Im looking to put bigger tires on my truck and increase its offroad capabilities. which is better with a 98 f150 4x4 4.6L engine with the stock 3.55 gearing and limited slip (regearing is not an option to expensive)33' tires or 35'. Also what other performance add ons can i get to improve performance?

 

Well unless you like rebuilding your trans and since you think regearing is too expensive then a $1500 trans rebuild is probably too much too. I ran my 97 F150 with basically the same setup you have with 35s and lost the trans in about a years time. The 4R70W just can't handle that much stress. 33s are about the max until you get into gears.

 

As previously stated, it's definately a good idea to stay with 33's until you can regear. You'll hate the way it runs anyway with big tires and tall gears. Even the 33's will bog it down some. A set of BFG m/t's in 33x12.5 weigh around 65 lbs each...

 

Would getting a power programmer help? If so do you recommend one? How about other things like a throttle body spacer or a better intake? If im only goin with 33' ill have more money to spend on other mods.

 

If you're sticking to stock gears and 33's...

Programmer/Tune, yes. Throttle body spacer, no. Air intake, yes.

Also, efans and exhaust.

 

Hey there, I am running 315/70/17 BFG's on my 02 f150 4.6l with the 4r70w trans. These tires are pritty well a 35 or 36 by 12.5 wide. I don't find much of a difference with power and gained in milage. I had to crank my TB to clear the tires in front( no rubbing at all), then she was sitting to high in the front so I put 2" block in the rear... I also have a sn/do flowmaster, two of the rear cats cut out, k&n air filter in stock box and a transflow shift kit in the trans. Shift kit is wicked highly reccommend.

 

A programmer won't help with 35s, but will actually make it worse as you're trying to cover up by throwing more power at it. This puts an insane load on the trans that the clutches and bands can't handle.


I can tell you that with my 97 with a 4.6L, 3" body lift, 3.55 gears, and 315/75/16 MTRs the truck had to downshift into D on almost any hill, and I had to lock it out of OD if there was any headwind. Keep in mind that this was in northern Iowa, so the hills aren't anything like you've got in VA. I wouldn't even think of driving that setup on the east coast.


Even if you go with 33s the shift kit/valve body is a must. A larger trans cooler should be added to. The 4R70W will live a long happy life at that point. I'd also suggest a trans temp gauge. Should anything go wrong it'll warn you.

 

powerstroke73: all of that for moving up to 33's? There not that much bigger

Tune wise what should i go with would A custom tuned Xcal2?

how about a new mas airflow sensor?

 

Yes, all of that should be required for 33s, but you CAN get away without it. The 4R70W is one weak SOB of a transmission, so anything beyond stock tires will make it hate life. Even when I had my 285s on the F150 the shifts were less than desireable. The extra trans cooler is something that every transmission can benefit from. It hard to get too much cooling, plus they're not all that expensive.

Now when you say "all that stuff" (its only 3 items) we're talking peanuts here compared to the alternative. A Factory Tech valve body is $200-$250 and is a 30min bolt in deal. A trans cooler is $40 from Summit, though if you wanted to go all out you could get a 6.0L trans cooler, but they're $200+. A trans temp gauge is only $40 from Summit again. If I'd had one on my 97 it would have saved me a $1400 rebuild. I would have seen that my trans was overheating from the headwind I was having to drive into. All I'd have had to do was pull over and let it cool and then continue on my way. Instead it overheated and burnt the clutches up.

You tell me, is $300 worth of parts worse than a $1400 rebuild? Thats why I dropped $2000 on my 4R100 in my 250. Its built for alot more than its ever going to see, but I never have to worry about destroying it. A rebuild for my truck is $4000+.

 

throttle body spacers are a waste of $$$ and energy, they make a great annoying whistling sound though.

a factory tech valve body, factory tech C-plate and a trans cooler are all great ideas expecially since you do not want to regear your truck.

a custom tuner like an Xcal2 or diablo (YES, there are others out there) would help with power and can be reprogrammable for future mods, tires, gears etc.