Diff identity

[richard mason]

Hi,
Anyone know of a diff with a rating of 3.58:1 I have one with just such a tag bolted on to the cover, it is a sailsbury L/S with treble bolt input flange, I want to over haul it and possibly de-rate it after reading some of the threads from members having experienced driving problems. I have not seen any mention of 3.58 diffs, however I have seen 3.058 can any one help? Also any one got info on de-rating.

Thanks, Richard.

[Migge]

Maybe that helps:

....Morgan deemed that the brakes would only require modest enhancement. The front 11in discs, assisted by a Girling Powerstop servo (which was later abandoned), used 16P Girling callipers with greater resistance to fade than the 14P units used on the Plus 4, while the 9in rear drums were unchanged.

Similarly the rear axle was carried over, although the Salisbury 7HA unit now had a 3.58 ratio, the highest available, and a Power lock limited slip differential was fitted. Rear suspension was by the traditional five-leaf springs, although a stiffer six-leaf set was used for a time; Armstrong lever-arm dampers were retained.

The Plus 8 was capable of over 120mph, which was an....

[richard mason]

Originally Posted by Migge

Maybe that helps:

....Morgan deemed that the brakes would only require modest enhancement. The front 11in discs, assisted by a Girling Powerstop servo (which was later abandoned), used 16P Girling callipers with greater resistance to fade than the 14P units used on the Plus 4, while the 9in rear drums were unchanged.

Similarly the rear axle was carried over, although the Salisbury 7HA unit now had a 3.58 ratio, the highest available, and a Power lock limited slip differential was fitted. Rear suspension was by the traditional five-leaf springs, although a stiffer six-leaf set was used for a time; Armstrong lever-arm dampers were retained.

The Plus 8 was capable of over 120mph, which was an....

Thanks,
But Im'e afraid I don't fully understand, does the quote mean the diff I have was from a Morgan??? Is it suitable for a Cobra, it looks the same as other Jag diffs apart from the prop falange.

[dave]

The 3.58 diff is fairly common in the XJ40 Jags. As is the 3 point propshaft drive flange.
Quite often the power lock part of these diffs is quite slack/soft and wouldn't need de-rating. If you can twist the output flanges in opposite directions with a pair of 12" socket extensions with moderate force it will be fine.

P.S. The XJ40 diff is the right one for a Dax De Dion, but will not fit any of the other Jag based Cobra kits.

[RobinH]

I have a 3.54 which came from a 1989 XJS 3.6
Mine allows has a pretty low amount of static PL torque (27 lb ft) before it 'gives' which I gather is good. I guess this was the setting used for such cars which had lesser engine torque than the bigger V12. Either that or someone has put the wrong sort of oil in at some point!

[richard mason]

Originally Posted by dave

The 3.58 diff is fairly common in the XJ40 Jags. As is the 3 point propshaft drive flange.
Quite often the power lock part of these diffs is quite slack/soft and wouldn't need de-rating. If you can twist the output flanges in opposite directions with a pair of 12" socket extensions with moderate force it will be fine.

P.S. The XJ40 diff is the right one for a Dax De Dion, but will not fit any of the other Jag based Cobra kits.

Thanks, I will try locking one side and turning the other, have to change the bearings first as one has some damage evident. Will let you know how I get on.
Thanks again, this forum is such a mine of information!

Cheers, Richard.