Gearing Issues

[Rivilou]

I have undertaken the challage of making a Discovery 1 be as capably off road as a 90. My issue at this time is with the gearing. I have heard mention that if you fit 33" to 35" tyres the gearing must be changed because it causes all manner of problems, does anyone know what the required gearing changes are and what parts are needed?

[Disco Mike]

Yes you will be needing gears, I am assuming you will use 4:11's ans well as some H.D. rear axles and some ones lockers.
I would suggest you contact Bill @ http://www.greatbasinrovers.com/
They can supply all the parts you need. Now all you need to do is decide how capable.
Good luck
Mike

[Geobloke]

Originally Posted by Rivilou

I have undertaken the challage of making a Discovery 1 be as capably off road as a 90. My issue at this time is with the gearing. I have heard mention that if you fit 33" to 35" tyres the gearing must be changed because it causes all manner of problems, does anyone know what the required gearing changes are and what parts are needed?

Hey you made it! Welcome to the forum mate!

[Monty]

Nice avatar! Welcome to lro. If you end up with 35's on your disco, I'd think about lower gearing like 4.70's, definately new axles and cv's. Keep us posted if you go through with it.

[apbtpetey]

Why would you have go with something like the 4.70's instead of the 4.11's???

4.70 is kind of a steep jump isn't it

[Funrover]

Welcome first off!! I would say 4:11 would do what you are looking for!!!!

[Rivilou]

Thanks for the replies they've all be helpful, and hi to everyone so I need to change the gearing in the transfer box, if I changed the gearing then fitted Dana 60's front and back would the gearing need to be changed again? I've read Dana 60's are quite tough, or could I just go for the uprated Maxi drive half shafts and lockers, with the uprated cv's? Does anyone know, I've fitted an OME 2" lift and will be fitting a 2" body lift with spacers on the axles and I've widened the outside wheel arches, will this give me enough clearance for the 35" tires?

[Disco Mike]

Sounds like you are talking about 2 differents gearing options, the t/case and the diff's.
I wouldn' suggest going to Danas, Rovers are strong enough, just need to us HD axles and some lockers. If you gear the t/case while running 35"s you will have a nice crawler but terrible on the road, no power and terrible gas mileage.
Most people run diff gears especially if this is also a main driver.
Mike

[freeflytim]

Anything over a 3" lift you're gonna need driveshafts also. Plus brake lines. With 35's you're gonna need HD axles and if its not a trail truck... regeared to at least 4:11. And what others have said... for axles, regearing, lockers and shafts.. go GBR!

[Rivilou]

Originally Posted by Disco Mike

Sounds like you are talking about 2 differents gearing options, the t/case and the diff's.
I wouldn' suggest going to Danas, Rovers are strong enough, just need to us HD axles and some lockers. If you gear the t/case while running 35"s you will have a nice crawler but terrible on the road, no power and terrible gas mileage.
Most people run diff gears especially if this is also a main driver.
Mike

Glad I didn't go for the t/case alteration thanks for the warning! I do use it as a main driver I cover around 10 to 15 thousand miles a year in it. I'll definately put an airlocker in the back but I've heard if you put anything more than a limited slip in the front it wears the cv's out too quickly. I thought ahead with the breaklines, I put braided +4's on when I did the 2" lift. I've seen what happens when off roading and a breakline ripps off. I reckon it'll be about three months before its finished, like with all things its a hobby not and occupation.

[300bhp/ton]

You have lots of choices here. And as for being as good as a 90, well yes it possible but it depends. A Discovery has longer overhangs and will always limit it's ability somewhat, plus it's bigger, taller and heavier.

Many years back Land Rover after much research decided that a 101" wheel base is about idea for off roading (90" being a tad too short).

So the wheel base of a Classic Range Rover or Discovery is according to Land Rover - ideal.

What people often do in the UK is make a 'bob-tail' out of them:



The other popular option (although it's rarer these days as they are not legal for ARC events).

Is to modify the rear cross memeber of a Classic Range Rover and re-body it with a 90 bodywork, you essentially end up with a 101" wheel base 90.

That aside the same things apply for modding.

Personally I really like the look of Scorpion Racings EXTREME kit, it includes everything you need to make an extreme off roaded. Other options such as propshafts are also available. (There's a link for this kit in the thread about body lifts, check it out).

Yes if you are planning on running 33 or 35" tyres then a final drive diff ratio swap would be worth while else performance will be poor and the vehicle will move faster in low 1st.

If you fit a transfer box from a 90 this will help with highway performance also (but probably not mpg) it won't however affect low range as the transfer ratio is the same.

ARB air-lockers are pretty cool, just remember when you get stuck using lockers you usually are REALLY stuck .

You'll want some protection also, the Discovery's use plastic fuel tanks and are easily damaged, so get a tank guard.

[Rivilou]

Thanks for the tips, I've planned to get it bobtailed, I'm having 16" cut from the rear and 3" cut from the front. I will be getting a smaller alloy fuel tank where the plastic one would have fitted, lpg tank in the boot. I've decided to do a 2" body lift but this will only allow me to fit 255/85R16's, about 33.4"s, so I'm going to cut off the inner wheel arches and re-weld them 2" higher, so at the end I'll have increased the distance from wheel to wheel arch by 6". I have a tubular winch bumper on already which gives me excellent approach, I'm having a custom one made for the rear, similar to a 90 cross-member/back door look, so my overhang will be less than that of a 90. My rock/tree sliders are 80mm shorter either end to allow for the tires. I have been contemplating removing about 3" of the sill to increase the distance from ground to body work. Obviously the discovery's are wider but this I don't mind, I have a 90 anyway so if I'm going somewhere tight, I'll take that.
I'm rebuilding a set of axles, getting them galvanised and fitting swivel gaiters. I'll fit the 4.11 ratio diff/locker in each axle. I'm doing various other things to it too, just for a personal touch, cruise control for long distance and shaved door handles/ door poppers, just for something different.