Starting a new thread as we are back full circle to thinking the issue is in the transmission. We have eliminated the brake system at this point. Original theroy was transmission but thate symptos really pointed to brakes. We have eliminated that now after a great deal adjustments and readjustments.
The vehicle runs foward flawlessly and when cold backes up forever with no issues. after driving over 7 to 10 miles we find reverese is an issue. I believe when the transmission is hot that is when the issue arises. We have looked into this and found our transmission is about 208 degrees measured with a thermal laser on the tail housing where it meets the transmission housing. The rear end at the pinion is 106 degrees and I am in Arizona so ambiant temp is over 85 plus today.
When the issue appears there is a sever shudder and grating noise and the rear end drops downward 5 to 6 inches. Torque on the bolts to the springs are correct. We find when there is no resistance on the rear i.e. jaked up fom the ground no issue. When in nutral rolls back no issue but when engaged in reverse and applying gas the issue occurs after transmission is hot. I have uploaded a video of the propeller shaft at the pinion one clearly can see and hear the issue. We also looked at the transmission tail shaft but saw no shudder movement coming out. Any ideas before we open up the transmission and if this is in the reverse planatery gears or parking prawl or valves can they be accessed with transmission in place?
Strange indeed...
If the transmission is the problem how is the driveshaft still transmitting power to the rear axle?
Phil as you know we have replaced the rearend and the brake system and have chased down all possibilities there. The only common in the equation now is the transmission which I suspected on the beginning. Our issue does not exist unless the transmission warms up 7 to 10 miles with some highway speeds. Only under load. with wheels off the ground transmission in reverse it turns with no sounds or issues, or transmission in nuetral wheels on the ground it rolls backwards fine. Once the problem appears it has to sit overnight to clear up again but then returns with driving. I have had it sit 6 to 7 hours after it appears and the sytem cools down to ambiant temps and still have reverse issues but sitting 15 hours or more it clears up. I am thinking possibly a valve issue? maybe takes long time to clear whatever is happening after it warms up? maybe a piece of a seal is clogging it and leaks back out after it sits long enough. whatever is going on it is transferring power to the rear and causing the dif nose to drop if you push through the grinding (like brake lock up but not the brakes) the shudder seen in the video seems lik something is catching as it tries to turn through it and you ucan hear the noise. seems like it we can be causing damage to the clutch plates. Maybe a clutch plate is hanging up somehow? Anyone had the hydro apart on the car can this be verified still on the car??
You need to find a diagnosis chart for your transmission to see what parts could cause the lockup in reverse. I didn't see one for 1953 in the shop manual and later years the transmission is different to go by those charts.
Craig with all you have been through, and seeing
@Roger Zimmermann (the Hydra-Matic Man in my eyes) state "strange indeed" is powerful to me,
BUT try viewing the 1 thru 4 or 5 part video on the first Hydra-Matics by John Kelly and then contact John @ Weber University and ask him.
google "The Worlds First Mass-Produced Hydra-Matic Transmission"
Just some thoughts,
Bob
Quote from: CRAIG LEWIS on November 02, 2023, 09:33:38 AMPhil as you know we have replaced the rearend and the brake system and have chased down all possibilities there. The only common in the equation now is the transmission which I suspected on the beginning. Our issue does not exist unless the transmission warms up 7 to 10 miles with some highway speeds. Only under load. with wheels off the ground transmission in reverse it turns with no sounds or issues, or transmission in nuetral wheels on the ground it rolls backwards fine. Once the problem appears it has to sit overnight to clear up again but then returns with driving. I have had it sit 6 to 7 hours after it appears and the sytem cools down to ambiant temps and still have reverse issues but sitting 15 hours or more it clears up. I am thinking possibly a valve issue? maybe takes long time to clear whatever is happening after it warms up? maybe a piece of a seal is clogging it and leaks back out after it sits long enough. whatever is going on it is transferring power to the rear and causing the dif nose to drop if you push through the grinding (like brake lock up but not the brakes) the shudder seen in the video seems lik something is catching as it tries to turn through it and you ucan hear the noise. seems like it we can be causing damage to the clutch plates. Maybe a clutch plate is hanging up somehow? Anyone had the hydro apart on the car can this be verified still on the car??
