. All your common square sections are HREW and may not even be held to as tight a spec as round HREW tube as far as material quality, wall thickness, and construction quality go.

I've contacted some engineers, and they also noted that when you're loading any structural member as a beam, you figure the vertical leg height as your primary factor in strength. A square tube will have two totally vertical "legs" that are the full height of the tube. A round tube will have a mathematical average of the round section that gives you an equivalent vertical "leg." The square section's "leg" is always way more since all the material is oriented in the correct direction.

If you have tight-fitting joints, solid-quality welds, and a design that utilizes triangles to disperse forces, then using square tube isn't a bad choice. In fact the biggest reason square or rectangular tubing isn't used for rollcages is because round tube just looks better.

Nuts, I'm Confused
Load-Sensing Steering?
Question: I have a '94 Dodge Ram with a 5.9L Cummins and 33-inch mud-terrain tires. The problem I'm having is keeping the front steering components alive. I have replaced the track bar/panhard bar three times, and that gets pretty expensive at right around $300 from the dealer. And now the steering box has play in the sector shaft and the truck wanders so badly down the road that I have to constantly correct it. Any help would be greatly appreciated.
Garrett N.

Answer: The problem is partially due to the massive weight of the Cummins engine (over 1,000 pounds). Add larger tires and the considerable miles your 15-year-old truck has likely seen and you have quite a strain on your steering components. As the track bar end mounted to the frame wears out, it causes a lot of slop in the front end. After time the side-to-side force that the track bar is supposed to control ends up abusing the steering box. Add in the turning of 33-inch tires, and the sector shaft bearing can wear out quickly. This is a common problem among early '90s dodge owners.

Lukeslink (800.962.4090, makes a track bar end that is fully serviceable and rebuildable. All you use is your existing track bar, and with a little work the Lukeslink components install right into your old track bar. It can be tightened whenever needed and costs less than half the price of a new track bar.

PSC Motorsports (817.270.0102, has a steering box brace that installs using the existing sway bar bolt holes and runs from framerail to framerail. You remove the existing nut off of the pitman arm and install a threaded shaft that will slide through the brace with a bearing in the end. This will transfer all the steering box side-to-side movement into the brace and out to the framerails. The brace will act like a crossmember and reduce frame flex.

Even though your question is Dodge based, it reminds us that adding weight to the front of your vehicle- heavy tires, bumpers, and such-must be considered in all your steering and front suspension components. A steering box brace is a good suggestion for any 4x4. I'd like to reward your questions with this month's Nuts, I'm Confused prize. This month we are giving away a 10,000-pound Midnight Series electric recovery winch from Gorilla (888.657.9997 This winch is outfitted with a 12V, 5.8hp series wound motor, three-stage metal planetary gears, and a 265:1 final gear ratio. The 87 feet of cable should be very useful in helping extract your Dodge from any muddy pits or snow trails. Just remember with the additional weight of the winch on your Dodge, I'd definitely recommend you get the steering box brace and track bar reinforcement.

Power Wagon Problem
Question: Somehow my son managed to convince me to buy a '53 Dodge M37 at an auction for $2,200, kind of a father-son bonding deal. The M37 is in really great shape, hardly any rust at all, and only has a slight dent in the front bumper. It has 30,000 miles on it, and the engine turns over but will not start. After brainstorming a bit, I believe we have two options: We either get the original engine running or we swap in a modern drivetrain out of a wrecked '90s truck.

The reason I ask is because the body is in such great shape, I'm not sure I want to swap in an unoriginal drivetrain if the truck is worth something with the original working parts. If that's the case, we will sell it and buy something else for our project. I do not know much about the value of these old military trucks and would appreciate it if you could point me in the right direction.
Dave D.

Answer: Oh no, Dave, you had to be the guy who turned on the flashlight in the dark room full of restoration fanatics and modification nuts. Let me explain. It seems that if you start messing with any truck older than about 1973, you run into the exact situation you mentioned. Do you restore it the way it was originally or do you change it into something that will be a bit more street-safe and highway-speed-friendly (not to mention possibly more trail-capable)? It will be impossible to keep everyone happy with your buildup, so rule number one: What will make you happy? I think if you and your son restore the M37 to stock form you'll have an easier project, with very basic parts (no fuel injection, no automatic transmission, no power steering), and end up with a truck great for cruising to get ice cream and for wheeling easy-to-moderate trails, and you will definitely have fun learning together with your boy.

M37s are tough as heck and a great safe truck for your son to go explore the world in. If you modify it, you'll need to be innovative to make the new parts work in the old body and to work safely without the help of the original engineers' intentions. My advice is that if this is your first project truck, start with the restoration, then you and your son-or your son and his future son-can always modify it down the road. However, if you have some previous hot rodding experience and believe that you can do a good job swapping the late-model drivetrain in, then don't feel bad about changing it.

I think about it this way: What would those original engineers use if they had the technology we have today? I bet that the M37 would have at least a fuel-injected engine under the hood and disc brakes at each corner if those original Dodge engineers and designers had any input. In fact, I recently dragged home an M37 of my own. I know I'll have a few purists at my throat, but I'm definitely going to change the powertrain to something newer, as mine didn't have any engine or trans in it and is far from perfect. Some parts won't even be of the Mopar variety, but don't tell anyone.

If your son is excited about the project then that is 50 percent of the work. A lot of father-son projects fail when the kid gets bored. And why not weigh the pros and cons of each direction with him? It won't hurt him to drive a slow, nonpower-steering, original '53 truck for a few years, and then eventually if he feels up to it he can swap in newer parts.

One last thing. Llots of people will tell you that you did it wrong, but if it makes you happy then you made the right choice.

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