Hello,
I am going to look at a 3.07 P/L diff to buy for my 66 S1 4.2
Just wondering if anyone can tell me what numbers (i) either on the outer diff casing or (ii) on the crown wheel or elsewhere when back cover is off, which I should be looking for to confirm it is an original 3.07 P/L.
Also what should I look for or check, to assess whether the diff is in good condition, given it’s already out of the car.
Thanks for your help
Michael
A 3.07 has 43 teeth on the crown wheel and 14 teeth on the pinion. These came with a little tag that is fixed under a cover bolt (like a washer) that will show 43/14. Absent anything more helpful from others you can confirm the ratio by turning a rear wheel and counting off the matching turns of the tail shaft. For a power lock both wheels will turn in the same direction. I did this on my XJ6 (not a power lock) to find that it had a 3.07, and the wheels rotate in opposite directions (from memory).
Jaguar fitted Salisbury and Dana Diffs in the IRS cage.
The Dana diff was fitted for a few years only in the 80’s. You can recognise it because it has no drain plug.
You want the Salisbury 4HU diff.for an E type. The Dana diff uses different brake caliper mounts and calipers.
Apart from the ratio tag, they are date stamped as well. To identify a locking diff over an open diff, turn then an output shaft on one side and the other side should spin in the same direction.
Paul and James,
Thank you for the knowledge…I just want to learn
Mitch
Thanks very much for your replies. Any suggestions on what to look for regarding condition. The diff is out of the car. Regards Michael
Take off the back cover (drain oil first) and check that there is no metal in the residue oil thats left in the case…unfortunatly when buying a second hand diff it should be stripped and rebuilt with new bearings. Seals etc and set up correctly…you have no way of knowing unless its rebuilt…or you just take a chance and fit it…but if its noisy or leaks it has to then come out…Steve
Do you have the diff mount bracket that the diff sits on… these are specific to E types and you cannot use brackets from other Jag models
Best way is to pull the rear cover. All ring gears are stamped on the edge with the ratio and Spicer/Salisbury part number. It will also be obvious if it is limited slip.
If it is not possible to remove the rear cover, there may, or may not, be metal tags attached to one or two of the rear cover bolts. They often go missing and some years probably never had them. If it is there, PowerLok diffs have a tag marked P-L. The tag for the ratio has the numbers stamped as a fraction, ring gear teeth over pinion teeth.
Visually, a PowerLok is can-shaped, while an open diff is bell-shaped. P-L on the right, below.
Hi Michael, I have two E types, a 65 OTS with a 3:54, and a 66FHC with a 3:07. Years ago I met Norman Dewis, the development engineer for the E type. So i asked him what was his favorite gear ratio…without hesitation he said the 3:31. Now many years later I would have to agree. You will notice the difference immediately, the 3:07 is sluggish of the line, but does offer a more acceptable cruising rpm. When I drive the 65OTS I do love the rapid acceleration but don`t like cruising at 3000 rpm. If I had to do it again, I would either try to find a 3:31 or a 5 speed, which obviously is much more expensive.
Regards,
Allen
Thanks very much for all your great feedback. It has been extremely helpful, regards Michael from Aus
Be sure and let us know how the story unfolds
Cheers
If you are going to inspect the diff and pull the cover, which you should do if at all possible, you may as well take a small tube of engineers blue and a can of degreaser $20
a quick pattern check will usually reveal if its “in spec” for the main bearings
You dont want one that has had water in it
Thanks for the tip Tony, I will definitely let you all know what happens, Michael
