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Towing Difference Between 3.55 and 3.73 gears

mojactuary

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Hi all. I have an '05 Automaric Ford Explorer V6 with a gear ratio of 3.55. The owners manual puts the max trailer at 3,380. The max trailer for a gear ratio of 3.73 is 5,380. The only difference I can see is under the engine section which lists that the 3.55 comes with a class II towing, while the 3.73 comes with a class III/IV towing.

My understanding is that the difference in towing between a 3.55 and a 3.73, all else being equal, is about 5% ( [3.73 - 3.55] / 3.55 ). So, why is there such a big difference according to the manual?

Thanks in advance for your help.
 
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IZwack

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Because of the hitch class thats bolted to the vehicle:

5.1.3.1_hitch_chart.gif
 
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manaen

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that and the towing package includes things like an auxilary tranny cooler to keep the auto tranny cool. If you have the 5 speed manual that would be the limiting factor as well (which is controversial)
 
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jrford

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I would agree the Class III is twice as big as the ClassII hitch, much more beef. I swapped mine out for the more 2” receiver options, I posted a pic in the towing section.
That 5% sure doesn’t seem much but it does equate to a 200rpm jump at highway speeds. A transmission guy once told me, unconfirmed, that the transmission will run ‘tighter’ with the increase in RPM’s. Another change would be the PCM they might be running different ‘logic’ one more suited for Torque (unconfirmed too).
My ’04 originally equipped as a Class II has a trans cooler already when you look for a replacement it’s the same ClassII and ClassIII part no. Last time I towed at about 2,000lbs I left the OD off, towed great too.
 
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90ranajo

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That 5% sure doesn’t seem much but it does equate to a 200rpm jump at highway speeds. A transmission guy once told me, unconfirmed, that the transmission will run ‘tighter’ with the increase in RPM’s.

With the engine spinning a little faster; the trans fluid pump will spin faster creating more fluid pressure; thus more holding power.
 
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Albino 94LTD

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That 5% sure doesn’t seem much but it does equate to a 200rpm jump at highway speeds.


Remember this is not a static measurement, it is a 5% increase in the linear RPM:MPH ratio. Big difference.

Result is significantly more torque. Try pulling the trailer in low range, bet you can't even tell it's there. Masssive torque but low top speed.
 
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mojactuary

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Thanks for the respnses thus far. I am still a bit confused however. Everything I have read states that you can't increase a vehicles towing capacity simply by adding a better hitch. My owners manual only allows around 3,500 lbs, and I do have the factory type II hitch. Would going to a type III hitch increase the capacity to around 5,000 lbs (less the 5% difference in gear ratio)? Or, are the other differences in the vehicle design that would preclude my from towing something like 4,000 lbs?
 
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Thelt

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You could probably upgrade your hitch and add a transmission cooler and be OK. I would take it out of overdrive for sure when I towed using that setup. I have the tow package and pulling a 1300 pound popup camper is so easy I almost forget it is back there, which can be bad in certain situations.
 
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Albino 94LTD

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Ford put the tiny hitch on there for a reason, If it had a Class III/IV hitch, people would tow things heavier than they should.

Changing anything will probably void your warranty but,,,,to increase your towing capacity you need to do a combination of things, Stronger hitch, Auxillary tranny cooler, Regear.

More than likely, occasional towing with your stock set up will be just fine.4000lbs with 3.55 is pushing it.

How far and what terrain will you be towing?
 
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Thelt

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If you have the towing package then you get a factory class 3 hitch. The tow rating on V6 with the tow package is over 5000 pounds. I would imagine one could tow 4000 pounds with a non tow package if you made some mods. That is only 500 pounds over the factory recomended number. I would just get a class 3 hitch and a transmission cooler an go for it. It wont be a safety issue as much as it will be a possibility of premature failure of your vehicle. With that being said towing can be a safety issue whether in the weight limits or not so make sure you know what you are doing.
 
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justchecking

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I had the 3.55 and class II. I changed the hitch to class III/iv because the camper I bought came with a Reese load distributing hitch for a 2" reciever. I tow a lot and have OD off a lot. My coworker has the 3.73 and he also has the OD off a lot. Doesn't seem to make much difference between 3.55 and 3.73. Just take it easy. I have 130668 on the odometer tonight with original engine and transmission (02 XLT V6), but new rear springs after the driver's side broke. If your trailer is much above 2000 Lb, then I would recommend trailer brakes with an inertia brake controller (like Tekonsha P3). I tried to stop once at an intersection with a load of mulch (probably about 3000 Lb) and stopped in the middle of it. There was something on the street (like sand) and every extra braking tire would have helped. My coworker had a lady pull out in front of him when he was towing his boat (without trailer brakes) and he stopped with inches to spare. It feels like you are being pushed from behind. (well you are :eek:). I bought a Scangauge to monitor trans fluid temp but haven't towed with it yet. With the sealed transmission, it's difficult to monitor the fluid condition. I have it changed every 30K, and always plan to ask what the color/condition is, but always forget! Oh, well.
 
