Gear Ratio
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Joined: Mar 2004
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From: missouri
Gear Ratio
Hi everyone! I was wondering about towing with my 1966 ford F-100. I recently replaced the stock 300 with 3 on the tree with a 302 and c-4 tranny out of a 1979 ford F-100. Will I be able to tow okay with the stock gear ratio in the rear end or should I change it. Also anyone know of what kind of rear bumpers will fit my truck. I was thinkink one from a bronco 2 should fit. I want to put a step bumper on the truck, but most Ive seen are chrome but not step bumpers. Thanks for the help 
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
Hi Jim, I tow with my 66 F100 with FE C6 & 3.00 rears. You didn't say what you are wanting to tow. I have a class 4 (12,000) reciever hitch and pull an 18 ft car hauler. I weighed one haul with a 4X4 F150 on board and the three pieces totaled 10,520 lb. I have 76 I-beams with discs & upgraded the rear brakes with a 69 axle & hub.
The 302/C4 that you have will handle small trailers and boats just fine. The 302 is not a torque monster like the FE, but is a good engine.
Rear bumper mounts to 72 are the same. You can use a 73-79 but you will have to use spacers, and stepping on it is about all that you could do with it. Folks have done it, but do not install a step bumper to tow with, purchase a reciever hitch and mount it to the chassis.
You can change your rear ratio if you find that you need to. I was running a 2.75 under my truck but the trailer loaded dogged it. Changing to a 3.00 made a big difference. If I want more snap I can change again, but will sacrefice gas milage.
hope you have something to chew on.
John
The 302/C4 that you have will handle small trailers and boats just fine. The 302 is not a torque monster like the FE, but is a good engine.
Rear bumper mounts to 72 are the same. You can use a 73-79 but you will have to use spacers, and stepping on it is about all that you could do with it. Folks have done it, but do not install a step bumper to tow with, purchase a reciever hitch and mount it to the chassis.
You can change your rear ratio if you find that you need to. I was running a 2.75 under my truck but the trailer loaded dogged it. Changing to a 3.00 made a big difference. If I want more snap I can change again, but will sacrefice gas milage.
hope you have something to chew on.
John
Postmaster
Joined: Jan 2003
Posts: 3,775
Likes: 2
From: Conway Arkansas
Not to be a jerk, but I wouldn't tow a whole lot with a C4.
My 77 F-100 came stock with a 302/c4. My grandfather had over 12 transmission in it over the years. I sold him the last one. It was a very well built C4 w/ shift kit and a good servo (forgot what letter off top of my head) built buy a very reputable guy in town.... then I bought the truck 3 months later and the tranny was slipping. I replaced it with a c6 and have had NO problems with it.
My buddy had no luck w/ a C4 in his 66 truck pulling very much weight at all.
My suggestion try a C6.
But for gears... depends on what you are going to tow.
I have 3.70 gears behind my 390/C6 and could tow a house. 3.50s behind my stock 302/c6 and i wouldn't pull a car trailer with it, but id pull 4 wheeler trailers and stuff with it easily. The C4s aren't as heavy duty as a c6. I could pull a car trailer with my 302 but dont feel like strainin the motor.
If your running a fairly stock motor I'd go with 3.50/3.70/4.10 etc gears.
If you have put in a cam/manifold etc id go with the 3.50s or so.
Sorry for the long post, just returned to FTE from a Maverick board and got carried away.
My 77 F-100 came stock with a 302/c4. My grandfather had over 12 transmission in it over the years. I sold him the last one. It was a very well built C4 w/ shift kit and a good servo (forgot what letter off top of my head) built buy a very reputable guy in town.... then I bought the truck 3 months later and the tranny was slipping. I replaced it with a c6 and have had NO problems with it.
My buddy had no luck w/ a C4 in his 66 truck pulling very much weight at all.
My suggestion try a C6.
But for gears... depends on what you are going to tow.
I have 3.70 gears behind my 390/C6 and could tow a house. 3.50s behind my stock 302/c6 and i wouldn't pull a car trailer with it, but id pull 4 wheeler trailers and stuff with it easily. The C4s aren't as heavy duty as a c6. I could pull a car trailer with my 302 but dont feel like strainin the motor.
