Ring & Pinion Ratios

[LRDONE]

Good Morning, So I've run into a little bit of an issue and would like to pick everyone's brain. I just bought a pop up camper and the thing weighs 1,500LBS dry. I pulled it home with the D1 and I could barely maintain 55mph with deceleration on small inclines and sky high down shifts. I've got 32s and stock R&P ratios. My thought was to 4.11 or 4.12s whatever is offered now in hopes that would help out a bit. My question is; Would 4.11 or 4.12 be enough to help with pulling also without compromising too much? And am I going to be breaking stock axles all the time.

 

[robertf]

have you thought about a transfercase regear? 1.4 is practically free these days, and low range would be the same so axle breakage wouldn't be any more of a concern

 

[LRDONE]

have you thought about a transfercase regear? 1.4 is practically free these days, and low range would be the same so axle breakage wouldn't be any more of a concern

I've never had the transfer case a part on this truck, It's a little bit foreign to me but not a bad route to go I suppose. So the 1.4 transfer case ratio is somewhat comparable to a 4.14 R&P Ratio? I'll have to get on Ashcrofts ratio calculator.

 

[Greg_M]

I'll have to get on Ashcrofts ratio calculator.

Here's a screenshot of a calculator I made for myself.

 

[LRDONE]

Here's a screenshot of a calculator I made for myself

Oh wow yeah. So with my tires, (235/85r16) stock 3.54 R&P and 1.410 transfer case ratio is identical to doing 4.12 R&P.

So how smooth sailing is the ratio change in the transfer case? Anything to watch out for? I suppose that gives me a chance to look at bearings and get everything sealed back up nicely.

 

[Greg_M]

So with my tires, (235/85r16) stock 3.54 R&P and 1.410 transfer case ratio is identical to doing 4.12 R&P.

But 4.12 RP lowers low range as well to compensate for your taller tires. 1.4 TC doesn't. Nothing's perfect.

 

[robertf]

I think PM has mentioned having done this swap. Ive been eyeing the ashcroft 1.31 custom gear set for mine because the transmission really needs a 4th and half gear for cruising at big altitude

 

[special ed]

I tow regularly with my D1 and my trailer is 5000lbs loaded. Also flatbed other rovers behind my car so you know how heavy that is. I am on 255/85/16s so basically a 33" tire. running 471s from GBR. My top speed towing is 65 for the most part but i can do it easily on the freeway and does not matter whats behind me. I dont need to go any faster anyways in my disco and i learned to just take it easy and enjoy the ride years ago when i got into land rovers. If you are towing light loads like that i would probably recommend something in the low 400s like 411 or 435 range. You loose top end speed but these are not race cars and the engines love to run right around 2800-3000 rpms where they develop the most power.

 

[terryjm1]

have you thought about a transfercase regear? 1.4 is practically free these days, and low range would be the same so axle breakage wouldn't be any more of a concern

I just purchased a 1.4 from a forum member. It was $250 and appears to be in good condition but shipping was $200. I am going with the 1.4 because my 300tdi is too wimpy for a 1.2.

 

[LRDONE]

I tow regularly with my D1 and my trailer is 5000lbs loaded. Also flatbed other rovers behind my car so you know how heavy that is. I am on 255/85/16s so basically a 33" tire. running 471s from GBR. My top speed towing is 65 for the most part but i can do it easily on the freeway and does not matter whats behind me. I dont need to go any faster anyways in my disco and i learned to just take it easy and enjoy the ride years ago when i got into land rovers. If you are towing light loads like that i would probably recommend something in the low 400s like 411 or 435 range. You loose top end speed but these are not race cars and the engines love to run right around 2800-3000 rpms where they develop the most power.

Awesome, this is what I needed to know. Yeah I don't care to go high speed at all. I just want to be able to get up to whatever speed and be able to stay there. I just thought something wasn't right pulling this baby pop up and my rover not wanting to do it at all. I was literally decelerating from 57-49 on slight inclines so then it would drop a gear, jump to 3100,3200rpm and hold there for about a minute getting back to 57, upshift and then start decelerating again. 65mpg, forget about that, I wasn't gonna get to that speed on a down hill air strip.

 

[LRDONE]

I just purchased a 1.4 from a forum member. It was $250 and appears to be in good condition but shipping was $200. I am going with the 1.4 because my 300tdi is too wimpy for a 1.2.

I was really tossed up between the two but, I think I'm going 4.12 R&P gears. I have an ashcroft ATB in the front right now and that was fun to set up, so my thought was to yank that out, change the R&P and upgrade the rear to an ATB diff at the same time.

 

[p m]

I think PM has mentioned having done this swap. Ive been eyeing the ashcroft 1.31 custom gear set for mine because the transmission really needs a 4th and half gear for cruising at big altitude

I've done this swap on a D1 and on a Classic.
Yes, it only helps with highway driving; a very slight benefit is that the t-case high/low ratios are closer, which allows an easy mixed gear driving off pavement.
Really, the R&P is the right way to regear the vehicle - my side concern was that I can have a factory R&P or the entire 3rd within a day anywhere in CONUS, while any aftermarket gears may be more of a wait.

 

[Gordo]

We love our 1.4 box with 33s. Works great. We did upgrade the old defender box with an oil slinger. At the time cross drilled 1.4 input gears we’re out of stock. Just something to consider if ur going that route as many of the old boxes do not have cross drilled gears. Easy fix for piece of mind