I'm sorry to bang on about this but I just don't understand how the transmission can be seized in reverse yet still turn the propshaft? What about the differential or the propshaft U joints? From everything you've said (unless I've misunderstood) it is after the transmission that the problem occurs.
Also have you tried turning the wheels off the ground as soon as possible after it has locked up?
Would seem to me that the drive shaft has to be turning in order to make the differential react as described. How can it turn if the transmission is locked up?
All thanks for the feedback.
Phil, to answer your point we thought the same after much debate, we replaced the rear and the brake system and have fully adjusted per the manual even putting all the 1952 parts in place just to be sure. We still have the same issue, we did test it when it locked up in reverse and shifted to nueteral and were able to easily hand push it backwards so nothing was locking up at that point. We returned to the shop put it on the lift and raised it then jacked the rear end up while on the lift and ran it with wheel in the air. Reverse ran fine, wheels turned, not a sound from the rear. Once we lower it back and they wheels are on the ground it locks and the rear diff drops nose down and chatters and squals like in the video till it moves backwards and then frees up a bit only to bind again as soon as stopping or releasing the gas padel while in reverse. Shifting and holding in neutral like the 47's needed does not help and shifting throught the gears before going into reverese does not help. Again this only occurs after warm up.
How it can be the transmission is we eliminated the brakes and differential. We attacked that as we thought as you do with power going back it cant be tranny. However now that we have watched it from underneath it is my theory that the clutch discs are binding. Similar to slipping in foward gears or a throw out bearing in a manual will produce shuudder and screetching grrindin noise in foward gears this is doing it in reverse. Perhaps it is a pressure valve issue or similar. The problem develops with extended driving 10 miles or so and only in reverse It dissaptes on its own back takes 15+ hours of sitting to clear out. Phil you are correct the transmission does not seize but it does not move in reverese without applying gas to the point that it breaks loose and moves. Perhaps I shouild not call it lockup so much it is more like slipping and hard grabbing as the clutch pack rotates, causing chatter and torque transfer issues to the rearend?
I will reach out to John Kelly at Webber University. Keep tossing ideas we are open to learning anything we can.
You have a problem that is difficult to diagnose. I would suspect the transmission as well but your comments about the rear axle pinion angle dropping down as this problem occurs tells me that power is being applied to the rear axle. The rear axle pinion angle wouldn't change if the lockup occurred in the transmission.
Your symptoms are very strange.
Putting the car on a lift shouldn't cure the problem.
Unfortunately, I don't have any good advice for you other than I am no conviced your transmission is the culprit.
I doubt it would be practical but doing a transmission swap would be useful for diagnosing.
Once you open up your transmission you should rebuild it or you will wish you did down the road.
Good luck!
Joe
There is a parking pawl that is engaged when the engine is off and the lever is put in reverse. Maybe that is your problem?
and the lever is
Quote from: CRAIG LEWIS on November 02, 2023, 07:35:43 PMAll thanks for the feedback.
Phil, to answer your point we thought the same after much debate, we replaced the rear and the brake system and have fully adjusted per the manual even putting all the 1952 parts in place just to be sure. We still have the same issue, we did test it when it locked up in reverse and shifted to nueteral and were able to easily hand push it backwards so nothing was locking up at that point. We returned to the shop put it on the lift and raised it then jacked the rear end up while on the lift and ran it with wheel in the air. Reverse ran fine, wheels turned, not a sound from the rear. Once we lower it back and they wheels are on the ground it locks and the rear diff drops nose down and chatters and squals like in the video till it moves backwards and then frees up a bit only to bind again as soon as stopping or releasing the gas padel while in reverse. Shifting and holding in neutral like the 47's needed does not help and shifting throught the gears before going into reverese does not help. Again this only occurs after warm up.