If your running a fairly stock motor I'd go with 3.50/3.70/4.10 etc gears.
If you have put in a cam/manifold etc id go with the 3.50s or so.
Sorry for the long post, just returned to FTE from a Maverick board and got carried away.
Posting Guru
Joined: Jul 2003
Posts: 2,222
Likes: 1
From: East Central Florida
Hi Cooper, 
1st of all, welcome to FTE & our world of "Slicks", 61-66 F Series trucks. Now let me see if I can offer you some answers to your query here. . . .
It depends on a lot of things which aren't mentioned in your post.
For example what rear end & gear ratio do you have now? Also what do you plan to tow or more correctly what weight & type of conveyence do you plan to tow? A two axle tag flatbed trailer with a Bobcat is a "load", while a small aluminum boat towed on a 2 wheel trailer is hardly any load at all. Terrain matters, so does type of driving off road compared to on road, and local vs highway(stop & start vs rolling along) etc. So you see there's a lot that goes into it.
Make sure your C4 A/T has extra cooling in the form of a remote, radiating, ATF type airflow oil cooler for a Motor Home or RV is a good addition. Heat is what kills A/Ts and that's regardless of what A/T or Engine or Load.
A 302 (5.0L V8) Windsor engine has less initial torque output than 300 (4.9L I-6) does just because less cyls produce more proportionate, or relative torque than more cylinders do. In this comparison, 302 V8 & 300 I-6 are virtually same CID so a 302W (5.0L V8) produces less while a 300 (4.9L I-6) produces more actual initial torque in terms of pounds feet.
So after saying all that above, If you're towing heavy or off road or w/ alot of stop & go involved, I'd stick with nothing less than 3.89- 3.90- 3.93 or shorter rear gear. But if you plan to tow highway with light loads & little stop & go I could see a 3.70- 3.73 &
if you're running flatland, opposed to rolling or foot hills on highways you may even get away w/a 3.50 gear. But if you run rolling & foot hills, run a shorter 3.90 & lower gear.
If you have the Dana 40 style rear your gear ratio choices are limited, and if you are running a FoMoCo 9" your ratio choices are nearly unlimited. I personally dislike Dana Rear Ends especially the light duty ones like Dana40. I wouldn't run one if I was towing anything. In fact I changed a Dana(Spicer)50 in my 88 recently to a FoMoCo 9" & all I do with it is drive it. Another advantage with 9" FoMoCo rears over a Dana is you can install 3" wide rear brake set up with a few "bolt up" mods, if you want to stop great if towing or not.
As for rear bumpers I don't know that a Bronco II bumper will fit.
If you're thinking about a Step & Tow rear bumper, I suggest you consider a frame mounted type reciever hitch to tow with.
They don't loosen up & move around on ya. There's width difference between 65 -72 & 73-79 rear frames. 73-79's are 3" wider. This means is it's possible to adapt things that bolt on a rear frame of 73-79 Ford F Series to our 65-72 trucks by using substantial spacers and longer grade #8 bolts.
I'd adapt a Reese hitch, or other frame mounted receiver hitch if I couldn't find one to fit the narrower 65-72 style frame. This can be done by narrowing cross/ tow bar, or as mentioned, spacing mounts out (my 2nd choice!). I'd not space mounts if planning to tow heavy loads or a long trailers. I'd have a good welder narrow frame mount for a receiver type hitch, for sure.
If you're just thinking about "hiding" the back under your tailgate then by all means spacing the mounts works fine and any rear bumper from 65 thru 79 will, or can be made to, fit relatively easy.
Lastly, With a FoMoCo 9" rear if you plan on tow ing medium to heavy loads say 750# & up, ya ought to add a rear Antisway bar from mid 70s F150/F250 Trailer or Camper Special and a set of "progressive" shocks like Sensi-Tracks or equiv. The OEM rear Antisway bars I mention will bolt on to a 65 & later F Series with 9" FoMoCo rear end set up, however will not bolt up to a Dana without some modification involved. The addition of a rear Anti Sway Bar, progressive shocks & 3" brakes make a world of difference as far as stability, handling, stopping & all that = More Control. When towing anything Control is what it's all about & a good objective to maintain.
