Rear axle ratio\ trailer towing.

[Dave Lehnert]

May need to tow a pontoon boat soon and was looking at the info for my truck to make sure it will handle it.

I have a 1997 Ford F-150 super cab 4.2L V6, Auto,with a Rear Axle ratio of 3.08.
The owners manual said it will handle 4,600 pounds trailer weight (If I don't exceed max weight for truck) The sales brochure I still have says not recommended to exceed 20,000 lbs trailer weight with 3.08 axle ratio. Assuming the 20,000 lb is a typo in the sale brochure and should be 2,000 lbs.
In your experience, what would seem to be correct. 2,000 lb or 4,600 lbs.?

Also about Rear axle gear ratio. When buying a truck why would it be offered for sale with a 3.08 or 3.55 gear ratio. and what would one do for you over the other.

[Joe Pelonio]

The difference in axle ratio is power vs fuel economy.

My Ranger with 4.0 V6 is rated 2,000 lbs on the bumper, but 6,000 lbs on the class III hitch which came with the trailer towing package (also heavy duty suspension and better transmission cooling.)

[Matt Meiser]

Your owners manual sounds more like what I remember from a similarly equipped 99 I had. I bet that 20k number is the 5.4l with all the right equipment.

[Scott T Smith]

For starters, totally dismiss the 20,000 trailer weight, as this is way beyond what an F150 is rated at. With 3.08 gears, you could not get this amount of weight started pulling up a hill, let alone have the braking capability.

In order to pull a trailer that weighs 20,000 lbs (while meeting manufacturers specs), you would need at least an F450 dual wheel pickup with the optional 33,000 CGWR package. Far from having a 3.08 rear end ratio, these F450's have either 4.30 or 4.88 rear end ratios in order to handle the weight. Since an F450 itself weighs around 10,000 lbs w/o a trailer (full of fuel and a toolbox), 20K of trailer takes you to 30K lbs, which also would require a commercial drivers license.

Joe's advice re the real towing capacity is spot on. Re your question about rear axle ratio's, the lower the ratio, the increased amount of torque multiplication for towing a heavy load. For an occasional pull, 3.08's are fine. If you tow heavy loads a lot, you may end up damaging the transmission.

[Ken Fitzgerald]

I sold my F-350 last year. It was set up for towing. One of the reasons I bought it used was....it already had a gooseneck hitch and wiring buried through the floor of the bed....it already had a extremely heavy duty step bumber with ball and wiring. I added a Reese 20K 5th wheel hitch to it.

I elk hunted with 5 other guys for 18 years. With my pickup, I could haul anything in camp including the horse trailers. We camped at 7,000 feet and hunted the last 10 days of the season. We hunted the last 10 days because at that altitude, the snow had already driven most other hunters out. About 1 out of every 5 or 6 years, we got snowed out early. We had make the decision to get out and then get out quickly.

My F-350 had a 460 cubic inch engine with a 4:10 year end, 5 speed manual transmission. 11 mpg....uphill, downhill, loaded, unloaded, into the wind...downwind, empty or pulling my 9,000 lb. 5th wheel camper. It didn't matter....11 mpg.

[Dave Wagner]

Bumper ball hitch or separate class III mounted underneath? That might affect the max. towing (2000 vs. 4600).

[Dave Lehnert]

From what I can figure I am more than good for towing the pontoon boat. The max I would ever go would be an hour away. And would be lucky to get it in the water 6 or 8 times a year.

[Matt Meiser]

I think that's a good assessment. I towed a 2800lb Mustang on a trailer with my 99. The trailer had brakes and I upgraded the shocks and it was fine.

[Jason Roehl]

I've driven an E150 (full size van, might have been a '98 or '99) with the 4.2L V6. I wouldn't tow ANYTHING with that setup. The 4.2 is underpowered to begin with, unless you rev the snot out of it, then the 3.08 rear will keep your RPM low no matter what gear you're in, keeping the engine out of its power band.

I'm absolutely sure that 20,000lb number is one of a couple things. One, it could be, as you mentioned, a typo. Two, it could be the maximum GCVWR (Gross Combined Vehicle Weight Rating)--truck, trailer, passengers, cargo and all fluids of the F350 with the 7.3L PowerStroke diesel. In other words, the top tow rating of all the light-duty F-series trucks of that year (yes, an F-350 is considered a "light-duty" truck--F450 begins the "medium-duty" line, up to maybe the F750, and tractor-trailers are heavy duty).

[Chris Damm]

I wouldn't put much stock into a what a sales brochure had printed in it! After all they are printed by the marketing department. Go by what the owners manual says. A 3.08 gear ratio is a little high (low numerical) for towing. Most trucks set up for towing have a 3.73 or lower ratio. My '99 Gmc 2500HD had a 3.73 gear, 350 engine and would tow 6000#. My 2007 2500HD has a 4.10 and a 6L engine and will tow 9200#. I think yours is a little light duty to tow that much weight. If I was going to try it I would want brakes on the trailer too!

