Your 4x4 Tech Questions Answered
Back to Basics
Q I actually have two questions. First, I have a ’94 Chevy 1500 with 6 inches of lift and 35-inch Goodyear Wranglers, and I was wondering what the best way to “liven up” my TBI 350 would be without spending a lot of money, but giving it a noticeable power difference. I’m also running straight pipes with no muffler or converter; will this have any negative effect on horsepower?
My second question is which of these two trucks would be the best choice if I wanted to use it mostly off-road? An ’88-’98 Chevy 1500 or a ’94 IFS Toyota pickup? I don’t really know a whole lot about Toyotas or how good their aftermarket support is, so any feedback would be very helpful.
A TBI 350 Chevys are workhorse engines that deliver decent power and torque, but they aren’t rocket ships. Late-model LS engines will frankly run circles around them. However, that’s not to say you can’t improve on what the factory did.
In terms of relatively inexpensive bolt-on aftermarket parts, the trifecta is usually an intake, exhaust, and a tune. An engine is an air pump, so anything you can do to eliminate restrictions on the intake and exhaust, the better you will be. While you think you may have improved performance by cutting off the catalytic converter and mufflers, you are probably hurting performance with that arrangement. Cats are federally controlled emissions equipment, so we can’t recommend removing them, but we assume you live someplace where this doesn’t matter.
As for the mufflers, engines do generally benefit from a little backpressure in the exhaust because it helps scavenge spent gases, not to mention that your neighbors would probably appreciate some mufflers when you come home from four-wheeling at 1 a.m. So, you might actually pick up a little gain (not to mention more friendly neighbors) by installing free-flowing mufflers from any number of reputable aftermarket companies.
Quality headers are another good option rather than the notoriously restrictive factory exhaust manifolds. A good cold-air intake system would also help a lot, as the factory intakes on these engines leave room for improvement. Combine these mods with the tunes available via performance chips from companies such as JET Performance (www.jetchip.com), and you’ll have a very noticeable difference. Going a step further, a good cam can make a big difference, as can a set of heads; it just depends on your budget and how far you want to go.
The biggest difference you can make in terms of performance, however, is re-gearing the axles. Your truck is probably equipped with 3.55s, which worked great for the 30-inch-tall tires it came with from the factory. You’ve since installed 35s, which is the biggest hindrance on the performance meter. It’s like a 1⁄2-inch breaker bar: try and break loose a stubborn bolt with your breaker bar. When you can’t do it, what do you do? You throw a “cheater pipe” on that breaker bar and try again. Why do you do that? Because there’s more leverage for you with the longer cheater pipe. Putting bigger tires on your truck without changing the gearing does the same thing, only in reverse. You’re taking the engine’s 14-inch breaker bar and only making it 11.5 inches long. If you were doing the same thing with the stubborn bolt, wouldn’t it be a heck of a lot harder to break loose?
As to your second question, really, either would be a good choice. The ’88-’98 Chevys and mid ’90s Toyotas can be picked up cheap and have a lot of aftermarket support. The Chevys were plagued with more IFS frontend problems, while the Toyotas are considered reliable if somewhat lacking in the power department. All of the advantages and drawbacks of both have been well documented in our past issues and at 4wheeloffroad.com. You can choose to keep the IFS frontends in either truck or do a solid axle swap, both of which are quite viable and worth doing and are made easier with a large amount of aftermarket support.
$4K 4Runner Revisited
Q In the most recent installment of the $4K 4Runner, you mentioned component strength as one of the reasons you opted against a front locker. Would you have the same concerns if you were running a near-stock tire size? I am currently running 235/75 R15s on my second-generation 4Runner, and I’ve had a front locker on my wish list for a while.
A Harry Wagner responds: I definitely think that tire size is a factor, due both to weight and leverage of the rotating assembly. The front-end components on the second-gen 4Runner are relatively small (ring-and-pinion, CV axles), and with the low-profile bumpstops we used to maximize wheel travel, we sacrificed strength of the CVs even more, since they are weakest at their maximum angle.
That said, a front locker will greatly increase the capabilities of your 4Runner. I recommend running a selectable locker like the ARB Air Locker or a limited slip like a True Trac in order limit the strain on the front-end components, even with your smaller tires.
On the $4K 4Runner I see a solid axle swap in the future, so the other factor (beyond strength) is spending money twice. We did spend money on regearing, but hopefully can sell the front diff to offset some of those costs when/if we do a solid axle swap.
Q I have an ’03 Dodge 1500 with the 4.7. Overall I enjoy the truck, but I would like a lower gear in low range. I have looked but only find gear kits for Jeep, Toyota, and Suzuki. Is there a company that offers something like this for my truck and I’m just not finding it? If I have an NP231, could I use one of the Jeep kits? I am trying to not to change the axle gears because the gearing feels right when in high range.
A Actually, this is easier than you might think. Your Dodge should be equipped with the 5-45RFE and an NP231D or NP241D transfer case (or their electric-shift equivalents), which are very similar externally. The best way to tell is to crawl underneath the truck and look at the circular tag right in the center on the back of the transfer case; it will be clearly marked. The NP231 and NP241 have the same low-range ratios, so swapping a Jeep NP231 would do nothing for you. But interestingly the NV241OR, or Rock-Trac, transfer case used in the Jeep Rubicon features a 4:1 ratio and is very, very similar to the transfer case in your Dodge.
We took your question to our friends at JB Conversions (www.jbconversions.com) and they had some interesting answers. First, the bolt pattern and spline count on the NP241OR Rock-Trac are the same as your existing transfer case, making it a theoretical bolt-in affair in terms of attaching it to the transmission. Spline engagement is critical, however, and JB Conversions recommends checking the engagement because it varies from year to year with your transmission. Bare minimum engagement would be around 1 inch, with 1 1⁄4 to 1 1⁄2 preferred. Second, there is a seal in the tailshaft of the transmission that needs to mate with the input shaft of the Rock-Trac, otherwise you’ll have a major fluid leak. If the seal isn’t in the right spot or the right diameter, then a seal can be sourced or a bushing machined that will space the seal where it needs to be (again, they vary from year to year). If you stick to sourcing the transfer case from a similar year Wrangler as your Dodge, then the speedometer gear/tone ring arrangement should work, but be prepared to tackle that if you find a Rock-Trac out of a later JK.
There is also shift linkage and driveshafts to consider. If you have a manual-shift transfer case in the Dodge, then the linkage can be made to work but would be potentially backwards from the Jeep configuration, which, from up to down, is 2-Hi, 4-Hi, Neutral, 4-Low . If it’s electric-shift, then you would need to source and adapt the Dodge linkage to the Jeep linkage. Regardless of the transfer case it’s a straight-throw lever, so this should be relatively easy.
For drivesahfts, the Rock-Trac has a fixed rear yoke while your Dodge driveshaft is a slip-yoke design, so there will be some driveshaft modifications required. However, there’s nothing exotic; any competent local shop could do it. There’s a chance that the front shaft could bolt up if it has a fixed front output, but there are no guarantees, so count on front driveshaft modifications and be surprised if you don’t need them. Good luck, and let us know how it turns out!
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