sefus

im new to gear changes and to 4x4 suspension stuff so im looking for a few answers: ive got 33inch tires and a high lift cam with the 5spd, if i step up to say 4.56's from my stock 4.10's whats it going to do to my cruising rpm, top speed, and mpg? and if i step down to a smaller cam? also if you change the rear gears, how does that effect the front when in 4wd, or do you have to change them both to match? thanks!

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wrenchmonster

4.56 will make you faster off the line, but limit your top end speed more. Your engine will work a little harder to cruise than it did before. Mpg will go down.

Your cams, well that's just a matter of preference, what you intend to use the vehicle for, etc. A more aggressive cam will tend to worsen your mpgs. However, if you're running 33s and 4.56s I'm guessing this isn't a daily driver? If so, and you want good mpgs, but a small car and save the yota for the trails.

YES, ABSOLUTELY YES, your gears in the front and rear diffs MUST MATCH. You will destroy stuff if they don't match. Have you set up gears before?

-Wrench

Ganoid

I would opt for 4.88's or even 5.29's. Your truck should get better milage and clutches should last longer. Im assuming your truck came with 28" tires stock it would be safe to say that 4.88's would have your truck performing like it had 28" tires on it again.

If your truck did come with the stock 235 or what ever it is tire then although your speedo is reading say 65 you are actually going about 76 miles per hour. You will notice more recorded miles per gallon as well since you are only recording about 85% of the actual miles you travel. In the older trucks the speedo is cable driven off the back of the T case so the speedo only counts rotations of the drive line and has no way to calibrate for tire size difference.

If your one of those 65-70 miles per hour guys on the freeway I would say go 5.29 and you will be very happy with the new found "get up and go" around town and not having to shift down to 3rd or 4th for every little hill any more.. If your one of those 85-90 miles per hour on the freeway guy then go 4.88's. Either way you will probably see more improvment from the gearing than any cam will ever show you.

if you want to play with gearing equivelants look here for some intresting calculators to play with..... http://www.nyjeepin.8k.com/calc.html


edit.... above poster is absolutly right in saying that you front and rear differential gears MUST match if you plan on using 4wd at all. If you use 4wd with say 4.88's in the back and 4.10's in the front you will probably only go about 6 ft before the front tnd of your truck tries to drag the rear end. Think of it as the ole 2 person horse costume in the school play, Both people must walk at the same speed and if one stops the other will either drag or push the slower one. In the 4wd world we call this drive train bind and it WILL break somthing in a very short time (say 50 feet?)

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uboatcmndr

Thanx. That's great analogy and something I've been wondering about for a while

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