Re: [AMC-list] Towing capacity (was why is it?)

[Frank Swygert <farna@xxxxxxx>]

The 4.0L has a good bit more power than a 258, no real comparison. 96-00 models are rated 190 hp @ 4600 rpm, 225 ft/lbs @ 3000 rpm (91-95 225 ft/lbs @ 4750, 87-90 Renix 224 ft/lbs @ 2400). The last 258s (83-87) were rated 110 hp @ 3000 rpm, 210 ft/lbs @ 1800 rpm. So yes, the max torque comes in a lot sooner, but the 4.0L still pulls a bit better. The 4.0L is still making 200 ft/lbs @ 1000 rpm, and makes that much even at 5000 rpm (91-96 models, see torque graph at http://www.jeep4.0performance.4mg.com/stroker.html). I'm certain the 258 torque curve is similar, but peaks at 210 ft/lbs a lot earlier (than the 4.0L peaks) and doesn't carry it more than 3500 rpm.

Someone mentioned tractor/trailer tractors being smaller/weighing less than their loads. As stated, they are designed for that type of work. They also have good trailer brake systems that work in unison with the tractor brakes, and have drivers trained for that kind of towing. There's a good reason the trailer brakes can be locked without applying tractor brakes too! If you're careful and have good trailer brakes a vehicle can tow it's own weight easily as long as it has enough power. But you still have to be more careful.

Gear ratios were also mentioned. I too wouldn't recommend towing another vehicle with less than a 3.08 axle ratio. The Cherokee/Commanche was rated 5000 lbs towing capacity with the five speed, 5500 lbs with the auto. 4.0L/5spd got 3.08, autos got 3.55 (with the steeper 3.73 optional, I suppose 3.55 or some other gear was optional with 5 speed). When I towed that V-8 65 Classic with my 5 speed 4WD Commanche I had to pull out of a steep driveway near Atlanta. Had to put it in low range to pull out! On a level or with more normal inclines it was okay. No low range in the Eagle unless the T-case has been swapped. You wouldn't want to run in low range for an extended period of time though. My J-10 (4:1 low, might be more than XJ/MJ) would only run about 45 mph with the engine really turning (no tach, but I'd guess around 3K, maybe more, by the sound of it).

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Date: Fri, 15 Apr 2011 13:06:51 -0700 (PDT)
From: russ hathaway<russh97309@xxxxxxxxx>
Subject: Re: [AMC-list] why is it?

Jason; a lot of people use the Jeep with the 4.0 to tow, and that is basically a 258. I used my Gremlin with a 258 to tow a mobile home, but only a block. It pulled it fine but I could tell the car didn't like it. My neighbor got a charge out of it, too.
I think you would want a full frame car with a good hitch, though we towed big loads with my 65 Ambo. Again, it is the size of the tow vehicle that gives a safe tow.
I would put sub frame connectors on the Concord, a good class 3 or 4 hitch, and yank off the cat....Russ

--
Frank Swygert
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