1948 Plymouth Vibration

[Labrauer]

I have a 1948 Plymouth Special Deluxe Coupe that has a vibration in it when driving down the road. At slow speeds you can't tell it but when you get up to around 45 mph you can tell it and the faster you go the more it gets. Anyone have any ideas on what it might be. I have heard that it could be the u joints but before I spend $190 dollars on them I would like some feed back from the forum people in what you all think it could be. I have had the tires ballanced and they are fine except one on the back right has a little bent rim but it isn't bad. Was told by the ballance people that wouuldn't cause the problem I am having.

Thanks,

Larry Brauer

Edited December 8, 2010 by Labrauer

[captden29]

Lab, i think you are smart not to just start throwing money and time at it. if i had this problem, balancing is a great first step. knowing the rear rim is bent i would definitely change it before proceeding to other fixes. it will not be that expensive and it should be replaced anyway. the bent rim could be the problem even if you are told different. vibrations can be difficult to trubleshoot as they often seem to come from one area of the car when they really originate elsewhere. when my 79 lincoln had vibe problems, i balanced the tires and that did not fix it. i found an old time mechanic to take the car for a test drive and he came back and said it was the carb.. i did not totally agree, but i had him rebuild it and as it turned out he was right. this forum will have many good suggestions, probably the right one in there somewhere, but if you can get some local hands on help it could add to all the info you get here and solve your problem for the least cost. good luck, capt den

[Don Coatney]

First question is has this car always had this vivration problem or did it just start?

[old stovebolt]

First question is has this car always had this vivration problem or did it just start?

Very good question, when was it first noticed?

Investigative steps might include rotating the wheels front to rear and see

if any steering wheel vibration changes. Before you rotate the wheels, drive the car and note if the brake pedal pulses when the brakes are applied ....this might

suggest a bent rim. Also while driving, pop it in neutral and see what, if any, vibration changes occur. Also, rotate in your spare wheel onto the car and see what effect that makes. You could also have a tire internally coming apart - cord separation- which could be the cause. Good luck.

[TodFitch]

First question is has this car always had this vibration problem or did it just start?

And the next question is have you examined anything? Like maybe seeing if the driveshaft appears to be straight and the universal joints have any radial or side play in them. And you might want to check if it is related to engine speed or vehicle speed. Does it change if you are braking or turning? All are easy and free things to check that could help isolate the problem.

[Labrauer]

The car has had this vibration in it since I got it about 3 months ago. I will check what you all have told me to check. The car has radirol tires on it except for the spare tire. It is a bias tire that I think came on the car before the guy I got it from changed the tires on the car. I will climb under the car and check for play in the drive shaft. I don't know a lot about the car except it is a nice car. I know I have to adjust the breaks on it because the break pedal goes to far down when applied. If there is no change in the vibration when shifted into neutral going down the road I have been told it would be the u joints.

Thanks for the information so far and look forward to more feedback from the forum.

Larry Brauer

[P-12 Tommy]

Same vehicle, same problem.

Tom

[greg g]

So now that there are two threads regarding your issue, did you investigate to determine which style of joints your car is equiped with? did you try to flip your drive shaft end to end and or 180 degrees to see if the phase change modified your symptom?

Did not find information to your initial question helpful, or did you just not find it?

Is your vibration at 30 then again at 60, if so that usually goes back to a wheel balance problem. Where do you feel the vibration hand on the wheel or seat of the pants.

Do you have a bent rim, did you try to isolate it by putting on the spare tire. Do you have a sidewall bulge or a slipped belt in a radial?

Did you ever have any one drive down the road behind you to observe your wheels and or tires to see what's going on at the speeds you mentioned?

[Labrauer]

I haven't had the chance to change the drive shaft around yet nor have I had the chance to change the tire to the spare. I will do this as soon as I can and get back to you on the results. The vibration is from about 30 to 60 all the time. It is not a stop and again problem. I can feel it in the steering wheel and also in the seat of the car also in the dash and floor board. The mirrows even shack back and forth. I am also going to check the motor mounts to see if they are ok. The car has plenty of power and will do 70 but I don't drive it that fast because of the vibration. It seems to get worse at a higher speed than a lower one. The car has dual exhaust on it and I thought that maybe the pipes where hitting each other but they have more than plenty of room all around them. Oh the car is fitted with the touinon ball type u joints. I would like to change to a more modern type but don't know if that can be done and what it all involves to do it.

thanks for all the information and I'll keep in touch on the outcome,

Larry Brauer

braular@yahoo.com

713-410-7481

Edited December 9, 2010 by Labrauer

[John Reddie]

Welcome to the board. There is a guy in the Plymouth Owners Club bulletin that sells driveshafts with the modern type of universal joints. He claims that the new driveshaft bolts right up to the car with no modifications necessary. Let me know if you want more info.

