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I have a vibration, can you help? 1927 Chrysler 50 (4 cylinder)


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I just purchased a 27 Chrysler 50 (4 cylinder).

I has a vibration which seems like the motor is the cause.

It slowly gets worse the faster I go and when driving along if I slip it in neutral and let the engine idle the vibration goes away as I glide but it comes back when the engine is revved even with the car is still free wheeling in neutral.

Any suggestions guys?

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4 hours ago, avgwarhawk said:

Is there a U-joint in the drive line?  Check it for binding. 

Yes....check the fabric u-joint.

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With your description I would be looking forward of the transmission.

Open the hood and bring the engine speed up in neutral and see what you can see. Or feel.

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The model 50 had fabric universal joints originally, these would cause a vibration if they are worn or not in good condition. From your description it sounds more likely to be motor related than from the propshaft.

 The rear of your motor should be directly bolted to the chassis frame, the front has a small multi leaf spring that supports the front on the cross member, this is held in place by small U shaped brackets with lined parts to stop it bouncing up and down, check to make sure these parts are all there and that both sides are there.

 Also on the top of the motor, on the very back left stud of the head there should be a short "link" that connects to a vibration damper mounted on the firewall, see if that is there.

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I agree with keiser31. I have a ‘25 Maxwell that had the same symptoms. I too thought it was engine related so replaced plugs, condenser, cleaned and reset points.  Nope. Checked wheels for wobble or alignment issues. Nope. Thought it might be an out-of-balance or bent drive shaft. Crawled under to remove it, and surprise! These cars do not have a U-joint per se. They have a “rag joint”, a thick, fibrous disc  connecting the drive shaft to the differential. On mine, one of three bolts holding it in place was gone. When under load the drive shaft would shift, making it out-of-round (unbalanced). When I put it in neutral (clutch in), no vibration.  Replaced the missing bolt, tightened the rest, and she hums right along now.

 

Check the rag joint, and good luck!

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Somebody in the past had a normal driveshaft made for the car so its uni joints at each end.

But I checked the front engine mounts as you suggested Viv and the cross spring is just sitting on a few strip of rubber by the look of it. There is no clamp on one side and the other has what looks like a spring shackle but it is very loose and doing nothing. I can lever the front of the engine up with a small bar?

Hopefully this is the cause of the vibration.

Can I buy new engine mounts anywhere?

Any chance of posting a pic of what the correct mounts and correct clamp looks like?

 

Thanks again 

 

 

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Here is pics of the existing mounting set up, pretty slack. 

Might try replacing the rubbers then clamping the ends down and doing a test run to compare.

 

 

image.jpeg.8fc795c038afe9c1789b63c3cdcc932e.jpegimage.jpeg.59b6f2c584c1cfd15e5a0323010c66e6.jpeg

 

I had a 1930 Triumph Super 7 with a drive train vibration (stored 21 yrs) which had the same flexi joint system and apparently when parked up for years they sag slightly with the weight of the shaft and the joints set hard & slightly off square. So I had an normal driveshaft built for that, much better as it ran true and had grease uni joints. Presumably a previous owner of this car had the same thoughts.

Nice tidy setup

 

 

image.jpeg.fe0a02f88ce112195e6e3c8149074909.jpeg

 

DSCN3980.JPG

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Not really, most people would get it balanced before fitting.

You have to remember when test driven on the flat or even going down a hill where the speed is maintained there is the vibration but when the clutch is engaged and the motor idles the car run smooth, when neutral is selected and the clutch released with motor idling but the road speed is maintained the vibration goes away. While free wheeling with the motor idling travelling at speed there is no vibration but as soon as you rev the motor up (still in neutral) the vibration comes back so no its not the drive shaft, the wheel balance etc I think it can only be from the engine.

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New rubbers fitted under the front mount made a slight improvement but it still isnt good enough. Very frustrating as its a lovely car to drive if it wasn't for the vibration.

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  • Peter Gariepy changed the title to I have a vibration, can you help? 1927 Chrysler 50 (4 cylinder)

Hi Rata road,

 The picture you posted showing the one side "U" shape mounting is partly correct. There should be a second mounting on the other side exactly the same and each of them should have 3 components not 2. 

