How easy to launch car with non-posi rear?

[bison]

It remains equal till one wheel slips? Unless absolutely EVERYthing was perfect. Plumb and square roads, with zero rocks, no road crown, no water, precisely the same PSI in each tire, with equal tire wear etc. etc. which we all know never happens. Basically 99.9% of the time one wheel will always have a little more traction than the other. Sooo.... if this defeats the entire purpose of a posi, why was it ever invented? I, like most people think, that once you hit it hard, it shocks the clutches into grabbing, (something you don't do on turns, so the slip test doesn't count, because that's not how it was intended to be operated in the first place) thus locking both wheels together. If it didn't do this, then you're saying that an open and a posi are absolutely identical. And they can't be. What's the point of a diff that doesn't lock wheels together under torque?
Then why when you see a guy floor it in an open diff car, one wheel spins forever, equaling zero traction, and when the posi cars floor it, the car hooks up and goes forward? If the clutches are doing absolutely nothing for the wheel spin at launch, then it's behaving exactly like an open diff: no control of wheelspin at launch. Which doesn't make any sense. So if they don't control wheel spin at launch, how would you ever know your clutches are worn?

Why are you debating laws of physics? If you read my posts and absorbed it the way I posted which states the traction is equal until one spins. If none spin the torque to each axle is equal. If you know how a differential works why would you post here?Go watch videos of phoneguy at BG. His limited slip was shot and he had a hard time doing a proper burnout yet the was still able to knock down decent 60' times with a slow spooling turbo. You can search the service manual for the test to determine if you're limited slip is shot. Id imagine it's similar to the method I described in the last post that a certain break away tq is required or it's no good. You can put a lug at 12 or 6 o'clock and use the torque wrench at 3 or 9 o'clock to easily simulate the torque at the center of the axle shaft because the leverage is cancelled on both planes when there is a 90 degree angle. It will work in any location if you can maintain a 90 degree angle.


BPE2013@hotmail.com

 

[Thunder]

You can put a lug at 12 or 6 o'clock and use the torque wrench at 3 or 9 o'clock to easily simulate the torque at the center of the axle shaft because the leverage is cancelled on both planes when there is a 90 degree angle. It will work in any location if you can maintain a 90 degree angle.


BPE2013@hotmail.com

Very cool, prob just showing my noobness, but I never knew that. As I think about it makes sense.
I learn something new all the time.

 

[bison]

Very cool, prob just showing my noobness, but I never knew that. As I think about it makes sense.
I learn something new all the time.

This works on an engine or anything else for that matter. Like an intake manifold bolt. Can't get the torque wrench on it but can get a wrench. You use an open end 9/16 with an open 1/2 on the other side. If you keep the angle 90* the torque at the fasteners head is the same as at the head of the torque wrench


BPE2013@hotmail.com

 

[4timesT]

This works on an engine or anything else for that matter. Like an intake manifold bolt. Can't get the torque wrench on it but can get a wrench. You use an open end 9/16 with an open 1/2 on the other side. If you keep the angle 90* the torque at the fasteners head is the same as at the head of the torque wrench


BPE2013@hotmail.com

Cool tip, thank you!

 

[Turbo6Smackdown]

Why are you debating laws of physics? If you read my posts and absorbed it the way I posted which states the traction is equal until one spins. If none spin the torque to each axle is equal. If you know how a differential works why would you post here?Go watch videos of phoneguy at BG. His limited slip was shot and he had a hard time doing a proper burnout yet the was still able to knock down decent 60' times with a slow spooling turbo. You can search the service manual for the test to determine if you're limited slip is shot. Id imagine it's similar to the method I described in the last post that a certain break away tq is required or it's no good. You can put a lug at 12 or 6 o'clock and use the torque wrench at 3 or 9 o'clock to easily simulate the torque at the center of the axle shaft because the leverage is cancelled on both planes when there is a 90 degree angle. It will work in any location if you can maintain a 90 degree angle.


