ENV axle ratios

(Chris Lackner) #1

I’m always keeping an eye out for an ENV axle (or crownwheel & pinion) of the optional high ratio - 3.27:1 (18/59 tooth count). Most early 120s with the ENV came with the standard 3.64:1 ratio, like mine has. This is a bit low-geared for cruising (about 60mph at 3000rpm) and it would be nice to be able to drop the revs a bit. I’m not going to go down the 5-speed route, as I want to keep everything that’s visible as original as I possibly can. I know it’s a slim chance of finding one, and it may well be that I end up getting a crownwheel & pinion made eventually - not a cheap option!

0 Likes

(Christopher Potempa) #2

If having more than one set made helps to bring the cost down, then count me in. It took me a long time to undo an amateurish gearbox conversion (a MkII gearbox w/ overdrive in a '120) but that’s not to say I’d still like the possible benefits of higher speed/ lower revs cruising.

0 Likes

(John) #3

I am under the impression that with tires of the correct circumference and a true 3000 rpm on the tach and the standard 3.54 (?) R&P ratio
You will be moving at close to 70mph.

0 Likes

(Chris Lackner) #4

I wouldn’t be doing it for a while yet, But I’ll certainly bear it in mind, Christopher.

0 Likes

(Chris Lackner) #5

Standard ratio on the ENV was 3.64, a bit lower than the Salisbury’s 3.54. I’m running on 600x16" Michelin X tyres.

0 Likes

(PhilW) #6

Is there a place on the ENV housing where the axle ratio is stamped? The Jag IRS has a tag with the ratio and wonder if the ENV has something similar. I’d rather not take these apart to find out.

Phil.

0 Likes

(Chris Lackner) #7

There is a number stamped by the dipstick, but not sure if the ratio is there as well. Easiest thing is to count the turns of the pinion for one revolution of the wheel, or axle shaft.
Chris

0 Likes

(Daniel Cusick) #8

I prefer the 3800-4000 range, bigger grin!
But in all honesty for the few thousands of miles I put on a year the stock setup is good enough without spending big bucks

1 Like

(Mike Spoelker) #9

I would seriously consider swapping the entire rear axle for a 4HA. Its similarity to the modern Dana 44 means you can select any gear ratio your heart desires. Hang the ENV on the wall and give it to the next owner.

0 Likes

(Rob Reilly) #10

So now we’re looking for old American cars that used the Eaton rear axle, to see if the parts interchange?

0 Likes

(Mike Spoelker) #11

Not me! I no longer own a 120 with the ENV axle! (Is that what the ENV US equivalent is, Eaton?)

1 Like

(Chris Lackner) #12

I like the idea of the ENV - from what I’ve read it’s a very well-engineered axle, easier than the Salisbury to get to the guts of the differential, plus because of the design there are never any problems with the axle tubes working loose from the diff, as can sometimes happen with the Salisbury. I even like the idea of the little dipstick. Most importantly, it’s original to my car. 3.31:1 was the highest Salisbury ratio, so 3.27 is just a tiny bit higher still…

0 Likes

(Mike Spoelker) #13

If you include the ratios available for the Dana 44, 4HA ratios are almost limitless.

It is exceedingly rare to see loose axle tubes. You are more likely to be struck by lightning or bitten by a shark. The Salisbury design has been adopted by GM, Ford and Chrysler and has been used in hundreds of millions of rear wheel drive cars and trucks, including everything since 1987. The Dana 60 and 70 front and rear axles are the standard in medium commercial duty trucks.

0 Likes

(Ed Nantes) #14

If they are early 120s with an ENV diff,of 3.66 I would imagine some SS or maybe Mk V owners would like to buy the CW&P.
Hypoid CW&Ps are expensive to have cut , Spiral Bevel are only moderately expensive.

0 Likes

(Rob Reilly) #15

I looked in a Motor’s Manual from 1950, covering all US cars 1935-50.
Chrysler DeSoto Dodge Plymouth '35-50 had a diff that looks very much like the ENV and may be a good candidate to look into further.
Also '49-50 Ford, but not Lincoln Mercury.
Hudson Terraplane '35-50 is another possible.
Olds Pontiac had three diffs '35-36, '37-46, '48-50 but all look sort of like the ENV.
Cadillac LaSalle had no pictures but the text described taking the diff carrier out the front.
Packard had a diff carrier in front but on a 45 degree angle, weird but may have been made by the same axle company.
No axle maker was mentioned, but Eaton is still known for truck axles with the diff carrier that drops out the front.

Kaiser Frazer Studebaker Willys and '49-50 Lincoln Mercury all had Dana.
Buick Chevy Nash Lafayette all had torque tube.
'35-48 Ford had clamshell.

0 Likes

(Chris Lackner) #16

Don’t you think al these old US cars would have lower, rather than higher ratios…?

0 Likes

(Chris Lackner) #17

Price back in 2016 was apparently about £1600 to have a hypoid CW&P cut. Then there is the cost of fitting into axle and setting it up…

0 Likes

(Rob Reilly) #18

I think you mean they were lower speed cars and had higher ratios.
Possibly, there was no mention of ratios in the Motor’s Manual.
But some of those cars such as Dodge, Olds and Hudson spent time on oval tracks, and all are still driven on our Interstate highways, so there may have been, and may still be, lower ratios in the aftermarket world.

0 Likes

(Christopher Potempa) #19

That’s still more reasonable than the cost of an aftermarket 5 speed plus butchering the chassis cross member in order to get it to fit.

0 Likes

(Christopher Potempa) #20

Also, if you do the majority of the work yourself as I did on my last one, you can leave it to a shop to then check and dial in the correct amount of gear back lash, bearing pre-load, etc. The local differentials-only shop here in San Jose charged me $90 for that.

0 Likes