Laurie:

I would take exception with what your Mechanic said. The 2.73 gears will make for difficult grade climbs and a lack of engine braking on steep decents. If you plan to haul more than about 3,000 pounds, a gear change is definately in order. By the way, if the tag is missing, or if you want to verify for sure that the gear ratio is what is listed, then here's what to do. Mark the driveshaft with an index mark to the rear end housing assembly. Next, mark each rear tire with an index mark. While under the truck, have an assistant (or better yet, two assistants) turn each wheel one revolution. It may be neccessary to hold one wheel from turning while turning the other. While the wheels are turning, however, you count driveshaft revolutions. about 2 3/4 revolutions is 2.73. About 3 even is 3.08. About 3 1/4 is 3.23, and about 3 1/2 is 3.55. About 3 3/4 is a 3.73, and a smidge more than 4 is a 4.11. It all comes down to speed vrs torque. 2.73 is like 10th gear on your ten speed. Little acceleration force, alot of speed at (relatively) low rpm (2.73 driveshaft revolutions for every one revolution of the axle). 5th gear, slower, but more power (like 3.55). 1st gear, you could nearly climb a vertical surface with this, but can't go too quick. That'd be a 4.11 ratio. Hope this helps. Glad you are happy with our input so far, glad to oblige.

 

Hi Argo, remember me?, you gave some valuable input regarding rear axle ratio, etc... I just found out what gear ratio I have (2WD Bronco, C-6 I-6 300 all stock...), I have a code 18, which people tell me is the 3.08. I understand this is a speed-economy gearing. However, since I have a torqueish, towing engine and not very fast like the 300, if I were to swap into a bigger, faster engine, say a 351W or 351C, should I keep the same gears?. I am thinking about installing an overdrive tranny, would that make a difference, other than economy-wise?, that is keeping the old six...? you told me I should get like 3.55 gears I think? thanks again...

 

Thanks Argo.... I guess I should have mentioned that I live in Saskatchewan, Canada. A relatively common statement about our landscape (and also very nearly true): "on a clear day you can see the back of your head." I'm also only going to be hauling short distances for the time being - probably not much more than 150 miles in a day. And my horse is my family, so we'll be grannying along holding up traffic (but we will be doing so in the right lane)!

 

Calazo:

The trouble is that even a 460 would be somewhat sluggish with that 3.08 ratio. Adding overdrive to the 3.08 will make it act like about a 2.16 ratio (assuming a .70 overdrive). Conversely, a 3.55 ratio with Overdrive will act like a 2.49 ratio. What's all this mean? Pretend your engine makes 100 ft lbs of torque. The 300 and all the other engines make alot more than this, but it's an easy number to work with, so we'll use it. Lets pretend your transmission has a first gear ratio of 3.00, a second gear ratio of 1.50, and a third gear ratio of 1.00, and an overdrive of .70. With a 3.08 ratio, we'd multiply 3.00 (1st gear) by the final drive ratio of 3.08, and multiply by torque for a grand total of 924 lb ft at the wheels. Second would be 3.08x1.5x100lb ft for a total of 462 ft.lb., and so on, 308 lb ft in third, and 216 in O/D. Compare this to the same setup but with 3.55 gears. 1st gear torque jumps to 1,065, second to 533, third to 355, and O/D to 249. That means more pulling power, plain and simple. O/D is for fuel savings. You propably wouldn't use it with a loaded truck. The gear ratio would be so deep in O/D with the 3.08 ratio that even an empty truck might have trouble with slight grades in a headwind. Granted, the real numbers would be much greater when actual engine torque is considered (instead of the 100 lb ft listed) but you get the idea. I have moved great loads with a 300. I have had great luck with mine. I am certainly jaded and prejudice towards this engine because I feel so strongly that it is the greatest light truck engine ever produced, so I'd advise you to keep the six. Keep in mind, that is my totaly biased opinion. I think you'd be better off keeping the six, due to reduced operating costs, reduced effort of swapping in a V8 for the six, but no matter what engine you choose, proper gearing is essential. I'd switch out the gears and run the truck and see if I were happy with it before swapping engines. You're bound to increse the performance substantially, and propably pick up some milage as well.