BPE2013@hotmail.com

Not debating physics, I'm just curious as to how the rear works in detail. Although I'm not an expert on our rears, I do know the difference in operation. I just want to learn a little more. But when I see "the clutches won't help wheel spin at launch" I tend to ask more questions, as I know that wasn't the original intention of the unit during designing. Regardless of physics, if it didn't help, they would have just kept the open diff, and that's just from a manufacturing and finance standpoint. No need to invent something if there was never a problem to begin with. But wheelspin is a problem, and the posi helped it. But there's no way that it could help that situation, if it doesn't control wheelspin at launch.

 

[bison]

Not debating physics, I'm just curious as to how the rear works in detail. Although I'm not an expert on our rears, I do know the difference in operation. I just want to learn a little more. But when I see "the clutches won't help wheel spin at launch" I tend to ask more questions, as I know that wasn't the original intention of the unit during designing. Regardless of physics, if it didn't help, they would have just kept the open diff, and that's just from a manufacturing and finance standpoint. No need to invent something if there was never a problem to begin with. But wheelspin is a problem, and the posi helped it. But there's no way that it could help that situation, if it doesn't control wheelspin at launch.

The theory of the limited slip has nothing to do with drag racing.


BPE2013@hotmail.com

 

[Turbo6Smackdown]

But limited slips do.

 

[earlbrown]

on an open diff, the spider gears act as a 'balance' to send an equal amount to both tires. (and allows one to spin faster than the other while turning)

As long as both tires have traction, they'll both get the same amount of power. When one tire comes loose the load changes. The tire that has grip locks down to the ground and send every bit of power to the unloaded tire. (the unloaded tire also spins at 2X normal speed, making it even harder to regain a grip).

On a posi, it's the same exact thing, but there's a set of clutches throwing 60~#/ft of drag. That helps a little with keeping power to both wheels. It allows there to be a slight imbalance is CoF between the tires and still keep power going to both.



Here's a fun experiment to try at home. Get a brass wye split for a garden hose and put a balloon over each end... Turn on the water and notice the balloons inflate pretty much the same. Both take the load (giggity) pretty much equally. They balance each other....

....now poke a hole in the right balloon and do the experiment again. Notice the left balloon won't fill up anymore. The one with the hole in it (no traction load) now dumps all the energy and leaves none for the other side.

 

[Turbo6Smackdown]

I see. So if a traction imbalance is pretty much guaranteed, should I be going with a detroit locker then?

 

[69RSCLONE]

What about the added load applied to the clutches from the spider gears walking? As torque is applied to the gears they naturally want to spread apart due to the tapered cut. Same reason we put reinforced covers on the rear, to minimize the spread of the case. As they spread, they load the clutches and increase the breakaway torque needed to slip. Might be 60ft/lbs with no load but increases under launch. As the clutches wear the lash increases and the spiders eventually get ripped apart. Correct me if I'm wrong.

 

[earlbrown]

You're wrong. The clutches just make it harder for the spiders to free spin. They're still able to do so with enough difference in load.


If anyone lose sleep at night at the thought of right tire fire, the only option is a spool (or go shadetree style and weld up the spider gears)

 

[Turbo6Smackdown]

Then on the street, even with a good tire, do you think the "right tire fire" is a common problem? Do you think rear end slip is something that realistically happens to most of us?

 

[pacecarta]

your assuming the clutches spin and side gears spin , they dont the whole carrier spins

What about the added load applied to the clutches from the spider gears walking? As torque is applied to the gears they naturally want to spread apart due to the tapered cut. Same reason we put reinforced covers on the rear, to minimize the spread of the case. As they spread, they load the clutches and increase the breakaway torque needed to slip. Might be 60ft/lbs with no load but increases under launch. As the clutches wear the lash increases and the spiders eventually get ripped apart. Correct me if I'm wrong.

you're assuming the clutches spin and side gears spin , they dont ....the whole carrier spins carrying the side gears

 

[TurboTnZ06]

This works on an engine or anything else for that matter. Like an intake manifold bolt. Can't get the torque wrench on it but can get a wrench. You use an open end 9/16 with an open 1/2 on the other side. If you keep the angle 90* the torque at the fasteners head is the same as at the head of the torque wrench


BPE2013@hotmail.com

And press down parallel with the first wrench so the torque is right, if using a torque wrench on in-lbs on soft alum stuff.