How it can be the transmission is we eliminated the brakes and differential. We attacked that as we thought as you do with power going back it cant be tranny. However now that we have watched it from underneath it is my theory that the clutch discs are binding. Similar to slipping in foward gears or a throw out bearing in a manual will produce shuudder and screetching grrindin noise in foward gears this is doing it in reverse. Perhaps it is a pressure valve issue or similar. The problem develops with extended driving 10 miles or so and only in reverse It dissaptes on its own back takes 15+ hours of sitting to clear out. Phil you are correct the transmission does not seize but it does not move in reverese without applying gas to the point that it breaks loose and moves. Perhaps I shouild not call it lockup so much it is more like slipping and hard grabbing as the clutch pack rotates, causing chatter and torque transfer issues to the rearend?
I will reach out to John Kelly at Webber University. Keep tossing ideas we are open to learning anything we can.
The "nosing down" of the differential when the reversing problem occurs indicates that the transmission and drive shaft are transmitting power to the differential. Possibly the U-bolts holding the axle housing to the rear springs are loose, allowing unwanted movement of the axle housing, with the problem only being apparent in reverse.
Try tightening the U-bolts to the spec. of 45 foot-pounds of torque, a quick and easy job to do. If the bolts were found too loose, maybe that is what has been causing your problem.
Craig,
Have you try removing the differential shaft at the transmission yoke and see if the same issue persist, this way you only have the transmission in-line for the test?
Just an option for isolation. ;)
Good luck..!
I was going to suggest this as well but it is no good. It is stated that the transmission WILL reverse while hot, with the wheels off the ground. It will NOT reverse while hot, with wheels on the ground.
Quote from: J. Gomez on November 03, 2023, 11:43:09 AMCraig,
Have you try removing the differential shaft at the transmission yoke and see if the same issue persist, this way you only have the transmission in-line for the test?
Just an option for isolation. ;)
Good luck..!
Phil beat me to it I was going to suggest the parking pawl as well.
There is a parking pawl that is engaged when the engine is off and the lever is put in reverse. Maybe that is your problem?
Regards,
Bob
possible but it only happens after driving a bit. I would think the parking prawl which is a sping activated mechanism would engage wther it is warm or cold. I suppose the spring might expand under heat but it catches and releases more like clutch slippage. i dont want to pull the transmission if i can avoid it. I am thinking of pulling the tailpiece housing which contains the reverse cone clutch pack. Can this be done with transmission still attached to motor
You would really benefit from having the transmission manual. The 52-53 Hydramatic manual states the problem could be as follows:
1: Shift Linkage
2: Check line pressure in reverse. Excessive pressure loss may be caused by missing or mispositioned pressure regulator reverse oil pipe, or reverse clutch pipe.
3: Leak in rear servo release passage - check release passage with air pressure with servo mounted on case. Make certain servo applies and releases freely without tendency to stick or chatter.
4: Line exhaust valve sticking or leaking. The line exhaust valve is located in the case under the front servo on 1952 models and in the front servo valve body on 1953 models.
According to the book, you can remove the front servo with the transmission in the car.
Quote from: CRAIG LEWIS on November 03, 2023, 01:41:45 PMpossible but it only happens after driving a bit. I would think the parking prawl which is a sping activated mechanism would engage wther it is warm or cold. I suppose the spring might expand under heat but it catches and releases more like clutch slippage. i dont want to pull the transmission if i can avoid it. I am thinking of pulling the tailpiece housing which contains the reverse cone clutch pack. Can this be done with transmission still attached to motor
If I remember correctly the parking pawl is held off by the line pressure when the transmission is being used, it applies with the engine off as the lack of pressure allows it to engage. I still am not convinced that it is the transmission for the simple reason that the power is getting to the propshaft.
Power may be getting to the driveshaft, but look at that amount of chatter...