Auto lockers are, in fact, locked at all times until one wheel overspeeds the crown wheel.
if at times they allow one wheel to rotate at a different speed to the other then by the very definition they are not "locked all the time"? and do in fact give a limited amount of "slip" to one wheel? be it in the case of something like a lockright its a mechanical, ratcheting type of "clutch" somewhat like a dog clutch? where as you are right that an after market nissan diff is very similar but rather than the ratchet type arrangement they use clutch packs.
the way i understand them is the similarities comes in the way they achieve the locking where they both use the pinion shaft to apply pressure to the clutch arrangement (in both the dog clutch and plated clutch setups) which is what forces the diff to lock?
Gwagensteve wrote:
Nissan LSD's are ramp loading and an excellent design but still operate as a differential, but with limited slip. They aren't able to 100% lock.
they absolutely can and do lock if that how you have them set up. even under a standing start, normally paced, full lock u turn my car always binds up and usually end up having to either give the wheels a chirp or if your lucky and on something slippery the inside wheel will skip.
I posted this video before for Steve, but he still doesn't grasp the concept.
hahaha why does this not surprise me? ive had very similar experiences on other forums. the very last time i posted on a very well known car forum was when someone asked a fairly simple question about diff removals and the day before i had done exactly what he was asking on THREE separate vehicles (swapped diffs between the 3). i explained very clearly exactly how it was done and 90% of the forum members told me that it could not be done that way......... even tho that was exactly how i had just done it.......
the sad thing about the internet is that everyone gets an equal weight to their opinion..... no matter how poorly thought out, uneducated and simply wrong that opinion really is.....
I posted this video before for Steve, but he still doesn't grasp the concept.
hahaha why does this not surprise me? ive had very similar experiences on other forums. the very last time i posted on a very well known car forum was when someone asked a fairly simple question about diff removals and the day before i had done exactly what he was asking on THREE separate vehicles (swapped diffs between the 3). i explained very clearly exactly how it was done and 90% of the forum members told me that it could not be done that way......... even tho that was exactly how i had just done it.......
the sad thing about the internet is that everyone gets an equal weight to their opinion..... no matter how poorly thought out, uneducated and simply wrong that opinion really is.....
Joined: Wed Apr 03, 2013 9:37 pm Posts: 50 Location: Darwin
Vehicle: 1995 Sierra
Posted: Fri Mar 25, 2016 10:30 pm
the problem here sounds like what you're defining as a 'locked' differential. a differential (in automotive applications) allows the inside and outside wheels to travel at different speeds, where it gets confusing is the actual mechanical function. if you were to take the average speeds of the inside and outside wheel travelling around a bend, it would be equal to the speed of the input shaft on the differential (this is the mechanical definition of a standard open differential). An LSD operates much the same except with the addition of clutch packs to limit the amount of 'slip' between the two wheels. An auto locker acts like neither. By design one wheel is always engaged or 'locked' to differential, and the differential input shaft turns at the speed of that wheel, the other wheel is over driven by the torque it generates which is what causes the characteristic clicking as the clutch engages and disengages. Before anyone says 'hey you just said that outside wheel disengages therefore its not locked', the differential itself is still locked to the inside wheel, and only turns as fast as that wheel.
Joined: Sun Sep 18, 2011 11:23 pm Posts: 256 Location: Maroochydore Sunny Coast
Vehicle: SWB Vit
Posted: Sat Mar 26, 2016 7:20 am
Find a steep hill in rwd, flex out, so one rear wheel is holding the car. Engine off, car in gear, remove handbrake. If the diff is always locked it will stay there.
I understand precisely why you hold the diff is unlocked, because there's no torque to apply load to the couplers when the diff isn't being powered. I don't accept that definition. The default position of the differential is locked, regardless of how much torque is being applied to the couplers by the cross pin. Only torque applied to the coupler from the axle can unlock the diff, and that torque must overcome the spring tension IN ORDER TO UNLOCK THE DIFF
That's visible in every photograph of an auto locking diff, it's apparent when you operate one manually on a bench, and it's apparent when you drive I car with one fitted. As I have stated before, if your position was correct, an auto locker wouldn't exhibit the negative traits they do.
So, despite understanding your position, I don't and will not agree with it. It's functionally incorrect and confusing. If the locker did not have springs the keep it locked, Id be more willing to entertain your view, but they don't function without the springs that keep the diff locked.
