Frank&Beans - you seem to have a lot of info on gear swaps. I have 98/4.6/355gears & std 235/70/16 tires. I pull a 5000lb 5th wheel & of course in O/D it sucks - (wont stay in)

I'm getting ready to put LT255/70 BFG Long trail T/A's on, I may go to 265/75 - as long as I stay with the 8D rating for sidewall toughness.

Would you think 410 gears would give me enough revs to stay in O/D.

I usually haul on the I'states @ 100 KPH. presently it's too slow to keep in O/D, but I don't particularly like doing 3300, or 3400 rpm's out of O/D.

Other than that - I'm not interested in "jackrabbit" starts - Just want better preformance hauling the 5th.

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98 F150 S/C 4.6 2wd Vermillion/Silver,HD Tow Pkg, Boards, Vents, Lund Bug Chaser, DIY "breezer" Tailgate, 5th whl hitch, Tool box, 16" OEM Mag's,BEEP,BEEP roadrunner floor mats.
Mobil1 /Wix Oil filter/ K&N / air box mod.
In looks & go - Chevy - like a rock.

 

I just had my gears changed to 4.56 with 33" tires. In my opinion, for most people, this is too low. I do little to no highway driving and when I do I have a Jeep hooked to the back, and 35" tires may be in the future, so for me it works. During normal cruising the trans shifts into 3rd at 25mph and into OD at 32mph. This makes for high revs at 60mph, but it takes off like a..well...you know. According to all the calculations I did before the swap, 4.56's would put the RPMs at just the right spot, but it just seems like its geared too low. Sorry I don't have a tach or I'd give you more details.

 

Nice site. Thanks for the info. I am always calculating tire dia, diff ratio, rpm etc. This will help a lot when shopping for a SuperCrew with 16" vs 17" tires and 3.55LS.

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Mine: '97F150,XLT,SC,4x4 ORP,4.6L,3.55LS,auto,6 CD,Towing package,alarm,Rhino grill guard w/PICCA lights,dual exhaust.

Wife: '99Explorer Limited,pearl white/tan leather,4.0L,4:10LS,CD,sunroof,towing pkg.,alarm

 

Darren Dude

This is another great site: www.ring-pinion.com. Look for the calculator.

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98 4x4 Lariat SC 5.4L ORP, Tow Package, 3.55 LS in oxford white two tone. Only modifications, K&N Filtercharger and Stepshield door still protectors. Many more to come.

 

roadrunner,
My truck was shifting in and out of OD ALL THE TIME with my 265's and the 3.55 gears, funny thing is I wasn't pulling or hualing anything. ( I do have the 4.2 Liter ). Now my tranny shifts just fine w/ the 4.10's. The only time it shifts out of OD is when I encounter a rather large incline on the open road.

If you are buying the 255/70 tires (30.05" tall), you will need to theoretically install 3.68 gears. (New tire height/old tire height x current gear ratio = new gear ratio. ex.;(30.05"/28.95"x3.55 = 3.68.) This set-up would return you to a stock set-up, like you are running now.
The 265/75 tires like mine (31.65") you will need "theoretically" the 3.88 gears.(31.65"/28.95"x3.55 = 3.88) this, again is like running like your current set-up.

The only choices, (in your case) are the 3.73 or 4.10 gear sets.

Ok,
in my opinion "I" would install the 4.10's. This will give you the power you need to pull your rig and keep it in Over Drive without having the tranny shift in and out of OD (this constant shifting will shorten your tranny life, and your left leg ;-). The 3.73 gears would "theoretically" work for both tire sizes, but the 3.68 gears are SO close to the 3.73's that you wouldn't really feel or notice a power difference and the tranny will continue to shift in and out of OD. The 3.88's are a little better but you are pulling a lot of weight. The 4.10's will best fit this situation. For some more advice call some of these adds in the back of the 4x4 mags. and see what they say. I am not an expert here, but I do have some experience w/ my own F-150 and have driven others w/ gear swaps and bigger tires. Best of luck to you, I hope I have steered you in the right direction.
Oh yea if you do install new gears, then make darn sure you follow the proper break-in proceedure. This is VERY important!

Read this: http://www.ring-pinion.com/Gear%20Talk/NewGear.html

F&B's


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98 F-150 XLT, SC, SWB, 2WD, Pac. Grn., 4.2L auto, 4.10 gears w/ LS, Tow Pkg., BFG AT's 265/75/16, K&N air filter, Dynomax muffler, Superchip, Edelbrock shocks, Hellwig sway bar, 3" body lift, signal mirrors, ...tons of cosmetic products

 

F&B - Hey man, tnx for the info - it sounds like thats what I want, the 4.10's. - I read all the stuff re breakin, so no probs there.

I do have auto tranny & only 2w/d - so my left leg wont get too tired.

Once again - F150OnLine comes to the rescue.

Great stuff.

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98 F150 S/C 4.6 2wd Vermillion/Silver,HD Tow Pkg, Boards, Vents, Lund Bug Chaser, DIY "breezer" Tailgate, 5th whl hitch, Tool box, 16" OEM Mag's,BEEP,BEEP roadrunner floor mats.
Mobil1 /Wix Oil filter/ K&N / air box mod.
In looks & go - Chevy - like a rock.

 

roadrunner ,
I misread your sig. when you posted the other day, my bust!

Regards,

F&B's


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98 F-150 XLT, SC, SWB, 2WD, Pac. Grn., 4.2L auto, 4.10 gears w/ LS, Tow Pkg., BFG AT's 265/75/16, K&N air filter, Dynomax muffler, Superchip, Edelbrock shocks, Hellwig sway bar, 3" body lift, signal mirrors, ...tons of cosmetic products