A568 shaft forces

[5DIGITS]

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

Brian,
This another good point but there are a few things that will influence this with one of them is the engine calibration.
While actively participating in transmission spin loss testing, minimized negative torques are always used on the dyno during testing.
This is because the negative torque realized during engine braking is far less than the positive torque capability of the engine.
I mention the engine calibration because there are MAP calibrations used for vacuum control during deceleration to avoid excessive vacuum and engine oil 'pull-over'.
The decel control is not RPM based until the vehicle is near or at 0 MPH, until that occurs it is a 'target MAP' strategy or engine load strategy.
Additionally, these calibrations control how abruptly the vehicle crosses drive-line backlash and the related 'clunk' when you tip out of the throttle.
This can all greatly minimize the negative torque during decels, depending how they are calibrated, to minimize the thrust loading in the opposite direction.

On a side note:
The forces will be slightly different when comparing the 555/568 transmission families with their 520/523 counter parts.
If I recall correctly there is a minor pitch change between the low and high torque transmissions along with the obvious change in tooth count , their related taper and resulting tooth contact/engagement.
This will also be true/realized when combining gear sets to make a hybrid version of the above transmissions.

[turboshad]

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

[A bunch of stuff]

...maybe

Ohhhh, so now we need to care that there's a diff? Man I should not have been at work yesterday. Using JT's picture, some calipers, the gear ratios from DDG, the calculations from the site I linked, and a mock torque input I made a spreadsheet (famous last words). When looking at the whole gear set, assuming full traction, and for any given torque the ratio of input shaft loading to intermediate shaft loading on the bearing plate is as follows.....

1st gear - 18% more on int.
2nd gear - 10% less on int.
3rd gear - 27% less on int.
4th gear - 59% less on int.
5th gear - not on JTs picture and I didn't feel like doing the calculated guess work, but the trend will obviously follow.

In all cases both the input shaft and int. shaft pushed on the bearing plate.

[lengel]

Ohhhh, so now we need to care that there's a diff? Man I should not have been at work yesterday. Using JT's picture, some calipers, the gear ratios from DDG, the calculations from the site I linked, and a mock torque input I made a spreadsheet (famous last words). When looking at the whole gear set, assuming full traction, and for any given torque the ratio of input shaft loading to intermediate shaft loading on the bearing plate is as follows.....

1st gear - 18% more on int.
2nd gear - 10% less on int.
3rd gear - 27% less on int.
4th gear - 59% less on int.
5th gear - not on JTs picture and I didn't feel like doing the calculated guess work, but the trend will obviously follow.

In all cases both the input shaft and int. shaft pushed on the bearing plate.

Thanks DJ!

If both push toward the bearing plate, and if we could keep that side of trans ridged enough not to flex by using a custom steel end plate. Do you think tapered roller on the intermediate shaft would be something to consider?

[BadAssPerformance]

Nice work DJ!

I think tapered rollers on the int-shaft could would help but would be concerned about:
-the mods required to the front bell housing
-do we need to set pinion gear lash now?
-proper bearing lubrication?

Thinking of the two pinion teeth failures I have had, probably due to the shaft walking enough to make the gear teeth improperly loaded. After enough passed fatigue cycles accumulated, they just broke off. Both broke at the starting line but the damage was done previously.

If a stronger plate helps hold the shaft where it needs to be... that might be enough?

[cordes]

Brian,
This another good point but there are a few things that will influence this with one of them is the engine calibration.
While actively participating in transmission spin loss testing, minimized negative torques are always used on the dyno during testing.
This is because the negative torque realized during engine braking is far less than the positive torque capability of the engine.
I mention the engine calibration because there are MAP calibrations used for vacuum control during deceleration to avoid excessive vacuum and engine oil 'pull-over'.
The decel control is not RPM based until the vehicle is near or at 0 MPH, until that occurs it is a 'target MAP' strategy or engine load strategy.
Additionally, these calibrations control how abruptly the vehicle crosses drive-line backlash and the related 'clunk' when you tip out of the throttle.
This can all greatly minimize the negative torque during decels, depending how they are calibrated, to minimize the thrust loading in the opposite direction.

On a side note:
The forces will be slightly different when comparing the 555/568 transmission families with their 520/523 counter parts.
If I recall correctly there is a minor pitch change between the low and high torque transmissions along with the obvious change in tooth count , their related taper and resulting tooth contact/engagement.
This will also be true/realized when combining gear sets to make a hybrid version of the above transmissions.

Thanks for that info. That does make a lot of sense. When I had my black omni the calibration was such that it was a pretty clunky affair when you let off the gas. I know that I did that with the cal as my goal at the time was to cut fuel when off the throttle and get better gas mileage. I'm sure I could have made it a smoother transition. Now that I know this I'll likely do so in the future.