 

Thanks for the detailed message. By the way, I've also heard that 3.73 gears would also be a good choice in my case, what do you think?. Maybe I'll switch the gears to 3.55 of whatever, and put in the O/D tranny because I do need some extra MPGs for the highway, and finally, as far as the 300, I might put headers, increase valve diameter, put in a 2bbl carb with intake, to improve the engine, I believe I can do all of that for less than $1000, since I already got a quote on a AOD tranny and I have switched gears before in another car I had, and it worked!...

 

3.73 gears are ok as well. I'd avoid anything deeper, because of gear strength. The deeper the ratio, the less teeth are engaged at any given time. On an 8.8 inch Ford rear, 3.73 and taller gears are stronger than 4.10 and deeper gears. Any time you increase an engine's ability to breathe, it's a good thing. I think that if you do the 3.55 or 3.73 gearset, and the 2bbl intake, exhaust headers (or EFI exhaust manifolds), some port and polish work, bigger valves, and a mild cam and free flowing exhaust, you'll realy wake up the six. Reduced pumping losses means reduced friction, which means more power to the drivewheels. Think of how little strain the engine will have around town and when climbing hills, and yet the final drive ratio for the highway will still be taller than it is now, for better cruise efficiency. If you can manage to drive conservatively, then you can manage to get close to 20 mpgs out of her. That's assuming you can resist temptation and keep your foot out of her. The AOD will work well with this combo, but you must make an extra effort to kep it cool. Get the highest rated auxiliary trans cooler you can fit, and plumb it so that you cool the fluid with the built in trans cooler in the radiator, then to the auxiliary cooler before going back to the trans. Keep it cool and it'll haul anything. Also very important with the AOD... make sure you have good adjustment on the Throttle Valve cable (T.V. for short). This trans does not have a vaccum modulator on it. Shift feel, shift timing, and kickdown are all controlled by this cable. If it's not guitar string tight when an assistant mashes the pedal to the floor (with engine off), then adjust it untill it is.

 

Same thing with mine, I think its just the way the gearing is set up, It always wants to go a bit faster or slower than the speed limit.

 

My 1992 f-150 4x4 dana 44 front 3.55 and 8.8 rear 3.55 strait 6 4.9 has aod with column aod kick in and out switch sounds like it wants to rev high rpms then change gears what can i do . I am not pulling anything but will be adding a 4 in susp lift and 33 in tires soon .

 

Hey i got a 88 f150 4x2 with a 300, 3 on the tree and 308 gears. how much can I tow? someone mighyt have already stated this but i didnt feel like reading all that ****

 

i have a 86 f250 with a 300/6 pump motor that ran on butane now its gas the rear axle code is 29 factory tires were 215/75 /16s now 245/75/16s does anybody know what the 29 means the truck has a t19 trans can im moving to arizona in december and i want to tow my 71 f250 but i dont want to hurt my 86 and i dont want to be stuck driving at 50 to 60 mph the state police in new mexico will make me get off the interstate or i will get run off the road by a tailgaiting truck driver
thank you lrd56

 

I just know with my 87 EFI with the Granny gear manual, 3.55 gears, and 31" tires...that 6300 pounds towing limit is quite an understatement of what it can do.

 

The heaviest I pulled is 6,200 lbs, and the engine had plenty of reserve power. I could propably do 8,000 lbs, but I'd be scared to try and control that much mass with a half ton truck.

 

hi, I’m also In the same situation. Before y’all call me dumb, I’m trying to borrow my dads 2018 f150 5.0 to tow a camper to the darlington 300. If he does not let me, I have a 1979 Ford f100 with the 4.9 inline 6, 3 on the tree tranny, and 2:73 rear end. I’m running 29 inch BFG all terrain ko2s on stock 15 inch steels. Darlington is around a hour and 15 minutes from where I live. My guess is the trailer is around 6300 pounds. Besides brakes, do you think it could tow it driving under 50 mph? This truck has 69k miles with original everything, and it’s pulled trees out of the ground.

 

What kind of hitch do you have, and what kind of brakes on the trailer?

Your truck was probably rated for 3500 or 5000 lbs.

You can "get away with" more weight BUT you MUST have working trailer brakes, and you MUST have a frame mounted trailer hitch that will take that weight.

 

I have a custom frame mounted hitch shown below. I currently do not have electronic trailer brakes. If I’m correct, the trailer possibly has mechanical trailer brakes which has no need for the controller. My biggest other worry is over heating. Being a 2:73 rear end with rpms roughly around 2500 At 50mph, I’m worried that it would overheat. I’ve got some work to do before all of this. I need to repair my shocks and fix my temp gauge.