I typically wouldn't bother with a reply and didn't intend to, but your continued attempt to demonstrate your superior knowledge on this topic, despite the fact it will do nothing but confuse, demands it.
Sorry Steve, but you're still incorrect. If you still think 4 little springs can hold the diff 'locked', we've got some work ahead. As I've stated before when I tried to educate you on auto lockers, the springs are the to merely hold the clutch in place so they are not floating or chattering in the diff housing. The force of those springs can be easily overcome by barely using any force and rotating the wheel by hand. The clutches are forced into any usable locking ability only by load applied by the cross pin.
And this negative trait you keep mentioning on slick roads. Mate, that is their primary job. To lock both axles on low traction surfaces!!! The little auto locker buried inside the diff housing doesn't know if you're on a wet road, or bogged sill deep in mud. It's job it to lock both axles on low traction surfaces and that's what it does. Now you may say where's the open diff action when going around a corner in the wet or something. If you know how to drive with an auto locker which some may not, you wont have such a problem. Most people come straight from a open centre diff vehicle, chuck in an auto locker in and expect it to handle exactly the same around a corner, well it doesn't. You need to float or coast (so yes have some accelerator) the vehicle around the corner, this will de-energise the cross pin and allow the load of the clutches and then allow differential action. As long as there is enough traction to be had.
No most new people to auto lockers would go into a corner as per normal, back off the accelerator (as you would normally do to be safe in the wet) and guess what, the cross pin then rotates back, ramps up and engages the clutches from that deceleration. Then we people say 'Oh no, negative trait'. No that is called learn how to drive with the new piece of equipment in your diff.
And unlocking part is achieved by 'coasting' the vehicle around a corner and allowing the outside wheel to overrun the inside, wheel therefore taking load off the cam gear and clutch on that axle and allowing diff action on that wheel.
It's not about attempts to demonstrate superior knowledge, it's all about the facts.
sadly some people will never admit they are wrong even in the face of overwhelming evidence, i gave him a chance to explain to me how i was wrong originally and how different an auto locker is to a nissan type mechanical LSD which ive had quite a bit of experience with and not only did he fail to do so but his very explanation proved my point that they are more similar than they are different.
oh a different note, a bit of testing trying to embed my YT link above.... bear with me.
The force of those springs can be easily overcome by barely using any force and rotating the wheel by hand.
i would also like to point out that in a mechanical lsd you can NOT turn the wheels independently by hand, so in fact they are far more "locked" than a mechanical locker is to begin with.
but within all this i think my original point was probably lost, that using different oils has had the effect of making the clunking associated with mechanical diffs all but non existent and is worth thinking about if OP wanted to keep his locker. every brand of mechanical LSD who has changed to different oils has found that it effects the mechanical thumping in the diffs so its not just some coincidence that ive had in the 2 nissans i currently own with mechanical lsd's, even guys with toyotas have had similar experiences.
and the other thing still stands that if you wish to sell your locker if your sick of it, give me a yell im willing to give it a try (assuming it fits a coily diff, only had my coily a couple of weeks so much to learn about yet)
Joined: Wed Apr 03, 2013 9:37 pm Posts: 50 Location: Darwin
Vehicle: 1995 Sierra
Posted: Sat Mar 26, 2016 10:15 am
when the locker is over driven on one side the springs compress and force the two halves of the locker together, this physically prevents the clutch on the opposite side of the locker from disengaging, which is why they are never truly unlocked. i jacked my car up this morning and tried it just to prove my point, i can freely spin one wheel any which ways and the locker engages and disengages as it should, but the other wheel cannot move independent of the diff center. the comment above about ramping the rear, putting the car in gear and letting it roll away, auto lockers do that. As gwagen said, when torque is not applied by the diff center one wheel can over speed the diff center if it applies torque to the center, allowing the car to roll back, but the differential itself is still locked to the other wheel.
Joined: Wed Apr 03, 2013 9:37 pm Posts: 50 Location: Darwin
Vehicle: 1995 Sierra
Posted: Sat Mar 26, 2016 10:27 am
that second video posted explains what has been said before, as one wheel is over driven, the two halves of the locker are forced together, and hence it becomes physically impossible for the other wheel to disengage from the diff center.
Sadly, that video is misleading because it implies the clutches sit away from the couplers at rest, which they don't.
