The V8 Owners Forum -

Hi folks, i'm running 37 inch rubber on the standard axle and the driveability is poor unsurprisingly.
Any ideas what i can do to the diffs / diff ratio to make this more friendly.
It barely moves at 4k revs and needs 2nd gear, flat out is possibly 60mph if the speedo worked!

Trying to keep this locost as i'm about to stip all the body and rear seats out so eight will be considerably less if this makes a difference.

Hi
Is it an auto or manual? if it is an auto then substitute a manual transfer box with it's lower ratio and fit a looser (higher stall) torque converter.
If it is a manual then it is another problem as the landrover diffs won't be strong enough and will snap half shafts (though the ratios will be better). You could look for a pair of 101fc axels, convert them for coil springs, fit the auto transfer box and you should get something reasonable.
Alternativly fit a small block chevy with a 383 crank and a th400 box.
Best regards
Mike

I have no idea how big 37inch rubber is, (don't say 37inches!!), but assuming it's much larger than standard, and that you have standard Rangie diffs (3.54:1), then the gearing may well be a bit 'tall'. You could fit a couple of Land Rover series diffs (4.7:1) if you ensure you have 10spine half-shafts. They are a straight swap.

Chris.

Hi
Standard range rover wheels are 29" diamiter, standard 101s are 36", if the 10 spline landrover diffs are a straight swap into the RR casing then they would bring the gearing back to something around normal (I thought RR was 3.44??). Anyway early landrover diffs were not anything like as strong as rangerover but they would also not fit in RR casings so I would go with what Chris suggests.
Best regards
Mike

Ok, so just so my head gets this right, i'm looking to put in some series ones (which are not that strong)

i must have been thinking backwards as i thought that i'd need to drop down to 3.38:1 as an example in order to gain more road drivability.

rebuild of an engine, big foot conversion no problems but bits like this and what can and can't mate with gearboxes and engines is over my head.
Got a similar thing with my fiesta track car and fuelling

Definitely just get some Series 2 or 3 Land Rover diffs, and they will fit straight in if you have 10spline half-shafts. Worth popping a half-shaft to be sure.

I'm not sure there's a significant strength difference, but either way, if you spend some dosh, somebody like KAM will be able to sort you out.

Chris.

Thanks very much chaps

Hi Richard.
I'm a bit confused by your first statements regarding 4k revs and not going anywhere. Do you mean the engine is reving its nuts off and you have no significant road speed.
If this is the case you may just have a clutch problem or torque converter/auto box problem.

Cheers Denis

Hi

If your Classic is a V8 manual then your transfer box ratio will be 1.192:1

If it's the old 3 speed auto then it'll be 1.003:1

If it's the 4 speed auto it'll be 1.222

On 37 inch tyres all these will be too tall and you'll need to look at the 1.410:1 or the 1.667:1 transfer gear sets. These will drop your gearing down to a reasonable level.

As Devonman says you may have other problems though.

Gearbox is a 5sp manual and tops out really quickly.
compression, leads, plugs, rotar arm, dizzy cap all ok
coil fine, and all lubed up fine.
am going to check the half shafts for splines, i suspect there are 24 on there.

Hi
As an aside, having stuck these big tyres on I presume you have done both a chassis and body lift to get them to fit under the archers. I would very strongly recommend you get an engineers report stating that the work has been done correctly, safley and to a high standard, don't rely on the MOT. There was a case a while ago where a chap had done a big wheel conversion and chassis lift where he had been involved in a fatal accident, he did not have an engineers survay on the vehicle (only an MOT) and he ended up going to jail for manslaughter as the vehicle was deamed unsafe and he had done the work himself. Needless to say his insurance company did not cover him and he lost everything!
Best regards
Mike

cheers, i knew the guy that did it and we did 2 others together before he passed away and left me his one.