Search around for info on the Supra and IS300 diffs... Not sure if either would work, but that would be where I would start...

 

I think the problem here is one of paradigm.
Those that fail to understand what is being said feel compelled to condemn.

Some are suggesting that I somehow claim that this phenomena is equivilant to an engineered LSD...
I did NOT... and this phenomena is NOT.

Some are suggesting that I somehow recommend people abuse or fail to perform adequate maintenance on their car...
I did NOT and would NOT.
In fact I changed my diff fluid... but the condition manifested anyway.

Fact: ALL street legal cars utilize a differential and by design all differentials SLIP.
IOW, they allow one wheel to rotate at a different speed than the other as needed in cornering.

There are several LIMITED slip designs that REDUCE the possibility of one tire spinning in a "full" slip condition.

Some have indicated that it is normal for a powerful car with a standard "un-limited" slip differential to spin both tires given enough power is applied or low enough traction.
This is simply NOT the case.

The REASON is that it takes considerable power to break traction. When enough power is applied to overcome traction... keeping in mind that the standard diff applies torque equally to both tires UNLESS traction is lost on one tire... the reason... on a RWD car... is the TORQUE of the engine rotates/transfers weight in the direction of rotation. This CAUSES the drivers side tire to have more weight and the passenger side tire to have less weight applied. This is WHY for a powerful car with a un-limited slip differential the NORMAL situation when applying excessive power is for the passenger side tire to SPIN.

It was postulated by mitsuguy that possibly older cars with worn suspension would not have as much weight transfer. Weight transfers more violently in cars with loose suspensions. The more violently the applied torque causes the weight to transfer from the passenger side to drivers side the more likely it is for the passenger side tire to spin. So, this theory works against itself.

I have outlined a condition that OCCURS with the Toyota/Lexus differentials. It does NOT appear to be maintenance related. It has been reported by MANY. My personal car CHANGED from spinning one tire to spinning both. I have given a very reasoned explanation that I believe to be factual. What is FACT is that for a car to overcome the weight transfer that creates the loss of traction on one tire SOME limited slip action HAS OCCURED.

I am NOT claiming that this is equal to an engineed clutch type, cone type, torsen type or other LIMITED slip DESIGN... I am only claiming (with more than a little supporting evidence) that a change OCCURS with miles driven and that change creates BETTER traction DUE to LESS slip... IOW... LIMITED SLIP.

Anyone that feels otherwise is obviously free to comment.
I would HOPE that the comments would address my SPECIFIC reasons and NOT... without doing just that... suggest that I fail to understand the mechanical workings in question.
In FACT I do.

 

It is not a paradigm, it is just something you and a few others believe to be going on, most likely without fully understanding the mechanics behind differentials.


Amongst other claims you have made, this is simply not true at all. Locking differentials do not allow different rotational speeds under power, some do not allow different rotational speeds ever. The "automatic" lockers allow a tire to spin faster than it is being powered to spin, but not slower. This is not a "slip", this is simply allowing one tire to turn faster than the axle speed.

I'm not completely sure you understand how a Limited Slip differential works either. They don't reduce the possibility of one spinning faster than the other, they reduce the maximum amount of difference in speed. It is a function of limited slip that they have a difference in rotational speeds, but the difference will be generally small in a properly functioning LSD...


Actually, by your own admittance, it simply IS the case. Everyone that has posted unscientific "hey both my tires spin'' is proof positive that it is the case. There is no paradigm as you claim that as a differential gets old that it acts more like a limited slip differential. If there was, then it wouldn't be limited to straight line burnouts, it would be noticeable under all traction conditions.

On Independent Rear suspension cars, this weight transfer is not nearly as much as you make it out to be. On live axle rears, when one tire lifts for whatever reason, it is equivalent to using a 4 foot lever to change the entire drive axle angle. On IRS rears (like all of ours), the position of one tire has no effect on the position or drive axle angle of the other tire.

This is completely untrue, and I suggest you re-examine your theory. Weight does not transfer more violently, it may transfer farther, but not more violently. It is quite easy to see if you have ever driven a car with a very tight suspension. Go to a parking lot, slow speed, 10 mph maybe, and jerk the steering wheel 90 degrees one direction. With a tight suspension car, you feel an immediate jerk, followed by the rest of the turn. With a loose suspension car, there is no immediate jerk, instead the force of the turn is spread out through the first portion of the turn. It could be measured the same way an impact could. Same force applied, the faster the impact, the more violent it is, whereas the slower the impact, the less violent (would be measured in G's). Thus, the softer suspension is going to transfer weight SLOWER from side to side.

