Check Limited Slip Differential (LSD) Performance from T-285 TRD 2-way for Toyota Corolla AE86 Levin / Trueno
11th April 2004 Sunday
One of the way to check the LSD performance is to measure the torque required to break traction between the two wheels.
First stuck one side of the wheel dead / un-turn-able / firm then use a torque wrench to turn the opposite wheel. Use low torque value to start with.
It is found that the LSD under study has a bit of a slack before LSD gripping. 1/4 of the wheel manages to turn before the opposite wheel will lock in synchronization to the active wheel. Due to this, the torque wrench needs to be turned fast instead of slow. Else it will not click consistently and may give rise to doubt of LSD locking torque value.
If the torque wrench click, it means the LSD is able to hold the two wheels together against "that" torque value set on the torque wrench. If so, please proceed with higher torque values until the torque wrench does not click, where it is able to turn one wheel against the LSD resistance.
Mine was found to be 50 lbs/ft. Then 60 lbs/ft was tried and it could turn against the LSD resistance. It would not click regardless of fast wrench turning or slow. It is then reduced to 55 lbs/ft and found the torque wrench to click at fast turning action, while the LSD hesitated to lock on slow turning action. So, it is assumed to be performing around 55 lbs/ft.
This is not exactly 100% accurate because we were lazy. The torque wrench is turning using one of the lugs, instead of true center of the drive shaft. Still this is some measurable difference / record for future study / references, which is better than none.
This torque value is known as the LSD pre-load effect / setting. Different situation / road condition / track races / gravel / tarmac / hill races will required different setting. However I am not an expert in this field so I do not know how much to use for what purposes. You will have to find out via trial and error.
That is if you are hard-working enough to take out the LSD diffential, disassemble the entire unit, change the clutch thickness or change the spring rate or insert a washer to pre-load the spring harder.
According to Bill Sherwood, OEM LSD should be around 20 lbs/ft. This LSD under study is way better than what he anticipated from what I always tell him as a OEM LSD.
Since the gadget to pull the drive-shaft out is missing, loan by another workshop, hence the differential cannot be removed as well as bearings cannot be replaced :(
Call it a day ........
LSD replacement clutches & springs left to the mechanic with verbal instructions, as well as visual instructions and left over the printed manual from internet. So of I go :(
At home ............... nah ........... can't let it go in my heart. Taking a emergency leave tomorrow to come back to workshop to make sure ......... :)
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