 As shown in your picture, there is the large U shaped bracket bolted thru the x member, then that odd shaped bracket as shown in your picture covers the bolt that attaches the big U to the x member. This odd shaped piece has a small about 2mm thick pad rivetted to it. The pad is made of a material similar to woven brake lining and the leaf spring almost sits on the pad. Above the leaf spring there should be a second smaller U shaped piece that also has a pad facing down. This smaller U piece fits inside the bigger U and uses the same bolt going thru both the U brackets. The smaller top U piece sits just above the leaf spring, allowing the spring to move slightly but it stops the motor bouncing up and down. 

 There should be NO rubber pad , of any sort between the ends of the leaf spring and the x member, someone has added those, perhapd because the leaf spring is weak or broken

 Regards Viv.

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10 hours ago, viv w said:

Hi Rata road,

 The picture you posted showing the one side "U" shape mounting is partly correct. There should be a second mounting on the other side exactly the same and each of them should have 3 components not 2. 

 As shown in your picture, there is the large U shaped bracket bolted thru the x member, then that odd shaped bracket as shown in your picture covers the bolt that attaches the big U to the x member. This odd shaped piece has a small about 2mm thick pad rivetted to it. The pad is made of a material similar to woven brake lining and the leaf spring almost sits on the pad. Above the leaf spring there should be a second smaller U shaped piece that also has a pad facing down. This smaller U piece fits inside the bigger U and uses the same bolt going thru both the U brackets. The smaller top U piece sits just above the leaf spring, allowing the spring to move slightly but it stops the motor bouncing up and down. 

 There should be NO rubber pad , of any sort between the ends of the leaf spring and the x member, someone has added those, perhapd because the leaf spring is weak or broken

 Regards Viv.

 

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That very interesting Viv, any chance of a few pics to clarify?

I done some more testing today and when you look at the motor running it doesn't look to vibrate that much to the eye, I even done a glass of water test (see the link) and I know dont think its the cause so I'm starting to think that "Max4Me" might be onto something.

Why do you think looking at the water movement?

I jacked her up and monitored the driveshaft today.

I pulled the front unit off the driveshaft and will take it to town tomorrow (4 hr return trip) and get 2 new uni joints if that doesnt help I think I will get the driveshaft balanced and go from there.

It might take time but I enjoy this sort of work, part of the hobby.

 

 

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On 3/18/2023 at 5:30 PM, Rata Road said:

Not really, most people would get it balanced before fitting.

You have to remember when test driven on the flat or even going down a hill where the speed is maintained there is the vibration but when the clutch is engaged and the motor idles the car run smooth, when neutral is selected and the clutch released with motor idling but the road speed is maintained the vibration goes away. While free wheeling with the motor idling travelling at speed there is no vibration but as soon as you rev the motor up (still in neutral) the vibration comes back so no its not the drive shaft, the wheel balance etc I think it can only be from the engine.

I agree. That doesn't sound like driveline trouble.

 

On 3/18/2023 at 12:46 AM, Rata Road said:

Somebody in the past had a normal driveshaft made for the car so its uni joints at each end.

That doesn't sound like a particularly great idea. I assume the rag joints would have run dead straight at normal ride height to avoid tearing themselves up.

 

Conventional u-joints on the other hand need a little angle to keep the bearings rolling back and forth. The rub is, when there is any angle, the driven end of the u-joint speeds up and slows down as it turns causing vibration. You mitigate this by using 2 of them. If the angles on the 2 joints are identical the speed variations will cancel. The angles can be equal and opposite, or equal and additive. Either works. The rotation coming off of the second u joint will be smooth, and so no additional vibration. This is a completely separate issue from balance, which can also cause vibration.

 

Conventional u joints will run smooth if you run them dead straight too, just not for very long. The little bearings do not roll, and they pound or wear dents in the cross where they contact it. The damage looks very similar to what happens when a u-joint runs out of lubricant. Here is a picture Gerty the Gremlin posted in a Pontiac thread. This probably wasn't caused by wrong angle, but it is a nice clear picture that shows exactly the kind if damage I am talking about.

 

5903E06F-A8BE-42EC-8D2A-704CBAAC26A1.jpe

If you have the driveshaft out of the car, I would be really tempted to take those u-joints apart and inspect them. If you do, make marks so that it goes back together with the flanges "clocked" the same way in relation to the driveshaft tube, and on the same end they came from. Getting a flange 180 degrees out will upset the original balance job on the driveshaft.

 

Still, I think you are dealing with engine or flywheel/clutch vibration due to your description.

