DII 4:11 gearing

[romigenv]

Would like to hear from those of you who have changed the gearing in your diffs to 4:11 or something else (GBR, etc.). What difference has this made?

I've got a 2001 DII with 2" OME lift and 265 coopers. I tow a military cargo trailer from time to time and it struggles when loaded. I also would like a little more oomph going up the hills and pulling the trailer. What effect will the gears have? I off road every chance I get, but it amounts to every now and then. So not a huge concern.

Any info and advice is greatly appreciated.

Jake

 

[JSQ]

you'll like it.

 

[sean]

go with 3.9's unless you want to go to larger tires and lift or if you really like driving under 70.

 

[JSQ]

go with 3.9's unless you want to go to larger tires and lift or if you really like driving under 70.

the truck is geared too tall from the factory.

why not improve it?

how fast do you need to go in a disco?

a truck with 4.11s and and 32" tires will still do 75mph at a reasonable rpm.

 

[noee]

4.11 might be too much for 32" tires. On the D2, 33" tires with the 4.11 gearing is just about right.

 

[sean]

yes 32's would be better, but 265's are 31's. they will be almost 3000 rpm's at 70. just make sure you have a well balanced driveshafts. or 70mph will give alot of vibrations.
I bought my set off of a guy who couldn't get a drive shaft that would balance out obove 70.
I'M on my 3rd rear driveshhaft I finally found one that was perfect, and would push 90 on passing, but with a lot of vibration.
With 33's it's great, vibe free faster than i want to drive.

 

[NW DISCO]

Heck, I am running 4.11's on my 04 D2 with stock tires and love it (rarely drive over 60 though). Need lift and 32's so my highway milage does not suffer so much.

 

[sean]

oh don't get me wrong, they are fun around town. just not good for highway use.
it was great having that much power, it made my 4.6 RR feel like a snail in comparision.
I have thought many times about how much fun 4.11's and stock tires would be, but then i wouldn't be able to drive it to work without taking backroads.
Now with the 33's it is still lower gearing than stock and the shifting feels smoother and less clunky than the 265's.
befor the 4.11's i ran sport mode all the time with 265's ,now even with 33's i find no need for sport mode.

 

[Steve Rupp]

I agree that 4.11's are too much if you're running 265's. I ran that combo on my DI the last trip out to Moab and I didn't care for it at all. When I put my 255's on it's so much better and with the 35's the speedo is right on.

 

[Barry]

Would like to hear from those of you who have changed the gearing in your diffs to 4:11 or something else (GBR, etc.). What difference has this made?

I've got a 2001 DII with 2" OME lift and 265 coopers. I tow a military cargo trailer from time to time and it struggles when loaded. I also would like a little more oomph going up the hills and pulling the trailer. What effect will the gears have? I off road every chance I get, but it amounts to every now and then. So not a huge concern.

Any info and advice is greatly appreciated.

Jake

2000D2 here. I have 265/75 AT's and run the GBR 4:11 with GBR HD rear driveshaft. The engine turns a really noisy 3000rpm at 70mph. Keeping up with traffic at 75mph sounds extremely punishing to the 4.0 Buick. The HD driveline vibrations are absolutely obnoxious. I have unfortunately removed any trace of civility from the factory set-up... which worked quite well for expedition travel AND off-road. On the other hand, the improvement in off-road crawl for traction and descending steep rocky trails is phenomenal.

Practically speaking, if you don't run technical trails very often, you would accomplish the majority of your needs (For less money) by simply downsizing to a 30" or 31" tire.

-Barry

 

[kennith]

I know it sounds bad, and kills milage, but these motors don't mind being revved at all, so long as you keep them up properly throughout their life.

Some people have had these things (not the same valvetrain and cam, mind you) to 8000 RPMs. The powerband on these motors the way we have them caps off at around 4500 RPMs. If I am not mistaken, the real "mechanical" redline for the current Rover V8 is around 6K.

I can see the irritation in running at 3000 revs for a few hours, nevertheless, that swap is on my list of things to do. It's the easiest grunt available right now. In the future, I will be increasing my tire size, though, as now I am running the 265s. I almost bought the 33s this time around, but I thought I'd wait until I got the driveline properly sorted out and another inch of bounce in there.

