37 inch wheels, need to verift wether to change transfer box

[Bushcrusher]

Good morning fellow mud seekers, I have a discovery 1 1998 es v8i  3.9 automatic and have 37 inch wheels to put on. I've done all the lift side of things, corrective radius arms 6 degree, cranked rear arms,2 inch spring lift on 3 inch suspension blocks and 2 inch body lift.

I've got to cut some more of arches away etc,my concern is the gearing of transfer box. I will get under the old girl and have a look for serial numbers.  Would my transfer box below enough though?  Or do v8 discovery 1 automatics be ok with the tyres size? What exactly would be affected if I did nothing? 

I know some will say why such big wheels etc, I'm the type of person who likes challenges and not to blend in, besides these wheels are beadlockers and off set so why not

I await your guidance and comments on this.

Many thanks 

Dave 

[FridgeFreezer]

If you haven't already you may want to consider uprating diffs & half-shafts, 37's is really pushing the limits for LR stuff.

I suspect a 1.4 transfer box would help, unless you intend on doing a lot of motorway cruising.... and looking at the tread on those I suspect they're not great for high-speed handling

Have you tried the ratio calculator on Ashcroft's website?

[Chicken Drumstick]

Are those tyres road legal? I've not seen that kind of tread pattern that is before.

Personally I think it'll completely kill your crawl speed off road. And on road will be pretty horrendous. 1.4 or even a 1.6 transfer box will help on road (if the tyres are road legal). But won't help off road. I'd have thought a min of 4.10:1 diffs would be needed. And as per Fridge's advice. I can't see stock axles lasting long with any 37" tyre, let alone aggressive ones. Axles are easy enough to break with a 235/85's...

However, please do keep us posted. Will be interesting to see how you get on fitting and running them.

[simonr]

I don't know whether the tread pattern is legal - they look a lot like Maxi-Cross which you couldn't even take to most sides as they tore up the ground so much!  Fantastic tyres off road though!

However, I used to run 37" Tyres on my V8 Auto Defender.  The transfer box was whatever came as standard in a V8, 90..  It did have uprated half shafts (after I'd broken too many standard ones) and Diff Locks.  It went fairly well.  A bit wobbly at times on the road.  I didn't have any issues crawling with it.  If it were a Manual box, I think you'd have more issues - but the auto has a Torque Converter (which turns RPM into Torque).  I think that increased the input torque enough not to really notice the difference in torque available at the wheels.

Still my favorite vehicle I've owned!

 

[Nonimouse]

If they aren't maxi cross, then they might be alligators - Neither tyre was speed rated for a Disco

 

That's a 27.6% increase in diameter so yes it's going to effect everything about the vehicle apart from the seat comfort. Brakes will be appalling (even without the tyres), any fault in the autobox is going to be announcing itself very quickly. But hey, why not. 

Most folk who run 37's on a Land rover auto, swap in a 1.66:1 T Box, and spend a fortune on uprated drive train components

Might also be an idea to move the form axle forward, to avoid the huge lift needed to clear the footwells

[Escape]

I had 37" Baja Claws on my Defender TD5. It came as standard on 205R16, so I had the same increase in diameter as you'll have on the Discovery. On road it was fine with the 1.4 transfer case. Your Disco will have a 1.2 transfer case, but the V8 and autobox should be able to handle the difference. Off road I would have liked lower ratios, both for more control and more torque at the wheels. Again V8 and autobox will help when driving off, but very little engine braking will be available on steep descents. In hindsight, I should have gone for higher R&P ratios, as mentioned above. I also quickly found out the standard axles weren't up to the job, so upgraded everything to Ashcroft. That didn't stop me breaking ring and pinions though (one more reason to go for uprated and higher ratio).

Filip

[Anderzander]

Conveniently posted by Nige today:

 

[Hybrid_From_Hell]

maybe this is worth a watch too : 

 

[Hybrid_From_Hell]

Discos don't help at all for this sort of thing as they are very arse end heavy ...

 

but

 

You would really need HD  4.75 CWPs,

pegged casings without Question

and stronger centers of some sorts,

HD shafts, preferably 300M all around

HD CVs

HD Flanges all around

and a 1.4 poss even i.6 TBOX

and a bible to pray on each outing 

 

...and it can still all go "Ferking BIG POP" on 37s at the 1st sign of "Hold my beer and watch this" 

 

My advice ...Don't

........35s max,

and still most of the above applies 

[tommobot]

If you are looking for a 1.6 LT230 send me a pm, I've got a spare one sat in the shed..

Edited February 27, 2022 by tommobot