1988 7.3l deisel towing question
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1988 7.3l deisel towing question
I recently purchased a 1988 f250 deisel 7.3l/ auto with a 4 something gear rear end. I was told by the previous owner it was a 4.10, however in doing the math (336 x speed x gear ratio/ wheel diameter= rpm) I come up closer to 4.4+ . Anyway at 63 mph I'm turning 3000 rpm, at 55, 2700. I have 30" dia. tires. Redline is about 33 to 3500 or there about. I plan on towing a trailer which weighs 6500+ lbs. I would like to travel 60 to 65 mph without having to be max out the motor(I'm thinking 2500 would be a good cruising rpm). The local junkyard has a 3.55 rearend of which I was thinking of installing. My question is would a vehicle with 160,000 miles pull that trailer with this new 3.55 rearend or would I be better off leaving things alone? Or to word it another way, does the engine have enough torque to pull the trailer with taller gears without compromising the integrity of the 3 speed non overdrive tranny? Any comments would be appreciated... Rich
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1988 7.3l deisel towing question
Mathematically, your numbers tell me little. Experience wise, I'll say that you owe it to yourself, and your vehicle,to just listen. Listen to the engine itself. Let your hearing answer this question. Myself, I pull, loaded, a thirty foot trailer weighing in around 93000. I've been pulling this same weight, within five hundred pounds native or positive, throughout the better part of the last ten years. My speed usually averages five mph over the legal limit. I've yet to have the first problem with either the engine or transition.(knock on wood) Just a thought to ponder.
Layne
90E250, 96E250, 2000E350 Turbo Diesel
Layne
90E250, 96E250, 2000E350 Turbo Diesel
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From: Indianapolis
1988 7.3l deisel towing question
[font size="1" color="#FF0000"]LAST EDITED ON 23-Jul-01 AT 12:45 PM (EST)[/font][p]To determine axel ratio by the method you are using, first make sure you're not running in overdrive (your truck probably has an AOD transmission) and do all your tests at 60MPH (60MPH is a mile per minute -- RPM is revolutions per MINUTE). Tire diameter times pi (3.1416) equals tire circumference in inches. Divide that into the number of inches in a mile (63,360). This gives you the number of tire revolutions per mile. Multiply that times axel ratio and you will have the number of RPM's at 60 MPH. Assuming 30 inches for tire diameter is correct, you should be running 2756 in drive (not over drive) at 60 MPH. All of that assumes your ratio in drive is 1:1 (which it is on an AOD transmission). I checked your formula against mine and it works. Your trans may be a C6 in which case your RPM's at 63 MPH would also reflect the "slippage" of the torque converter (assuming a C6 instead of an AOD). 1:1 ratio at 63 MPH with no slippage should be 2893. Also, this truck (non factory turbo) is rated at 3300 RPM's so the governor will begin to kick in above that RPM and your power will go away.
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