When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello all, I have a 1988 f250 351w c6 auto 2wd and I am doing the rear gears on it. I'm trying to decide between 3.55, 3.73, and 4.10. It sees highway miles but also pulls (not too frequently but definitely enough for consideration) #10k +. Thoughts? (New truck isn't an option because $$$$)
How tall are your tires? My '79 F350 has a 460, 4.10 gears, 33 inch tires and with the C6 transmission it was awful on the interstate. I would only run it about 62 mph. If I remember right 70mph was about 3200rpm. I still have the same gears but 2 years ago I built and installed an E4OD transmission in place of the C6 so that now have overdrive and a lock up converter. No load mileage on the interstate increased about 25% but the truck is just so much better on the highway and running 70mph is very comfortable now when in OD my truck thinks that it has a 2.91 ring and pinion. My point is don't go too low without an overdrive.
My tires are 31" diameter. 3300 rpm right now with the 3.55 is 87 mph but with 4.11 that will drop to about 75 mph. I do pull a 20' flatbed with duals on it and a 20k gvw so I could use the torque gained from a 4.11
I think that your RPM with the 4.11 will be higher than 3300 @ 75 with a 31 inch tire but I guess that all depends on how much the converter slips. It will slip less with the lower gear.
I was just thinking a 4.11 would make pulling a 7% grade loaded a little easier. I have no problem sticking to 70 on the highway as opposed to 75 or 80
Absolutely it'll help. Thinking about it; a long time ago we changed the gears in a Ford pickup truck for a customer and I'm thinking that it went from a 3.55 down to a 4.11 or maybe even a 4.56. He was towing a big heavy camper to Florida and he wasn't in a hurry. It worked out great.
If you want to figure out the numbers you can put your gearing, transmission gears, tire size etc. into this site and it will calculate your RPM at various speeds (or maybe the reverse) and you can get a pretty close answer before changing anything. https://www.blocklayer.com/rpm-gear.aspx
Here's a chart from that site with what I could google for the C6's gear ratios with a 3.55 rear end and a guess at how big new 31" tires would be.
I would be worried if trailer had electric brakes, because legally, your almost 4,000lbs over weight, and should not be towing that...ever. 1990 Ford Towing Guide, the numbers should be the same for 88 or 89. GVWR=11,500lbs with 3.55 gears and 13,000lbs with 4.10 gears. Max towing is 7700lbs with 4x2 and 4.10, 7500lbs with 4x2, 4.10, DRW and 7300 with 4x4 and 4.10. with 7.5L, With 3.55 gears 6200 4x2, 6000 4x2 DRW, 5900 with 4x4. No way this truck with 5.8L is enough to tow 10k loads.
I would be worried if trailer had electric brakes, because legally, your almost 4,000lbs over weight, and should not be towing that...ever. 1990 Ford Towing Guide, the numbers should be the same for 88 or 89. GVWR=11,500lbs with 3.55 gears and 13,000lbs with 4.10 gears. Max towing is 7700lbs with 4x2 and 4.10, 7500lbs with 4x2, 4.10, DRW and 7300 with 4x4 and 4.10. with 7.5L, With 3.55 gears 6200 4x2, 6000 4x2 DRW, 5900 with 4x4. No way this truck with 5.8L is enough to tow 10k loads.
Well, well, well,,,,,,,,The old Ford will likely disintegrate then...........BOOM. He is likely not taking off across the good ol’ USA with his rig, just local stuff around big wonderful Wyoming. @Doc. Dewey I pulled bigger loads than that with my ‘78, 351M, 4 speed with 4.10 gears and was happy. Just did not get in a hurry (couldn’t)!
It was an old workhorse. I would drag a loaded grain trailer out of the fields to the bin, no problem. Probably better than 30,000 lb. Drag loads of firewood up off of the river bottom, weights would be approximately the same. I worked that thing that way for almost 30 years 2 engines, 1 transmission overhaul, 1 transfer case overhaul, 1 rear end overhaul. Odometer quit working at about 65000 miles, so who knows what it had for mileage when I finally just gave it away. Oh, it drug a 12 X 55 mobile home about 50 miles one time also. So with 4.10’s I think your re-gear will work pretty good for you.
I've got a very similar thought and truck, '88 f350 351 c6 2wd dually. That I've been considering re-gearing for better towing/hauling around town. I have not physically checked the current ratio but Its pretty sad getting a trailer, or a load in the body going from a stop or up a hill.
