Willys’ CJ-5 Universal Jeep - October 2013 Vintage VaultPosted in Features on September 13, 2013 Comment (0)
(Editor’s note: While thumbing through the vast Source Interlink Media archives, we came across photos taken by Pat Brollier of an early CJ-5. With a little digging we found out that the pictures were associated with an article written by Bob Ames for the September ’61 issue of Motor Trend for their “For Men Only” department. Since we can’t beg, buy, or borrow a brand new early CJ-5 with an F-head, optional T-98 transmission, and 4.27 axle-gearing for Jp-style testing (we are working on a Jp time machine, but it needs a new Mr. Fusion), we will do the next best thing and reprint this article here in Vintage Vault covering the same topic. Also, we welcome men, women, and children—as long as you are a Jeep nut.)
For the past month, I have driven a Willys CJ-5 Jeep Universal. This car was not a run-of-the-production-line car, but was, in my opinion, the best all-around Jeep for the average back-country driver.
There were three major operational items, and each will be discussed later with the reasons as to why I think it improves the stock Jeep. These options were: in front, a Koenig winch; in the center, a four-speed transmission; and in the rear, a 4.27 axle ratio.
For those who are not familiar with the mechanical components, here is a brief rundown. The Jeep is powered by an F-head, four-cylinder engine displacing 134 cubic inches and producing 72hp at 4,000 rpm. The carburetor is a single-barrel, and the compression ratio is 6.9:1, which gives the car excellent tolerance to low-octane fuels.
As with any conventional car with manual shift, power is directed through the transmission—but here the similarity ends. From the transmission it is taken through a transfer case, where it may be transmitted directly to the rear wheels or multiplied again and divided equally between the rear and front wheels. Or the transfer case can be put in Neutral, and another lever engaged and the engine power directed to the winch. In other words, there are three choices for power: conventional drive, four-wheel-drive, or operating the winch. To control the power output, there are four levers—a conventional manual shift, a front axle shift, an underdrive, and a PTO shift.
The ride is best described as a “rump” ride. It is harsh over almost any type of terrain, but the new seats in the CJ-5 are a great improvement in smoothing out the worst of the ride. From the standpoint of purpose, this ride is entirely justifiable. There are seven leaf springs in front and nine in the rear. This gives the CJ-5 a payload of 1,500 pounds, better than most conventional station wagons. Naturally, it is bound to ride stiff. On the other hand, I drove this Jeep over a rocky, washboard road at 30 mph—a trip that would have shaken many conventional cars to little pieces in less than a mile.
Acceleration of this CJ-5 was down from its normal potential. This is a natural result of the 4.27 axle ratio. I would judge acceleration to be equal to the slower compacts.
Gas mileage is the hardest figure to report. I recorded a range from 10 to 20 mpg. The 10-mpg figure included mostly compound-low, four-wheel-driving with some winching; the 20 mpg figure was almost all highway driving. Overall average for the 1,500 miles, which included all types of gearing and some winching, was 15.5 mpg. This is exceptionally good, considering the types of terrain driven during the test.
Those who are accustomed to Detroit’s plushier products might be a little shocked at the Jeep’s interior. Perhaps the most revealing thing is that so much of the interior is also the exterior. Not only is instrumentation at a bare minimum, there are virtually no decorations at all. Everything about the Jeep is picked not for decor, but for durability.
The Jeep is probably the only Detroit car that is designed without a top and without doors. But there are about a dozen tops available optionally, from all-metal jobs to the new convertible canvas outfit that was on the test Jeep. It has a wide, zippered rear door that can be rolled up for full-open back space. The doors are removable to give about 50 percent open space, or in about five minutes, one man can take the top down (or put it up) and fold the windshield down for complete open-air travel.
As mentioned earlier, this Jeep had three options that I believe improved its practicality a lot. The standard rear axle ratio, 5.38, was changed to 4.27. The three-speed transmission, with ratios of 2.79, 1.55 and 1.00, was eliminated in favor of the four-speed option with ratios of 6.39, 3.09, 1.68, and 1.00. Reverse jumped from 3.79 to 7.82. To show how this improves the two most important driving characteristics of a Jeep, low-speed power and top speed, it is necessary to resort to mathematical formulas.
Maximum top speed with the 4.27 is 77 mph; with the 5.38 it drops to 65 mph. Allowing for the effect of variables, this is about 85 percent efficiency, meaning that a practical top speed would be 65 mph with the optional axle, as opposed to 52 mph with the standard. The only disadvantage to the 4.27 is slowing down for long hills. But during the test, hills didn’t make any significant difference in the time it took to make a long trip, although the top speed did.
To show just how much low-gear performance is improved with the four-speed transmission, it is necessary to compute the grade ability in percent, which is the grade on which the Jeep will start or the grade it will climb after it is started. First of all, look at the change in overall ratio in compound low: 68:1 for the four-speed and 4.27 axle, compared to 38:1 for the standard axle and three-speed transmission
In computing the grade ability I have used maximum torque, 114 lb-ft, 85 percent efficiency, total ratio, a road resistance factor for good gravel surface, 14-inch loaded radius for the tires (6.70x15, another option), and a payload of approximately 750 pounds.
Mathematically, the grade that the test Jeep would climb would be a 168 percent, or about a 59-degree hill. A stock Jeep under similar circumstances has a maximum potential of 94 percent, or about 43 degrees. This is the best way the difference in power potential between the two models can be stated.
This may explain why I prefer the 4.27 axle with a four-speed transmission. Top speed is about 15 mph better, while the low-gear performance is almost doubled. And although these mathematical figures are theoretical, the test proved them to be just as practical on the road.
Just a word of caution, though. The trucker or experienced Jeeper will have no difficulty in using these figures. They will treat them as comparative ratios between the two cars, which the figures are. The fellow who tries to climb a 59-degree hill will undoubtedly get more than he bargained for. There are simply too many variables: the road surface may be poorer, the front wheels may lift, the carburetor may flood, the fuel pump may quit, the payload may be heavier. Granted, the potential is there, but for practical purposes it boils down to the fact that the four-speed transmission increases the power.
The third major option on the test car was the Koenig winch. I am going to discuss it only as extra weight in this article. In a later issue I intend to get deeper into the subject of winching with this winch, and the areas to be covered (deadman anchor stakes, snatch blocks, A-frame, doubling winch power, etc.) will fill another column. But the change that the winch makes in performance is worthy of mentioning. (Editor’s note: This article never happened, but we did find some pictures of the winch in action and included one in our reprinting of the article).
Logically, any four-wheel drive car works better when the weight is distributed equally over the four wheels. Unloaded, a Jeep has about 58 percent of its weight on the front wheels, but since the payload puts most of its weight on the rear wheels, this ratio changes rapidly. When climbing a hill, the front wheels have a tendency to lift. The extra weight of a winch helps keep them down—one of the most important factors in climbing hills. Loaded, the test Jeep had no difficulty with some very steep hills that were encountered during back-country driving.
Never Before Seen
(Editor’s note: These images were not in the original article from 1961, but we thought they were cool and decided to publish them here for the first time. You’re welcome!)