DMS Posted May 24, 2002 Share Posted May 24, 2002 Just when I thought I was ready to sort out the rear suspension after deciding what to do about the fuel pipe I've struck another problem. I ordered a LSD and this is what the invoice states but I have no idea how to verify that what I have is a LSD as opposed to the ordinary variety. I've heard that a simple test is to turn one of the output flanges and the other should turn the same way (or the opposite way if you have an ordinary diff). I tried this. I turned one and the other seemed to go in the opposite direction, i.e. standing on side A the output flange turns clockwise and standing on side B the other output flange also goes clockwise. Have I got an ordinary diff or am I worrying myself unnecessarily? Quote Link to comment Share on other sites More sharing options...
tomo Posted May 24, 2002 Share Posted May 24, 2002 You were right first time. Both should turn the same waywhen looking from one side if its a LSD. Tomo Quote Link to comment Share on other sites More sharing options...
ian crocker Posted May 24, 2002 Share Posted May 24, 2002 Depends what sort of LSD you have. With a Quaife they will both turn in the same direction and if you hold one still you will not be able to turn the other. I'd guess that a plate type would do the same ? The viscous LSD from the Sierra will probably behave like an open diff if you turn it by hand as it IS an open diff until the oil gets heated up by slip between the plates and it starts to lock. I think the Haynes manual has a test procedure for the Sierra unit that involves jacking up one wheel and using a torque wrench on the other. If it is new you are worrying unnecessarilly. If it is second hand then, yes, I have heard of a number of people who have bought 'LSDs' only to find later that they have an open diff! Ian Quote Link to comment Share on other sites More sharing options...
JamesD Posted May 24, 2002 Share Posted May 24, 2002 DMS, I believe you are right and it looks like you have an ordinary diff However I would wait and check that this can be verified by some of the wiser members of the forum. Best 'o' luck JD Quote Link to comment Share on other sites More sharing options...
rkenyon Posted May 24, 2002 Share Posted May 24, 2002 If it's new, check the number on the little metal plate attached to the casing, I beleive you can tell from the code on the plate whether it is LSD or not..... Can't remember what the code for LSD is, though! Someone must remember..... Quote Link to comment Share on other sites More sharing options...
steppenwolf Posted May 24, 2002 Share Posted May 24, 2002 Even with the Sierra LSD (filled with oil), if you turn one of the flanges anti-clockwise, the other should turn clockwise when looking onto each flange face on i.e. if you turn one of them in a direction and imagine that the flange in driving the car along, the other flange should look as though it too is driving the imaginary car in the same direction. If I imagine hard enough, I can see fairies at the bottom of my garden .... Quote Link to comment Share on other sites More sharing options...
David_East Posted May 24, 2002 Share Posted May 24, 2002 Steve? I not only had to imagine hard, but think hard after that description You are right of course Got your message last night (well this morning actually) but didn't think you would appreciate a reply at 1:30 a.m. I gather from the postings you got your question answered If not, how can I be of assistance Quote Link to comment Share on other sites More sharing options...
JimNoble Posted May 26, 2002 Share Posted May 26, 2002 I have to agree with what Ian says - I have a 4.09:1 viscous LSD (ie standard speedsport item), and it does not behave in the way you would expect a LSD to behave. I think this makes sense though - if the propshaft flange is held stationary, the two wheels are connected both through the diff, and the viscous coupling. In which case, the wheels are more likely to turn in opposite directions, surely? (The viscous coupling can slip, but the diff cogs can't) It is quite difficult to turn the diff like this on mine, presumably because the viscous coupling is resisting the difference in wheel speeds? If the propshaft flange is allowed to move, the other wheel on mine will either turn slowly in the same direction, or not turn at all (and the propshaft [flange] rotates)... Jim Quote Link to comment Share on other sites More sharing options...
juansolo Posted May 27, 2002 Share Posted May 27, 2002 If it is second hand then, yes, I have heard of a number of people who have bought 'LSDs' only to find later that they have an open diff! This happened to me and I was not very happy about it in the least. To identify whether you've got one, try the donut test. Find a nice big area of tarmac, turn the front wheels and boot it. If your inside wheel is spinning and you are driving round in a circle then no LSD. If you spin the car round on the spot then you have one. Best way to check though is to open the casing and take it out... If it's open you'll be able to see the 4 cogs in the diff, if it's an LSD it should look like a cylinder. This is certainly the case with the Quaife ATB and Tran-X plate diffs anyway. Quote Link to comment Share on other sites More sharing options...
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