4:1 gears in a 34mm split case (1 Viewer)

MoaByte

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Ok so 10% reduction in high
And 56% reduction in low?
That's perfect.
What am I missing?
 

NookShneer

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Ok so 10% reduction in high
And 56% reduction in low?
That's perfect.
What am I missing?

that’s it. Add gear wine concerns and re-build/modification costs.

I put 3:1 gears into a 38mm case with a h55. 1st gear stock falls between 2nd and 3rd.

having the extra low gearing helps on steep ups and downs. Loose and muddy isn’t as much help but going down Black Bear Pass with lower gearing makes it easy and not very challenging.
 
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Said screw it and decided to pull the transmission. Will make it easier to rebuild on a bench and I can further fix some oil leaks...

959F1D09-CDB0-462E-B794-D2EA6BB5559D.jpeg
 

MoaByte

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I h8 mud.... Lol. Well Ih8 is a strong word. The places I normally go are out west, sand, rock with mountains that are rocky. First low with the 4-speed and 3.70's is too fast to safely get up some obstacles. I've nearly bounced off the edge. I'm saving for the H55 anyway, but this seems to be a better choice for me then swapping out the 3rd members.
 

HemiAlex

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I h8 mud.... Lol. Well Ih8 is a strong word. The places I normally go are out west, sand, rock with mountains that are rocky. First low with the 4-speed and 3.70's is too fast to safely get up some obstacles. I've nearly bounced off the edge. I'm saving for the H55 anyway, but this seems to be a better choice for me then swapping out the 3rd members.

The h55f makes it better, but even 1st, 4lo with my 2.28 t case is still too fast.
 
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This gearing change has been on my radar for some time. I'm running heavy E rated 35's with 4.88's and my engine is begging me for 10% gear reduction in Hi.

I ran 37s and 4.11s for years. Drove ok on the street, high way RPMs were great. Then when I was building my axles moved to 4.88s as well. Drove much better around town. We’ll see how it does on the highway, a little nervous that I won’t be able to go over 65. Which I suppose is just fine 😂
 
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I can hit 80 mph on the flats easy. Up large grades and I'm down around 45-55 mph in the slow lane. My problem is wheeling in hard rocks and the obstacle gets vertical. My low gears aren't low enough to push me up.
 

MoaByte

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4.11's with 33" tires is very close to 3.70's with 235/70's or 4.56 with 35's. The 10% reduction only applies to high range. It make 3.70 into 4.10s, 4.10's into 4.56's, 4.56's into 5.0's. The Sumo gears are $1000.
 
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Please record any little detail you can about the clearance needed. I would be eternally grateful!

To be honest I didn’t take any preliminary measurements of the case. I just jumped right in. I still have a fair amount of sanding and clearancing to do. I’d be happy to take some post measurements for you. You’ll have to keep in mind there are differences in the 34mm cases along all production years so it may not be applicable to your application.
 

MoaByte

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I built a spreadsheet to compare. Totally geeked out for hours. Something I haven't looked at is the easy crawling. Normally on a trail I'm leisurely in 2nd low. First is for the rougher or steeper areas. I rarely use 3rd, usually just shift out of low range. With a 4.1 ratio, 3rd will be like 1st was (I think). I'll have a look tomorrow. Does this mean 4th gear will be the new easy crawl? I'll check it out and post up a comparison.
 

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