A568 shaft forces

[BadAssPerformance]

A568 ... Which shaft hammers the end plate more?


...discuss

[Dr. Johny Dodge]

wise azz answer would be the one with the most fubar'ed bearings
but I'd say the input shaft
to start with it's mounted between plains that leave it wanting to push against each end
ie , the cup & cone bearings on the input shaft

the secondary shaft with the roller bearings wouldn't push so much against the end plate or case at the front in my opinion

[83scamp]

I would agree it is the input shaft, but for different reasons:

1. Look at the way Chrysler designed the trans. The input shaft has tapered roller bearings on both ends. They are designed to take side loads. Part of that being clutch/pressure plate loading(from engaging/disengaging the clutch, which should be minimal), but the majority being thrust loading from the helical cut gears. The shaft is built with the larger bearing on the end plate end, which will naturally lead you to believe that is the major thrust direction, which the cut of the helical gears confirms. The intermediate shaft has a straight roller bearing on the pinion end, which is a great bearing for radial loading( but will not take side loading), and a ball bearing on the end plate. Ball bearings will take some side loading, but again, are designed primarily to take radial loading.
2. By looking at the helical cut of the gears, when you are moving forward, the main shaft is trying to push out towards the end plate, while the intermediate shaft is pushing in towards the bellhousing. The torque transfer from the intermediate shaft to the ring gear pushes back towards the end plate. My guess is, based on the way the trans is design, that the force from the primary shaft, and the force from the ring gear pretty much cancel each other out on the intermediate shaft. This is why the intermediate shaft doesn't use "thrust" bearings...



Of course, I may be all wet, this is just my opinion based on my mechanical knowledge of the way bearings work. Please feel free to discuss....

[5DIGITS]

A568 ... Which shaft hammers the end plate more?

The point of the radial vs straight bearing is true, regarding the input shaft vs output shaft loading.
But also consider it's also based on which gear your in.
1st thru 3rd will provide further axial load on the input shaft while 4th and 5th will realize it on the output shaft.
In short, the closer you get to 1:1 and beyond (into OD ratios) the loading will transfer from the input to the output shaft but will be less due to the reduced level of multiplication through ratio.

[turboshad]

http://www.khkgears.co.jp/en/gear_te...df/455-461.pdf

Page 456 (second page of the link). We have a right had drive gear (input shaft) and a left hand driven gear (intermediate shaft) with a clockwise driving force when going forward. This is displayed in the left photo of fig. 8.4. It shows that the force the input shaft exhibits on the case will be towards the bell housing and the int. shaft will be towards the bearing plate. It also makes sense with how the trans is built and the wear that is often seen on the retainer plate. If the int. shaft was applying a force on the bell housing side there wouldn't be wear on the bearing plate.

So to answer/discuss the question I would stand that the intermediate shaft hammers the end plate more, unless you break your tranny in reverse. Then it's the input shaft.

[Ondonti]

Do I win yet with my 2 seconds of thought and quick watching of a video with little mental manipulation and meshing of my fingers to pretend they are gears? I didn't even want to read that thread anymore with all the bandwagoning. Sky is yellow per 10 second car. I know a lot of guys seriously posting have gone through these transmissions but a lot of others have not and sometimes we think more about rebuild procedure than how they work. I had Reaper1 walk me through my first teardown so I just made endless annoying observations instead of worrying if we did it right. We didn't! lol. Had to redo the intermediate shaft again.

I don't even need science if I just look at the design of the transmission. The ball bearing is press fit on and then forces on the shaft push on the ID of the bearing where the OD of the bearing presses against the plate. If it was the other way around then the clip is in charge of handling all FWD gear forces and the retainer plate is in charge of reverse gear and you fire your idiot engineer.

Look at the bracing in the bellhousing around the input shaft! Nobody made the transmission for drag racing in reverse. JT was pretty clear previously about his bearing plate getting hammered by the bearing and nobody questioned it, then someone says the opposite and nobody questions it. I stuck with JT's statement that had some evidence behind it and then googled for proof.

BTW I love this whole thing because it means people with the weird but helpful small bearing AWD diff might not need to worry because the passenger side bearing is taking the forces and that one is ALWAYS the large bearing. I previously thought I didn't want to get involved with the small bearing. This is probably why there is a giant truss on the passenger side of the diff on some cases. The later 3 speed cases have a steel plate that helps support that same area as part of the engine mount.

[83scamp]

http://www.khkgears.co.jp/en/gear_te...df/455-461.pdf

Page 456 (second page of the link). We have a right had drive gear (input shaft) and a left hand driven gear (intermediate shaft) with a clockwise driving force when going forward. This is displayed in the left photo of fig. 8.4. It shows that the force the input shaft exhibits on the case will be towards the bell housing and the int. shaft will be towards the bearing plate. It also makes sense with how the trans is built and the wear that is often seen on the retainer plate. If the int. shaft was applying a force on the bell housing side there wouldn't be wear on the bearing plate.

