I bet the 95SR rear 9.25in rear diff with 1.4in 31 spline shafts will stand up to 38s fairly well.

I am running 36s with a 2.4 4banger with 5.29 axle gears, it's not too bad on road.

No you can't. The RATIO is gonna be the same. But you're going to have a slower vehicle.

It's prob going to be fine, and you'll be able to do the same stuff you did before, BUT don't think for a second that everything is a wash, and it is going to be the same.

You can reduce the ratio all you want, but there is alot more to the whole system that you are missing. It's not as simple as JUST reducing the gear ratio.

You're not going to have the same acceleration, or decel as before, and you are effectivly going to lose power overall.

If the effective ratio is the same, what else is there to overcome?

1) The additional inertia of the heavier tires/wheels

2) Maybe a very small different coefficient of friction -- tire to road friction is small, because it's roughly the same weight vehicle on a bigger tire contact patch (less friction over a bigger area), plus probably a little more internal friction in a bigger piece of rubber, but that can't amount to much.

What am I missing?

Does'nt "Partytruck" run 38s on his GenI? His is a oil-burner, but he did a three inch BL and got them under there.

Link to post with pics

Possible, but not practical.

38s on IFS?? <img src="/forums/images/graemlins/smile.gif" alt="" />

Look guys, more horsepower would be great, but I just don't feel like going through all the time and money to transplant a new engine when the one I have is enough for me, especially since I am going to have an overall crawl ratio of 15.4!!! Can you say 200 hp stump puller????!!!!! <img src="/forums/images/graemlins/smile.gif" alt="" /> <img src="/forums/images/graemlins/notooth.gif" alt="" />

for those that are wondering how i got 15.4:

4.9(diff)X3.15(tcase)=15.4

When I had the stock Mitsubishi axles I was running 33" tires and snapping the axles like toothpicks, especially the front.

...uhhhh, usually you would express the final crawl ratio as:
1st gear ratio x tcase low x diff ratio...

(Not trying to sound toooo nit-picky here.)

With a M/T, 50:1 is good, and >100:1 is fantastic, with an A/T 35:1 is good, an >80:1 is fantastic.


So the basic Gen1 A/T = 2.826 x 1.944 x 4.625 = 25.4:1, which is nothing too special.
Hence the usefullness of the 3.15 tcase gears = 2.826 x 3.15 x 4.625 = 41.2:1

On the 4.3 swap with GM A/T and tcase and Mitsu diffs = 3.060 x 2.72 x 4.625 = 38.5:1
The GM tcase can get a 4.0:1 swapped in from TerraLow, and then give me 3.060 x 4.0 x 4.625 = 56.6:1, which starts to get pretty serious crawl.

Adding a 2nd tcase/or crawl box or KluneV underdrive (if you got room) would multiply everything up by those extra gears, which are usually 2.7:1 or 4.0:1, which gets you into the truly excellent crawl ratios!
So my "dream" system would be a 2.7:1 KluneV added to my existing 2.72:1 GM tcase which would give 3.060 x 2.72 x 2.7 x 4.652 = 103.9:1, which would give me a truly excellent final crawl ratio...
But I doubt I'd ever need it.

But fun to do the math, though!
Oddly enough, I've yet to see anyone correct for tire size, though. And that also comes into play here...

Then, to complete the picture, you'd have to consider engine rpm - but what you'd ultimately want to know is how fast (or in this case, how slow) you can go. So - to be on a level playing field, all measured contestants (it is a contest, right?) would have to peg the rpms at the same level - say 650 rpms (to be fair to the A/Ts). Then, of course, the M/T folks would try to slip the clutch... the A/T guys would apply the brakes.... and all would be instantly criticized by the others as cheaters. <img src="/forums/images/graemlins/wink.gif" alt="" />

A low crawl ratio is nice - but in the end, it all boils down to whether or not you can get where you want to go..... or not..... and maybe how you look in the doings.

Frank <img src="/forums/images/graemlins/cheers.gif" alt="" />

My 2.6 will turn those tires no problem, down hill both ways in 4 Low, reverse <img src="/forums/images/graemlins/smile.gif" alt="" />

Sawzall offer still stands...you will love it Dewalt 18v <img src="/forums/images/graemlins/wink.gif" alt="" />