XJ6 & XJ12 Series I, II & III 1968-1992

Diff question

 
  #1  
Old 11-13-2014, 01:34 AM
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Default Diff question

Goodmorning all.

Yesterday I bought a scrapper series 3. I still have to pick it up, but I have a question. The previous owner mentioned it had a limited slip diff.

I never looked into the diffs or so, but don't know if this is more or less common. And I also would like to know the ratios of the diffs, so if somebody could tell me?

The car is a 5 speed manual, which I also haven't seen too often over here. Most are automatic.

I am thinking of taking the whole rear piece, make it nice, and replace it with my current rear end. As I have brake discs that need to be replaced, but I cant miss the car too long. Fixing the one, and simply swapping will in my opinion consume less time in which I cant drive.
 
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Old 11-13-2014, 05:17 AM
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Limited slip is unusual on the Ser III 6 cylinder cars.

Since the car in question has the 5-speed (also unusual) it will likely have the 3.54 ratio.

Cheers
DD
 
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  #3  
Old 11-13-2014, 06:46 AM
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thanks for the reply. So the limited slip could be considered an upgrade, as it is very unlikely that my series 1 has it. (unless a previous owner had a go at it, a never took a close look at the diff yet)

the ratio is higher than the usual 3.01 (or 3.07) ratio for the series 1. That means lower revs at same speed right? that would also be a bonus for me, as I basically only drive on the highway.

so basically, considering what I want, it would be sensible to replace the diff.

I will keep you updated once I have the car.
 
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Old 11-13-2014, 07:03 AM
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Originally Posted by Wilfred88 View Post
the ratio is higher than the usual 3.01 (or 3.07) ratio for the series 1. That means lower revs at same speed right? that would also be a bonus for me, as I basically only drive on the highway.


No. Just the opposite.

If you have a 3.07 and switch to a 3.54, your revs will be *higher* at the same speed


Cheers
DD
 
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Old 11-13-2014, 07:04 PM
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I believe that some of the non US (non Federal) cars did come with a Power Lock differential..
I bought a Sovereign that was a grey market car originally from Belgium.. IIRC it had a locking 3:07 on it.. (may have been a 2:88)...
Also had an 87 Sovereign with a locking 2:88....

It's probably going to depend on the country of origin (destination market)... and could be a number of different configurations..
If it's a deal breaker for you, check the tags on the differential, seen here:
Jaguar IRS

Cheers
David
 
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Old 11-14-2014, 03:05 AM
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THanks for the replies. I will just have to wait and see what diff it has. It sure has a limited slip, but the ratio could make me doubt. I dont care about quick take offs, I'd rather have a sweet cruise at low revs and nice fuel economy.

I will get back once I have the scrapper.
 
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Old 11-14-2014, 09:36 AM
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Points"


1. As to quick takeoff's with a higher numerical ratio (actually lower), merely apply less throttle for the desired result.


2. Fun way to ascertain if the differential is limited slip or merely open. Do a burn out.
two nice black stripes = limited slip. Only one? Oh, open differential, a one legged car!! Too bad you can't do this one, unless the car is operable.


3. The not so fun way. Jack up both back wheels. Properly chocked. No restraints this way. Turn a wheel by hand. If the opposite wheel turns the same way, it is a limited slip unit.


Carl
 
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  #8  
Old 11-14-2014, 06:32 PM
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Originally Posted by Wilfred88 View Post
Goodmorning all.

Yesterday I bought a scrapper series 3. I still have to pick it up, but I have a question. The previous owner mentioned it had a limited slip diff.

I never looked into the diffs or so, but don't know if this is more or less common. And I also would like to know the ratios of the diffs, so if somebody could tell me?

The car is a 5 speed manual, which I also haven't seen too often over here. Most are automatic.

I am thinking of taking the whole rear piece, make it nice, and replace it with my current rear end. As I have brake discs that need to be replaced, but I cant miss the car too long. Fixing the one, and simply swapping will in my opinion consume less time in which I cant drive.
Give my eye teeth to find a manual series 3 scrapper!!! Shame you are not in England. I'd buy the gearbox and the rest of the bits to convert mine to a manual.
 
 
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