on my way to work this morning i was at a stop light and when the light went green i gave it some gas and a little more up until maybe 50 or 60 yards down the road then something went bang a loud bang and started to run funky so i gave it a little more gas and thats when i heard a clunking and a rough grinding sound and thats when i knew something went in the rear. so i had it towed to my job then to my home after a long day at work. i put up on jack stands popped the diff cover and saw metal pieces fall out. then when i took the cover off i saw a whole bunch of metal. i looked at the ring gear and it looked like almost half of the ring gear was on the bottom of the rear end. i can only imagine what the pinion must look like. i just had the 3.55 put in about 3 or 4 months ago. i was like wtf and started to laugh. i just couldn't believe it. i laid there under my truck for i don't know how long after i saw this just looking up at the gears. now i'm considering going to 3.73 or just keep it at go ol' 3.55. gas and mileage wasn't to bad with the 3.55. i was thinking how it would be with the 3.73 in there with a 302 and a aode trans. what do ya'll think. should i go to 3.73 or what. i had the gears checked before it was installed and it was good. don't know why it broke. tell me what ya'll is thinking. right now i just feel like i just don't want to f==k with it at all. i just feel sick to my stomach. i just felt like writing this tonight just to get it off my chest. thanks for listening to my broken heart. feels like i need to get the knife out of my back. anyways i need to get me some dinner and a shower. i need to check the lsd unit to see if there are any metal pieces in it before something else happens to it. talk to you guys later............rock on...............

 

No advice on the gears, as I dunno what tires you run or where you drive your truck most or how spirited you drive it, heck I dunno even what truck it is, but may I suggest that you stay away from the AODE if possible - AODs are nice and can be built strong, 4R70Ws are stronger from the factory but need a computer to shift them, but the AODE is not too great of a transmission.

 

well its a 94 f150 2wd with 275 60 15 tires on it. forgot to post i was getting sleepy. goodnight.

 

Ain't that already got the 4R70W trans in it? Just keep that and install a shift kit in it, if the 302 has the silly speed-density batch-fire setup convert it to SEFI with MAF and a matching HO cam, that will wake it up pretty good. Those tires are 28" in diameter which is not to large, 3.55s will be a decent match for an all-around daily driver but if it was mostly city-driven truck I personally would go with the 3.73 for better acceleration - the highway engine cruise speed will go up, but the HO 302 don't mind revving a bit higher so it will still do alright on fuel.

 

That sucks.

I would go with 3.73 too. The 302 needs 3.55 gears minimum even with stock tires if you ask me. Especially if it has OD.

Are you going to keep that size tire on it?

The gears shouldn't hurt fuel economy because the engine is not lugging. The 302 needs gears more than the 300 or 351, since it doesn't make as much low end power.

Have you considered upgrading the diff to a limited slip unit like a traction lock?

 

TexasGuy, his F150 is lighter than a fullsize passenger car, and those can fly on the freeway in OD rather nice with 27" tires and 3.08 gears - acceleration is not great, but good cruise speed is definitely there. Additionally if he does indeed have the 4R70W transmission, then he has lower 1st and 2nd gear than a 302-equipped passenger car, so his acceleration will be way better too. So I'd say if he does lots of freeway driving 3.55s would be a better match, but for mostly stop-and-go driving conditions go with the 3.73s.

Also if I read his last sentence in the first post correct, I think he already has the posi differential.

 

Since our trucks are not aerodynamic they need at least 3.55 gears even on the highway with a 302. The 300 and 351 don't nearly as much with stock sized tires.

If it is windy or there is a moderately steep hill it is hard for the truck to maintain speed unless the RPMs are up and your going 80. From 60-70 or so its lugging too much and looses speed or down shifts. Every truck I have driven with a 302 and OD is like this.

My truck has 302 4R70W and 3.55 and I want more gear for all around driving and on the highway. It was this way even with the stock 235 75 15 tires and the 255 70 15 tires. I have 31 10.50 now though. I had 31 10.50 before too, thats why I swapped from 3.08-3.55 initially. My truck had 3.08 to start with and when I got the truck 10 years ago it was really a lame gearing for the truck.

 

Sorry to hear about your gear problem. If they were professionally installed a few months ago, I think they must have not set them up properly. May be worth talking to them about it...

I have 3.73 gears in my truck without OD, My tires are 30" instead of your 28", but with OD, I think I'd go for 4.10 gears. If I did the math correctly, with 4.10 you'd still be pulling around 2250 rpm at 65 MPH and you'd have more pulling/hauling truck power.

 

Wouldn't have thought they are that bad aerodynamically, but I guess they are... All I've driven is 351s, 460s, and diesels, and neither of those needed more than 3.55s to maintain freeways speeds... I do agree that 3.08 is rather poor choice for a small-block truck tho, as them factory engines leave quite a lot to be desired in the power department (thank you EPA).

 

Aerodynamically speaking, These trucks are a nightmare. I own a 3.08 truck with a 351 and I still think the 3.08 is a lame gear. In my opinion 3.55 should be the minimum gear period. It's been said that the 3.08 gear can run the RPM's so low on the highway, that it actually hurts fuel economy by keeping the computer in open loop.

 

The 302 LOVES low gears. The 02 and 4.10 set were a match made in Heaven. Can't say I know anything about the fue milage, but power wise the lower the better with the 302.

 

When my truck had the 3.08 gear set I never had any complaints about power. Of course my truck ran a lot beter back then and I had 27'' tires.

3.55 and 3.73 should be the gear choices for the 300 (1/2 ton)

3.73 and 4.10 should be the gear choices for the 302. (1/2 ton)

There shouldn't be any of this 2.73, 3.08, and if you're LUCKY, 3.55 gear set crap options.

 

yeah, bill has it just about right. I would add that the 351 would be happy with the same gears as the 300.

 

im with andyman if those gears were professionally installed recently you should have a talk with them they should not fail

 

this is kinda off topic because his truck has electronic speedometer

but if it was an older one with cable driven speedometer from the transmission would u have to get a new sending unit or is there any other way to adjust it?