[Pat Germain]

I also think you'll be OK. Just turn the overdrive off when you're towing the boat. If you're truck doesn't have a transmission fluid cooler, it would probably be a good idea to install one. They're not very expensive and you can do it yourself. Those coolers go a long way toward protecting an automatic transmission.

If in fact you find you're truck is just lugging down too much when towing, you can always have a new rear gear set installed. Any good transmission shop can do it. It's certainly a lot cheaper than buying a new truck. And you just put a new, little plastic gear in the transmission for the speedometer to stay accurate. It's really no big deal.

[Dave Lehnert]

I also think you'll be OK. Just turn the overdrive off when you're towing the boat. If you're truck doesn't have a transmission fluid cooler, it would probably be a good idea to install one. They're not very expensive and you can do it yourself. Those coolers go a long way toward protecting an automatic transmission.

If in fact you find you're truck is just lugging down too much when towing, you can always have a new rear gear set installed. Any good transmission shop can do it. It's certainly a lot cheaper than buying a new truck. And you just put a new, little plastic gear in the transmission for the speedometer to stay accurate. It's really no big deal.

Thats good info. Thanks for sharing.

Ball Park, What does a cooler cost?

[Jason Roehl]

And you just put a new, little plastic gear in the transmission for the speedometer to stay accurate. It's really no big deal.

Since about '92, the drivetrain computers get their info from a VSS (vehicle speed sensor) in the rear axle in Ford trucks. You just have to figure out how to reprogram the instrument cluster, but it's only affected by tire size changes, not differential gear changes, since it reads off a tone ring on the axle (after the rear gears). I know how to do the reprogramming on '92-'96 Ford trucks, but not newer than that.

A tranny cooler is typically about $50 or so for an aftermarket setup (not installed, of course).

[Scott T Smith]

Dave, in addition to Pat's suggestion re a tranny cooler, I would suggest that you change your transmission fluid to a higher quality fluid. Lubrication Engineers has the best transmission and hydraulic fluid that I'm aware of; I typically see a 20 degree decrease in transmission temps when I replace the factory fluid with it on my farm equipment, which means that friction is being reduced.

Unless you want to drill, tap and plug your torque converter, you will need to drain the fluid about 3x times in order to get a full replacement. This is because the transmission drain pan only contains a portion of the total fluid volume.

One of our local woodworking club members hauled a 5,000 lb trailer from eastern NC to Utah a few months back, towing it with a Ford Explorer (that had a 6 cylinder engine). He added a tranny cooler and swapped out his fluid for LE, and made the trip w/o any problems.

[Rick Potter]

Dave,

To answer your questions: Higher numeric axle ratios equal higher RPM, lower numbers equal lower RPM. A low one like a 3.08 on a pickup is basically there to equate to the best theoretical gas mileage on the government MPG test.

If you tow with your pickup, you can't go wrong with a 3.90 or 4.10 gear ratio. You might get away with towing something light with the OD on, but for any appreciable weight you want it off. With new gears, you might lose a MPG or two on the highway, but will gain about the same around town.

Check any auto parts store. If you put it on, a cooler will be anywhere from $40 to $100. You need it.

Rick Potter

[Matt Meiser]

Unless you want to drill, tap and plug your torque converter, you will need to drain the fluid about 3x times in order to get a full replacement.

I don't know about the newer transmissions, but Ford used drain plugs in the converters on many older (70's/80's) vehicles. Still a messy job because its going to first drain down on the bell housing, especially with the front of the vehicle jacked up.

[Jason Roehl]

In addition to what Matt said, Ford trannies are all (to my knowledge) setup with cooler ports on the transmission. You can open the "to cooler" port (often the front-most one) with the engine running, in gear (helper in cab with parking brake set, foot on brake, wheels chocked, etc.) to pump the old fluid out of the tranny. It's even better if you add a few fresh quarts of fluid while doing this to flush the tranny. HOWEVER, if the tranny fluid has not been changed in a long time (more than 40-50k miles), DON'T CHANGE IT IF IT ISN'T BURNT. When tranny fluid gets old, it allows deposits to form that can become the seals in various places. New fluid can partially dislodge/dissolve those deposits causing bad seals and tranny failure.

[Cliff Rohrabacher]

twenty thousand pounds huh?
That's saying something.

[Matt Meiser]

I've never seen a Ford that didn't have a cooler. There's a cooling coil in the radiator. When they say it has a trans cooler, they are talking an external air-fluid cooler in addition to or instead of the anti-freeze cooler. The Chevy Colorado I had was the same. You can install a cooler by cutting the return line and plumbing the external cooler into that line. Getting the cooler behind the grill and finding a good route for the hoses is the hardest part. On the Colorado it probably took 90 minutes. My 99 had a factory tow package so it had an external cooler.