Thread: Reverse Cut Ring & Pinion / aka High Pinion - front Rover diff

Reverse cut refers to the type of cut on the crown wheel and pinion. It's used on the front diff so that when driving the load side of the gear teeth are loaded rather than the coast side. The Rover type diff in the front is a spiral bevel type, so the pinion is centralised in its height rather than being low or high. The rear being a Salisbury is a hypoid design diff which is a low pinion setup. Short of installing replacement entire diffs, you can't change it between high and low pinion or with spiral bevel.

Thanks Slunnie... have a look at this link... Coil Sprung - Diff Gearing

I have the 4.14 reverse cut...

So i assume this is simply a spiral bevel reverse cut and nothing to to with high/low... i think the shop is using the wrong terminology here....

I have the 4.11 normal cut for the rear sals.

They're the right gears you're after, but that's not to comment on combining 4.14 and 4.11. The reverse direction is in relation to the cut of the gear rather than the direction that it drives the gear in. If you look at the crown wheel of the reverse cut 4.14 and compare that to the normal cut on the crown wheel pictured above it you will see what I mean. The pinion is cut in the other direction to match also.

Yeah it should work... cut and paste from the same link:

...Here is an example, a 4.10, 4.11,4.12 and a 4.14 ratios are all interchangable but there is a considerable difference in durability between these four gears.

4.10 (10X41) 41 tooth ring gear

4.11 (9X37) 37 tooth ring gear

4.12 (8X33) 33 tooth ring gear

4.14 (7X29) 29 tooth ring gear

Here is the approximate durability increases (shock loading) as calculated by Gleason Corporation.

4.10 to 4.14 +30%

4.11 to 4.14 +20%

4.12 to 4.14 +10%

I'm going to pop down there tomorrow morning to see it with my own eyes, i think they might assume that it will not work, as typically reverse cut hypoid gears are high pinion, which isn't applicable to the Rover diff

I'll report back tomorrow...

Originally Posted by Slunnie

They're the right gears you're after, but that's not to comment on combining 4.14 and 4.11. The reverse direction is in relation to the cut of the gear rather than the direction that it drives the gear in. If you look at the crown wheel of the reverse cut 4.14 and compare that to the normal cut on the crown wheel pictured above it you will see what I mean. The pinion is cut in the other direction to match also.

I can't see that working out too well.

Originally Posted by Slunnie

They're the right gears you're after, but that's not to comment on combining 4.14 and 4.11. The reverse direction is in relation to the cut of the gear rather than the direction that it drives the gear in. If you look at the crown wheel of the reverse cut 4.14 and compare that to the normal cut on the crown wheel pictured above it you will see what I mean. The pinion is cut in the other direction to match also.

Ahhh now i see what you mean, it's the cut / bevel in the gear is on the opposite side compared to the stock front 3.54... now it makes more sense.

Not sure why they refer to it on the link as 'reverse rotation' as there isn't anything being reversed!

Originally Posted by Davo

I can't see that working out too well.

Refer post above.. the 4.11 is a 37 tooth and the 4.14 is a 29 tooth... the 29 tooth is chunkier / spaced further apart to make up the difference in the tooth count. At least i bloody hope it does, otherwise i'll be looking for a front 4.11 tomorrow morning!!!!!

The variation whilst small won't work out well for you!