Came across this ENV axle recently. Curiously, the ratio stamp is 12/47 (3.92), but the 3.92 fitted to XK120 was 13/51… Is this an XK120 axle, or did the tooth count change at some point??
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I’ve just seen a 2018 thread where Rob Reilly quotes the ENV ratio for 3.92 as 14/47, and quotes from the Jaguar SPC. Looks like Viart was wrong on this one - he quotes 3.92 as 13/51.
The external parts certainly all look like XK120 parts.
I don’t know that XK120 owners would want that ratio, unless they were into short track racing. But some Mark Vs had an ENV axle with a 4:30 ratio, so it might be good for Mark V owners wanting something a little better for cruising the interstate highways, motorways, autobahns.
I remember the Manual showing a 4.27 and 4.55 for the Mark VII…were those ENV or Salisbury…or both?
this one looks to be built in dec 1947 ie 1247
I think it is just a coincidence it comes out at 3.92 almost
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14/47 comes out at 3.357 not a ratio i have come across
13/51 comes out at 3.923 ie 3.92 so Viart is correct
the other XK120 ratios are 3.27 and 3.64
first number is number of teeth on pinion second number is number of teeth on crownwheel
My mistake, Terry - I wrote 14 47 in error - the diff is stamped 12 47 as seen in the picture above. The Jaguar spare parts list gives the tooth count for the 3.92 as 12 47. No mention there of a 13 51. My car has the standard 14 51 (3.64). I haven’t yet deciphered what the other numbers/letters stamped on the diff refer to. Another picture of the axle shows the taller spring saddles which don’t require the alloy wedge, suggesting it’s a later ENV axle.
chris,
whereabouts in SPC does it give the tooth count?
one number on diff is a straight serial number. All Salisbury diffs have date stamped on them
the SPC doesn’t list 2 types of casing is this the actual taller one? to me it doesn’t look as high as what I expect on a salibury diff.
On my cars I have gone with Salisbury 4HA on them all so unlimited availability parts and ratios
Here is what the XK120 manual has for ENV axle ratios.
Here is what the Mark V manual has for ENV axle ratios.
Here are the tooth counts in the XK120 SPC.
None in the Mark V SPC.
My Nov '51 120 FHC 679187 has a 3.64 ENV. Here is the spring saddle.
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Will post a pic of my spring saddle when I get the chance. It should be the lower type with alloy blocks as the car is 660405.
I’ve finally managed to see the numbers stamped on my ENV axle. Some thoughtful soul in the past has made a little flush-fitting inspection door between the batteries. It already had 2 holes, and after drilling a third centrally between the two, my spare heater door knob fitted perfectly! Through this I was able to read the stamped numbers. They are: NO 3482 JHS 988 14 51. Quite what they mean I’m none too sure, except that 14/51 denotes the ratio of 3.64:1.
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Enlarging your photo shows 3452. C3452 is the part number for the 3.64:1 ENV rear axle.
Thanks, Mike. Try as I might, even enlarging it massively, I cannot make out a 5 in 34?2. If anything, I now think it might be a 6… It would surprise me if ENV would stamp a Jaguar part number on their axle, but I might be wrong. I do agree that C3452 is the part number for the 3.64 axle, but I think it might be a coincidence that mine has a similar number? The stamp on the ENV axle I posted earlier shows NO 5721, with the12 47 (3.92:1) ratio, and the part number for that is C5152.
I went the 5-speed route. Yes, it required a different trans mount, but I don’t think there was any “butchering” of the crossmember involved.
Finally managed to acquire a 3.27 ENV axle, for about a quarter the cost of making a new crown wheel & pinion! It seems to be a very early one, and may even be the first 3.27…? As mine is also the early first type, I’m confident that the swap will not be too difficult at all.
Lucky you. I’m envious. As I understand it, fitting one of these should be a matter of unbolting the half-shafts on each side, pulling out an inch or two, removing the old “pumpkin” and replacing with your new one, followed by securing the half shafts again. This, as opposed to hacking out the chassis center section and fitting a brand X replacement transmission. I hope this works out for you and it’s too bad none of the major suppliers carry crown and pinion gears in this ratio. It would seem to be much more cost effective and less intrusive while achieving the same end results.
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As a structural engineer, I would vigorously oppose that scheme.
LOL You guys are SO sensitive! You’ll appreciate this. One Monday morning our engineering firm received a phone call from a furniture manufacturer located in a 150 year old wood-framed building about 30 miles out of town. When we got there, the problem was abundantly obvious. The roof had collapsed. When we got inside, the cause was even more obvious. To make more floor space for new machines, someone had gone through the place and cut out every other support column.
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That’s a good one! Reminds me of the old Chicago carriage house I lived in while I was a young railroad apprentice for Burlington Northern. I recall being puzzled as to why the upper floor used to sag near the bathroom. I subsequently noticed how from the ground floor the overhead beam supporting the upper floor joists had been drilled through with all manner of cast iron drain pipe and supply lines when indoor plumbing had been fitted back in the day. Brought it to the attention of the landlord but he seemed indifferent.
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Yes, Christopher, reading up on the procedure in the Service Manual for replacing an ENV diff looks pretty straightforward. No need to take out the whole axle. I will get the diff cleaned out and checked over first, though. We have an ENV specialist not far from me, fortunately.