# QUESTION

'85 Suburban 4x4 w/ a 12bolt rear of mid to late '70's vintage with 3.08's and a Gov-Lock...
What is the rated speed of the diff(rpm) have to be to release the
'lock'? Also, how many revolutions is typical before the diff 'locks'?
Anyone know where I could find out, if no one knows that is...
BTW, I do know that a Gov-Lock is, more or less, a variable pressure limited slip. I know it doesn't LOCK...
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Your questions are a bit vague.....when you ask what does the rated speed of the diff have to be to release the lock....what does that mean? Your next question is vague too...are you looking for the speed differential between the two wheels in order for the diff to lock....or are you asking how many revolutions the spinning wheel must spin before it locks?
I'll hazard a guess as to what info you want...if it works for you, use it.
The first question makes no sense....unless you are asking at what speed (road speed) will the locking mechanism no longer lock in if you have one wheel spinning. I believe that above about 20 miles an hour it will not operate as a locking diff.
2nd question......the diff needs to see about 100 rpm difference between the two wheels before it locks. The locking action is almost instantaneous......I can make these locking diffs actuate on a hoist by just spinning one wheel by hand.....they will actuate within a half of a turn...if not sooner.
Ian
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I was told that at a certain speed of the vehicle traveling down the road, the locking mechanism will release so that it is no longer ratcheted to its maximum pressure. What is the speed, either speed of the tire, or RPM's of the diff?
For the diff to increase its pressure on the clutches, there is a certain number of revolutions that on one tire has to make more than the other tire. What is that number?

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its
tire.
I think I answered both questions in the previous post.
Ian
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of
certain
Yup, ya did, 20 mph and 100 RPM.
Doc

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Well mine must be totally lunched then! It seems to take about 2-3 revolutions of one tire before the other one grabs substantially. It doesn't seem to matter the speed. Everything was in great shape inside. Plenty of clutch surface, springs fine, ratchet teeth, everything! So what can be wrong? When it comes to releasing, 20mph seems to be pretty close!

to
RPM's
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It takes about 100 rpm DIFFERENCE in tire rotation speed to trigger the weight. I would say yours is working fine if the one tire has to turn a couple of times before it hooks up.
--
Steve W.

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