Billyzack Posted January 16, 2009 Report Posted January 16, 2009 I have a 48 Desoto with a Fluid Drive trans and I believe I have gone as far as I can go. It refuses to upshift. The idle is correct, all the electrical tests seem to pass, I am very frustrated! Can anyone recommend someone in the Phoenix area I can ask to look at this? I want to drive the car but this is my last hurdle. Thanks, Bill B Peoria, Az Quote
55 Fargo Posted January 17, 2009 Report Posted January 17, 2009 I have a 48 Desoto with a Fluid Drive trans and I believe I have gone as far as I can go. It refuses to upshift. The idle is correct, all the electrical tests seem to pass, I am very frustrated! Can anyone recommend someone in the Phoenix area I can ask to look at this? I want to drive the car but this is my last hurdle. Thanks, Bill B Peoria, Az I will see what I can find out and post later. Try the WPC forum, and Yahoos PWHM 1946 t 1948 Chryslers, there are a lot of guys on these 2 forums that know plenty about this M5 trans..........Fred Quote
greg g Posted January 17, 2009 Report Posted January 17, 2009 The imperial club website has a complete trouble shooting guide in their repair section. It is the book that was distributrd to tech back in the day reproduced page by page. Quote
Fluid drive Posted January 17, 2009 Report Posted January 17, 2009 One of the first things that need to be verified is that the trans. is filled to the proper level with 10W NON DETERGENT oil. Usually that is the simple cause. From there check the relayand make sure the relay fuse isn't blown. If you are sure the electrical components arent grounded, kickdown switch and governor-wiring harness.Then check the pilot valve( big hex plug on trans bottom and make sure the relief valve isn't stuck in the open position. Sometimes the engine idle is set too fast . In order to operate correctly these old gals have to idle down or they just refuse to shift.If these things do not remedy your problem it is probably internal and could be the oil pump -low output (less than 40 #) or direct speed sleeve ,shift rail and guide or free wheeling control sleeve and countershaft gear. How many of you have had one of these with a worn blocker ring and had to endure that CRUNCH when the trans. upshifts into main drive? A good trick to use when filling the fluid drive unit is to elevate the right side of the car so that you can get more fluid into the unit. That stiffens the coupling considerably and makes the car much more responsive. Quote
Frank Elder Posted January 17, 2009 Report Posted January 17, 2009 eeking extra fluid into the coupling won't "over pressure" it? Fluid must have been put in with a pressurized pump for it to have reserve capacity? I mean that you can't fill it all the way by simply pouring it in. Quote
PatS.... Posted January 17, 2009 Report Posted January 17, 2009 Two things: Check the emergency brake to ensure that it's not full of dirt or out of adjustment and dragging a bit. That drag would make upshifting impossible, even if it was just a bit of dirt. If that isn't it, take the governor off, take the cover off (4 screws)and give it a generous blast of carb cleaner, followed by a generous blast of brake cleaner to dry it out, then coat the weights with some white lithium grease or light 10 wt oil, reassemble and try that. Quote
Dodgeb4ya Posted January 17, 2009 Report Posted January 17, 2009 Pull the 30 amp fuse out of the electrical trans relay- after of course making sure the ttrans is full of 10 weight oil and drive it. It should upshift almost imediately upon accelerating and then letting off on the gas pedal- it also should not downshift when coming to a complete stop until you push in the clutch and wait a few seconds. If it does not upshift by disabling the transmission electrical circuit (removing the fuse) then you most likely have an internal trans problem- low oil pressure - oil pump/pressure regulator/bypass valve ect.or a bad blocker ring and bad input shaft. Bob Quote
Dodgeb4ya Posted January 17, 2009 Report Posted January 17, 2009 Forgot to mention idle speed has to be 650 or lower -500 is about right. Too high can cause delayed or no upshifts too. Quote
Tom Skinner Posted January 17, 2009 Report Posted January 17, 2009 All great advice! I run my motor at 450-475rpm's warmed up, at idle. When they are running good thats enough rpm's. Tom Quote
Billyzack Posted January 25, 2009 Author Report Posted January 25, 2009 Thanks for all the help, I tried all of your suggestions and still no upshift. The electrical system seems fine so I am assuming the problem is internal..I found a rebuilt trans on Ebay for $399 + $95 shipping. Does anyone know anyone that will take the 2 old ones off of my hands, I have a motor too. Thanks for the help, Billy Z Quote
Gary Manes Posted January 25, 2009 Report Posted January 25, 2009 When we got to the tranny on my 1948 New Yorker we took the car out for what we thought would be the maiden voyage. We had testors on all the switches, etc. to verify function. NO up-shift regardless of our efforts. EVERYTHING in the books, and outiside of the tranny were checked and double checked. Finally, the tranny was removed and examined "inside." Sure enough there was a damaged gear. No fear; I had another one from a '48 New Yorker I use to have as a parts car. Upon examination, "exactly" the same gear was toast in it. Gears were located, and the primary tranny was re-assembled. Ran like a top. After a couple of years it now shifts into "neutral" when driving on city streets at around 30 mph to 35 mph (it re-ingages with a tap of the accelerator). Because there does not seem to be any pattern, I have not pursued it. I also have a 1948 Desoto Custom club coupe in the wings trying to decide whether to modernize the drive train or just the transmission now that the adaptor plate is available for a 350. Quote
James_Douglas Posted January 25, 2009 Report Posted January 25, 2009 Gary, How the heck are you ? James Quote
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