Gear Question

[bigd65]

Okgetting the suspension straightened out on my truck. I believe it has 4.56 gears. I am thinking about some 3.73 gears for more drivability. It has 35 in tall tires right now. What do yall think

[bigd65]

WOW, Nobody !!!!!

[Stocker]

It would be helpful to know something about your engine... transmission... how you use your truck... and it would be nice to know for sure if you have 4.56 gears now.

[bigd65]

Well that makes sense doesnt it SORRY. I really just wanted an opinion of the difference in the gears.

I have an 82 K20 4x4. It was a diesel but converted to gas, now has a 80 model 350, it must be a commercial engine because the numbers say its a 1980 350 4 bolt main, how ever the mount for the mechanical fuel pump is there on the block buts its not plumbed. so I have an electric fuel pump. The heads are newer heads because it has the center bolt valve covers, what heads there are I dont know. Tranny is a Th400.

Im not going to do a awhole lot of mudding, towing, etc... but it will be driven. I want this thing to be more drivable. I will be inclined to play in the mud if an opprotunity arises but nothing hard core.

[Critter]

My opinion is 3.73s for the street with the setup you have, but 4.10s is probably what most will say.

I use this a lot...

http://www.grimmjeeper.com/gears.html

Remember to be realistic/accurate with your tire size. The absolute best way to do it is to go out and actually measure from the ground to the CENTER OF YOUR WHEEL HUB, then multiply that times 2 to get an effective "tire height" for the calculator to work with. More often than not, a tire that has "35 inch" stamped on the side will come out to 33.5 inches when done the way I just mentioned. That can effect your RPM more than you would would think.

[packratcffc]

Iam running 4.10 with 33x12.5 on my 88 sub.I had 3.73 and the were ok around town.I have a700r4 so every small hill I would hit the truck would have to down shift.

If your running 35s I would not go taller than 4.10s

The 4.10s on my truck also have my speedo set back to the right speed.

[Stocker]

With your basically stock 350 engine and non-overdrive trans, I would think you'd be happier with 4.10 gears (instead of 3.73s). The truck would feel more lively, but not as frantic at highway speeds as your 4.56s. Speaking of which, what kind of highway speeds are you typically running? If you are over 70 very often, 3.73s might be a better choice.

That link posted by Critter is great -- easy to use and incredibly helpful. Play around with it a little and see what RPMs you'd be running in top gear. That might make your decision a little easier.

Oh, as to actual tire height... http://www.tirerack.com/ has specs on everything they sell, and you can also get specs at most manufacturers' web sites. They are typically a bit shorter than the size on the sidewall.