Discussion
Hi,
I was wondering if anyone might be able to offer advice regarding the Sierra XR4x4 LSD which I have fitted to a Fisher Fury which I am currently trying to build.
I have been trying to take the measurements which are needed to calibrate a mechanical speedo. This is the cardboard disc test, which involves raising the back end of the car, rotating the rear wheels, and measuring the resulting rotation of the speedo cable. While tuning one rear wheel, I noticed that the other did not seem to be keeping up. One revolution of the wheel I was turning resulted in approximately 3/4 of a turn on the other side. I also noticed that if one wheel was turned slowly enough, the other did not rotate at all.
Does this sound normal, or do I have a worn out friction coupling (or whatever it's called) in the LSD? The diff was purchased from a breaker, so it's not possible to say what kind of a previous life it has had.
Thanks for any help.
I was wondering if anyone might be able to offer advice regarding the Sierra XR4x4 LSD which I have fitted to a Fisher Fury which I am currently trying to build.
I have been trying to take the measurements which are needed to calibrate a mechanical speedo. This is the cardboard disc test, which involves raising the back end of the car, rotating the rear wheels, and measuring the resulting rotation of the speedo cable. While tuning one rear wheel, I noticed that the other did not seem to be keeping up. One revolution of the wheel I was turning resulted in approximately 3/4 of a turn on the other side. I also noticed that if one wheel was turned slowly enough, the other did not rotate at all.
Does this sound normal, or do I have a worn out friction coupling (or whatever it's called) in the LSD? The diff was purchased from a breaker, so it's not possible to say what kind of a previous life it has had.
Thanks for any help.
I stand to be corrected by more experienced members, but I would expect the results you would get for a limited slip diff: the slow manual movement of the diff would not be enough to lock it, therefore it would be meaningless.
Not quite sure how you would measure the effectiveless of the diff with a LSD!
Not quite sure how you would measure the effectiveless of the diff with a LSD!
The LSD fitted to Sierra XR4x4's should be a viscous type and not a plate type, so there are no parts to wear in the diff. Do the wheels turn in the same direction when one of them is rotated? They should do.
I've got the same diff sat on my workbench in the garage waiting to go in my Westy, I can't turn one drive flange and keep the other stationary.
There normally is a tag with a number stamped in it bolted to the back of the casing. This number can be cross referenced to tell you whether it is an LSD.
Try Mitchell Cotts Transmissions - www.gearboxes.com or Gripper Diffs.
Warren
I've got the same diff sat on my workbench in the garage waiting to go in my Westy, I can't turn one drive flange and keep the other stationary.
There normally is a tag with a number stamped in it bolted to the back of the casing. This number can be cross referenced to tell you whether it is an LSD.
Try Mitchell Cotts Transmissions - www.gearboxes.com or Gripper Diffs.
Warren
Interestig that the XR4x4 diff is a viscous type LSD. I didn't realise that.
When I turn one wheel, the other does turn in the same direction so I'm confident that my diff is an LSD. Before fitting, I did find that I could hold one drive flange still and turn the other. Now that I have wheels on each end, this can be achieved quite easily. However, perhaps this is simply due to the fact that with the very low relative speeds produced when turning by hand, little viscous force is generated.
Regarding the speedo calibration, I followed the instructions which came with my ETB instruments. I overcame the problem of one wheel not keeping up with the other by asking my wife to complete the revolution of the 'dragging' wheel each time I made 1 revolution of my wheel. This is just the sort of involvement with my kit car build that she craves, but after an hour or so her patience was wearing a bit thin! Anyway, I was hoping that ETB would make some allowance for the tyres deforming under the weight of the car. Following your suggestions, maybe I should check this.
Cheers,
Richard
>> Edited by rtasker on Monday 10th January 13:07
When I turn one wheel, the other does turn in the same direction so I'm confident that my diff is an LSD. Before fitting, I did find that I could hold one drive flange still and turn the other. Now that I have wheels on each end, this can be achieved quite easily. However, perhaps this is simply due to the fact that with the very low relative speeds produced when turning by hand, little viscous force is generated.
Regarding the speedo calibration, I followed the instructions which came with my ETB instruments. I overcame the problem of one wheel not keeping up with the other by asking my wife to complete the revolution of the 'dragging' wheel each time I made 1 revolution of my wheel. This is just the sort of involvement with my kit car build that she craves, but after an hour or so her patience was wearing a bit thin! Anyway, I was hoping that ETB would make some allowance for the tyres deforming under the weight of the car. Following your suggestions, maybe I should check this.
Cheers,
Richard
>> Edited by rtasker on Monday 10th January 13:07
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