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May 2008 4x4 Tech Questions - Techline

Posted in How To: Tech Qa on May 1, 2008 Comment (0)
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Question: I recently bought a '98 Ford F-150 and was talking to my neighbor who is a mechanic. He says a lot of these trucks catch fire under the hood for no particular reason. Usually they are just parked when it happens. Is this really true?
Marlon Smith
Las Vegas, NV

Answer: There were quite a few Ford trucks and cars built between 1992 and 2004 that did have engine compartment fires. However, it's no mystery as to what's causing them.

There is a switch on the end of the master cylinder that cancels the cruise control when you touch the brake. Unfortunately, this switch has a tendency to leak and drip brake fluid (and yes, it's flammable) onto the wiring harness connector right below it. One of the wires in the harness always has power to it, even with the ignition key off. Get the picture? Not a pretty one!

Ford has listed a recall on this and at first did kind of a Band Aid-type fix. If the previous owner had it repaired under the new guidelines, there should be a blue tag on or near the harness saying that a special jumper wire has been installed that has an internal fuse. If not, get down to your dealer and see if your truck is on the "fix it" list.

Question: I just bought an '01 Cherokee XJ with a manual five-speed. I got a great deal on the Jeep and now I see why. The transmission has this terrible noise in it when in Neutral, like someone filled it full of marbles. It grinds when shifting gears and sometimes even jumps out of gear. What is this trans? Can I rebuild it myself? Where do I get parts? Would I be better off replacing it with something different? I plan in the future to rebuild the motor to a 4.6L, so if I rebuild the trans, will it hold up?
Aaron Newman
via fourwheeler.com

Answer: Your transmission is the New Venture 3550 that was used in '00-'01 XJs and '01-'04 Wrangler TJs. When the 3550 first came out, everyone thought it was just a smaller version of the very stout 4500-series five-speed used behind diesels in fullsize trucks. Well, it turns out that it is not, and while stronger than previously offered, it is not as good as expected.

I have been told by the rebuilders that U.S.-built "new old-stock" parts are getting scarce and can only be ordered through Jeep dealers, so that means that most of the replacement parts may be of questionable overseas manufacture. Instead of rebuilding the trans, may I suggest replacing it? Mainly because down the road you're going to have to rebuild it again and it will always rattle in Neutral. The noise comes from the countershaft kind of floating back and forth within the case. Note that if you put some side pressure on the stick, the noise will stop.

Probably the easiest swap would be to use a five-speed "Terminator" trans from Rockland Standard Gear (877/774-4327, www.rocklandstandard.com). This is a special version that Rockland had Aisin-Warner build, which was designed to handle all the torque and horsepower that any 4.6 motor can put out, plus it's a heck of a lot quieter, and has much smoother shifting. The best thing is that it's a direct replacement, meaning no adapters needed and no floor modifications. The only downfall to the trans is that first gear is slightly higher at 3.80:1 as compared to the 4.0:1 of the 3550.

Another trans to consider is the Jeep/Mercedes NSG-370 six-speed. It has a 4.46:1 First gear and a 0.83:1 Overdrive. It should bolt right up to the present bellhousing, and even the clutch disc will work. I think that it is a couple of inches longer, so new driveshafts may be necessary. From what I can find out, the six-speed may not be as strong as the NV3550.

Question: I live in France and do a lot of 'wheeling with a modified Range Rover classic V-8. My buddy and I break front CVs and rear half-axles. I run 35s and he runs 38s, so he breaks more than I do.

Yesterday I learned that the rear axles in Defender 110s were modified Dana 60s up until a few years ago. I also heard that the British Army had special armored Defenders for use in Northern Ireland, and they even had Dana 60s in front too.

Do you know about these LR Dana 60s? LR called them Salisbury axles. What kind of 60 are they, and can I get parts for them easily? Or did LR modify them so much that parts are not interchangeable?
Ceferino Lamb
via fourwheeler.com

Answer: To be honest with you, I really don't know all that much about Land Rovers/Range Rovers, so I had to ask a bunch of questions and my search led me to a local Land Rover owner (actually he has, like, five or six of them), who just happened to own two that had Salisbury axles under them. One was an ex-Desert Storm military vehicle, and the other was a special factory order. They don't look anything like a Dana 60. He provided me with a contact in England. Steve Clifton runs a Rover-based business (steve@lrspares.com) and says he can locate rear axles without a problem, but fronts are a bit more difficult to obtain. If you would contact him, he's sure he can find and ship (read: expensive) the Salisbury axles.

Then I remembered that longtime friend, historian, technical writer, and book author, Jim Allen used to own one of those machines, and actually worked as a mechanic for a major East Coast LR dealer and as a LR factory driving instructor. Jim had a wealth of information to pass on:

"The Salisbury axle is essentially a Brit-built Dana. If you recall, Dana bought the Salisbury Axle Company in 1919 and they became the Salisbury axle division of Spicer. I think the Salisbury name was dropped around 1970, but they had a division in England that built a variety of axles for MGs, Volvos, and others.

"The Salisbury used in Land Rover D110s and 101FCs, and some 109 V-8s was a "Wimpy-Sixty." Even wimpier than normal. It had a normal-sized D60 ring gear of 9.75 inches (as compared to the standard 8.25), but had 1.25-inch 24-spline axles. Most of the Salisburys used four-pinion differentials, while most of the Rover axles were two-pinion designs (there were some four-pinions). No limited slips or lockers were offered from the factory, except-for a couple of years-a very wimpy LS in the early '60s for the Rover differentials.

"Until the early '90s ('93 is the generally acknowledged year), Rover differentials were 10-spline (about 1-inch major diameter, about 0.8-inch minor). From '94, Rover diffs adopted the 24-spline.

