Different transmissions for towing.
10-26-2018, 07:12 PM
#1
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Different transmissions for towing.
So I was looking through the owners manual of my 1989 f150. It said that a 4.9l with a 4.10/1 diff and a manual transmission could tow up to 5800 lbs. and an auto could tow even more. But I’m just curious because wouldn’t different transmissions effect the towing capacity? The zf is geared a lot lower than the m5od. And the t18 is geared even lower than that. So wouldn’t it make sense for them to be able to tow more than the m5od? And I mean both the t18 and the zf have lower gears and higher torque ratings than all three of the autos available. So maybe the chart in the manual is only talking about the m5od?
10-28-2018, 12:04 PM
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No, the chart is talking about the WHOLE TRUCK. It wouldn't matter if you put in a trans that could handle 3x the torque - the truck still can't handle any more weight behind it. Probably LESS because the trans weighs more. There's more to trailer towing capacity than JUST engine, or trans, or gears, or tires, or...
10-28-2018, 02:05 PM
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No, the chart is talking about the WHOLE TRUCK. It wouldn't matter if you put in a trans that could handle 3x the torque - the truck still can't handle any more weight behind it. Probably LESS because the trans weighs more. There's more to trailer towing capacity than JUST engine, or trans, or gears, or tires, or...
Ok that mostly answers the question. But it still says that a truck with a 4.9l and 4.10 diff can tow 5800 lbs max trailer weight. While the same engine and diff with an automatic transmission it says can tow a max trailer weight of 6900 lbs. and wouldn’t an automatic usually weigh more than than a manual?
10-28-2018, 09:56 PM
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Yes. But the manual trans is rated for less towing than the truck. There are fullsize transmissions that can't tow much (like the Mazda M5OD-R2 & the Ford 4R70W), and some that can tow a LOT (like the NP435 & Ford E4OD/4R100); so there's a sweet-spot of weight vs. capacity. The best you can do is what the Ford engineers calculated, according to that chart.
...but that's for towing that Ford would have warranted (parts) & stood behind (liability), and which complied with the 50 states' laws, DC's, & federal laws. The truck CAN tow more - if you drive slower, &/or are on private property/roads. I've towed a stalled Peterbilt dump truck with my 4.9L & 4sp stickshift. But I only towed it a couple hundred feet, and the yoke on the rear diff exploded (it showed signs of having been cracked for years). Ford wouldn't have warranted that failure if it had happened when the truck was still in-warranty. I've towed other ridiculously-heavy things, too, without problems. But I towed them SLOWLY - not at highway speeds. The Ford ratings are for highway speeds on public roads in any weather.
...but that's for towing that Ford would have warranted (parts) & stood behind (liability), and which complied with the 50 states' laws, DC's, & federal laws. The truck CAN tow more - if you drive slower, &/or are on private property/roads. I've towed a stalled Peterbilt dump truck with my 4.9L & 4sp stickshift. But I only towed it a couple hundred feet, and the yoke on the rear diff exploded (it showed signs of having been cracked for years). Ford wouldn't have warranted that failure if it had happened when the truck was still in-warranty. I've towed other ridiculously-heavy things, too, without problems. But I towed them SLOWLY - not at highway speeds. The Ford ratings are for highway speeds on public roads in any weather.
10-29-2018, 12:18 AM
#6
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Yes. But the manual trans is rated for less towing than the truck. There are fullsize transmissions that can't tow much (like the Mazda M5OD-R2 & the Ford 4R70W), and some that can tow a LOT (like the NP435 & Ford E4OD/4R100); so there's a sweet-spot of weight vs. capacity. The best you can do is what the Ford engineers calculated, according to that chart.
...but that's for towing that Ford would have warranted (parts) & stood behind (liability), and which complied with the 50 states' laws, DC's, & federal laws. The truck CAN tow more - if you drive slower, &/or are on private property/roads. I've towed a stalled Peterbilt dump truck with my 4.9L & 4sp stickshift. But I only towed it a couple hundred feet, and the yoke on the rear diff exploded (it showed signs of having been cracked for years). Ford wouldn't have warranted that failure if it had happened when the truck was still in-warranty. I've towed other ridiculously-heavy things, too, without problems. But I towed them SLOWLY - not at highway speeds. The Ford ratings are for highway speeds on public roads in any weather.
...but that's for towing that Ford would have warranted (parts) & stood behind (liability), and which complied with the 50 states' laws, DC's, & federal laws. The truck CAN tow more - if you drive slower, &/or are on private property/roads. I've towed a stalled Peterbilt dump truck with my 4.9L & 4sp stickshift. But I only towed it a couple hundred feet, and the yoke on the rear diff exploded (it showed signs of having been cracked for years). Ford wouldn't have warranted that failure if it had happened when the truck was still in-warranty. I've towed other ridiculously-heavy things, too, without problems. But I towed them SLOWLY - not at highway speeds. The Ford ratings are for highway speeds on public roads in any weather.
10-29-2018, 10:20 PM
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The 1st-gear ratio isn't what makes it a towing transmission, or not. You might find a transmission with an 8:1 1st gear - but if it's built with thin gears & narrow shafts, it won't pull anything. It might have been made for a tiny low-speed vehicle with a fast-spinning engine. To tow, a trans has to be built heavily, so it can handle the torque created between the engine & the load. It might have a high 1st-gear ratio, and be installed in a vehicle with a low axle ratio.
Similarly; you can't judge a highway transmission by itself. My NP has a lower 1st-gear ratio than yours, but it does great on the highway because I run 3.08 gears (which are physically stronger for towing) and 33" tires (which give me highway speeds). But it can also tow because of the transfer case's low range. In 1st-gear low-range, I can walk faster than the truck idles, so it's really good at parking my father's travel trailers on hills. It's not quite as good at towing them because of the Bronco's super-short wheelbase & small engine, but it does OK if I drive conscientiously.
Similarly; you can't judge a highway transmission by itself. My NP has a lower 1st-gear ratio than yours, but it does great on the highway because I run 3.08 gears (which are physically stronger for towing) and 33" tires (which give me highway speeds). But it can also tow because of the transfer case's low range. In 1st-gear low-range, I can walk faster than the truck idles, so it's really good at parking my father's travel trailers on hills. It's not quite as good at towing them because of the Bronco's super-short wheelbase & small engine, but it does OK if I drive conscientiously.