1979 3000S - Jaguar diff ?

[duncscz]

Anyone know which Jaguar car the diff is from (I understand from AV that a diff with the filler plug to the rear is from a Jag). Also, there are no grease nipples on any of the UJs.
I rememebr reading that grease nipples should be added, but is this necessary for these later 'Jaguar' diffs.

[bigtone]

Do you mean the Salisbury diff? Otherwise known as the fg heavy diff?

Mine was a two man carry!

[davidy]

You shouldn't be able to break a Salisbury (Jag) diff. UJs are available with and without grease nipples, the ones without are supposed greased for life. I personally would replay them all with geasable ones, then you know where you are. While you're at it check the splines in the halfshafts for play.

Most clonking rear noises come from UJs of halfshafts!!!

davidy

[duncscz]

It's the one shown in DG's spare parts catalogue, pages 3.16-3.17, on later chassis (mine's 4682). I'm looking for a Haynes guide which covers it.

[Terminator]

Later M-series cars used the 4HU diff, I was told it was the same as the Jag 420 saloon, amongst others. I bought a reconditioned one from a Jaguar specialists many years ago.

Ratio for the 3000S is 3.31:1. Turbo Ms used a 3.07:1

[davidy]

Not all M Turbos used a 3.07 (it was an option). I have had a 3.31 that came out of M Turbo.

There are also 2.88's and 3.54's (the later liked by anyone who Sprinted/Hillclimbed the car). There are also LSDs and diffs labelled Powrlok (essentially an LSD). The ratio should be stamped on the rear of the crown wheel. (sometimes there is a metal tag on the box with the ratio and type of diff eg Powrlok)

If you have an LSD make sure that its topped up with Limited Slip Diff oil not normal gearbox oil.

davidy

[mk1]

My original 4HU (3.31)on my M Turbo was LSD-Less.I replaced it with a 3.54 LSD'd unit out of a twice raced E-type. The LSD has been "Adjusted to allow for a different 'break away' torque. On researching the ratio (3.31) with the extra 5th gear I fitted i have found a happy balance between acceleration with a comfortable 'top' speed (i guess it depends what you want to do 3.07 = topend, aso). I was warned about the possible drippy 'nose/input' seal and the cost of a rebuild to replace. As for UJ's there is i believe a different, and supposedly, stronger GKN alternative. As for the drive shaft play i had mine plasma coated to reduce the backlash. What about going the cosworth 2wd route?