Its kinda like how polyurethane bushings actually work to make a car handle worse than factory bushings. Sure, they feel great when you drive the car, but, the added stiction that they induce means that the car will not handle as predictably, and at the same time, the added effort needed to rotate inside the bushings causes a harsher ride, as well as reduced traction. (here is a quick primer on why most polyurethane bushings are bad http://www.elephantracing.com/techto...nefriction.htm)

Again, not true at all. your car may have more of a tendency to spin one to both, but you have yet to explain the why. Because a) you do not know why and b) because it isn't happening to start. Open differentials have a tendency to want to spin both tires the same direction and the same speed. It is not a function of wear that causes them to do this, it is simply physics in action. To make one wheel spin faster than the other in an Open Differential, the planet gear(s) need to start turning. It takes some amount of unequal force for these to start turning. The amount, I do not know, but it could simply be a matter of loose suspension making the initial impact of a wheel spin situation much slower which makes it less likely for them to spin. Its the impact gun scenario. Apply the same torque with a standard socket wrench and you may not be able to loosen a bolt because you are easing in to it. Apply that same torque (or less) with an impact wrench and the bolt spins. Quick impact = spin, slowly applied force = less likely to spin. (Same reason automatic cars get off the line so well in comparison to an identical manual car, also same reason rear suspension is generally set up very soft for a drag racing car)

There is no supporting evidence whatsoever. I am yet to see one circular burnout, or a burnout in which one tire is on a surface with more or less traction than the other and the same results. This same "phenomena" as you call it, is not just limited to old Lexus' - it happens with all cars, both old and new

If you understand them so well, then perhaps you should go into more detail with a reason why open differentials do this, aside from just claiming they do as a fact. Pretend you are the lawyer trying to plead a case - we are the judge and jury. Even with your supposed "supporting evidence," if your case doesn't make sense and you can't make it make sense to us, we aren't going to be swayed your way.

 

http://www.rangerpowersports.com/for...ff-188358.html

http://www.dakota-durango.com/forum/...d.php?t=131090

http://mmb.maverick.to/showthread.php?t=44037

http://answers.yahoo.com/question/in...9180145AAtlBrI

http://forum.miata.net/vb/archive/in.../t-282693.html

http://ls1tech.com/forums/gears-axle...open-diff.html

Here is one that is exactly as you propose - he was convinced he had an LSD until he tested http://www.dodgetalk.com/forums/arch.../t-324339.html

This is a good one - he even mentions about the difference with independent rear suspensions... http://www.challengertalk.com/forums...p/t-61755.html

Every one of those threads (and there are hundreds more) speak of this two wheel peel on open differentials. The difference, however, is that they haven't tried to come up with some crazy explanation (Aside from mine being that if it is truly acting like a LSD that something is close to breaking)...

 

Cody, this is frustrating because you are smart AND you obviously want to ARGUE and you BELIEVE that I am wrong and therefore willing to make a large effort to PROVE me wrong.

Unfortunately your initial post had the line indicating that I was in some way IGNORANT about how differentials work. You removed it in an edit but you just can't seem to help it and put it in your last LENGTHY post. Kind of insulting don't you think? You are probably thinking "well, yes, but it is true"...

By making such a lengthy post it makes a LOT of work for ME to address EACH of your issues.
Since it is my thread and my reputation at risk here this somewhat forces me to respond or by default be deemed proven ignorant. As you have indicated opinion is not proof but it can look like it to the uninformed.

It is clear that you are NOT following what I am writing so I am going to break down my responses into smaller posts.

PLEASE address each point on its OWN merit and do not attempt to "win" your "case" with VOLUME. While many if not most will be won over by that strategy if you REALLY want to determine the reason for what is going on you will hold back on the personal degradation towards me and respond in the spirit of learning EVEN if in your opinion that learning is your effort to "help" me understand my errors.

I may take your positions out of the order you posted but I will try to address each one.

Fair enough? Let's try...

 

Ok, let's start here.
I will address your other concerns in later posts.
To EVERYONE that is following please refer back to my post #35 to understand why I am making this effort.


I stated "Fact: ALL street legal cars utilize a differential..."

This is a fact.

If we cannot agree to this simple point then I doubt we can make any respectful progress in a discussion.

Locking differentials, limited slip differentials, torque sensing differentials are all differentials.

Let's start by agreeing that the above is accurate.
This will show that we are communicating and that we are reasonable and creates an atmosphere of furthering knowledge.
A simple "yes, I agree is all that is needed.
That will set a non-argumentative tone and we can move to more complex parts of the discussion.
I will address the second part of my above quote in another post for discussion.

