• Help Support Hardline Crawlers :

Tow Rig Gearing 7.3/auto

RustyC

Well-Known Member
Joined
Dec 15, 2010
Messages
1,251
Looking for a little input. I am looking into re-gearing my tow rig after installing larger tires. The truck is a 2002 F250 cc, srw 7.3/auto/4x4. The truck originally had 265/75/16 tires. It now has 315/75/16 tires.
With the 35" tire and 3.73 gear it needs a little help in the gearing. Truck has an 4r100 transmission. Truck pulls a 20' enclosed that weights about 10klbs plus. I find myself towing in 3rd gear/OD off.
My converter does not lock in 3rd and I'm concerned about towing in 4th. The converter does lock in 4th gear.
I am looking at a couple of options on re-gearing. It is splitting hairs but still looking for input. I am looking into a 4.10 or 4.30 ratio gear. The 4.10 put me back to the factory gearing with the 35"s.
I only use the truck to tow and occasionally on the weekends. The truck does have a TS 6 position chip,4" exhaust, gauges and extra trans cooling. Injectors are stock but will be upgraded with one size larger and the chip reflashed.
I have no desire to stress this engine with big turbos, BIG injectors etc. Goals after injector upgrade in 350hp and low exhaust temps. I'm not sure it the trans can be tuned to lock in 3rd over 45 mph but I would love that if possible.
I am leaning towards the 4.30 ratio because its a 7700 lb truck on larger tires and doesn't need to be running over 75 anyway and I'm getting older so...

If anyone has any similar experience or advice on gearing, towing in 3rd vs 4th on a 4r100 trans, lets here it.
 
Even in ford blue, this is still true...

Not the answer you was looking for nor is it the right answer..just humor.
0de1a0ab808372e2d6ae5acad1a97b1f.jpg


Sent from my XT1635-01 using Tapatalk
 
My buddy ran 4.88s in his 97 F250 on 35s with the auto and 7.3 and it would pull anything he wanted but the gas mileage empty sucked and it he couldn't really go over 70 without being worried that it was spinning too fast. He just gear swapped to 4.10s or 4.56 I can't remember. Says it seems much better empty but hasn't pulled with it yet. I'll check with him on what he actually swapped to. He's also upgraded the turbo, injectors, fuel system and has it tuned.

Sent from my SM-G930T using Tapatalk
 
I have a very similar truck but mines just extended cab, my rig trailer is probably 6500-7000lbs I'm guessing, not real sure of my gears but I tow in overdrive with no real problems, I sometimes switch od off of it starts shifting too much, truck gets about 14 mpg, I've got programmer and cold air intake and muffler deleted, if I get time I will try to see what gears it has this weekend, I did notice a big mpg loss when I went to 35's and some power loss
Now my excursion is totally different, it's 2wd and gets 21 mpg and has no problem towing my stuff and I prefer towing with it, I put injectors in in about 18 months ago and been best investment, mileage went from 17-18 to 21 and a big power difference, it's got cold air kit and programmer too through stock exhaust, the injectors are built for maximum torque for towing and made a world of difference, this thing will fly now, so I would try injectors first to see if that gets ya back in the power band ya want, if not you was gonna regear anyways, here's the link for what I got, these guys are the best 7.3 injector builders in the country http://unlimiteddiesel.com/high-output-ad-powerstroke-fuel-injectors
 
I have an 03 7.3 with 3.73 and 33" tires. I pull around 12,000 lbs quite a bit and it does great as long as your clicking around 75 mph or in the 50s with overdrive locked out. I have a built trans though and most the time my converter will lock up in 2nd gear. I think the 4.30 gear will be to low to run 70 plus mph but it'll be great around 60 -65 mph. Unless your going to push big power in the future then 4.10 is the only way to go IMO. With 35s and 4.10s you should have decent rpm still around 75 mph or faster. Or put a big turbo and injectors in it and leave the gear alone :dblthumb:
 