[Ondonti]

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.

Well 2 seconds was also based on JT's weeks of transmission rebuilds and his assumed reason that nobody disagreed with at the time. Got locked out of T-M when I tried to post Photobucket pictures since this thread lacks pictures. I couldn't edit/fix my post about the bracing in in the bellhousing area which I was going to post a picture of.

Its well received outside this community that wheelhop breaks drivetrain and its not different in the transmission.

How exactly are people explaining the intermediate gear sleeve falling off now? Are people assuming the clips are perfectly fine and only the structure needs to be improved?
The ID bearing clip on this transmission is barely able to hold on anymore.

Trying to post 9 more pictures and I just got the 403 error Fixed it by cheating and just posting 2 pics 5 times.

Just looking at this I would say that there is not a lot of room for a larger bearing on the driver input shaft. Makes me wonder about how our forced upgrade on that intermediate bearing means boring out more metal.

[Ondonti]

- - - Updated - - -



- - - Updated - - -



- - - Updated - - -



- - - Updated - - -



- - - Updated - - -

Found out I couldn't post more than 4 pictures in the same post without getting RESOURCE DENIED 403, but if I just posted another reply the forum will drop them back into the same post due to the short period of time between posts.

I tried to post these before and edit my post but oh well.

[5DIGITS]

Found out I couldn't post more than 4 pictures in the same post without getting RESOURCE DENIED 403.
But if I just posted another reply the forum will drop them back into the same post due to the short period of time between posts.
I tried to post these before and edit my post but oh well.

I found that responding to your post also gives the 403 error message, unless the photos are deleted before selecting the 'advanced' button during editing a response.

It's amazing how much time and effort has been dedicated to improving the original design and aspects of these cars.
The forethought and skill set of the many people within the forum and the people dedicated within the clubs is truly worth recognizing and applauding.

As a few added tidbits and considerations, there are some items that help during the rebuild process for those who are interested.



The press-on bearing race on the output shaft was a separate item if the transmission was serviced in the field.
The dealership techs would need to apply the press-on bearing race and many would simply force it on, within an arbor press.
This was a bad idea on Chrysler's part to reduce production cost because the race either needed to be heated or the shaft required nitrogen chilling to install it without scoring the shaft.
Furthermore, Chrysler's awful machining tolerances had press fitment issues that would allow the race to walk off the shaft as 'Ondonti' has shown, whether in a high performance application or not.
Also captured within the photos is the residual casting flash that resided in these transmissions.
Whether in the Chrysler transmission lab or during a high performance build, this casting flash was ground off to reduce stress risers, eliminate the opportunity for them to release during operation while supporting improved oil flow.
In other words, get rid of them and smooth the area to minimize the stress risers while improving a smooth path for oil flow.
Lastly, the reverse spring on the 523/568 shift detent springs was a higher rate spring.
It was standard/good practice to use the reverse (or equivalent high rate) springs in all of the locations as it improved the 'positive' detents throughout all of the gears and holding the shaft to minimize 'bump-out' which is when the trans pops out of gear.
The down side was a slight increase of shifter effort but the plus side is its aiding in snapping the gear into its engaged position and holding it there.

I hope this helps in some way and contributes to the many efforts and improvements everyone has already made.

[BadAssPerformance]

Great info as always!

[Lotashelbys]

Speaking of that race walking off the shaft has anyone yet had a welded race start to walk off?

[BadAssPerformance]

Speaking of that race walking off the shaft has anyone yet had a welded race start to walk off?

The very first one I tacked on cracked the tacks and walked off a bit and rotated when I caught it. They were small tacks cuz I wanted to keep as much heat out of it as I could. I pressed it back on and put a small bead instead of a tack. Pics:

[135sohc]

Lastly, the reverse spring on the 523/568 shift detent springs was a higher rate spring.

Perhaps in a prototype ? Per the 1990 and 1994 parts catalogs and I feel safe saying every year in between the part number for the detent springs is the same with a qty listed at 4 and from my personal observations all 4 springs are/were identical in every single unit I have opened up.

[5DIGITS]

Perhaps in a prototype ? Per the 1990 and 1994 parts catalogs and I feel safe saying every year in between the part number for the detent springs is the same with a qty listed at 4 and from my personal observations all 4 springs are/were identical in every single unit I have opened up.

Prototype or early running change - it would not be a surprise to find the part was commonized to reduce cost.
My 1990 production VNT Shadow had yellow paint on one end to denote the unique reverse spring.
It was an October 89 built vehicle.