I just got my truck back, and i dont have a ton of extra cash (im actually in the hole) but.... i was hauling hay the other day with a 3 horse 20ft trailer, and i really could of used a lot more umpff going up the hills with my 3.55s, once i got on the level and picked up momentum i was a-ok, but starting up a hill was a killer. So i was looking into putting new gears in the rear, maybe 3.73s because i kinda want gas mileage, and i wanted to know how much different the 3.73s would be from my 3.55s, ex gas mileage, how much it'll help towing etc... I also wanted to know how i find out wat rear end i have, possibly a 8.8"? idk, and also if i change my rear gears will i have to change my front ones? Thanks

 

When figuring gear ratios I always think in percentages. Going to 3.73 would only be 5% or slighly more. Thats not even worth the effort of changing in my opinion. Three MPH difference at 60 MPH might put it in better perspective. 4.10 would be more like it. Yes you definitely have to change the front differential gears also.

 

I seem to be having the same trouble that reyncreed is experiencing. I recently replaced the engine (5.0 EFI) in my 95 F150 FWD after turning a main bearing. I guess I was expecting my truck to be better able to pull my 3 horse gooseneck with the new engine. However, it continues to struggle to pull off and on grades. I am pretty sure my truck has the 3:55 differentials. Should I consider some performance enhancements for the engine, or look into regearing the differentials.

If I should choose to change my gears, how do I get my speedometer to read accurately.

Thanks for any advice that anyone could provide.

BTW, please accept my apology if I should have started a new thread to post this question..

 

There is a thread titled "owners who went from 3.55 to 4.10" in the "Other Powertrain" forum on this site, still on page one, 32 replies. It may interest the two of you. As far as recalibrating the speedometer, I believe it is done electronically on 1992 and up models. It has been discussed somewhere around here on this site, I think maybe on this very forum, I'm not sure.

 

What we should start is a thread called "my 5.0 has no low end grunt!" :o

I'd say don't sink $$ into the engine, because by the time you gain enough ft-lbs to make a real towing difference, you could have swapped in a 351. Gear it down to 4:10 if you want to feel the difference. Also, I talked to my local tranny guy, and he suggested a nice torque convertor. I haven't investigated the idea yet, but it did seem like good advice, since I need to replace my leaking rear main seal anyway...

As far as the speedo goes, mine didn't change when I geared down. It only changed with tire size.

 

But with a 4X4, he needs to change 2 sets of gears. That's a fairly expensive proposition, especially if he has to pay to have it done.

It costs a whole lot less to add some torque capability to the engine, assuming that he can do that work himself. A good cam like a Crane 2020 or even a simple mod like high lift rocker arms can give a noticable gain but probably not enough to make the difference he's looking for

Basically though there's nothing you can do to a 302 short of a positive displacement supercharger that's going to make it a torque monster.

 

What would be the feasability of replacing the differentials with OEM gears, or is there a suitable aftermarket product that could be substituted? Also I have read in several threads about replacing the factory intake and exhaust system to free up air movement through the engine. In 188000 miles, the engine is the only thing that has been replaced. Is it possible that the CAT Converter is blocking up?

mike

 

Replacing the gears is feasible but like I said it can be expensive. If you have the tools and knowledge to do it yourself then it is substantially less costly. At a minimum, figure on $300 per axle in parts for the ring & pinion and the install kit. When you get it apart you may find other things that need replaced. IIRC the Dana 44 uses a different carrier with 4.10 gears; if so that will add a couple of hundred more to the front diff on a 4X4. If you have to hire it done, don't be surprised if the bill is on the order of $2K.

 

You hit it right on the head. I had the 4:10's done at a 4x4 drivetrain shop, and the carrier in my D44 did need to be swapped, and the job landed right at $1800, including the LS pack option. But, like you said, gears will make the biggest difference for the money when it comes to towing.

As for intake and exhaust, those mods will bring you some hp gains in the higher rpm's, but not much down low. It has even been argued that opening up the exhaust can cause decreases in torque.

 

You don't have to swap out the front gears, but if you don't you'll never be able to use 4wd again. If you engage it, the hubs will pop in no time.

It would be cheaper to find a 351 somewhere and swap it in than do extensive mods or a gear swap on the 302. Hell, you could probably find and buy another truck with the larger motor for less. The 302 and 351 share about everything, so it's a pretty easy swap. The 351 has makes it's power down low, around 2000 RPM, wheras the 302 doesn't start to do much of anything until after 3000. Which is fine for a race motor, for towing, it's an annoyance and hard on both the motor and tranny.

You'll pick up a good 20-25 hp gain with the 351, and about the same ft/lbs of torque if I remember.(180hp/270tq for the 302, and 200/300 for the 351, don't quote me on that it's just off the top of my head) But the fact the torque comes a lot sooner is what will make the difference with a load.

 

Depends.
He has a 96 with a 302. That means he may have a 4R70W tranny. If so, that would need to change to an E4OD to fit the 351 and keep the OBD-II happy. That's not an inexpensive proposition.

BTW the peak HP difference between a 351 abd a 302 is almost nil, the shape of the HP curves is way different, with the 351 developing way more power at all RPMs below peak.