ok, I have a couple questions on the rear end of this Jag, (84 XJS V12)

are there options to change the rear end ratio? best as I can tell, I have a 2:73 in the car now...would love to move that to a 3:93 or 4:11, but I can't seem to find any options

I currently have the rear-end dropped, to change the calipers, rotors, ect, and figured I would change the diff oil while I was at it...what should I use?

I'm seeing it should be 80 weight, but should I add a friction modifier to it? what is recommended?

any help would be greatly appreciated!

thank you,
John

 

You should have 2.88 now

Jaguar used 2.88 3.07 3.31 3.54 3.77 4.09. You might be able to find some of those gearsets somewhere.

The Jaguar/Salisbury diff you have is a kissn' cousin to the common Dana 44 diff used in many other vehicles. Others have used Dana 44 gear sets successfully....but different bolts are required. Others will chime in and/or I'm sure there are write-ups from others in the archives with all the details




Many modern gear lubes (especially the synthetics) are already "limited slip compatible". The label on the bottle will say. No additive needed.

If not, use a friction modifier such as GM # 1052358. I think most parts stores sell an suitable additive if a GM dealer isn't close by.

I use 80/90 weight in my Jag diffs

Cheers
DD

 

[QUOTE=Doug;727412]You should have 2.88 now

Jaguar used 2.88 3.07 3.31 3.54 3.77 4.09. You might be able to find some of those gearsets somewhere.

The Jaguar/Salisbury diff you have is a kissn' cousin to the common Dana 44 diff used in many other vehicles. Others have used Dana 44 gear sets successfully....but different bolts are required. Others will chime in and/or I'm sure there are write-ups from others in the archives with all the details



I did a site search, and can't seem to find any information on this swap...although I may just be missing it, if anyone has this information, or a link to the writeup, I would greatly appreciate it, Dana 44 gearsets are common and plentiful, so I would love to use one of those in this Jag

thanks for the info!

John

 

You realize that with a 4.10 gear and the original 3 spd t400 trans you will be turning roughly 4400 rpm at 60 mph.....

 

the engine has been pulled, it is currently a 327 chevy from a 65 Impala SS, the trans has also been changed to the T400 from that car...not sure what it's ratios are... the car currently can do 65mph at 1500 RPM, I'm thinking I can up the ratios a bit and still keep it's driveablity and this car is also just a toy, for going to car shows, and maybe the track on weekends

 

Regardless of engine, with a T400 and stock 2.88 rear end, if you're turning 1500 @ 65mph, what you have is either a broken tach or 40 inch tall tires.....

On 235-60-15 tires or similar diameter, with the stock gears, rpm at 65 should be roughly 2400.

 

I may be off on some things, including an inaccurate tach...but I know the car isn't struggling at all to do 65mph on the highway, but I would love to step up the gears a bit in the rear... 3.92 might be too aggressive...but I definitely want to move up from the 2.88s

 

I have 3.58 and a couple of guys I know have 4.09's. It's not too difficult I used a complete XJR LSD center. A couple of guys here in Aus use the stock diff center with a spacer so long as it is done correctly it will last and take the power.

Another option is to use a 19 spline Dana 44 center. There are a couple of things - the crownwheel bolts in 44 are 3/8 not 7/16 so a center and gears will be needed then the pinion spline is different so a new tailshaft yoke will be required.

3.58 with said tyres will give 2100rpm at 65
4.09 will give 2400rpm at 65 both of these are with the T700

T400 at 65
3.58 = 3000rpm
4.09 = 3400rpm

 

so, to use the dana 44 ring and pinion to change the gear ratios, I would need to use different bolts, as well as getting a different yoke, but otherwise...it would bolt up?

I'm hoping that would work out...the original jag center sections are VERY pricey, but a ring and pinion set for a dana 44 is quite affordable, and plentiful...so I can choose any ratio I want

thank you for the information everyone...I think I know what route I need to go down now...and I can get this baby back on the road confusing Mustang and Camaro drivers again...