John R

[Reg Evans]

Welcome to the board. There is a guy in the Plymouth Owners Club bulletin that sells driveshafts with the modern type of universal joints. He claims that the new driveshaft bolts right up to the car with no modifications necessary. Let me know if you want more info.

John R

If they'll work for a 42 Dodge coupe I'd be interested too.

[Roadkingcoupe]

If they'll work for a 42 Dodge coupe I'd be interested too.

Try a Truck Spring and Driveline shop in your area. A good shop can make one easy.

or the ad:

Driveshafts for Plymouth Dodge DeSoto Chrysler

New shaft replaces old trunion type, bolt in, no modifying. $395.00 and up, plus shipping. Joe McGinnis joe.callent@gmail.com

706 781 2805

info from Plymouth Bulletin, I have no direct knowledge of the service or product.

[Labrauer]

John R I would like more information on the guy that has a modern drive shaft for my 48 plymouth coupe that will bolt right in.

Thanks,

Larry Brauer:confused:

[Roadkingcoupe]

John R I would like more information on the guy that has a modern drive shaft for my 48 plymouth coupe that will bolt right in.

Thanks,

Larry Brauer:confused:

Try a Truck Spring and Driveline shop in your area. A good shop can make one easy.

or the ad:

Driveshafts for Plymouth Dodge DeSoto Chrysler

New shaft replaces old trunion type, bolt in, no modifying. $395.00 and up, plus shipping. Joe McGinnis joe.callent@gmail.com

706 781 2805

info from Plymouth Bulletin, I have no direct knowledge of the service or product.

[John Reddie]

That is the guy in the Plymouth Bulletin that appears in the previous post. Good luck to you Larry.

John R

[old stovebolt]

you ever fix the problem?

[Labrauer]

;)Not yet I have been busy on other things now. I will get on it as soon as I get some free time. You know it is that time of the year when everything is in a rush to get done so you put other things off for a while till Christmas is over and your life gets back to normal.

Larry Brauer

[Labrauer]

Yesterday I jacked the car up and put it on jack stands and got in it started it up and put in first gear. Let it idle in first gear then looked under it to look at the drive shaft. The drive shaft was moving a little up and down when the wheels were turning. So I am thinking it is maybe the u joints or (Ihope not) the drive shaft is a little bent. I have priced the u joints and they are $125 each which means 250 for both front and back plus the shipping. I guess I better take it out and check this. How can you tell it you have a bent drive shaft? Lay it on the floor and roll it back and forth or what?

Thanks for the information as alway,

Larry Brauer

[greg g]

At that price you are half way or better to having a new shaft with new style joints made up. I guess were I in that position I would see about having one done.

I had a shaft shortened straightened, balanced and 2 new joints done fo an offtopic truck for 175.00 locally.

The consideration with the Mopar shaft is that the ball and trunion joints do the deal for lengtheing and shortening the shaft as it moves over bumos and deals with loads, instead of a splined length of shaft. So that would have to be dealt with somehow in a newly built shaft.

[Alshere59]

Blue skies site has a parts list that I am fairly confident will give you the various parts you need to have a drive shaft made. I just took his list to a couple of locals shops and had mine done. Even got a discount from having the list. No research for them. I did leave off the price he paid.

It is found here.

http://www.50plymouth.com/07-cha/cha.html

Al

Edited December 21, 2010 by Alshere59

[Greenbomb]

Not to hijack the thread, but why would going to "modern" u-joints be better than just putting in new stock u-joints. Other than not being able to find a replacement in Podunk, USA on a Sunday afternoon. Those old originals went alot of miles back in the day-shouldn't new replacements do the same or better?

[Young Ed]

Its hard to find someone that can properly install the old style joints. After having the wrong springs Dads 51 convert needed new ones. $400 bucks later and the rebuilt driveshaft is on a shelf because they couldn't get it right. He's running a good used one in his convert now.

[TodFitch]

Its hard to find someone that can properly install the old style joints. After having the wrong springs Dads 51 convert needed new ones. $400 bucks later and the rebuilt driveshaft is on a shelf because they couldn't get it right. He's running a good used one in his convert now.

Not sure about straightening one of the old style, but replacing the ball and trunnion joints has only one critical step so far as balance is concerned: Getting the pin pressed in so it is exactly centered. Making a small collar of the correct height to go around the pin as it is pressed into place will keep the operation quick and simple.

[Labrauer]

I got the vibration in the car taken care of. I took the ball and trunion u-joints apart and one of the pins was off about an 1/8" so I used a vice and two sockets one deep one on one side and a small one the size of the pin and was able to push the pin and got it with in 1/2 thousands difference on each side. Checked both sides of the drive shaft and did both the same. Now the drive shaft runs true and straight instead of bouncing around like it was. There is nothing to those u joints you just have to take your time to get the pin right and all else falls into place. Also had to replace on of the boots as it was broken into.

Thanks for all the information on this subject,

Larry Brauer:D

[Joe Flanagan]

So now it runs good? No vibration?