i have 3.55 limited slip,5.4 4x2 screw with 33x12.5's.i have no motor mods at all.my truck is a slug and im looking to pep it up.my normal driving is about 75 everywhere i go.i plan on doing exhaust,intake and a programmer down the road.what gears would be recommended.my biggest disapointment is the low end not being fast enough,and i rarely go faster than 100.

 

4.56's atleast

 

4.56's seem kind of high don't you think? For 33" I suppose if you wanted lots of power I would have thought maybe 3.77 (I think those are the right ratio) or maybe 4.10's.....Then again I don't know much about gears..I could be wrong most likely am....correct if I am wrong.

 

4.56 is just about right for 33's

 

so what if i was gonna jack my truck up with a 6" suspension and 3" body and slap some 37"'s on? What kind of gear ratio would I need?

 

Just assuming two things. One, the original tires were the 30.0 inch tires that came stock on many of these trucks. Two, the tires you have are EXACTLY 33 inches in diameter. To put it to exactly the same gears you had when you bought the truck would take 3.90 gears. They don't offer them for your rear, so let’s move on...
If you matched the gearing exactly, it would still be a little more sluggish than when you bought it. The new tires are very much heavier. Thus harder to start rolling. The extra width exaggerates that. So if you went to 4.10 gears, you would have a very tiny increase in stock performance. You would be about the same RPMs as if you had not changed the tires, but had ordered the 3.73 gears.

So 4.10 gears put you in the normal range. Power, acceleration, RPMs at cruise would all be about where a stock truck with 30 inch tires and 3.73 gearing is. The exception is that your speedometer would read 5% higher than actual, assuming it was perfect to begin with. Right now it should be reading 10% lower.

Now if you drop the gearing even farther to 4.30 range it would throw your speedometer off exactly the same distance it is off now, but the other direction...
You would have very good acceleration and just a little bit worse gas mileage on the open road. Theoretically it would be 10% worse at a steady 65 mph, as your engine would be turning 10% higher than stock configuration.

If you go to the 4.56 the truck will be low geared. Your speedometer even with the 33 inch tires will read 17% higher. Your gas mileage will be 17% lower at 65.

Around town mileage should be a wash or get better with 4.10 or 4.30 gears. A little worse with 4.56.
If you want quick or tow, the 4.30 range may make you happy. If you want to highway, anything steeper than 4.10 is probably counter-indicated.
Chris

 

4.56.. Nuff said.

 

4.30s or 4.56s.

 

If I were on 37's I'd get 4.88's or 5.13's tops.

 

is there a good name brand gear to get,is there a place on line that sells them?my dad is a mechanic and ive seen him swap a few sets so i might get him to help me out with them.i need a good set and a cheap place to get them.

im going to go for the 4.56's
thank you to everyone .

 

randys ring and pinion.com or summitt racing or jegs .com all would have what you need.

Dale

 

I like to put this in all the "gear" threads so maybe some people will catch on....

I am runing 29" tires with 4.11's. Still make over 20mpg daily.

DON'T FEAR THE GEAR!

 

So with my lift and 35s. If I went from the stock 3.73s to 4.56 would I lose more mpg for the performance gains? Or would my mileage go up? the same?

 

It would go up

 

So if I read this correctly, if I go from my current 3.73 gear to a "technically" lower gear like 4.11 or more, I would get better gas mileage? That seems a little backwards to me, but I am probably not understanding the statement correctly. I remember back in the 80's we built street drag cars and a 4.11 was a lot lower gear than let's say a 2.72. (Camaro's) Even with the 3.73 gear in my truck it is still a slug and gets the sh@ttiest gas mileage at only 13.5 - 14 mpg. I was thinking of going to a higher gear to try and get better gas mileage but I am not sure it would be worth the money or not.

Please let me know where I am misunderstanding things here please.

Stephen