Happy Towing Cooper.
FBp
1st of all, welcome to FTE & our world of "Slicks", 61-66 F Series trucks. Now let me see if I can offer you some answers to your query here. . . .
It depends on a lot of things which aren't mentioned in your post.
For example what rear end & gear ratio do you have now? Also what do you plan to tow or more correctly what weight & type of conveyence do you plan to tow? A two axle tag flatbed trailer with a Bobcat is a "load", while a small aluminum boat towed on a 2 wheel trailer is hardly any load at all. Terrain matters, so does type of driving off road compared to on road, and local vs highway(stop & start vs rolling along) etc. So you see there's a lot that goes into it.
Make sure your C4 A/T has extra cooling in the form of a remote, radiating, ATF type airflow oil cooler for a Motor Home or RV is a good addition. Heat is what kills A/Ts and that's regardless of what A/T or Engine or Load.
A 302 (5.0L V8) Windsor engine has less initial torque output than 300 (4.9L I-6) does just because less cyls produce more proportionate, or relative torque than more cylinders do. In this comparison, 302 V8 & 300 I-6 are virtually same CID so a 302W (5.0L V8) produces less while a 300 (4.9L I-6) produces more actual initial torque in terms of pounds feet.
So after saying all that above, If you're towing heavy or off road or w/ alot of stop & go involved, I'd stick with nothing less than 3.89- 3.90- 3.93 or shorter rear gear. But if you plan to tow highway with light loads & little stop & go I could see a 3.70- 3.73 &
if you're running flatland, opposed to rolling or foot hills on highways you may even get away w/a 3.50 gear. But if you run rolling & foot hills, run a shorter 3.90 & lower gear.
If you have the Dana 40 style rear your gear ratio choices are limited, and if you are running a FoMoCo 9" your ratio choices are nearly unlimited. I personally dislike Dana Rear Ends especially the light duty ones like Dana40. I wouldn't run one if I was towing anything. In fact I changed a Dana(Spicer)50 in my 88 recently to a FoMoCo 9" & all I do with it is drive it. Another advantage with 9" FoMoCo rears over a Dana is you can install 3" wide rear brake set up with a few "bolt up" mods, if you want to stop great if towing or not.
As for rear bumpers I don't know that a Bronco II bumper will fit.
If you're thinking about a Step & Tow rear bumper, I suggest you consider a frame mounted type reciever hitch to tow with.
They don't loosen up & move around on ya. There's width difference between 65 -72 & 73-79 rear frames. 73-79's are 3" wider. This means is it's possible to adapt things that bolt on a rear frame of 73-79 Ford F Series to our 65-72 trucks by using substantial spacers and longer grade #8 bolts.
I'd adapt a Reese hitch, or other frame mounted receiver hitch if I couldn't find one to fit the narrower 65-72 style frame. This can be done by narrowing cross/ tow bar, or as mentioned, spacing mounts out (my 2nd choice!). I'd not space mounts if planning to tow heavy loads or a long trailers. I'd have a good welder narrow frame mount for a receiver type hitch, for sure.
If you're just thinking about "hiding" the back under your tailgate then by all means spacing the mounts works fine and any rear bumper from 65 thru 79 will, or can be made to, fit relatively easy.
Lastly, With a FoMoCo 9" rear if you plan on tow ing medium to heavy loads say 750# & up, ya ought to add a rear Antisway bar from mid 70s F150/F250 Trailer or Camper Special and a set of "progressive" shocks like Sensi-Tracks or equiv. The OEM rear Antisway bars I mention will bolt on to a 65 & later F Series with 9" FoMoCo rear end set up, however will not bolt up to a Dana without some modification involved. The addition of a rear Anti Sway Bar, progressive shocks & 3" brakes make a world of difference as far as stability, handling, stopping & all that = More Control. When towing anything Control is what it's all about & a good objective to maintain.
Happy Towing Cooper.
FBp
Last edited by FordBoypete; Jan 7, 2005 at 07:17 AM.
