15 replies to this topic

[warning634]

I will be upgrading my current diff to something more modern, any ideas what these jack knight lsd are worth?

Coming out of a working gearbox, with no issues.

Cheers kevin

[nicklouse]

I know what I paid for a used one 20 years ago. but no idea of values now. the biggest issue is wear.

[warning634]

I know what I paid for a used one 20 years ago. but no idea of values now. the biggest issue is wear.

When I bought this engine, it had the receipts from jack knight ;) a few hundred quid? If it's in good condition, would you say?

[Northernpower]

How much wear has it got on it?

[warning634]

How much wear has it got on it?

Unsure as it's still in the gearbox, it is working very well as it's very aggressive in its action, so I assume that it's not got much wear. This jack knight dog box was fitted at the same time as the diff, and it's still in very good condition.

[Northernpower]

 

How much wear has it got on it?

Unsure as it's still in the gearbox, it is working very well as it's very aggressive in its action, so I assume that it's not got much wear. This jack knight dog box was fitted at the same time as the diff, and it's still in very good condition.

 

To find out how much wear it has, you need to measure the resistance torque on the output shafts. Others on here will know what figure you're looking for and I know its not as high as you would think but IIRC it should be somewhere in the region of 15Ftlbs (but I'll stand to be corrected on that figure)

[nicklouse]

 

 

How much wear has it got on it?

Unsure as it's still in the gearbox, it is working very well as it's very aggressive in its action, so I assume that it's not got much wear. This jack knight dog box was fitted at the same time as the diff, and it's still in very good condition.

 

To find out how much wear it has, you need to measure the resistance torque on the output shafts. Others on here will know what figure you're looking for and I know its not as high as you would think but IIRC it should be somewhere in the region of 15Ftlbs (but I'll stand to be corrected on that figure)

 

so how does that work on a cam and pawl diff (a locking diff)?

[Northernpower]

 

 

 

How much wear has it got on it?

Unsure as it's still in the gearbox, it is working very well as it's very aggressive in its action, so I assume that it's not got much wear. This jack knight dog box was fitted at the same time as the diff, and it's still in very good condition.

 

To find out how much wear it has, you need to measure the resistance torque on the output shafts. Others on here will know what figure you're looking for and I know its not as high as you would think but IIRC it should be somewhere in the region of 15Ftlbs (but I'll stand to be corrected on that figure)

 

so how does that work on a cam and pawl diff (a locking diff)?

 

As far as I am aware the slippage is designed in to a set figure, so therfore, it can't be adjusted. Why do you think it can't be measured?

[nicklouse]

 

 

 

 

How much wear has it got on it?

Unsure as it's still in the gearbox, it is working very well as it's very aggressive in its action, so I assume that it's not got much wear. This jack knight dog box was fitted at the same time as the diff, and it's still in very good condition.

 

To find out how much wear it has, you need to measure the resistance torque on the output shafts. Others on here will know what figure you're looking for and I know its not as high as you would think but IIRC it should be somewhere in the region of 15Ftlbs (but I'll stand to be corrected on that figure)

 

so how does that work on a cam and pawl diff (a locking diff)?

 

As far as I am aware the slippage is designed in to a set figure, so therfore, it can't be adjusted. Why do you think it can't be measured?

 

well lets just say Mine does not slip when underload. it only slips when under light load. but again i have heard people say they are twitchy, never noticed but again in hill climbing you are either on or off the power. what i do notice is having to lift off before a corner to allow the car to steer. more so when it was in the GTM as it would want to push me off Farmhouse bend.

[Northernpower]

 

 

 

 

 

How much wear has it got on it?

Unsure as it's still in the gearbox, it is working very well as it's very aggressive in its action, so I assume that it's not got much wear. This jack knight dog box was fitted at the same time as the diff, and it's still in very good condition.

 

To find out how much wear it has, you need to measure the resistance torque on the output shafts. Others on here will know what figure you're looking for and I know its not as high as you would think but IIRC it should be somewhere in the region of 15Ftlbs (but I'll stand to be corrected on that figure)

 

so how does that work on a cam and pawl diff (a locking diff)?

 

As far as I am aware the slippage is designed in to a set figure, so therfore, it can't be adjusted. Why do you think it can't be measured?

 

well lets just say Mine does not slip when underload. it only slips when under light load. but again i have heard people say they are twitchy, never noticed but again in hill climbing you are either on or off the power. what i do notice is having to lift off before a corner to allow the car to steer. more so when it was in the GTM as it would want to push me off Farmhouse bend.

 

Like Rich Hawcroft.

[nicklouse]

 

 

 

 

 

 

How much wear has it got on it?

Unsure as it's still in the gearbox, it is working very well as it's very aggressive in its action, so I assume that it's not got much wear. This jack knight dog box was fitted at the same time as the diff, and it's still in very good condition.

 

To find out how much wear it has, you need to measure the resistance torque on the output shafts. Others on here will know what figure you're looking for and I know its not as high as you would think but IIRC it should be somewhere in the region of 15Ftlbs (but I'll stand to be corrected on that figure)

 

so how does that work on a cam and pawl diff (a locking diff)?

 

As far as I am aware the slippage is designed in to a set figure, so therfore, it can't be adjusted. Why do you think it can't be measured?

 

well lets just say Mine does not slip when underload. it only slips when under light load. but again i have heard people say they are twitchy, never noticed but again in hill climbing you are either on or off the power. what i do notice is having to lift off before a corner to allow the car to steer. more so when it was in the GTM as it would want to push me off Farmhouse bend.

 

Like Rich Hawcroft.

 

more like Matthew

[nicklouse]

Oh i still would like to know how one measure one for wear other than taking it out and measuring bits. as it would be very good to know.

[Northernpower]

Oh i still would like to know how one measure one for wear other than taking it out and measuring bits. as it would be very good to know.

My understanding was you find out what the original factory slippage is before locking, in Ftlbs. You put a torque wrench on one of the output shafts (using a double nut to lock on the end of the drive shaft) while locking the other and measure the torque.

EDIT: The last time I did this was in the 70's. As an aside, most experts said this style of diff was more suited to rear wheel drive.

Edited by Northernpower, 25 October 2017 - 11:35 PM.

[nicklouse]

yep i know that is what the experts say so why did it take the experts that long to beat the metros time?

 

in the front i loved it it would just pull you round the corner (more lock and more power) while in the back you could not be as aggressive or it would push you off. would never put it on the road though.

[Northernpower]

yep i know that is what the experts say so why did it take the experts that long to beat the metros time?
 
in the front i loved it it would just pull you round the corner (more lock and more power) while in the back you could not be as aggressive or it would push you off. would never put it on the road though.

I'm having to remember from a long time ago, I think it's because they're not adjustable it's difficult to fit the exact one for the specific car (matching up to the overall vehicle weight and the engine output torque) and very often the wrong one is fitted. This makes them lock very easily instead of gradually transitioning from free running to fully locked. The consequence of this is, they throw you into the scenery.

We had one in our Twin Cam Escort and it was aggressive in its transition, but very predicable.