Re: Re: Tow Rig Gearing 7.3/auto

Zjman said:
I have a very similar truck but mines just extended cab, my rig trailer is probably 6500-7000lbs I€™m guessing, not real sure of my gears but I tow in overdrive with no real problems, I sometimes switch od off of it starts shifting too much, truck gets about 14 mpg, I€™ve got programmer and cold air intake and muffler deleted, if I get time I will try to see what gears it has this weekend, I did notice a big mpg loss when I went to 35€™s and some power loss
Now my excursion is totally different, it€™s 2wd and gets 21 mpg and has no problem towing my stuff and I prefer towing with it, I put injectors in in about 18 months ago and been best investment, mileage went from 17-18 to 21 and a big power difference, it€™s got cold air kit and programmer too through stock exhaust, the injectors are built for maximum torque for towing and made a world of difference, this thing will fly now, so I would try injectors first to see if that gets ya back in the power band ya want, if not you was gonna regear anyways, here€™s the link for what I got, these guys are the best 7.3 injector builders in the country http://unlimiteddiesel.com/high-output-ad-powerstroke-fuel-injectors
I'd like to know what kind of mileage his excursion would get hauling around normal sized people. Always gotta figure any MPGs he gives you is gonna include him and his brother which is like hauling a family of 4 with enough luggage to go to Disney world for a week. They're big dudes and John has to carry around a lot of Coors Light to keep himself hydrated on wheeling trips.

Sent from my SM-G930T using Tapatalk
 
I have an 02 with 35's/3.73's, I hook 19K to it occasionally. My converter locks up in 3rd, I have a TS Informant monitor that will tell me when it is locked up, and I can monitor the trans temp. I would go with 4.10's in your case.
 
DO NOT REGEAR UNTILL YOU DO INJECTORS. :****: Do a set of stage 1.5's (160cc 30% nozzles) and get your chip re-tuned for the single shots by a good tuner. This set up will likely exceed your HP goal by 50hp in the "hot" tune but in a tow tune it will put you right where you want to be. The MPG's will go way down if you re-gear. As far as the transmission goes, the tunes will fix your lock up and towing in OD will not hurt a thing as it is the largest clutch in the transmission.
 
I was hoping you would chime in Matt. Waiting until after engine changes are made does make very good sense.
 
I have a very similar truck 2001 F250 4x4 CC SRW long bed auto with 315/75/16 and have done the stage 1.5 injectors, TS Chip, S&B cold air intake, and 4" turbo back exhaust and am still running the 3.73 gears and stock transmission. I tow mostly local with my gooseneck and farm tractor and equipment which puts my gross combined around 19K-20K depending upon what all is with me and it does pretty good. Some of the steeper hills on the two lane back roads make me wish I had 4.10 gears, but for the most part I am pleased with the 3.73's and haven't had any troubles pulling on the interstate or major highways. If I ever have to get into the differentials on my truck I will probably change to 4.10's, but unless it breaks I will probably just leave it as is. I might eventually go to a slightly bigger turbo, but that too falls into the it's not broke yet category. I daily drive my truck and like the way it runs empty up and down the interstate.

I think I am local to you, in the Hayden area, if you would like to meet up to drive my truck on day to compare to yours. Mines not the nicest truck around by no means, but it works for me and gets driven everyday.
 
Cool. Yes I'm over here in Argo/Springville area. It was a great place then J. opened Gear Grinders Garage and well we have a special CARNIE that lives over the hill. I"m originally from the Locust Fork area.
 
RustyC said:
Cool. Yes I'm over here in Argo/Springville area. It was a great place then J. opened Gear Grinders Garage and well we have a special CARNIE that lives over the hill. I"m originally from the Locust Fork area.

I work off of I459 between Liberty Park and Grants Mill during the week mostly and drive my truck pretty much everyday. You are welcome to drive it if you would like before dropping a lot of money into injectors and etc. over re-gearing. The injectors and tune do make a big difference, but I would still like to have 4.10's in the axles someday (just not enough to justify spending the money while my 3.73's aren't broke). I think the 4.10's would be just right for towing, especially if that was all I used the truck for.

I forgot to mention I typically tow in overdrive without any problems. It is very rarely I turn overdrive off in mine. My next upgrade will probably be the transmission when it needs rebuilt, but it has been hanging in there so far for the past 2-3 years with the injectors and tune.
 
Mattman347 said:
DO NOT REGEAR UNTILL YOU DO INJECTORS. :****: Do a set of stage 1.5's (160cc 30% nozzles) and get your chip re-tuned for the single shots by a good tuner. This set up will likely exceed your HP goal by 50hp in the "hot" tune but in a tow tune it will put you right where you want to be. The MPG's will go way down if you re-gear. As far as the transmission goes, the tunes will fix your lock up and towing in OD will not hurt a thing as it is the largest clutch in the transmission.

Good info, will try out the single shots when the time comes.
 

Latest posts

Top