So to answer/discuss the question I would stand that the intermediate shaft hammers the end plate more, unless you break your tranny in reverse. Then it's the input shaft.

Awesome link, very useful info, but by the drawing shown, we have a counterclockwise rotation, not clockwise. If you look at the flywheel as the engine is running, it rotates counter-clockwise, which is represented by the right drawing in the left picture. I'm looking at the drawing as if it were from the end plate of the trans, not the bellhousing side. By that drawing, it is the input shaft that applies force to the end plate.

[Ondonti]

Awesome link, very useful info, but by the drawing shown, we have a counterclockwise rotation, not clockwise. If you look at the flywheel as the engine is running, it rotates counter-clockwise, which is represented by the right drawing in the left picture. I'm looking at the drawing as if it were from the end plate of the trans, not the bellhousing side. By that drawing, it is the input shaft that applies force to the end plate.

From the driver side your tires rotate counterclockwise so the diff does the same, therefore the intermediate shaft rotates clockwise, input shaft counterclockwise.

Are you guys not able to just look at gears in mesh and how they move?

[Ondonti]

And has anyone seen how much bracing was added to newer 3 speed transmissions in the bellhousing?

[Dr. Johny Dodge]

looking over the driver's fender , the engine rotates counter clockwise - the timeing belt runs in the direction on the intermeadiate shaft from the cam ... so if the crank is turning counter colckwise , haveing the input shaft turning clockwise would mean your rolling down hill backwards and the splines in your clutch are striped

[lengel]

I would agree it is the input shaft, but for different reasons:

1. Look at the way Chrysler designed the trans. The input shaft has tapered roller bearings on both ends. They are designed to take side loads. Part of that being clutch/pressure plate loading(from engaging/disengaging the clutch, which should be minimal), but the majority being thrust loading from the helical cut gears. The shaft is built with the larger bearing on the end plate end, which will naturally lead you to believe that is the major thrust direction, which the cut of the helical gears confirms. The intermediate shaft has a straight roller bearing on the pinion end, which is a great bearing for radial loading( but will not take side loading), and a ball bearing on the end plate. Ball bearings will take some side loading, but again, are designed primarily to take radial loading.
2. By looking at the helical cut of the gears, when you are moving forward, the main shaft is trying to push out towards the end plate, while the intermediate shaft is pushing in towards the bellhousing. The torque transfer from the intermediate shaft to the ring gear pushes back towards the end plate. My guess is, based on the way the trans is design, that the force from the primary shaft, and the force from the ring gear pretty much cancel each other out on the intermediate shaft. This is why the intermediate shaft doesn't use "thrust" bearings...



Of course, I may be all wet, this is just my opinion based on my mechanical knowledge of the way bearings work. Please feel free to discuss....

This is my take on it as well. I thing what needs to be figured out is what direction of force is greater on the intermediate shaft in 1st and 2nd gear. If my thinking is right It will be input force minus output shaft force in 1st and 2nd gear will give you the direction of the intermediate shaft in those gears. I'm not smart enough to figure this out as I would think a lot of variables like gear ratios, tire diameter, how well the tire hooks, engine torque generated at launch, come in to play.

I'm going to take a quick video to night that show the direction of the intermediate shaft when a rotating force is applied to the input shaft. This hopefully will get us all on the same page when comes to the axial direction of the shafts.

[turboshad]

Whoops I was wrong and looking at the wrong diagram.

Here we go.



So I agree with the masses that the input shaft will have a force towards the bearing retainer which explains the larger bearing on that side.


For the force the only real contributor is the engine torque output at any given time. Fx=Ft(tan(beta)) so you can see the resultant axial load is a function of the force tangential. The tangential force is the engine torque output divided by the gear radius (pitch diameter/2). With that said for any given torque output the resultant axial force will be greater in first gear and decrease as you go up to 5th. I would say you will see the largest axial forces in second gear as you gain traction.

[lengel]

http://youtu.be/7AJAC3yNEYA

[BadAssPerformance]

OK... after talking it over with lengel last night, sleeping on it and seeing all this great info and comments, how about this theory...

