Thread: Diff Gearing

I run 4.14 GB diff gears and happy with them, run 35" and 37"s.
V8 auto.At 100kph my rpms are around the 2200/2300.Im not sure but think that is slightly higher than standard?.I find it crawls around in the rocks and hills pretty good. http://www.greatbasinrovers.com/cs_d...20gearing.html

Hi Craig, There is a great ratio calculator at gear ratio/speed/rpm calculator. It doesn't have a transfer ratio though. I multiplied the tranfer ratio by the diff ratio and punched it in. I have been looking at changing the transfer ratio in my 120 county and found it easy to use.
Tim

4.3 is the correct ratio to bring it all back to standard, but 4.11 is whats generally able to be found. As the ratio increases up to 4.7 and beyond the gears become weaker and less suitable strength wise for bigger tyres because despite the crownwheel becoming thicker, the pinion gear keeps becoming smaller and weaker as the contact area reduces also onto the crownwheel, so 4.11 is usually where the balance is found.

Around 4.11 there are 3 options for Rover type diffs, there is 4.1, 4.11 and 4.14. They are all practically the same for ratios, but they have different tooth counts. 4.1 is 10/41, 4.11 is 9/37 and 4.14 is 8/33. The latter is the strongest but will also be the most prone to gear noise. This is because the gear teeth are bigger, thicker and stronger.

I've found this ratio calculator to be really useful.

Ashcroft Transmissions - Ratio Calculator

i'd seriously be checking out the Ashcroft h/duty r&p, much stronger looking. I have a set in the shed and the teeth are much bigger than stasndard gears.

Ashcroft also do a 4.12 :1 r&p which is reverse cut for the front,and they work very nicely

Wayne

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Originally Posted by Slunnie

4.3 is the correct ratio to bring it all back to standard, but 4.11 is whats generally able to be found. As the ratio increases up to 4.7 and beyond the gears become weaker and less suitable strength wise for bigger tyres because despite the crownwheel becoming thicker, the pinion gear keeps becoming smaller and weaker as the contact area reduces also onto the crownwheel, so 4.11 is usually where the balance is found.

Around 4.11 there are 3 options for Rover type diffs, there is 4.1, 4.11 and 4.14. They are all practically the same for ratios, but they have different tooth counts. 4.1 is 10/41, 4.11 is 9/37 and 4.14 is 8/33. The latter is the strongest but will also be the most prone to gear noise. This is because the gear teeth are bigger, thicker and stronger.

Recon my rpm would be pretty high running 4.3s,is standard rpm at 100 about 2500? my 4.14s are 7/29 cw/p, and I do have a bit of gear noise in the back, the front is quiet.
Mark

I have decided to go with Ashcroft 4.37 R & P and decided to pick up a set of Ashcroft HD rear axles while I'm at it.

But a quick question for those people in the know out there. Will the Ashcroft fit up to the Detroit locker and truetrac, or will an adaptor be required?

Cheers
Craig