373's
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373's
Hello All,
I have an 89 F250 with 7.3/C6 4wd. It came with 513 final drives. I love this truck it is great for running around town and for pulling sailboats out of the water. I think this thing would drag the beach up here if i could get a chain on it.
The one undeniable fact is i get 13 around town and 9 on the highway. That is not backwards. I hit high gear between 17 and 25 depending on my driving and 50 requires me to hit the red line.
I have been thinking about changing it out the a set of later model 373's, not only for the gears, but the disc brakes as well. Wondering if anyone else has done this? Trying to think out the issues such as steering gear, leaf springs, ride and handling, before i pull the trigger.
Most importantly, will the truck have any strength left with that gear set?
Would be grateful for any experience.
Regards
" Education is expensive and it don't matter where you get it."
I have an 89 F250 with 7.3/C6 4wd. It came with 513 final drives. I love this truck it is great for running around town and for pulling sailboats out of the water. I think this thing would drag the beach up here if i could get a chain on it.
The one undeniable fact is i get 13 around town and 9 on the highway. That is not backwards. I hit high gear between 17 and 25 depending on my driving and 50 requires me to hit the red line.
I have been thinking about changing it out the a set of later model 373's, not only for the gears, but the disc brakes as well. Wondering if anyone else has done this? Trying to think out the issues such as steering gear, leaf springs, ride and handling, before i pull the trigger.
Most importantly, will the truck have any strength left with that gear set?
Would be grateful for any experience.
Regards
" Education is expensive and it don't matter where you get it."
Cargo Master
Joined: Oct 2005
Posts: 2,295
Likes: 25
From: NJ
I'm of the mind to gear it for acceptable RPM and economy at your desired max speed and add power until it performs acceptably. If you tow particularly heavy that may affect what gear ratio you choose, and maybe a double overdrive is more suitable.
3.73 would probably be an acceptable all around choice though. Rear disc brakes are a separate matter and there are several ways to achieve that. I wouldn't bother though as I find the fairly large factory rear drums adequate for my stopping needs and most ways to get rear disc involve some sacrifices like the strong parking brake.
3.73 would probably be an acceptable all around choice though. Rear disc brakes are a separate matter and there are several ways to achieve that. I wouldn't bother though as I find the fairly large factory rear drums adequate for my stopping needs and most ways to get rear disc involve some sacrifices like the strong parking brake.
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That is exactly the kid of thought provoking input i was hoping for. I wish i had better insight as to the engineering aspect of making the changes.
The rear disc's was strictly for stopping power. I am set up for trailer brakes and use them vigorously, there are often times when customers trailers have no brakes. I was thinking of using a micro lock or improved equivalent for a primary park brake, the in hub unit as a back up. As well as looking into install a brake hub on the rear of the transfer case, if possible?
As near as i can remember our trucks performed reasonably well with 410/411's. Never drove that setup with an automatic though. As I remember the 411's got a consistent 14 mpg without an over drive.
If you would, please tell me more about a double overdrive set up?
" Education is expensive and it don't matter where you get it"
The rear disc's was strictly for stopping power. I am set up for trailer brakes and use them vigorously, there are often times when customers trailers have no brakes. I was thinking of using a micro lock or improved equivalent for a primary park brake, the in hub unit as a back up. As well as looking into install a brake hub on the rear of the transfer case, if possible?
As near as i can remember our trucks performed reasonably well with 410/411's. Never drove that setup with an automatic though. As I remember the 411's got a consistent 14 mpg without an over drive.
If you would, please tell me more about a double overdrive set up?
" Education is expensive and it don't matter where you get it"
Fleet Mechanic
Joined: Apr 2015
Posts: 1,264
Likes: 7
as an avid boater, I own boats from 12' to 33'
pulling the 33 footer out with 3.73's (01 F350 SD) can be a chore on challenging ramps.
if you change gear ratios, you will loose final drive torque.
depending on the size of the sails you pull, you may want to do an overdrive.
I know that lead keels are not light.
pulling the 33 footer out with 3.73's (01 F350 SD) can be a chore on challenging ramps.
if you change gear ratios, you will loose final drive torque.
depending on the size of the sails you pull, you may want to do an overdrive.
I know that lead keels are not light.
Postmaster
Joined: Dec 2011
Posts: 3,860
Likes: 7
Of course, being able to use overdrive(or double overdrive) for towing requires adding power. NA, you'll be lucky to tow a 6k trailer at 60 on anything but flat ground.
Get it up to 250 at the wheels like I have... and you'll be pulling steep hills at 70 in overdrive.
So yes... Add turbo and power, then gear it appropriately. And with the C6, you'll definately want an aux cooler and such.
As far as crawling on ramps and such - that's what 4lo is for.