Please answer either "I agree" or "I disagree" on this one post.

 

too... much... info... (brain explodes)

 

As many times as I tried to write that I agree, I just can't. Put in some modifiers, "All cars come from the factory with differentials", and I would be more inclined to agree, but the way yours was and is worded, I can't agree with. There still may be some vehicles that do not, but I can't think of any right now...

I am not trying to belittle you, I promise, I just have a hard time when people claim something as fact without true supporting evidence. What we have is an effect, which is the perceived additional traction as a toyota ages, without a defined reason. You are putting a potential reason up and stating it as fact, but without proof. The claimed proof is the twin tire tracks, but that is not proof of your potential reason, instead it is proof of the original effect.

It would be the same as me saying that a front end shake when braking is caused by warped rotors. Because the front end shakes, the rotors must be warped. The actuality is that very rarely do rotors actually warp, instead the pulsation is caused by brake pad material building up. Without runout measurements, its hard to blame either. For your case, we need those measurements.

 

Cody, my nature is similar to yourself and I am inclined to make large explanations to cover all possible variables. That said we NEED to get some points of agreement to move this discussion forward.

Back to a relatively easy one.

Fact: ALL street legal cars utilize a differential...

Reason: The law requires it.

So, can we agree that all street LEGAL cars utilize a differential where the law requires it?
(as is the case in all 50 states + most of the world)

Agree or disagree?

 

To be honest, I'd like to see somewhere that it says that differentials are required. As an ex-Texas DOT safety inspector, it was not an item that we inspected or checked. I have never read nor heard of any law requiring one, or outlawing the use of a spool (which is not a differential). I would love to be proved wrong here, as it means I would learn something new, but I can't find a thing on it anywhere. I also can imagine street legal vehicles in the near future with no differential, drive shaft, or even conventional axle at all, though that is obviously not present day.

 

I also thought it would be easy to search for the legal code but that proved not to be the case.

I am 50 years old and all my life have always heard and taken as accurate that this is NOT legal.
Street driving a locked differential, welded or spool, is HIGHLY dangerous.
For something highly dangerous to be legal would be hard to imagine.
I also do not like to spread disinformation (which ironically is what I am being accused of here) so I will follow up on the subject and report back... MOVING ON.

I have been TRYING to achieve even the slightest bit of agreement between us... so far without luck. You wanted to agree but then felt that MAYBE somewhere some street legal car does not utilize a differential. Does that really matter to THIS discussion?

How about THIS...
For the MOST PART all street legal cars utilize a differential. Easy right? (should be)

 

Ok, hopefully Cody will be able to agree with the above.

The second part that may have caused him to denounce me was...

Fact: ALL street legal cars utilize a differential and by design all differentials SLIP

So, WHAT is SLIP?

Most jump to the obvious, tire slip. Yes this is slip BUT it can only occur if the differental slips.
This SLIP is the case, side and pinion gears moving relative to each other.
If this does not happen there is no slip.

The ring gear powers the case, the pinion shaft takes the case power to the pinion gears, (often called planet or spider gears), the pinion gears power the side gears, the side gears power the axles.

Since the pinion and side gears intersect with a bevel as power increases the force THRUSTS the gears away from each other.
They can only move a very tiny amount as there is a thrust washer between each of the 4 gears and the case.
Still, this increases friction between the gears, the thrust washers and the case.
The higher this friction the more resistance is created to SLIP.

Since an open differential is designed to allow SLIP and allow the differential action it is consider "open" but nevertheless SLIP is still occuring.
This is why I used the term UN-limited slip which is a reasonable term in for this discussion.
Open differentials are designed to allow UN-limited slip. Still, they do SLIP.
Limited SLIP differentials also SLIP but the action is LIMITED which decreases the chance of one axle free spinning.
This friction and relative slip resistance in an open differential is desirable.
If it were not there would be thrust BEARINGS instead of thrust WASHERS.

 

I just don't like agreeing with something I am not completely sure of. I have heard this same before - that cars are required to have differentials, but, lets be honest, would a spool really be that unsafe on the street? I've driven cars with them and they have been fine - uncomfortable around tighter turns, and you have to be careful with the throttle when its slick, but, no problem to me at all... I have read before that they are illegal, but have never found anything stating that specifically, nor even seen a spool marked as for off road use only.

But yes, I will definitely agree with that...

 

I agree with all of that, with one caveat - Limited slip doesn't decrease the chance of an axle free spinning, it decreases the maximum amount of difference in axle speed from one side to the other. Depending on the condition of the differential and its original design, they can be designed to allow virtually no maximum difference in axle speed, or 10-20% or more maximum difference in axle speed...