 

[69RSCLONE]

Earl, how am I wrong. Increased load on clutches increases holding power of spiders. The harder to slip the spiders in the carrier = a more even disbursement to the wheels. I'm not saying you won't have slippage, just not the 60 ft/lbs that was mentioned.

 

[69RSCLONE]

your assuming the clutches spin and side gears spin , they dont the whole carrier spins


you're assuming the clutches spin and side gears spin , they dont ....the whole carrier spins carrying the side gears

Correct about the clutches spinning with the carrier. What does that have to do with anything?

 

[Turbo6Smackdown]

Its very hard to do a burnout with an open rear. Thats why they are somewhat critical. The posi does little for traction after the car is launched under power. You need to equalize the force on both sides of the rear so that the tires have equal traction. Traction is equal till one of the tires slips. Preventing the less loaded tire from slipping will maintain traction. An air bag in the right side is a good start. Ballast over the right rear will help also. I cant believe people actually think a few clutches will actually prevent the tires from spinning. It sure as hell wont. You can easily make a posi rear slip with a breaker bar if one side of the car is on the ground and the other is jacked up. Our engines are supplying way more torque then we could ever apply by hand that is then multiplied through the converter, trans, and rear gear before it hits the tires. Nothing to do with a posi.

I see these cars launch hard and when they do the drivers side front comes up and the pass side rear squats, loading that tire. The airbag in the pass side rear helps counter that. How would more weight over the pass side tire help that issue? If doing that counters that lean, wouldn't you want the weight over the driver's side rear?

 

[earlbrown]

Earl, how am I wrong. Increased load on clutches increases holding power of spiders. The harder to slip the spiders in the carrier = a more even disbursement to the wheels. I'm not saying you won't have slippage, just not the 60 ft/lbs that was mentioned.

That 60# number came straight out of the factory shop book. The clutches really don't have anything to do with the spiders. They couple the axles together will a little bit of added friction. When I pull up my driveway sometimes I drop my RR into the yard going around my jetboat... needless to say there's no grass there anymore. It's not a problem with my posi, it's just asking too much of my clutches.

I see these cars launch hard and when they do the drivers side front comes up and the pass side rear squats, loading that tire. The airbag in the pass side rear helps counter that. How would more weight over the pass side tire help that issue? If doing that counters that lean, wouldn't you want the weight over the driver's side rear?

Since the axle is full of resistance, it want's to spin like a propeller. The driveshaft turns clockwise (when viewed from the front of the car) so it pushes down on the DS and up on the PS. The airbag uses the trunks mass to try and hold it down some.

At the same time the engine is trying to flip out of it's engine mounts. Since the crank is clockwise, the block is trying to rotate counterclockwise... and it picks up the drivers side of the frame.

 

[69RSCLONE]

Yeah, just like everything else on the Regals, all the planets have to align to work. It all relies on the initial hit from the trans. Without the added torque load you only have the preload from the wave spring. That's where the 60 lbs comes from. And you just spin one wheel.

Either way it doesn't matter if you have a posi, limited slip, locker, welded, whatever. The original post was about an open diff. So this is no help for him.

 

[Nascar83Fan]

Pretty much my understanding from what i read from all the posts in the thread was this.

If you have something like an airbag or other type of device that acts similar to a spring rubber which makes the RR spring stiffer causing it to be unable to compress as much when the weight transfers from the front to the rear under launching, it'd help aid in keeping the RR tire planted on the pavement working against the forces from the rear axle trying to twist counter-clockwise from the driveshaft being spun clockwise by the engine & transmission.
Adding some weight to the RR corner on top of making it harder for the RR spring to compress as much would aid in keeping the RR tire firmly planted to the surface preventing most traction loss from occuring first at the RR.

Which would help prevent the RR tire from slipping more than the LR tire was, allowing both tires to have an equal amount of torque etc being driven to them even with an open rear end.

Am i fully grasping what was trying to be said or am i only partially grasping what is being said here?



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