"The only reason the Salisbury had such a great reputation is that the Rover axles were so incredibly wimpy. The metallurgy in the Salisbury was pretty poor overall (the Rover, too). Bottom line, you can buy aftermarket upgrade parts for a Rover diff a lot cheaper than finding a "legendary" Salisbury.

"There are a lot of differences in a D60 versus a Salisbury, but you can see the resemblance (especially the older ones). If I remember correctly, you can swap the insides over and use custom 30-spline shafts. Remember, also, that there are different Salisbury axle models, just like there are Dana 44s, 53s, 60s, and so on. There are two types seen on LRs, but I don't have all the info at hand."

Jim also clued me into a couple of very interesting shops. One here in the U.S., and the other in Australia. Great Basin Rovers in Salt Lake City (801/486-5049, www.greatbasinrovers.com or www.expeditionexchange.com/gbr/), has lots of interesting stuff for the British-built Jeep imitators. They have some rear axleshafts that are 100-percent stronger than the factory axles. The owner, Bill Davis, tells me that he also has some special heavy-duty CV-joint axles for the front end that are not shown on his Web site. He said that Dana 60 parts will actually, with some variations, interchange with those in a version of the Salisbury which is currently being made by a company called GKN. Great Basin Rovers also stocks ARB Air Lockers and Truetracs, as well as Detroit Lockers for the Rover axles.

The source in Australia, Jack McNamara Differential Specialist (www.mcnamaradiffs.com.au/), offers a wide range of custom-built locking differentials for both the Rover and Salisbury. His Web site makes for some interesting reading.

Question: I have a '74 Blazer that I have been working on for 15 years now. The body, front axle, brakes, and hydraulic steering with four-wheel steering are the last things left to do. The body will become an Urban Guerrilla Wagon.

The brakes: I have trouble getting enough stopping power in the front end. I can lock up the back tires but the front brakes feel like they are just sliding. Would I be able to upgrade to a 1-ton or 3/4-ton brake master cylinder to get more pressure, or would I have to upgrade the whole front brake system?
Jeff D. Sommer
via fourwheeler.com

Answer: No, going to a 1-ton master cylinder is not going to give you more braking pressure. In fact, it just might take more pedal pressure to stop the vehicle. I am not sure of the bore size between a 1-ton and your Blazer, but if I had to guess, I would say it had a bigger bore to compensate for the larger calipers and wheel cylinders. This means that it will displace, or move, more fluid for a given amount of stroke than one with a smaller bore. In other words, with a larger cylinder-bore master cylinder-let's say, a 1-inch versus a 7/8-inch diameter-the pedal requires less travel to move a given amount of fluid, but will require more pedal-pushing power to gain the same amount of line pressure to stop the vehicle. The reverse happens when a smaller-bore cylinder replaces a larger one. It takes less pedal-pushing power but more pedal travel as the piston must make a longer stroke to move the same amount of fluid as the large bore cylinder. Something to keep in mind: a larger-bore master cylinder doesn't push any more fluid down the brake lines than a smaller-bore cylinder does because the brake lines and the wheel cylinders can only accept a given amount of fluid in a direct proportion to their given total capacity in cubic inches of volume.

There are several things that could be causing the lack of front braking. The first thing that I would do is to closely inspect the front brakes. Make sure that there is no rust and corrosion on any of the components that slide in and out. Excessive wear on the mounting brackets could also cause the sliders to bind and not move freely. Clean everything up, and apply a proper high-temperature lubricant to all moving parts.

It also could be that it's time for some replacement calipers. Corrosion and wear could allow the pistons to cock in the bore and not fully expand properly. Rotor finish is very important. Have a shop turn the rotors, and be sure to choose one that does a lot of brake jobs, not the local auto parts store that turn only a few a week. Chances are a shop will have a newer and better machine that will give a much better finish. Be sure to clean the rotors with soap and water before reinstalling them. Quality pads are very important, as well as following the manufacturer's break-in procedures.

Then again, it could be that all these components are just fine. I have seen brake problems where the combination valve was not allowing enough fluid to flow to the front brakes or that the master cylinder itself was leaking internally and bypassing fluid. One of the strangest complaints of lacking braking ability was caused by the simple fact that the brake line had been pinched by a rock and prevented fluid flow.

Now if you feel bucks-up, there are several companies that offer aftermarket brakes ranging from a completely new system to just rotors. An Internet search under "Chevy 4x4 brakes," or something of that nature, should bring up some information. One company that comes to mind is Stainless Steel Brake Corporation (www.stainlesssteelbrakes.com). They also have an inexpensive gauge kit that I have used where you can pull off a brake line and attach a pressure gauge to that line. It's a fairly quick test to make sure you're getting adequate line pressure to the brakes.

Question: I was wondering if you guys have ever heard of filling a flat tire with a broken bead away from the rim with starting fluid? I saw a guy change a tire on the rim and then spray it with starting fluid and then light it, which in turn sets the tire and fills it with enough air to drive on. Was wondering if this a good idea or if it is dangerous?
Daniel Krapp
Salem, OR

Answer: Yes, we have witnessed it first-hand. It's not something we would do or recommend as it can be quite dangerous. Why? First, just how much starter fluid do you inject into the tire? Not enough, and the bead will not seat; too much, and you could in theory blow the tire off the rim or cause a portion of the tire to break. What would happen if the tire went flat and came off the rim because of damage to the sidewall and you used the starter fluid method? How would you like a piece of tire in your face? Remember, you're not putting air into the tire but an explosive gas. What if the tire does seat before all the explosive gas burns up? Now you have a tire that is full of explosive gas. Not something that I would like to drive around with.

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