LC80 Open vs Lock rear diff differences (3 Viewers)

[zhonghuihe]

So...

Back story is that I am looking for a shop to install 3.55 gears in an LC80, gears are made by PDI from Australia, they have, along with at least one of the MUD member, successfully swapped in the 3.55 gear into the LC80 using a 100 series rear carrier and 80's side gear to compensate for the differences in spline count.

No one that I know of, has done this gear swap with a factory locked rear diff, even PDI themselves. Talking to ECGS, they said it is not possible with a factory-locked rear.

So my questions are:
1. What are the differences between a factory open and locked rear diff, aside from obviously one is locked and one is open.
2. Any one with knowledge on open and locked rear diff can comment on if this is feasible?

 

[SoTexCruiserDoc]

Why 3.55’s? Putting wheels from a golf cart on it?

 

[zhonghuihe]

Why 3.55’s? Putting wheels from a golf cart on it?
View attachment 3917560

Yup, that's exactly what I am gonna do.

Of course not, it is for diesel application

 

[lumbee1]

Yup, that's exactly what I am gonna do.

Of course not, it is for diesel application

What is the factory gearing for diesel? What size tires are you planning on installing? Bigger tires need a higher gear ratio. Obviously, if you've gone this far, you know what you are doing. These items were not covered in your original post.

 

[zhonghuihe]

What is the factory gearing for diesel? What size tires are you planning on installing? Bigger tires need a higher gear ratio. Obviously, if you've gone this far, you know what you are doing. These items were not covered in your original post.

410s and 35. 6bt cummins and they are not high reving diesel

 

[matzell]

410s and 35. 6bt cummins and they are not high reving diesel

I would think that would be spot on. I have a Duramax that Installed 4:10 gears in and with 35;s I am at 2k @70 mph. with 33's it bumps up to about 2250 rpms. How fast do you want to drive it? I have made several trips across country towing big trailers and it does fine. Most 12v's came with 3:55's factory and 31-32" tires.

Have you driven it yet?

 

[zhonghuihe]

I would think that would be spot on. I have a Duramax that Installed 4:10 gears in and with 35;s I am at 2k @70 mph. with 33's it bumps up to about 2250 rpms. How fast do you want to drive it? I have made several trips across country towing big trailers and it does fine. Most 12v's came with 3:55's factory and 31-32" tires.

Have you driven it yet?

My plan is to make it my commuter car. I put 5-600 miles of interstate driving per week, won't be going too too fast with a rig like that, but 70-80. I don't tow anything.

 

[matzell]

My plan is to make it my commuter car. I put 5-600 miles of interstate driving per week, won't be going too too fast with a rig like that, but 70-80. I don't tow anything.

I would drive it with 4:10's first. Guy in my club has a Toyota diesel HJ81 and runs 4:56 gears, 10% underdrive and 37's and loves it.