1996 XJR 122k

When at any speed, if I take my foot off the gas pedal I get an odd (and loud) roaring sound. Everything is normal when I accelerate.

Any ideas?

 

how does she idle, any idle problems?

 

I have similar thing with mine, although mine is manual, I guess it might be exhaust related, as there was few nasty holes in it already... And idle is fine on mine...

 

not wheel bearings or diff bearings?

long shot - mine made a horrible drown when decelerating from above 60km/h - it was the driveshaft hanger bearing. quiet below 60km/h, it sounded like truck engine brakes above 60km/h, and caused a harsh drivetrain.

get a mechanic to run the car up in the gears, up on the hoist... or do it yourself on axle stands if you're feeling keen.

 

Thanks fellas. It is the read differential.
Can I use one from an XJ6 in an XJR?

 

Yes, it'll fit fine, however the standard XJ6 uses a 3.58 ratio versus 3.27 for the XJR. Also, very few regular XJ6s had limited slip, versus all of the XJR6s having it.

Cheers
DD

 

So do I have to replace it with a limited slip, or can I just use one from a standard XJ6?

I ask because the limited slip is proving very hard to find.

 

Gotta check this info with those of you that are experts.
The mechanic that used to work on my car says I can drop a rear differential from an XJ6 into my XJR with no problems.
The lack of limited slip won't affect anything, he says. In fact I have never really been a big posi-track fan.
He also says it may improve my gas mileage as the gearing changes (to exactly what Doug said).
Can I just drop it in and go?
I am guessing it will affect the speedometer and what of the "traction control" button/light?

 

Going from a 3.27 to a 3.58 will reduce fuel econonmy by about 1 mpg at freeway speeds. I know, because I've done it . I didn't notice any change in city fuel economy.

The speedo runs off the left rear wheel speed sensor so you don't have to worry about your speedometer readings.

And, yes, you can go with non-limited-slip. I was lucky enough to find a 3.58 limited slip....but if you don't care, the car won't care, including the traction control system

Cheers
DD

 

Are you saying that all XJR/6 came with a 3.27 traction-lok?

 

Yes.

Well, let me rephrase.

The 3.27 limited slip was standard issue on all XJR6s. Perhaps a person could've special ordered an alternate ratio. I dunno.


Cheers
DD

 

Thank you very much Doug!