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k2sb2003

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Called FoMoCo and talked to a rep. They said if you have a V8 that the only difference is the gearing and the hitch. all of the extra cooling is there. He also said that if i swapped it out for a cl III/IV that i could very well tow the same as the 3.73 and that there would be no noticeable difference and it WONT void my warranty to add an after market hitch but advised to replace with a factory hitch and wiring.
 
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manaen

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Did Ford keep you on hold for two years:eek:!!!
 
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sportrac03

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The difference between the different hitch sizes how much the hitch can hold safely. If I am correct all of the Explorer's from 2002 and up came with trans coolers. When you got the towing package you got a oil cooler. The reason why Ford put 3.55 as standard is for better gas mileage. 3.55 has less torque off the line but has a more power in the higher gears and better gas mileage. 3.73 has more torque off the line to get you going but has less power in the higher gears and can be less gas mileage.

P.S.: Remeber just because the truck can, for example tow 5,000lbs., does not mean you can tow that. Regardless of what the truck can you have to add the weight of everything in the truck and trailer because you still have to be at or under GCWR of the truck. I believe I am correct.
 
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manaen

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P.S.: Remeber just because the truck can, for example tow 5,000lbs., does not mean you can tow that. Regardless of what the truck can you have to add the weight of everything in the truck and trailer because you still have to be at or under GCWR of the truck. I believe I am correct.

Yeah spot on... people often overlook the GCWR when calculating tow capacity. You also need to look at GVWR because you may be under the GCWR however due to loaded people/gear + Tongue weight it is easy to exceed GVWR



Just for clarification
GCWR - Gross Combine Weight Rating
-----(Truck + Trailer = GCWR)
GVWR - Gross Vehicle Weight Rating
-----(Truck - total weight on both axles, includes trailer tongue)
GTWR - Gross Tow Weight Rating
-----(Total trailer weight limit)
GAWR - Gross Axle Weight Rating
-----(the amount of weight each axle will carry, look at your door sticker)


how to find tow rating?

GCWR - (actual vehicle weight) = GTWR

you can quickly exceed GAWR or GVWR of the rear axle by loading up your truck and then dropping a 400 to 500 lb tongue on the back
 
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jrford

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Did Ford keep you on hold for two years:eek:!!!
. . . . . .rofl

For the new 3rd (4th gens) with the v8 and the 6spd, the 3.73 gears are no longer an option. It only comes with 3.55' supposedly with the 6spd's low gearing its not really needed. I'd still maybe kick the O/D off . . .just to keep the rpms up a tad.
 
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manaen

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I'd still maybe kick the O/D off . . .just to keep the rpms up a tad.

check your manual, but I believe even on the newer transmissions towing with the OD on is not an option unless you enjoy frequent tranny rebuilds.
 
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JCR

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The main difference in the two capacities for towing relate more to the differential. The 3.55 gears are standard and the 3.73's are a limited slip. The hitch is bigger with the limited slip rear.
 
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Dignan

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Called FoMoCo and talked to a rep. They said if you have a V8 that the only difference is the gearing and the hitch. all of the extra cooling is there. He also said that if i swapped it out for a cl III/IV that i could very well tow the same as the 3.73 and that there would be no noticeable difference and it WONT void my warranty to add an after market hitch but advised to replace with a factory hitch and wiring.

I would ask for that in writing. Manufacturers can try to get out of warranties and maybe more often, Insurance companies can get out of payouts. The instance described above where the guy towing a boat had inches to spare when the lady pulled out in front of him is a classic example. Towing adds another layer of danger to driving. If you can't stop your trailer and rearend someone, you will get the ticket and if you have modifications and/or you are over any type of weight rating or towing with the wrong class of hitch, etc. the insurance company can get out of everything and all the vehicle damage, medical bills, and all liability is on you.

There can be more to think about than whether or not your vehicle will physically get the trailer to go. There is a legal aspect too. Just wanted to give you more to think about. :)

PS I second the idea of trailer brakes. Trailer brakes and/or brake upgrades on the towing vehicle are great for safety. Most trucks and SUVs can get a trailer going, you just need to be able to stop it.
 
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