 

 

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On 3/18/2023 at 8:30 PM, Rata Road said:

While free wheeling with the motor idling travelling at speed there is no vibration but as soon as you rev the motor up (still in neutral) the vibration comes back so no its not the drive shaft, the wheel balance etc I think it can only be from the engine.

Have you ever had, or driven a 4 cylinder car of this age before?   Some new owners never had one and are used to modern cars running like silk at 80MPH with no vibrations.   

 

These engines are archaic technology as far as total lack of any internal balancing and engineers not even thinking about piston weight, etc,  while using a non-counterweighted crankshaft.  But bear in mind that in 1927,  most roads, even here in the USA were potholed dirt roads and people drove 35 to 40 MPH.   Today we are forced to run these cars much faster to try to stay away from getting rear-ended by modern drivers, and then the engine vibrates to high heaven with the nearly 5 to 1 rear axle ratios.

 

Within 3 or 4 years later, most car makers had scrapped the 4 cylinders for 6 and 8's to run smoother as the roads improved.  Chrysler even used the sales gimmick of the Floating Power mounting system, and that should tell you that they knew they did have awful vibrations compared to later car engines.  

 

You don't see many of the 4 cyl cars on the roads anymore, they sit in garages or get trailered to shows unless you are lucky enough to have lightly used roads to drive them at the speeds they were once driven, and designed for

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Glad I found this story. My 1926 model 50 has the solid engine mounts, leaf spring front mount and rag joints on drive shaft. And now I can see there is much room for improvement.

I have made new joints using the red 10mm polyurethane material. Red is a more flexi rating.

The car is a bit rough around 40mph, but I thought that wasn't too bad for a solid mount engine.

Earlier on I put the rear end up on stands and ran the motor in top gear with a few revs and could see the shaft was running fairly true. And in the future I was going to experiment with tail shaft using a hose clamp and tyre weight to see if balancing makes any difference.

The front engine mount has always had me puzzled so it would be great if Viv could show some pics as it sounds like I'm missing some (a lot of) bits as the ends of the spring are running bare on the cross member, and looking at the wear pattern it's been like that for a long time. I wonder if that mount can be replaced with a small rubberised engine mount.

I also have that friction damper on the firewall, but the link to the head has always been missing.

I remember reading else where the rag joint uni goes hand in hand with the solid engine mounts for a smoother drive, but I would never consider changing it as this is what makes the early 50s unique.

With FJs comments about early fours not being used much and slow cruising, yep, very true, so luckily I live on the western side of Toowoomba which opens up to the Darling Downs and it's fairly flat rural country side with miles and miles of quiet secondary roads and small townships.

So it's perfect for romping along at 35mph and taking 2 hours to do a regular 45 minute drive😆

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F & J yes I have had experience with 20's 4 cylinders, in fact I have 3 model T's a 28 & 30 Triumph Super 7 of which get driven on a regular basis. I probably drive a 20's 4 cylinder more often than most people (I'm lucky I live similar to Tonz) and no they are not a vibrating engine by nature. The Chrysler engine is a nice running engine, I was talking to a guy with a 27 Plymouth the other day and he has his 4 cylinder motor running super smooth and i hope to do achieve similar.

I had a vibration problem on my 30 Triumph (same flex driveshaft system) threw that out and got a driveshaft made up for it, problem gone. If this car didn't already have one fitted I would have changed it. The shaft doesn't run straight as the diff is on springs so every bump, turn, brake etc the uni joint will be working.

Update - yesterday I went to town (4 hr return trip) and took the front uni joint with me as there was a tiny bit of play in it. Managed to get that changed out and when I got home I refitted the shaft and then I done the chalk & hose clamp method on the drive shaft to try and semi balance it just to see, havent test driven it yet but it feels better on the jacks when revved up in top gear but the read test is the real test.

Stopped in at a country garage that specializes in old cars on the way home, they thought clutch/flywheel balance which makes sense but they said they had similar with a model A which turned out to be a timing slippage issue at road speeds which made the engine (and the car) vibrate.

One thing at a time but next I will probably get the driveshaft and attachment flanges balanced and then if no luck I might remove the gearbox and get the flywheel & clutch balanced.

Its been a very interesting thread, thanks so much for everybody's input.

I'm about to clean the Chrysler up as its a wedding car tomorrow then the next day is our local annual car show but I will post any progress.

Thanks again Guys

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