Guest acebopper Posted October 5, 2012 Share Posted October 5, 2012 I HAVE A 1931 30U PLYMOUTH BUSINESS COUPE. TWO THINGS, WHAT IS THE TOP SPEED OF THESE CARS AND DO THEY SUFFER FROM VIBRATION AT SPEEDS OVER 40mph as mine does. Link to comment Share on other sites More sharing options...
ply33 Posted October 5, 2012 Share Posted October 5, 2012 Can't say for sure what the top speed is, but they did some coast to coast record drives in, I think, 1930 with average speeds over 50 MPH. "They" in this case being a Plymouth sales man from San Francisco but apparently with factory sanction. I'll try to dig up some period ads that refer to that. I know a fellow with a '31 PA four door sedan and have caravaned with him to a couple of meets. I recall one such trip of about 250 miles where he led and averaged about 50 MPH. I doubt that he'd do that if he was having problems with vibrations.So my opinion is that if you have vibration above 40 MPH then something is wrong.Or, given age and maintenance issues, maybe more than one thing is wrong. Link to comment Share on other sites More sharing options...
Guest acebopper Posted October 5, 2012 Share Posted October 5, 2012 Can't say for sure what the top speed is, but they did some coast to coast record drives in, I think, 1930 with average speeds over 50 MPH. "They" in this case being a Plymouth sales man from San Francisco but apparently with factory sanction. I'll try to dig up some period ads that refer to that. I know a fellow with a '31 PA four door sedan and have caravaned with him to a couple of meets. I recall one such trip of about 250 miles where he led and averaged about 50 MPH. I doubt that he'd do that if he was having problems with vibrations.So my opinion is that if you have vibration above 40 MPH then something is wrong.Or, given age and maintenance issues, maybe more than one thing is wrong. Hi thanks for that. the car in question has only done 5000m since it was completely rebuilt top to bottom but has spent the last 22 years in a musium. Link to comment Share on other sites More sharing options...
ply33 Posted October 5, 2012 Share Posted October 5, 2012 Hi thanks for that. the car in question has only done 5000m since it was completely rebuilt top to bottom but has spent the last 22 years in a musium.Top to bottom can mean different things... If the car was restored for show with the expectation that it was being trailered everywhere there might not have been as much care about balancing the drive shaft or wheels and tires, etc. as there would have been if the intent was to make a good driver. Link to comment Share on other sites More sharing options...
Steve Braverman Posted October 6, 2012 Share Posted October 6, 2012 Mine cruises very comfortably at 50-55 with no vibrations. I've had it very briefly up to 70 just to see if it could do it. It did. No vibration, but asking for trouble. My car is completely original with 39k miles. Link to comment Share on other sites More sharing options...
keiser31 Posted October 6, 2012 Share Posted October 6, 2012 Top to bottom can mean different things... If the car was restored for show with the expectation that it was being trailered everywhere there might not have been as much care about balancing the drive shaft or wheels and tires, etc. as there would have been if the intent was to make a good driver.I agree....check the drive shaft balance. Link to comment Share on other sites More sharing options...
DavidAU Posted October 6, 2012 Share Posted October 6, 2012 How old are the tires? If they have been sitting around they could have a flat spot. They could also be out of balance. Link to comment Share on other sites More sharing options...
Guest acebopper Posted October 6, 2012 Share Posted October 6, 2012 Mine cruises very comfortably at 50-55 with no vibrations. I've had it very briefly up to 70 just to see if it could do it. It did. No vibration, but asking for trouble. My car is completely original with 39k miles.Hi Steve the car has only covered 32k from new and only 5k from rebuild, I will check the prop and wheels today. Link to comment Share on other sites More sharing options...
Guest acebopper Posted October 6, 2012 Share Posted October 6, 2012 (edited) Update, thought I would start with the engine its self. Put sparkplug testers on all 4 flugs, fired her up and she is firing on all 4 and running very smooth with no missing or vibration. Let her warm up for a while then sitting inside slowly aplied pressure to the throttle, ok to start with but the more thottle I gave her the vibration started and by about half throttle the vibration was being transmitted thoughout the car.As far as I cane tell there is only one rubber mounting for the engine, this being at the front, bottom of the engine which seems to be in very good condition, the rear engine mount is fitted to the chassis via the bell housing with is ridged. ie no rubber mounts, when I blip the throttle the engine remains ridged and does not flex at all . took her out for a test run, got her up to 50mph, vibrating very badly, take her out of gear at that speed and she is as smooth as silk. Edited October 6, 2012 by acebopper (see edit history) Link to comment Share on other sites More sharing options...
Steve Braverman Posted October 8, 2012 Share Posted October 8, 2012 Check out my video. 1932 Plymouth PA - YouTubeMy engine mounts are all new. See how the engine rocks when the throttle is blipped. Link to comment Share on other sites More sharing options...
dep5 Posted October 8, 2012 Share Posted October 8, 2012 (edited) excerpt:As far as I cane tell there is only one rubber mounting for the engine, this being at the front, bottom of the engine which seems to be in very good condition, the rear engine mount is fitted to the chassis via the bell housing with is ridged. ie no rubber mounts,.The 30U has two rear engine mounts, #313528, one on each side, between bell housing and frame. Tom Hannaford, Auto Parts Cellar/Then and Now .. .can rebuild them.Link->NORS and Re-vulcanized Motor Mounts and Other Parts Edited October 8, 2012 by dep5 (see edit history) Link to comment Share on other sites More sharing options...
Steve Braverman Posted October 8, 2012 Share Posted October 8, 2012 The PA uses two rubber motor mounts, one high in the front under the water pump, and one low under the transmission. Link to comment Share on other sites More sharing options...
ply33 Posted October 8, 2012 Share Posted October 8, 2012 The PA uses two rubber motor mounts, one high in the front under the water pump, and one low under the transmission.Original poster wrote "1931 30U" so I guess it was built later in the production run. The "30U is a 30 and a PA is a 31" stuff came later to keep from confusing people with Plymouth's penchant for rolling out new models without respecting the calendar.I was under the impression that the PA was the first with the Floating Power engine mounts so it is quite likely that the mounts on the OP's car are different than yours. Link to comment Share on other sites More sharing options...
Guest acebopper Posted October 8, 2012 Share Posted October 8, 2012 The 30U has two rear engine mounts, #313528, one on each side, between bell housing and frame. Tom Hannaford, Auto Parts Cellar/Then and Now .. .can rebuild them.Link->NORS and Re-vulcanized Motor Mounts and Other PartsThanks for that information, I thought it funny that my bellhousing was bolted directly via two plates to the shassis rails which made the engine ridged, all makes sense now, will phone them up today. Link to comment Share on other sites More sharing options...
Steve Braverman Posted October 8, 2012 Share Posted October 8, 2012 Ahh, I didn't notice that the original poster's car is a 30U. That's a totally different breed. Link to comment Share on other sites More sharing options...
Guest acebopper Posted October 8, 2012 Share Posted October 8, 2012 Oh, May have solved the problem. There are two rubber mountings at the end of the bellhousing but they can't be seen very easily as they are tucked inside the open chassis, you can only feel them. my two are very hard and perished so will order some new ones, may as well replace the front one while I am at it. many thanks for all the replies, will let you know if this cures the problem.John Maddocks. UK Link to comment Share on other sites More sharing options...
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