TennesseeCoronet Posted February 22, 2018 Share Posted February 22, 2018 (edited) Hi all! First time post for me. So glad I found this wonderful resource! I have a 1950 Dodge Coronet that's been lightly restored. It runs wonderfully and I adore the car. I have one problem that really holds it back. The car won't really go over 50 MPH because the engine revs too high to safely drive any faster. believe 4th gear, or as some people refer it as (High High gear) doesn't work, or it won't switch to it. What worries me is that the car was switched to a 12 volt system about 20 years ago, and I've been reading all about how this transmission works and I'm afraid that it might not be working or even capable of working with this 12 volt system. If you have any experience with these old cars electrical system, and or transmission, please let me know! -Aaron Edited February 22, 2018 by TennesseeCoronet (see edit history) Link to comment Share on other sites More sharing options...
JFranklin Posted February 22, 2018 Share Posted February 22, 2018 Don't blow up the engine! You might want to add a tachometer to see what is really going on. If it is really not shifting properly find a good transmission shop, or at least a good repair manual. Link to comment Share on other sites More sharing options...
Mike36 Posted February 22, 2018 Share Posted February 22, 2018 Welcome to the forum. Much help on these Dodges is available on the P15 - D24 web site. It’s all Chrysler products, and many members that really know these cars. 1 Link to comment Share on other sites More sharing options...
61polara Posted February 22, 2018 Share Posted February 22, 2018 In Low Range, will it shift from first to second? If not, the governor is the issue. I've read here that they won't shift unless the feed to the governor is dropped to 6v. There have been a lot of posts on here about this with most coming to the conclusion that you cannot convert this transmission to 12 volts and expect it to shift. Just do some searching. Link to comment Share on other sites More sharing options...
TennesseeCoronet Posted February 22, 2018 Author Share Posted February 22, 2018 I have the shop repair manual. I've been studying it the last few days. Good to know about the P15-D24 website. Link to comment Share on other sites More sharing options...
TennesseeCoronet Posted February 22, 2018 Author Share Posted February 22, 2018 It will shift from first to second. The pervious owner had a shop and two different guys look at it. Nobody know anything about it. I'm worried it is the 12 volt system. I wonder if I could run the transmission on a separate 6 volt system.. Any thoughts? Link to comment Share on other sites More sharing options...
JFranklin Posted February 22, 2018 Share Posted February 22, 2018 Maybe convert the car back to 6 volt. Is your battery installed + ground? Link to comment Share on other sites More sharing options...
TennesseeCoronet Posted February 22, 2018 Author Share Posted February 22, 2018 4 hours ago, JFranklin said: Maybe convert the car back to 6 volt. Is your battery installed + ground? Yes it is. Hmm Link to comment Share on other sites More sharing options...
Rusty_OToole Posted February 23, 2018 Share Posted February 23, 2018 The Gyromatic is the same as the Fluid Drive system used in Chrysler and DeSoto cars. There are 3 gear positions for Low, High and Reverse. Normally you start off in High and lift off the gas pedal at any speed above 14MPH. Then you hear a soft *click-clack* from under the floor boards, step on the gas and you are in High gear of High range (top gear). If the trans is not shifting properly it usually means the wiring is messed up, or engine is idling too fast although, it could be trans is low on oil. None of these things is difficult or expensive to fix. If you can't change it back to 6 volts at least take a center tap off the battery to run the trans controls and all other 6v accessories like radio, heater etc. The original setup was + ground, if it is now - ground most things will still work although it might mess up the radio. It is best and easiest to leave these cars 6v. 1 Link to comment Share on other sites More sharing options...
TennesseeCoronet Posted February 23, 2018 Author Share Posted February 23, 2018 16 hours ago, Rusty_OToole said: The Gyromatic is the same as the Fluid Drive system used in Chrysler and DeSoto cars. There are 3 gear positions for Low, High and Reverse. Normally you start off in High and lift off the gas pedal at any speed above 14MPH. Then you hear a soft *click-clack* from under the floor boards, step on the gas and you are in High gear of High range (top gear). If the trans is not shifting properly it usually means the wiring is messed up, or engine is idling too fast although, it could be trans is low on oil. None of these things is difficult or expensive to fix. If you can't change it back to 6 volts at least take a center tap off the battery to run the trans controls and all other 6v accessories like radio, heater etc. The original setup was + ground, if it is now - ground most things will still work although it might mess up the radio. It is best and easiest to leave these cars 6v. Thank you so much! Yes I will start with fluid level and idle speed! Fantastic advice. And I WILL keep this forum updated when I fix it. Link to comment Share on other sites More sharing options...
Curti Posted February 24, 2018 Share Posted February 24, 2018 Post a picture of your Dodge ! Link to comment Share on other sites More sharing options...
vermontboy Posted February 24, 2018 Share Posted February 24, 2018 If you aren't used to driving a 50's car doing so at 50 mph is a bit unnerving because there is no overdrive (4th gear) like modern cars have. So hooking up a tach might save you a lot of worry. I had a 51 Plymouth and I can assure you it should be able to cruise right along with traffic at 55 or even 60 - it will do 70 or better all day but sounds really busy doing so. Motor Trend found a top speed of 80 to 85 mph in a 1952 road test. The old rule of thumb was 20mph per 1000 rpm. That's 3000 rpm at 60 mph vs 1800-2000 rpm in modern cars. But these Mopar flathead 6 cylinders were made to run - Plymouth was even used in stock car racing successfully (it is lighter than your Dodge)... 1 Link to comment Share on other sites More sharing options...
JFranklin Posted February 24, 2018 Share Posted February 24, 2018 My '36 Chevrolet has a 4:11 rear gear-set, 60 sounds real racy. 1 Link to comment Share on other sites More sharing options...
TennesseeCoronet Posted February 25, 2018 Author Share Posted February 25, 2018 On 2/23/2018 at 8:05 PM, vermontboy said: If you aren't used to driving a 50's car doing so at 50 mph is a bit unnerving because there is no overdrive (4th gear) like modern cars have. So hooking up a tach might save you a lot of worry. I had a 51 Plymouth and I can assure you it should be able to cruise right along with traffic at 55 or even 60 - it will do 70 or better all day but sounds really busy doing so. Motor Trend found a top speed of 80 to 85 mph in a 1952 road test. The old rule of thumb was 20mph per 1000 rpm. That's 3000 rpm at 60 mph vs 1800-2000 rpm in modern cars. But these Mopar flathead 6 cylinders were made to run - Plymouth was even used in stock car racing successfully (it is lighter than your Dodge)... That's good information! I appreciate it. Yeah I don't have much experience with late 40s early 50s cars with higher speed driving. I've heard great things about these flathead sixes. They must be good since mine runs smooth as silk at 68 years old!! Link to comment Share on other sites More sharing options...
TennesseeCoronet Posted February 26, 2018 Author Share Posted February 26, 2018 On 2/23/2018 at 6:26 PM, Curti said: Post a picture of your Dodge ! I will get a picture to post next time I'm with the ole girl. My Coronet is back with a gray interior. I currently have her in storage. Pretty soon I'll have her full time Link to comment Share on other sites More sharing options...
Rusty_OToole Posted February 26, 2018 Share Posted February 26, 2018 If you want more info on your transmission system, how to operate it, how to service and repair it, go to the Chrysler section and do a search for Fluid Drive. There are a couple of long threads from 2008 that go into the subject very thoroughly but many questions have been answered in other threads. You can find out everything you need to know from the archives. 1 Link to comment Share on other sites More sharing options...
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