F-350 gears

[Gladiator9152]

well im pretty positive im going with 37s. and i wanted to get 38s but i got a 8 inch lift so i dont think they fit. and i would like to do it myself but i dont wanna mess something up. maybe ill just get the rear one done first since i dont use 4x4 that much.

[Gladiator9152]

then ive looked at some online and i wonder what does the number mean. like an 8.8". not sure what that is and which i need

[hotrodpc]

Originally Posted by eponator

You most likely have the factory 3.73 in there right now but they also came with the 4.10 or even the 4.30 if your lucky. The tag on the axle or the door jamb will tell you what you got. If you have anything but the 4.30 I'd recommend a 4.56 gearset with the 37's otherwise I'd just stick with the 4.30, it wouldn't be worth the cost of the swap.

36's will just run your RPM's a little higher than with 37's and 4.56 but only by a small amount. You will feel it in the seat of your pants guaranteed especially if you have the 3.73 now.

I agree. From 4.30 to 4.56, not a big bang for the buck. 3.73 in it now, sure, go 4.56's.

[hotrodpc]

Originally Posted by Gladiator9152

then ive looked at some online and i wonder what does the number mean. like an 8.8". not sure what that is and which i need

Geez, Brad is gonna kill me, here I go, post after post again. I'd imagine the 8.8 is the size of your ring gear which is a hair over 8 3/4 inch.

[bradrhale]

just an idea to throw out there and being the style out rigth now, what about dropping the 38s idea and moving to a nice set of alcoa rims and 22.5 truck rubber?? lonesome7.3 has them on his 350 and they look pretty good. it would take some modifications since you couldnt use your hub assemblies but the way i hear it, it is quite easy to fit the 10 lug hubs on your setup. not a muddin truck by any means but would look tough, nonetheless.

[Lonesome7.3]

I do like mine, but they are even heavier than the 38's he wants to run. So make sure you know what you want your truck to be used for.

[eponator]

With an 8" kit on your truck if you plan on wheelin it then I wouldn't go above a 37"tire on a 10" wide rim, unless you want to do some fender trimming. Anything larger than this and you will end up rubbing at the bottom corners of your bumper, the inner wheel well, and possibly on the fenders themselves during any mild articulation.

If its just a street queen I'm fairly positive you can fit a 38 without any rubs as long as you don't try to jump a curb at full steering lock. Some slight bumper trimming maybe required so please confirm this first.

The alcoa rim and 22.5 rubber looks nice on some trucks (moreso on dualies IMHO) but I hear the truck rides just like a cement truck after the swap. Also those tires would probably wear out suspension components faster than regular tires given the difference in weight. Hopefully Lonesome can give us some of his first hand experiences with them?

Oh and Brad you are correct, the 1 ton axles can definitely stand up to this size tire but my main concern with having him regear is to alleviate the additional stresses put on the naturally weak 4r100. That trans won't last long in stock form without a regear especially if you wheel that rig. I also suggest a tuner with custom tune to help adjust shift points to compensate for the tires and give you some more ponies to spin them with.

[Gladiator9152]

ya thats what they told me about the 38s. thats why my plan is to get 37s. cuz ive gone offroading a few times and dont do it a lot but once in a while i get the urge! ya those alcoas look real nice but i agree they porbly are meant more for a dually. mine aint a dually. thanks for the suggestion tho. and i think goin from 3.73 to 4.56 will help a lot.
i also am thinking of getting a mag-hytec diff cover while im at it down there.

so i also want to know what size i need for the ring.

and if iwere to do it myself. where would i find out how to do it?

[kyleswitch122]

Originally Posted by eponator

You most likely have the factory 3.73 in there right now but they also came with the 4.10 or even the 4.30 if your lucky. The tag on the axle or the door jamb will tell you what you got. If you have anything but the 4.30 I'd recommend a 4.56 gearset with the 37's otherwise I'd just stick with the 4.30, it wouldn't be worth the cost of the swap.

36's will just run your RPM's a little higher than with 37's and 4.56 but only by a small amount. You will feel it in the seat of your pants guaranteed especially if you have the 3.73 now.

Im running the 4.56's in my truck. Its not as big as yours will be but they will work with it even better. I get great top speed still, for a truck, and acceleration is good off the line. My trans temps run cool so there is no strain on them. 4.56's would be great for you.

My dad is running 4.10's on his 7.3L excursion on 38" Pro Comps. We have both gotten 50k miles on those tires, no problem, through mud snow and everyday concrete.

Hope that helps

[eponator]

Originally Posted by Gladiator9152

i also am thinking of getting a mag-hytec diff cover while im at it down there.

so i also want to know what size i need for the ring.

and if iwere to do it myself. where would i find out how to do it?

Mag hytec is a great addition given the dip stick for easy oil levels, larger oil capacity, fins for increased cooling, a real gasket, and its tapped for a temp probe too! A bit too pricey for me but if you can afford one congratulations, you've made me envious! May I also suggest an aluminum diff cover from the 08+ superduties? They will fit your truck, lighter weight, same capacity, fins for added cooling, aluminum finish that will never rust and always shine All at the cost of about $40-60, I don't remember exactly.

All Superduty's since 99 (yes that's ALL of them) have the Sterling 10.5 rear axle making your Ring gear 10.5

Honestly, I've learned most of what I know from the net, just make sure its a reliable source and cross reference! My hands on experience is gained from workin on my own rigs, family / friends, and random people I meet. I should say though that despite my own heavy studying on the subject I have yet to take the plunge of a pair of gears ($300 per axle approximately) because I've always heard it comes HIGHLY recommended to attempt this job for the first time ONLY with an experienced hand on deck. There's my little disclaimer on that subject, so don't say I didn't warn ya heh! In case you're wondering, I've yet to find a knowledgeable and kind enough soul near to me that I would feel comfortable asking such a thing of them, yet! Something to think about...

If you decide to tackle this job solo, your a bigger man than me! Get the right tools, special ones are required, study up on it and memorize the details, take your time and don't rush anything, it will eventually get together!

Hope I've answered all your quetions man, and forgive me if I've made a mystake, I spent all day installing my 6" lift (WOOOHOOOO FINALLY) and I'm BEAT! MAN the early 99's have all kinds of little differences you don't find out about untill you bump into them midway through a job!