I did throw them up there, though, and they did fit. The rubbed the radius arms a little more, but they fit without any other issues.

Cheers,

Kennith

 

[noee]

yes 32's would be better, but 265's are 31's.

Tire Size Calc

In case there's any confusion, scroll to the bottom, I think you'll find that 265/75s are generally accepted to be 32" tires (measuring over 31.5 typically depending on mfg). 255/85 and 285/75s are generally accepted to be 33s.

 

[JSQ]

I know it sounds bad, and kills milage, but these motors don't mind being revved at all, so long as you keep them up properly throughout their life.

Some people have had these things (not the same valvetrain and cam, mind you) to 8000 RPMs. The powerband on these motors the way we have them caps off at around 4500 RPMs. If I am not mistaken, the real "mechanical" redline for the current Rover V8 is around 6K.

I can see the irritation in running at 3000 revs for a few hours, nevertheless, that swap is on my list of things to do. It's the easiest grunt available right now. In the future, I will be increasing my tire size, though, as now I am running the 265s. I almost bought the 33s this time around, but I thought I'd wait until I got the driveline properly sorted out and another inch of bounce in there.

I did throw them up there, though, and they did fit. The rubbed the radius arms a little more, but they fit without any other issues.

Cheers,

Kennith

I agree completely.

there is absolutely nothing wrong with a rover v8 running at 3k.
it will happily do it all day long and the ratio of fuel consumption to power output is optimal in a motor that's efficiency is marginal at best.

 

[romigenv]

Thanks for all the replys. Good info and I appreciate it. Someone mentioned 3.9 gears. Any experience with this? Sounds like a better solution. I have to drive long distances quite a bit. Often enough for the 70 mph magical speed to be a potential issue. Not that I drive 90 though.

Thoughts/experience with 3.9s?

 

[JSQ]

another advantage to 32s and 4.11s is that your offroad gearing is that much lower and there's no arguing against that.

suddenly hi-range becomes useable again in the dirt and low is nice and low.


do a bit of searching.
greg hirst and i had long discussions about 3.91, but ultimately neither of us went that route.

 

[romigenv]

another advantage to 32s and 4.11s is that your offroad gearing is that much lower and there's no arguing against that.

suddenly hi-range becomes useable again in the dirt and low is nice and low.


do a bit of searching.
greg hirst and i had long discussions about 3.91, but ultimately neither of us went that route.

Did a bit of searching, but didn't get to a discussion on the 3.9 gears. Sounds like a compromise of sorts. Any experience out there with 3.9 gears in a DII?

 

[Gonzo]

I was talking to Eddie from WCR while picking up my Dicso from repairs , and I asked about regearing my Diff's to 4.11 cause I want to move to 265/75 tires he said that it would be cheaper to get a new transfer case with 3.9(I think that gearing is right I forgot) gearing and that would bring to gearing back to sock with the bigger tires. He said he was going to try this on a project turck of his , has anyone here done this? and is it better then regearing the Diff's? Or did I misunderstand what he said.

 

[JSQ]

I was talking to Eddie from WCR while picking up my Dicso from repairs , and I asked about regearing my Diff's to 4.11 cause I want to move to 265/75 tires he said that it would be cheaper to get a new transfer case with 3.9(I think that gearing is right I forgot) gearing and that would bring to gearing back to sock with the bigger tires. He said he was going to try this on a project turck of his , has anyone here done this? and is it better then regearing the Diff's? Or did I misunderstand what he said.

odds are it would NOT be cheaper,
but more importantly,
a 1.4 or 1.6 tcase would only change your high range leaving your low range too tall.

 

[marc olivares]

odds are it would NOT be cheaper,
but more importantly,
a 1.4 or 1.6 tcase would only change your high range leaving your low range too tall.

it won't be any cheaper!

and Jacks right, low range would suffer unless you installed a maixidrive lowrange kit while the transfer case was out....then your cheaper option just went to about $2200 without labor.

 

[JSQ]

I like how in your post it seems Eddie Bostock is recommending you do something he's only thought about "trying" on a "project truck".

sweet advice.