Playing around with a gearing calculator, I think that if I do re-gear i'm going with 4.88:1
This will put me at around 3k rpm at 50mph.
And the main roads going into town are 50's so that's plenty for me, and the AG registration only gives me 20 miles from home in NH, 50mph is plenty for this truck.
My only concern is will the 1st to 2nd gear shift be at too low of a speed and too big of a ratio change to keep me pulling hills at 30 (ish) miles an hour. ie; 1st gear 30mph 3900rpm 2nd gear 30mph 2300rpm. I doubt the truck will hold 4k rpm in 1st gear without shifting, but will that shift pull it out of the torque range and make it instantly want to down shift again? I keep coming back to it cant be worse than it is now.
I've got a very similar thought and truck, '88 f350 351 c6 2wd dually. That I've been considering re-gearing for better towing/hauling around town. I have not physically checked the current ratio but Its pretty sad getting a trailer, or a load in the body going from a stop or up a hill.
Playing around with a gearing calculator, I think that if I do re-gear i'm going with 4.88:1
This will put me at around 3k rpm at 50mph.
And the main roads going into town are 50's so that's plenty for me, and the AG registration only gives me 20 miles from home in NH, 50mph is plenty for this truck.
My only concern is will the 1st to 2nd gear shift be at too low of a speed and too big of a ratio change to keep me pulling hills at 30 (ish) miles an hour. ie; 1st gear 30mph 3900rpm 2nd gear 30mph 2300rpm. I doubt the truck will hold 4k rpm in 1st gear without shifting, but will that shift pull it out of the torque range and make it instantly want to down shift again? I keep coming back to it cant be worse than it is now.
Any thoughts?
You'd probably be fine but if it were me i would rev so high before shifting. Id up it at 2500 and it'll drop to around 1000 when you grab the next gear.
Well, well, well,,,,,,,,The old Ford will likely disintegrate then...........BOOM. He is likely not taking off across the good ol’ USA with his rig, just local stuff around big wonderful Wyoming. @Doc. Dewey I pulled bigger loads than that with my ‘78, 351M, 4 speed with 4.10 gears and was happy. Just did not get in a hurry (couldn’t)!
It was an old workhorse. I would drag a loaded grain trailer out of the fields to the bin, no problem. Probably better than 30,000 lb. Drag loads of firewood up off of the river bottom, weights would be approximately the same. I worked that thing that way for almost 30 years 2 engines, 1 transmission overhaul, 1 transfer case overhaul, 1 rear end overhaul. Odometer quit working at about 65000 miles, so who knows what it had for mileage when I finally just gave it away. Oh, it drug a 12 X 55 mobile home about 50 miles one time also. So with 4.10’s I think your re-gear will work pretty good for you.
You're right. Im not doing long haul. I use it for ranch work and hauling machines around the area. The heaviest trailer i pulled with it was 20k. (I didn't have trailer brakes because they weren't working). It pulled alright but it could have used lower gearing
I would be worried if trailer had electric brakes, because legally, your almost 4,000lbs over weight, and should not be towing that...ever. 1990 Ford Towing Guide, the numbers should be the same for 88 or 89. GVWR=11,500lbs with 3.55 gears and 13,000lbs with 4.10 gears. Max towing is 7700lbs with 4x2 and 4.10, 7500lbs with 4x2, 4.10, DRW and 7300 with 4x4 and 4.10. with 7.5L, With 3.55 gears 6200 4x2, 6000 4x2 DRW, 5900 with 4x4. No way this truck with 5.8L is enough to tow 10k loads.
D.O.T. dont care what gears you have, or how many overload springs or heavier axle you put under the truck. Its the sticker on the door post. if it says 6K thats all you can legally haul. And if the sticker is missing he can run the VIN. Its a long story but it cost me a few thousand dollars to learn this lesson.
D.O.T. dont care what gears you have, or how many overload springs or heavier axle you put under the truck. Its the sticker on the door post. if it says 6K thats all you can legally haul. And if the sticker is missing he can run the VIN. Its a long story but it cost me a few thousand dollars to learn this lesson.
When DOT comes snooping around the ranch, chase his/her azz out of there! None of their effing business happens there.
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Slideshow: The VelociRaptor Expedition gains a lift, upgraded suspension, Brembo brakes, and trail-ready equipment while retaining the stock 440-horsepower EcoBoost V6.
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.
