Royal Duke Posted August 28, 2020 Report Share Posted August 28, 2020 (edited) Hey guys, i am still working on my 1941 Chrysler Royal, more specifically the M4 Vacamatic transmission. When I shift the car into Reverse to backup and stop, I cannot shift it out of Reverse. The car must be in motion for me to shift it into Neutral. Furthermore, the car will not roll in either direction when in Reverse, even if I have clutch engaged. I don't have this problem while in Neutral or a forward gear. Any ideas as to resolve the problem could be would be greatly appreciated. Edited August 28, 2020 by Royal Duke Quote Link to comment Share on other sites More sharing options...
1949 Wraith Posted August 28, 2020 Report Share Posted August 28, 2020 I have the same issue with my M4 that has been disabled and used as a 2 speed manual using the direct gears, instead of the under drives. If there is any load on the gears through the differential when stopped it is impossible to shift out of gear. I have got used to shifting to neutral before coming to a complete stop. if I am backing up a slope or pulling up to a 2X4 that I use in the garage for a stop. When you are backing up are you going up a slope? Quote Link to comment Share on other sites More sharing options...
Royal Duke Posted August 28, 2020 Author Report Share Posted August 28, 2020 Yes , my driveway has a slight downward slope, so when I back up, I am going up a slope. However, the problem is evident even on a flat road surface. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 28, 2020 Report Share Posted August 28, 2020 You both need the factory service manual. Is the lockout cable in or out? Is the diaphragm broken? If the team (M4) already (stuck) in the high range? Are all the original controls / vacuum and electrical hooked up? The service manual is a must. Stupid to not have one. Quote Link to comment Share on other sites More sharing options...
Royal Duke Posted August 28, 2020 Author Report Share Posted August 28, 2020 Dodgeb4ya - Thanks for responding. I will answer each question: I do have the shop manual and portions of the "Service Reference Manuals" which I have been reading and rereading, however, none of them mention the type of problem i am experiencing. The lockout cable is in. I actually think my problem developed when i pulled that out while driving the car, but i now have the cable pushed in and the piston back in position for the lever shift. The diaphragm is not ripped or torn. It is in good shape. The M4 is not stuck in high range. It moves between the high and low ranges easily. In fact that is another problem I'm having. It won't "hold" the shift into the higher range. Later today I am going to check the transmission fluid to make sure I have enough pressure to "hold" the upshift. The original controls were jury rigged by the previous owner. I am going to have to rewire the system and am currently trying to find a source for the 10 ohm wire leading to the solenoid Any ideas as to a source? Thanks, Wayne. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 28, 2020 Report Share Posted August 28, 2020 If the transmission say is stuck in auto upshift high gear when you come to a complete stop and then try to move the shifter it will jam between gears. Won't roll at all.forward or backward. Especially when it gets stuck in reverse. You have to jack the rear wheel up to relieve the drive train torque...then can get back to neutral or low-in range. Lock out cable had to be in the non tow position... Cannot remember in or out. That can cause jam ups to as can the lockout cable adjustment. Once again make sure wiring ,electrical Kd relay, governor vacuum controls etc are 100% operating as designed. The M4's are a strong good transmission. They shift excellent when right. Quote Link to comment Share on other sites More sharing options...
Royal Duke Posted August 29, 2020 Author Report Share Posted August 29, 2020 I agree that the M4 is a good strong transmission and i am doing all i can to make it operate correctly. i did have to add some 10w oil to the tranny tonight, but so much, or so i think anyways, to have caused the tranny to not hold the upshift. This weekend I will perform the various tests noted in the shop manual. Depending on what i find, I will then document the current wiring, remove it, and. install new wiring using the correct colors as shown in the 1941-1948 Chrysler Shop Manual. I'll let you know how it turns out Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 29, 2020 Report Share Posted August 29, 2020 The M4 does not use oil pressure to to be able to upshift...there is no internal transmission oil pump. Unlike the 1946-48 M5 and 1949-53 M6 transmissions. Quote Link to comment Share on other sites More sharing options...
Royal Duke Posted September 13, 2020 Author Report Share Posted September 13, 2020 Dodge4ya - my brother helped me yesterday and today and we got it all figured out. He checked the wires the previous owner installed for the Fluid Drive system. we then hooked them up according to the shop manual. We also took the diaphragm apart and checked the operation of the stem. The stem was not extending all of the way out to push the transmission mounted lever into the power range. The tranny was stuck in the drive range which kept pressure on the gears and didn't allow the car to roll on an incline (Even with the clutch engaged) or shift out of reverse when stopped. Now that the wiring reflects the schematic and the tranny shifts into the power range, my problems are solved. I appreciate your earlier guidance because it gave me possible causes for the problems experienced. Wayne Quote Link to comment Share on other sites More sharing options...
greg g Posted September 13, 2020 Report Share Posted September 13, 2020 Glad you got it sorted, and posted a follow-up. Always nice to know when one of these great cars are rendered road Worthy. Sent you a personal message about an up coming event. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted September 13, 2020 Report Share Posted September 13, 2020 16 hours ago, Royal Duke said: Dodge4ya - my brother helped me yesterday and today and we got it all figured out. He checked the wires the previous owner installed for the Fluid Drive system. we then hooked them up according to the shop manual. We also took the diaphragm apart and checked the operation of the stem. The stem was not extending all of the way out to push the transmission mounted lever into the power range. The tranny was stuck in the drive range which kept pressure on the gears and didn't allow the car to roll on an incline (Even with the clutch engaged) or shift out of reverse when stopped. Now that the wiring reflects the schematic and the tranny shifts into the power range, my problems are solved. I appreciate your earlier guidance because it gave me possible causes for the problems experienced. Wayne When I was in my 20's I drove a 41 Windsor for a friend in a movie shoot....that occasionally locked up just as yours did...never forgot how awful that was! Since then I have worked on several of the M4 transmissions and appreciate how they work and their idiosyncrasies. Glad you got it figured out. Quote Link to comment Share on other sites More sharing options...
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