I have stock gears in my truck with 35" tires. It has the mazda m5od, problem is 5th gear is useless, no power. i can barely stay at highway speeds in 4th gear. It has 3.55s, if i went to 4.56 would this fix my problem? Is this a simple thing to install, i have a ford 8.8 in rear and dana 44 up front. what if i eventually want to go to a bigger tire? then i would have to change the 4.56s to 5.13s or something? Is 35" tires basically the max for dana 44 without breaking anything? would 37" tires be ok with dana 44 and 4.56 gears? I would also like a locker in the back or a spool, spools are alot cheeper than a locker, im on a limited budget. The truck is used probably 50% offroad and 50% on road, usually just around town. Is a spool reasonable? i understand turning will be a bitch, but is that the most of my worries besides faster tire wear? I need both tires spinning in the rear, an open diff is really annoying when im trying to go through some crazy trails.

95 f150 4x4
m5od
4" suspen 3" body
302 efi
35 x 12.5 x 15 mtrs and bald 35 x 14.5 x 15 tsl,s

 

The Dana 44 tops out at 4.88, so that's as low as you can go without changing axles. Also, I'm not sure about the TTB, but regular D-44 axles have a carrier change at 3.73 and down and 4.09 and up, so you'll need to change the carrier. There is also a carrier change for the 8.8, but you can get extra thick gears to compensate.

That said, 4.56 is a fine gear for 35's, but will be a tad high for 37's and up. I run 35's with 4.88 in my "other" wheeler, and that'd just a little too low for street driving...2850 rpm at 80. It's a dedicated wheeler, though, so I don't care. If I was going to use it for a Daily Driver, I'd pick a different gear.

I've seen lots of guys run 37's on D-44's, but those are on lighter Jeeps. I think under a full-size Ford truck, the axle might not be up to the task of anything bigger than 35. Same for the 8.8 in the rear. You could probably get away with it for a while, but it would be a ticking bomb, IMO. For sure nothing bigger than 35 with a spool, but I'd strongly recommend spending the little bit of extra money and getting something like a Detroit locker if you're going to drive it any significant amount of time on the street. There I go again, preaching a locker over a spool...LOL Seriously, if it does half duty on the street, you'll be MUCH happier with a locker.

 

[QUOTE=peteyg]The Dana 44 tops out at 4.88, so that's as low as you can go without changing axles. Also, I'm not sure about the TTB, but regular D-44 axles have a carrier change at 3.73 and down and 4.09 and up, so you'll need to change the carrier. There is also a carrier change for the 8.8, but you can get extra thick gears to compensate.

actually you can get upto 5.14 for the reverse rotation D44, you can go lower for the standard rotation but since we are dealing with later fords that is not an option. The TTB D44 is the same as the solid axle as far as gears, and carrier setup so to go to 4.56 you will have to change the carrier, and remember when getting gears you have to have the reverse rotation, and 4.56 should get you back to real close to the factory ratio

 

You don't want to drive a spool on the street. Had one in my '66 Mustang for a while. (Unintentional result of showing off in front of a friends house of exploding the spider gears.) The whole car would literally hop when trying to go around a corner. If you're going to spend the cash on gears, do it right and get a locker of some kind.

 

Ok, this is a topic where if you hafta ask, you are better having a shop do the install. Setting up gears is not that difficult, but the process requires a few special tools and a LOT of patience and a good understanding of the correct contact pattern for the gears. A spool is reasonable for a 50/50 vehicle, but you are gonna wear out tires fast on the street.

 

Wait, monsterbaby, you said:

"The TTB D44 is the same as the solid axle as far as gears, and carrier setup so to go to 4.56 you will have to change the carrier"

WHAT? How much extra does it cost to replace the carrier? BY "carrier" you mean the pumpkin right? Or am I on a completely different subject.

 

no not the pumpkin I mean the ring gear carrier or the part that the spider gears or limited slip goes into they are different for the gears series 3 is for 3.73, and numerically lower gears (ie higher gear ratios), and series 4 is for 3.92, and numerically higher gears (lower gear ratio) so in order to get the 4.56 gears to work you need the carrier from a D44 that has 3.92-5.14 gears on it now, by the way you can use the carrier from any D44, brand doesn't matter ie dodge chebbie, IH Jeep etc, you just can't use the R&p from them.

 

Ahh, thanks for clearing it up.

 

pete- do you have overdrive? I was wondering.. When I go with 35s on my f250, I was thinking either 4.56 or 4.88

 

yeah, I have an AOD in my Bronco, and a 5-speed in my Jeep, which is the one geared to 4.88. I'm not sure of the gears in the bronco, because I just bought it and haven't had a chance to open it up and take a look. 4.56 is the correct ratio for 35's, 4.88 will give you just a little more oomph, but you'll lose top end...it just moves the torque curve down somewhat.

An example (I know, I know, it's my Jeep, but that's what I have to explain it): I have a 4.0 six, and I can smoke just about anything in town, through 3rd gear, at least. I cannot run happily above 80, though. It's a trade-off.

All this advice applies to gas engines, btw...diesels need higher gears to stay in the lower rpm torque curve for anyone.

 

4.88 is what you want limited slips or lockers are what you will need to put them in.

 

I figured you had overdrive... I guess I'll get 4.56 gears, and some 36" IROKS..

 

Rebuilding the rear 8.8 is relatively easy if you have all the tools and info. I just got done rebuilding mine two weeks ago myself, putting in 4.56 gears and an ARB. Here is some helpfull sites that helped me:
http://www.corral.net/tech/drivetrain/gears.html
http://www.shizzot.com/rear.htm
http://www.auburn.edu/~brewibm/Ford88.html
http://members.***.net/rough-riders/...8/ford8_8.html

And finally an extreme reworking of the 8.8 rear: http://members.***.net/rough-riders/...8/ford8_8.html And since I have a spare 8.8 sitting in my back yard I may do something like that.

BTW: I would highly recomand an ARB, or some other type of locker. At least one locker in the rear. Having the ARB though you will end up having an air compresor to also fill up your tires when your done wheeling. Also, don't forget to change the gears in the front to match the rear. An ARB or other Selectable locker up front would be ideal, but a limited slip would sufice. The 4.56 gears would be okay for the 35's. If you do go with bigger tires, go with at least 4.88 gears.

 

There are 5.13 gears from Yukon for the 8.8 and D44, but I've seen guys have problems with the 8.8 by breaking teeth repeatedly. 4.56 or 4.88 would be a good choice but I strongly recommend that you get a reinforced diff cover for that 8.8 that has bearing supports as will as increase gear oil capacity. If you go with an agressive locker, I would go with the 4.56.

 

The lower the ratio you go, the weaker the gears become.