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| A CJ5 Owner on: Building short wheel base jeeps We will first describe the jeep and then the owner will share what he's learned in basic buildup on CJ5s. |
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 1977 CJ5
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| Building a Short WheelBase Vehicle (1977 CJ5)
When building a short wheel based vehicle like a flat fender or CJ5 (not CJ7 or Wranglers) the major problem is the drive line length. No matter what you do, you will never have enough room to stuff the latest and greatest drive line gizmo into your 4x4. You either run out of rear drive line length or you shorten the rear drive shaft to the point that the shaft angle is too steep, even for a CV joint. The following are some facts and expensive lessons I have learned over the years while building my 1977 CJ5. |
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| Transmissions
If you want an automatic transmission, the only one I could get to fit was a Turbo 350 coupled with a model 20 T-case. The Dana 300 adapter is about 1" longer than the adapter for the Model 20. I have had reputable shops recommend a Turbo 400 because it is stronger, but when I challenged them to give me the numbers for the fit, they backed down. This option would be fine for a street jeep or for running sand dunes, but there is not enough gearing for rock crawling. Any of the Jeep 3 speed manual transmissions will fit, but none are known for strength and you definitely can not use them for rock crawling. I have a broken T-150 3 speed in my garage. A 4 speed manual transmission is the most popular choice and there are plenty of them out there. The most popular 4-speeds are like the 3 speeds with an added low 6:1 first gear. You never use first on the street because it is too low. My first 4- speed was an NP435 with a 6.69:1 first gear. It meets all the length and strength requirements but mine suffered from one major flaw. It liked to pop out of first gear when climbing up steep hills. I had several shops attempt to fix the problem with no luck. I traded it in for a T-98 (watch out because my NP435 is still out there in the used parts market). The T-98 has a 6.40:1 first gear and has been performing flawlessly for over a year. The T-98 is a close relative to the T-18. I highly recommend both the T-18 and T-98. If you want to install a 5 speed manual transmission into a CJ5, you will first have to purchase a CJ7 or Wrangler adapter kit (i.e. a Wrangler frame and tub), then install the transmission and entire CJ5 drive train into the adapter kit. An other option is to stretch the CJ5 (which we will be exploring next year). Another option might be a World Class T-5 and the Advanced Adapters Atlas T-case. I don't know if it will fit, but my guess is that it will be close. If you know someone with a 5 speed in a stock CJ5, I would love to here from you! |
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| T-Cases
One of the big debates on T-cases is the gear drive verses chain drive; which is stronger? It depends on your point of view. I started out with a gear driven Model 20 and shortly replaced it with a Dana 300 T-case because the Model 20 low range gear reduction is only 2:1. My 300 T-case has one major flaw, it pops out of low range into neutral while descending steep hills. I know other 4-wheelers that have the same problem. I tell people who say they never have this problem that my concept of steep and theirs is different. The first time this happened was on the Hells Revenge trail in Moab, our guide, Dan Mick, said it is a common problem and the best fix was to Bungee cord the shift lever to the dash. Dan has a custom made latch connected to the dash to hold the lever in gear. The 231s and 241s are excellent choices for most 4x4s, but are too long for CJ5s. Even with the tail shaft shortening kit, they are 2" longer than a Dana 300 T-case. The only other option that I would consider is the Advanced Adapters Atlas T-case. I can not recommend it because I haven't tested one nor do I know anyone that is using it. If you are using the Atlas behind a V-8, I would like to here your opinion of the T-case. |
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Axles When I was having drive shaft vibration problems, I called Dynatrac to see if I could run a reversed Dana 44 rear end. The reversed Dana 44 places the pinion 2" higher than my Model 20 rear end, thus leveling my rear drive shaft angle. This was a poor choice of axle on my part because they explained that a reverse 44 will not holdup behind a V-8, and the best option was a reverse Dana 60. The reverse Dana 60 would not fit either because the pinion is 2" longer than the Model 20. My rear drive shaft is as short as it could get, 12.75". The only solution was to move the engine forward 2" to make room for the Dana 60. Those of you who are familiar with AMC V-8s know that the water pump is very long and leaves little room to shift the engine forward. Also, the stock fan with, a shroud, is the best cooling part on an older jeep, and it would have to be replaced with an electric fan. My solution; lower the transmission 1", reduce the suspension lift to 2.5" over stock, use a CV joint, cut the rear fender wells, and keep the Model 20 rear end which already had one piece axles and a Detroit locker. |
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| Jeep is a registered trademark of the Daimler-Chrysler Corporation. | |
1997