I have a Jeep Rubicon with a 4:1 t case with 4.10 axle gears and IMO with 35s 4:1 is too low there are times I wish I had regular 2.72:1, so I guess I can say at times I feel like I had too much gear..
CK5
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Anybody ever feel they geared their diffs too low?
- Thread starter Ned Kelly
- Start date
Good point, I was only thinking about this with respect to driving on the street. I have a Doubler in my Blazer and there are times when I wish I had the versatility of more diverse low ranges. I dream of one day finding a Lowmax 205 (discontinued unicorn) to add to my Doubler, I think 3:1 would be perfect for southeast wheeling.
My old ‘75 K5 was a great case study on gearing and the interaction with tire size. Consider the wheezy 350/465 and 3.73 gearing the constant.
When I first got it there were 31” tire on it. It screamed on the highway at speed. 2600 rpm @ 65mph which really isn’t that far off. The truck had all kinds of get up and go from a stop and still cruising in high gear.
I swapped on a set of crappy 33” tires and changed nothing else. Rpm at 65 mph dropped to 2400. Power off the line started to suffer.
Then I put 35’s on it. Looked awesome. Dropped cruise rpm another 100. The truck was gutless down low. It was gutless at speed. It was bad enough I actually could use granny gear taking off if I needed more torque.
The kicker here is if I was to do another I’d gear deeper just in case. If it’s too much you can offset with a little bigger tire.
One factor to take into account is the engine. An old small block is going to need more help than a fuel injected big block. An LS engine will need to rev more to build torque so more gear would be needed.
When I first got it there were 31” tire on it. It screamed on the highway at speed. 2600 rpm @ 65mph which really isn’t that far off. The truck had all kinds of get up and go from a stop and still cruising in high gear.
I swapped on a set of crappy 33” tires and changed nothing else. Rpm at 65 mph dropped to 2400. Power off the line started to suffer.
Then I put 35’s on it. Looked awesome. Dropped cruise rpm another 100. The truck was gutless down low. It was gutless at speed. It was bad enough I actually could use granny gear taking off if I needed more torque.
The kicker here is if I was to do another I’d gear deeper just in case. If it’s too much you can offset with a little bigger tire.
One factor to take into account is the engine. An old small block is going to need more help than a fuel injected big block. An LS engine will need to rev more to build torque so more gear would be needed.
I probably shared this before but ORD has a really good write-up on the subject.
www.offroaddesign.com
"I got some new big tires, what gears should I put in my axle?"
Here’s a question we get all the time: “What axle gears should I use for my combination?” Obviously there are a lot of engine, transmission, tire size,...
www.offroaddesign.com
I've never felt like my axle gearing is too low however I want an OD transmission in both of the trucks.
I looked into that before because I do have a 42RLE, but then I started messing around with fullsize trucks and just use the Jeep as a driver now...although I would like to try the 10.88 low range
Same boat. Even went to 40s. The 400sb does ok and the 700r doesn’t hunt while on the freeway. Going deeper gear would be nice but the pinion gets small. Don’t really need to go 75mph anyway, lower would be better. Hoping to go 6L80 in the future, probably end up locking out 6th.
Gear calculator. Really handy to compare current and what you might want.
I have a set of 5:13 gears in my 14-bolt full floater. and the pinion is still pretty beefy in a 14-bolt. It may be smaller in a 10/12 bolt, or dana-44. I say "go for the gusto". Every time I don't...I end up doing the job twice.
Correct.
For a wheeler I like 4.56 to keep the pinion head a little larger than the lower ratios. And just hammer all the gear reduction in the trans and tcases.
For a tow rig, low axle gears with a high od.
For a tow rig, low axle gears with a high od.