So you still think those fairy springs have the ability to hold an axle locked? They are only resting against the clutches. Like I said there is no usable locking ability applied with those little springs. What about the awesome part where the pin forces itself on the cam and 'locks' the auto locker, did you happen to miss that bit?
that second video posted explains what has been said before, as one wheel is over driven, the two halves of the locker are forced together, and hence it becomes physically impossible for the other wheel to disengage from the diff center.
Yes exactly, the under-run axle will continue to apply pressure to the clutch and remain locked.
Joined: Wed Apr 03, 2013 9:37 pm Posts: 50 Location: Darwin
Vehicle: 1995 Sierra
Posted: Sat Mar 26, 2016 10:43 am
i think im hitting my head on a brick wall here but ill try once more. the springs serve no function other than restoring the two halves of the locker when one side disengages. the locking force when the locker is 'disengaged' as you say it is, is applied by the two halves of the locker being forced together by torque from the over speeding wheel. the point is the differential itself is still locked to the other wheel, there is no physical way an auto locker can allow the two wheels to travel at speeds independent of the diff center, which is the definition of an open differential. when the diff center applies torque, it applies force to the cams which engage both sides of the locker.
Joined: Wed Apr 03, 2013 9:37 pm Posts: 50 Location: Darwin
Vehicle: 1995 Sierra
Posted: Sat Mar 26, 2016 10:50 am
DC3PTIKON wrote:
damø wrote:
that second video posted explains what has been said before, as one wheel is over driven, the two halves of the locker are forced together, and hence it becomes physically impossible for the other wheel to disengage from the diff center.
Yes exactly, the under-run axle will continue to apply pressure to the clutch and remain locked.
what do you mean 'under-run'? the inside wheel cannot physically travel slower or faster than the diff center when the other wheel is disengaged. by pressure im assuming you mean force since we are talking about differentials, the 'under-run' axle as you put it does not apply as much force as the outside axle. Why? force is mass x acceleration, the angular acceleration of the outside wheel is greater because its travelling at a higher speed, and hence that is the axle that disengages. this is assuming both wheels have traction however, as force is relative to friction coefficient of the surface. the force applied by the inside wheel has no effect on the whether it remains locked or not
The wheel on the inside of the turn, turning slower than the outside faster wheel. It you don't truly understand how an auto locker works, nothing I say is going to matter. Especially if it hasn't already with videos and all.
Joined: Sun Sep 18, 2011 11:23 pm Posts: 256 Location: Maroochydore Sunny Coast
Vehicle: SWB Vit
Posted: Sat Mar 26, 2016 11:35 am
Dan` wrote:
Gwagensteve wrote:
Nissan LSD's are ramp loading and an excellent design but still operate as a differential, but with limited slip. They aren't able to 100% lock.
they absolutely can and do lock if that how you have them set up. even under a standing start, normally paced, full lock u turn my car always binds up and usually end up having to either give the wheels a chirp or if your lucky and on something slippery the inside wheel will skip.
ozzycouch wrote:
Find a steep hill in rwd, flex out, so one rear wheel is holding the car. Engine off, car in gear, remove handbrake. If the diff is always locked it will stay there.
Question for you Dan, if your lsd 100% locks like you say it can, what happens with my example?
Question for you Dan, if your lsd 100% locks like you say it can, what happens with my example?
while the nissan diff is an LSD and can/will slip, you can add estra preload on the clutch plates so even before the mechanical forces work to lock it up even further they are effectively locked. bring that mine are in a road car not a 4x4 id not be able really do your test but it would depend on how much preload you have, how much traction you can keep on the grounded wheel and how steep of a hill you can put it on. with enough slope and enough grip you certainly could turn one wheel but i guess its all relative...... oh wait... you said car in gear.... ignore everything i just said haha. what i said would only apply without engaging the mechanical locking mech inside the diff. my explination above more applies to just the diff working but without the added force of the engine forcing more load onto the clutch packs...
with the car in gear it would be the same as engine breaking while driving which would definitely completely lock the diff and the elevated wheel would be just as locked as the wheel on the ground. my diffs are 2 way meaning they will lock both on acceleration as well as deceleration. you can also get 1.5way which fully locks on acceleration but only applies 1/2 as much force on engine breaking. a 1 way adds no more force on decel and only uses what ever preload you have on the clutch packs (which in its self is also something you can set to be as soft or stiff as you want)
hope that makes enough sense? im trying to do 5 things at once and sometimes something that is clear to me is as clear as mud in my explanations.
i didnt watch this all the way but i think goes into explaining it probably a lot better than i have.
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