Question: I am 16 years old finally and school has just ended. I have a job and have some money, and I'm interested in a summer project. I was looking into an M38-A1 that a guy near me has. I was just wondering if it would make a good summer road-legal machine with some trail prowess. The seller says it runs, and he has the windshield and everything. It is kinda rusty, but it's OK for Wisconsin. I have been doing a bit of research into the M38-A1s, but it is kinda empty in the realm of the aftermarket. Are the Spicer axles it has the same as Dana? The front is a 25 the rear is a 44. I want it to wheel OK but still take me to school.
Dan Gollnick
via fourwheeler.com
Answer: The M38-A1 was the forerunner of the CJ-5. It has a bit better frame than its civilian counterpart and a lot heavier springs, and a bunch of little things like the grille and fender mounting are different. The dash is lower and what a lot of people call a "knee-buster." Unless it has been converted, it runs on 24 volts, which is kind of a pain to deal with. It can be changed over to 12 volts by using the civilian counterparts such as the starter, generator, distributor, as well as changing out the gauges and bulbs.
Keep in mind that it is about 50 (or more) years old, so lots of things can be worn out. It has 5.38:1 gearing, and this makes it pretty darn slow on the highway with a limit of about 55 mph for continuous driving. The brakes flat suck with their little 9-inch drums.
Yes, the front and rear axles are a Dana 25 and a Dana 44, respectively. The rear uses 19-spline axles instead of 30-spline and uses a tapered axle and hub assembly. It's important to keep the nut on the end of the axle torqued properly.
If you were my son, I would tell you to convert to some 11x2-inch brakes from a pre-'72 Jeep Wagoneer and make sure they were always adjusted up; the stock master cylinder is a bit small in volume so will require more pedal travel (cylinder stroke) for stopping. I would have you also buy a used Warn or a new Saturn overdrive from Advance Adapters. This way, you would have not only an overdrive for the highway, but a way to "split the gears" with your three-speed T-90 transmission for better performance both on and off the highway.
Now, after going to this much work, if you plan to keep it for a while, I would suggest some much better seats, and swapping the tapered rear axleshafts out for some flanged axles.
With it being your first Jeep, you might want to buy a copy of my book, The Jeep Bible by King/Worthy. Any bookstore can get it for you. It's not a service manual, but has some pretty darn good information in it, and it's done on a humorous note. You might also want to buy a reprint of a factory service manual. These are available from places like Portrayal Press (P.O. Box 1913 G, Bloomfield, NJ 07003, 201/743-1851, www.portrayalpress.com).
Question: I am getting ready to build up a 4.0L engine for my '98 Cherokee. Is there any particular engine that I should look for? I want to build a separate engine and have it all ready for the swap instead of having my Jeep down for the buildup time.
Jim Combo
Boise, ID
Answer: It seems that there have been at least five different cylinder blocks and heads since its inception back in 1987, when the engine was rated at 177 hp and 224 lb-ft of torque. In 1991, there was a new design of the block and head, and the horsepower increased by 13 and the torque by 8 lb-ft. The casting number on these blocks is 53008405, and the head, I believe, is 7120. In 1996 a new engine block came out that is easily identified by the "NVH" on the side, which stands for "noise, vibration, and harshness." (This means that they did some strengthening of the block.) It also got a new cylinder head and a different piston design. In 1998, the oil-filter mounting location got changed so that the oil filter is mounted 90 degrees to the pan rail instead of pointing downward. A big change came in the '99-to-present blocks and cylinder heads, making them even stronger. Keep in mind that they also changed the way the accessory drives are mounted, and so they're not interchangeable with the earlier blocks. Also, the heads may not flow as well due to modifications made to improve emissions. These carry the casting numbers 53010327AB and 53010328AB. There were some changes also in the connecting-rod design, but overall, the center-to-center length, pin diameter, and weight all stayed the same.
There have been some major changes to the electrical system as well as the FI systems. The pre-'91 engines used a French designed Renix fuel-injection system that was, well, French, and it would be better to stay away from it if possible. There were also some major exhaust manifold cracking issues up to about 2001, but I would strongly suggest a set of aftermarket headers with whatever year engine you go with as it's a great performance gain.
When it comes down to it, I would suggest finding one built between 1996 and 1998 if possible. However, some states with emission testing require that the engine be the same year or newer than the vehicle that it's going in.
Now if you want to go all out, perhaps you should consider one of the stroker engines or engine kits from HESCO (205/251-1472, www.hesco.com) or Golen Engine Service (800/591-9171, www.golenengineservice.com). Rusty's Off Road (www.rustysoffroad.com) offers an aluminum cylinder head that not only flows better but is about 30 pounds lighter.