-The engine turns clockwise turning the input shaft clockwise
-The helical input shaft gears force it to the driver side into the end plate
-The reaction force on the speed gear rotating counterclockwise pushes the speed gear towards the passenger side

OK, now lets look at the opposite side of the equation

-The counterclockwise spinning speed gear drives the intermediate shaft and pinion into the diff gear
-The diff gear is spinning clockwise
-The diff gear is connected to the drivetrain and has the reactive forces of traction
-The driven pinion has to overcome the tractive forces from the diff and is pushed towards the driver side

So... both the input shaft and intermediate shaft are pushed towards the driver side while the speed gear is pushed towards the passenger side. To answer the question, the input shaft would hammer the end plate more, but the intermediate shaft also moves in that direction minus the counter force of the speed gear

...maybe

[83scamp]

Reading over all the responses here got me thinking some more about this. I'm going to throw another monkey wrench in the discussion. All these forces assume the helical gears are fixed to the shaft. That is true of the input, but on the intermediate shaft, they slide on splines, and are held in place by the clutch forks and synchros. So how much reactive force does the intermediate shaft really see? Is the reason the Chrysler engineers didn't use thrust-type bearing on the intermediate shaft, because it really doesn't see any significant side force?

The intermediate speed gears will see side force towards the bellhousing, but it really isn't transmitted to the intermediate shaft itself because they are splined to the shaft, not fixed to it. So maybe, the major thrust force the intermediate shaft sees is actually towards the end plate, because of the helical side loading from the ring gear....

Just more food for thought... Let me know if you think I'm off base here...

[lengel]

OK... after talking it over with lengel last night, sleeping on it and seeing all this great info and comments, how about this theory...

-The engine turns clockwise turning the input shaft clockwise
-The helical input shaft gears force it to the driver side into the end plate
-The reaction force on the speed gear rotating counterclockwise pushes the speed gear towards the passenger side

OK, now lets look at the opposite side of the equation

-The counterclockwise spinning speed gear drives the intermediate shaft and pinion into the diff gear
-The diff gear is spinning clockwise
-The diff gear is connected to the drivetrain and has the reactive forces of traction
-The driven pinion has to overcome the tractive forces from the diff and is pushed towards the driver side

So... both the input shaft and intermediate shaft are pushed towards the driver side while the speed gear is pushed towards the passenger side. To answer the question, the input shaft would hammer the end plate more, but the intermediate shaft also moves in that direction minus the counter force of the speed gear

...maybe

What! You took a day to come to this theory, and your not even 100% sure it's right. You must be a moron! Brent had this all figured out in 2 seconds of looking at a gear set, and his theory is the opposite of yours. You must be wrong.

[BadAssPerformance]

Reading over all the responses here got me thinking some more about this. I'm going to throw another monkey wrench in the discussion. All these forces assume the helical gears are fixed to the shaft. That is true of the input, but on the intermediate shaft, they slide on splines, and are held in place by the clutch forks and synchros. So how much reactive force does the intermediate shaft really see? Is the reason the Chrysler engineers didn't use thrust-type bearing on the intermediate shaft, because it really doesn't see any significant side force?

The intermediate speed gears will see side force towards the bellhousing, but it really isn't transmitted to the intermediate shaft itself because they are splined to the shaft, not fixed to it. So maybe, the major thrust force the intermediate shaft sees is actually towards the end plate, because of the helical side loading from the ring gear....

Just more food for thought... Let me know if you think I'm off base here...

Yeah that's kinda what I was saying with my last post...

I think the intermediate shaft floats so you don't have to set gearlash, it just kind of adjusts itself.

BTW... there is no doubt in my mind that that the intermediate shaft will push towards the driver side under hard acceleration and have cracked 4 aluminum end plates even cracked a bearing. Here is one set from 2013

Attachment 53566
Attachment 53567
Attachment 53568
Attachment 53569

[BadAssPerformance]

What! You took a day to come to this theory, and your not even 100% sure it's right. You must be a moron! Brent had this all figured out in 2 seconds of looking at a gear set, and his theory is the opposite of yours. You must be wrong.

LOL... OK, I'm sure BOTH shafts push toward the drivers side

[cordes]

How do the shafts react when you snap off the throttle quickly? Do the forces reverse? If so, is that significant, or very minor?

[83scamp]

How do the shafts react when you snap off the throttle quickly? Do the forces reverse? If so, is that significant, or very minor?

It's very significant. So much so, that Chrysler did a running change with the early trans, and then was redesigned to the beefed up A-555/520/523/568 diff housing.

The early A-460/465/525 only had 5 bolts holding the drivers side diff. bearing plate on. Under hard decelleration, that plate could deform, and even tear out the 5 bolts. Chryslers' fix for this was to add 3 more bolts to the assembly to increase load carrying. Unfortunately, since the original design basically put the left bearing directly under the ring gear, it didn't solve other weaknesses inherent to the design. This is why the A-555 and up were redesigned with the much beefier diff housing, and the drivers side bearing was moved out to reduce loads on it.