Cargo Master
Joined: Oct 2005
Posts: 2,295
Likes: 25
From: NJ
Indeed, I'd never worried about gearing on ramps. With my relatively small boats (18'-23') granny gear has been fine, but when in doubt just use low range. I'll often need to lock the hubs if it's more toward low tide, from debris on the ramp and wet slime. My other truck with a locker does fine in 2wd even on steep wet ramps.
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I have trailers that allow up to a 32' sailboat up to 11K+/-. Historically, i use this truck to pull them out of the water and run the road with my ton truck, a 6.9. On boats that large, positrack doesn't seem to help much. When the keel come out of the water it lifts the rear axle, unless your loaded enough to offset the lift, or have 4wd it stops right there.
In 4 lo you don't have to use much power to pull anything with current gearing. I was hoping i could still use it to pull some of the smaller stuff and be able to road with it?
Can you use a gearvendor aux on a 4wd auto?
The final goal here is to make this truck more all around drivable. Hoping it will be a good daily driver and pull smaller stuff. I am building a one ton 4wd for the bigger boats.
Thanks for all the input.
In 4 lo you don't have to use much power to pull anything with current gearing. I was hoping i could still use it to pull some of the smaller stuff and be able to road with it?
Can you use a gearvendor aux on a 4wd auto?
The final goal here is to make this truck more all around drivable. Hoping it will be a good daily driver and pull smaller stuff. I am building a one ton 4wd for the bigger boats.
Thanks for all the input.
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Cargo Master
Joined: Oct 2005
Posts: 2,295
Likes: 25
From: NJ
Don't bother with a gearvendors if you've got a C6 in there. GV units are around $3k new, few and far between for sale used, and GV viciously enforces the market on their proprietary parts so no individual parts or rebuilt kit availability. For a daily driver, swap in a ZF5. Shouldn't cost more than a grand, and my net cost on going C6 to ZF5 ended up paying me a few hundred bucks after selling off the parts I didn't need. That includes a new flywheel and clutch, and rebuilding the ZF. Sometimes you get lucky.
Use 4lo pulling heavy boats out of the water, with front axle locked or not depending on conditions. If power on the road isn't what you want add a turbo and bigger pump or additional improvements depending on your needs. My 6.9 with 3.55:1 gears, turbo adn bigger pump does well enough loaded down with ~5500 lbs. Factory pump and no turbo, if that's what your truck is, I can see why someone put 5.13:1 gears in it as these engines really are gutless wonders without a turbo.
Use 4lo pulling heavy boats out of the water, with front axle locked or not depending on conditions. If power on the road isn't what you want add a turbo and bigger pump or additional improvements depending on your needs. My 6.9 with 3.55:1 gears, turbo adn bigger pump does well enough loaded down with ~5500 lbs. Factory pump and no turbo, if that's what your truck is, I can see why someone put 5.13:1 gears in it as these engines really are gutless wonders without a turbo.
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Lead Driver
Joined: Apr 2008
Posts: 6,938
Likes: 13
I swapped in a 10.5 sterling with 3.73. The rear disc are AMAZING. Pull the plastic jobby out the master cylinder where the rear line connects and thats it. E-brake is tough to hook up tho. I have a zf5, good combo for my tired turbo / engine. When the new engine is in, think i will regear sometime to 3.55s to cruise under 2k, as 90% of my driving is 75mph, and i dont tow heavy or super often
Cargo Master
Joined: Oct 2005
Posts: 2,295
Likes: 25
From: NJ
It's surprising to me that rear disc made such a big difference for you unloaded. My rear drums lock up easily well before the fronts, since I can't find a serviceable load sensing proportioning valve I'll eventually install a manual proportioning valve.
Lead Driver
Joined: Apr 2008
Posts: 6,938
Likes: 13
My rears would never lockup with drum, or WELL after the fronts. Had them done by a local reputable shop, then an axle seal went out, and i did that and checked everything. All looked good, but as you say, the real gravy is when youre loaded. Can lock em up with 3k in the bed if i want, (i dont want, the spring wrap is real lol). Discs are alot easier to maintain imo too, small bonus, but a bonus. Only thing i dont like about the SAS stuff, is the front super poopy rotors are notorious for warping, and mine are starting too, even though they havent been abused, and i have newer high quality pads, and had the rotors surfaced.
i ain't rite
Joined: Mar 2005
Posts: 65,447
Likes: 5,517
From: Marlboro Mental Hospital.
my 88 has a turbo, C6 trans, and 410 gears. i find it perfect for in town driving and towing heavy loads, but a little short out on the highway. i don't run the road with it anymore, so the 4.10's are fine for me.
with the C6 and 4.10's it top out rite around 80 MPH at 3000 RPM
with the C6 and 4.10's it top out rite around 80 MPH at 3000 RPM
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