I am considering this upgrade due to towing. I have the 4.6 with Automatic tranny. The dealer is recommending I go with the 3.37 w/locker carrier. My 3.08 is whinning for a couple of years now. Anyone have comments/experience with this set-up? The dealer wants @$ 850 for the mod W/new waterpump.


Thanks in advance!!
CB

1997 F150 S-Cab 4X2 4.6 Flareside

 

id recommend 4.10's honestly!

 

Here's a link to a pretty cool gear calculator. It'll tell you what your rpms are going to be at a set speed while in a specific gear, etc..

I'd have to agree however, if the main goal with the gear change is for towing, the 4.10's will give you the best bang for your buck.. The 4.6 gets it's peak power at higher rpms anyway, so that couple hundred rpm difference between the two, could be the difference of holding third gear or having to downshift to second.

Since you have a 97, you can swap out the little plastic VSS gear to correct your odo/speedo. You'll need to 'slow' down your odo/speedo, so you'll need to pick up a gear with 'more' teeth then what you have now. Depending on what gear is in there now, and what your tire size is, you'll probably need one that has 3 or 4 more teeth on it.. I'm sure there is someone out there that's done this same swap in the world somewhere, so google around some and you might be able to hook up with a better idea of the VSS gear to get.

Good luck!

Mitch

 

Thanks ! I'm worried the 4.10 will kill me in everyday traffic(when i'm not towing) with decreased gas mileage. Do the gears have much effect on your mileage? I see in your Sig Mitch you are towing a trailer, Would you go to 4.10 if the option was there and paid for?
Thanks in advance!!!

CB

 

the 4.10's will help in city driving. But they "might" possibly hurt highway mileage. like over (65-70mph) other than that you will be fine. Its just not worth the $600 for 3.73.

 

hell, he has a 2WD. i'd go w/ a 4.30, just in case you want to mount bigger tires later.

 

CB,

I'd do 4.10's in a heartbeat if it was offered up to me! The only reason I don't go for it now is the $$$ really... I do pretty good with the 3.55's and even a 265/75/16 tire. I downshift into second more often on the hills and just ride it out in third going 60-65 mph while on the flats towing.. If I went back to the OEM 235/70/16 tires, it would be like I had 3.73 gears with the 265's.. No way I'm going to put those little 235's on again however! ha, ha!

With 4.10's, your city mpg might actually go up.. That's because the lower gear will get you moving easier from a stop and you would shift to the higher gears faster. Now, your cruise rpms at 60-65 and above mph will be higher, even in OD, so you might give up an mpg or 2, but I'll bet if you average out your daily mpgs, it won't be much different then it is now... Depending on how you drive of course!

There will always be some 'give and take' when doing any kind of 'performance' upgrade IMO.. You just have to decide how much of 'give' you want to give up to get the 'take'.

Mitch

 

you need to post what size tires your running and you will get the best answer for whatgears to run. if your still running the small factory 2wd tires 3.73 would be a great improvement. but if you did or may be going a little larger id go 4.10s or 4.30s for sure.

 

x2... he probably has the 235's by my guess due to the high gearing. he should be able to clear 285's at least no problem.

 

I am running 265's actually. I like the better ride height and longer wear. The spedo is @ 10% off though. So I want to address that at the same time. Right now I do mostly city driving with @ 2 miles of Hwy daily for a total of 22 miles round trip. So the improved city mileage would be helpful. I have calculated with the 10% correction about 16mpg for my driving. Mitch, Thanks a million for the info!! Let me know about the tire ratio. Is there a calculator somewhere?

 

personally, i would go w/ 4.30 gears if i were you. that way, if you ever decide to go a 285 or bigger later, you'll still be one (realized) step lower than the stock 3.73

if you feel those are too low, i definitely would not go any higher than a 4.10.

 

Ok! I'm doing a swap on my Dads 2000 F150. He and I both have 5.4s and automatics. Ihave 3.55s but he only has 3.31s. I am putting in 3.73s in his. (Mine are fine for me.) I have no real differential questions. I just wanna know about the speedometer. Is there a VSS gear in the tranny on the 2000 year model or is it electronic....or what? The speedo issue is my last hurdle. We've already chosen the locker, etc. Any help you all could give would be awesome because my searches are fruitless. Thanks -Mike

 

no, past 1998, there was no VSS gear. 3.73 was a stock gearing option, so you could probably get the speedo electronically recalibrated by a dealer.

 

Awesome! Thats just what I needed to know. I found it odd that I couldnt find a gear or an electronic device (i.e. Superlift's Tru-Speed, etc.) to correct the problem on that year model. I really appreciate the help and your timing was excellent too. I definitely like being a new member on this forum. It has answers! Now I wonder how much that recalibration is gonna cost..... -Mike

 

I was in your shoes about a month ago before I got a new truck. I had a '98 4.6 2WD S-Cab...and I tow a boat. It also had the 3.08's. I decided to get a new truck instead of making my older truck a towing machine.

I'm not suggesting you buy a new truck, unless it's time and you need a reason...towing...hint...hint...

Before I bought my '06, I did alot of research to figure what would be best for me and I decided the 4.10's would be better AND if you customize you exhaust you'll gain you mpg's back at higher rpm's.

I fabbed up a new exhaust by cutting my muffler out right after the "Y" comes together off the headers and welded in a turbo muffler and then a y pipe and dumped the tips out of the side before the rear tire. It sounded great and NO droning at all.

Having a short exhaust did cause me to lose some low end grunt however the 4.10's will make up for this and having great flow in the higher rpm's will keep your mpg's from dropping at all.

Now, I never got the 4.10's installed to test my theory however, driving form OH to GA constantly at 75mph netted me 22mpg's! I was gear seeking like a **** through the hills, but had I installed the 4.10's, I would've been set.

BTW - I was running stock tires and the only other mod was a K&N filter...

I hope this helps you make a decision. I vote for 4.10's BUT with a higher flowing exhaust.