Thread: Diff ratios on a series - different for petrol and diesel?

nope all series 1 , 2, 2a, 3 were 4.7:1 final drive ratio no matter which engine, SWB or LWB,
Tyres sizes were altered instead of Diff ratios, e.g. 600-16, 700-16 or 7.50-16

with the exemption of Series3 Stage 1 ( V8 or Izuzu 3,9) were 3.54:1 final drive same as Range Rover.

Originally Posted by goingbush

nope all series 1 , 2, 2a, 3 were 4.7:1 final drive ratio no matter which engine, SWB or LWB,
Tyres sizes were altered instead of Diff ratios, e.g. 600-16, 700-16 or 7.50-16

with the exemption of Series3 Stage 1 ( V8 or Izuzu 3,9) were 3.54:1 final drive same as Range Rover.

Except that the very early 1948 model vehicles had 4.88:1 diffs, but no diesel engines so outside the parameters of this thread.

Originally Posted by Lotz-A-Landies

Except that the very early 1948 model vehicles had 4.88:1 diffs, but no diesel engines so outside the parameters of this thread.

You sure about this Diana? Are you talking about prototypes using Willys diffs?

I always thought they just pillaged the rover car diff which was 4.7:1.

4.88:1 would be a (max) tooth count of 44/9, which is a much stronger tooth setup than the 4.7.

Absolutely sure about this and IIRC it was the diff used in the 10hp Rover p2.

Chris Baker's R860158 has 4.88:1 diffs, which I've seen in the flesh dissassembled on the bench at Graeme Coopers, before the Heritage Drive a couple of years ago. They are a very early design without tapered roller bearings but ball races with thrust washers.

Originally Posted by Lotz-A-Landies

Absolutely sure about this and IIRC it was the diff used in the 10hp Rover p2.

Chris Baker's R860158 has 4.88:1 diffs, which I've seen in the flesh dissassembled on the bench at Graeme Coopers, before the Heritage Drive a couple of years ago. They are a very early design without tapered roller bearings but ball races with thrust washers.

What are the crownwheel and pinion tooth counts?

Originally Posted by isuzurover

What are the crownwheel and pinion tooth counts?

IIRC 9 X 44 pretty sure about the 9 count on the pinion.

They are long nose and made of unobtanium, even some of the early '48s have 4.7s now.

A prized find for any '48 restorer.

I wish I got some in a big box that came this morning but it was gearbox parts from WA!

Originally Posted by Lotz-A-Landies

4.88:1 diffs,......They are a very early design without tapered roller bearings but ball races with thrust washers.

They were double ball race unit & parallel roller bearing for the pinion & had a round drive flange. Carrier & gears were the same. After the 4.88, some 4.7's were also of this early design. With the change to (roughly) square flange & opposed taper bearings, 4.7 was used on LR until the V8. However the Rover cars (P4 & P5) of similar periods had mostly 4.3 with some 4.7 & some 3.9. These car diffs are completely intechageable with LR 4.7s (in pairs of course). Rover P6 & P6Bs were entirely different. The Rover P5B with the V8 had 3.54s, Which is why the Rangy acquired that ratio. The 4.3 & 3.9 have been used in LR & I believe that the 4.3 would actually suit the diesel series, although I've never tried it. However, the 4.3 & 3.9 crown wheel & pinions are not as strong as later 4.7, there was a gradual improvement in the metallurgy, & the diff carriers of later production were vastly stronger.

[QUOTE=fc110;1623482].......... The Rover P5B with the V8 had 3.54s, Which is why the Rangy acquired that ratio. [QUOTE]

agreed that they would have used a suitable current ratio from their line up, but it would also have been determind by the gearbox-transfer case and its ratios, that was built for both it and the 101, with major preference going to the 101, which they felt had a more certain future with the military contract. The RR was new marketing ground.....little did they know