At the same time, what you are saying is that friction against the thrust washers is needed to be overcome in order for the open differential to spin one wheel faster. I agree with that. What I don't agree with is that as a differential ages that this friction increases so much to the point that what was once an open differential, now acts like a limited slip differential...

 

Cody, thank you for taking the time and effort to read and now agree with certain points as you have indicated above in your posts #43 and #44.

Let's continue and see where we get.

I took my LS400 to the drag strip, formerly Houston Raceway Park, multiple times when the vehicle had less than 50K miles. This was an excellent facility with a nicely prepared racing surface designed to optimize traction for racing. If there is a flat, dry, smooth surface available anywhere that is likely to provide equal traction to my car this track would be it.

With the VSC turned off the electronic throttle on my car is diffcult to modulate and once traction was lost it would flash the tire and I would have to completely lift off the throttle pedal to stop it and the run was lost. Trying and testing to get the best 60 foot times possible had several runs lost to this uncontrolled tire spin. One tire only. Best 60ft was 2.18 seconds which is mediocre. Best run of 14.22 ET was done on a 2.19 60ft. With more traction the car does/should have the power to run a 2.00 or better 60ft. This should have resulted in a 13 second pass for my car on the 14.22, the two 14.23 runs I made that night. If ONLY I had the traction of a limited slip I felt that I could have recorded 13 second runs. With just the one tire loosing traction and spinning I could not manage any better times.

I purchased what was supposed to be a TORSEN differential from a 1998 Supra TT automatic (3.769 ratio) from a respected (at the time) Supra tuner. When I removed the cover I was highly disappointed to find a standard differential. I requested to return it and he vehemently argued that it was in fact a TORSEN and claimed among other "proof" that it spun both tires at the drag strip.
After much back and forth he finally refunded my purchase.

As I have stated and posted pictures my car no longer spins one tire on straight drag racing launches. It spins both. Every time for as far as I have been able to test. So, something has changed on my car. Mine is not alone. The above Supra diff situation lead to much online discussion and many Lexus owners reported the same phenomena. The Supra differential did have a fair amount of fine silt in its fluid. Otherwise the gears were pristine and the unit turned without noise or excessive resistance. So I have personally examined, but did not take runout or clearance measurements on or of, a Toyota differential that exhibits the phenomena that I have been referring to here.

So, I have empirical test data on my personal car indicating that something has changed from a single tire loosing traction to both tires loosing traction on hard acceleration on smooth, dry, flat, equal traction surfaces. This condition IS a LIMITED slip condition. I have not claimed this is equivilant to an engineered LSD. BUT... still for the situation that is being tested and observed... my differential is now performing as a limited slip device.

WHY and WHAT has changed?

Other than "all IRS" cars do this... which is not and has not been the case with my car... the only theory offered other than mine is that the suspension has loosened and changed the rate of weight transfer. We can explore that thought further but IMO it does not seem as likely as the dominant cause as what I propose.

The thrust washers between the side gears and the case and the spider gears and the case create a specific clearance that is confirmed with a backlash measurement. It is clear that over time these washers will exhibit wear as they slip between the case and gears during cornering. It is highly likely the silt that I described is the worn material from these washers as the gears and bearings are much less likely to shedding material while remaining pristine and in good operation.

As the thrust washers wear they will change the clearance and the beveled pinion and side gears will be able to thrust further away from each other. This changes the point of contact of the gears and could well be increasing the force of the thrust. This action, just like in a clutch type LSD, would likely increase the friction between the washers, gears and case which in turn increases the RESISTANCE to slip between these components. This hypothesis would include and explain how the action on my car (and others reported) would change from allowing full slip of one tire on launch (previously) to LIMITING the slip on launch. This hypothesis is fair and likely the factual explanation. HOWEVER, even if some other variable is contributing or is the overriding cause of my car going from unlimited to LIMITED slip during "drag racing" launch situations the FACT remains that the differential in my car, for THIS situation only, NOW functions as a LIMITED slip differential.

This was and is ALL I claimed and as stated is a FACT.

So, over time, with wear, something changes and under "drag racing" type launches, the Lexus differentials in the covered models herein exhibit an increase in their limiting of slip. Any contribution of weight transfer, while worth examining to fully understand the variables, does not change the facts. My theory on why and how the differential action could be/is changed with wear of the thrust washers is solid and is the likely dominant reason for the condition. So, fact, what once was an unlimited slip situation (drag race launches) is now a limited slip situation and that can only be true if the differential is limiting the slip.