Vibration at higher RPMs

Discuss all things Model T related.
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules

Topic author
Phillip
Posts: 24
Joined: Mon Feb 11, 2019 2:33 pm
First Name: Phillip
Last Name: Lee
Location: Nashville, TN
MTFCA Number: 50230
Board Member Since: 2018

Vibration at higher RPMs

Post by Phillip » Mon Apr 08, 2019 8:15 pm

My 1927 T roadster pickup has a 1920 engine/transmission and at low to moderate RPMs it is smooth, but at high RPMs it starts to have lots of vibration under no load or running down the road. What would be the first suspect? I thought maybe the rear main bearing may be worn so I pulled the oil pan. I see no way with out my little 2 year old grandsons hands and arms to get to the rear main. Also, nun of the rod caps had dippers on them. Should they? The connecting rods all looked like they had plenty of oil all the way up into the piston skirts.
DSCN3499.JPG
DSCN3587.JPG
DSCN3588.JPG
DSCN3590.JPG
Phillip

User avatar

Henry K. Lee
Posts: 1888
Joined: Sun Jan 06, 2019 11:09 am
First Name: Henry
Last Name: Lee
Location: South Pittsburg, TN
MTFCA Life Member: YES

Re: Vibration at higher RPMs

Post by Henry K. Lee » Mon Apr 08, 2019 8:24 pm

Phillip I would first start looking at ignition. Plug breakdown at higher RPM's are common. Check your coils too. I had one that
drove me nuts, it was a bad plug. Sometimes loose connections at the timer, etc. Did this just start acting up?

All the Best,

Hank


Topic author
Phillip
Posts: 24
Joined: Mon Feb 11, 2019 2:33 pm
First Name: Phillip
Last Name: Lee
Location: Nashville, TN
MTFCA Number: 50230
Board Member Since: 2018

Re: Vibration at higher RPMs

Post by Phillip » Mon Apr 08, 2019 9:30 pm

Hank,
Had the coils rebuilt and adjusted by The Coil Doctor, new plugs and new New Day timer. Cleaned and tightened the plug wires and the wire under the coil box. Did not think about checking to see if missing at higher RPM. Got the truck last December and it was doing it then. Will do the ole screwdriver test on the plugs tomorrow. Thanks.
Do you have any kinfolks from Mississippi or Alabama?
Phillip

User avatar

Ruxstel24
Posts: 1657
Joined: Sun Jan 06, 2019 11:25 am
First Name: Dave
Last Name: Hanlon
Location: NE Ohio
MTFCA Number: 50191
Board Member Since: 2018

Re: Vibration at higher RPMs

Post by Ruxstel24 » Mon Apr 08, 2019 9:37 pm

How high of RPM/Mph are you talking ?
A stock T gearing, non counterbalanced crank is going to vibrate some, say over 40mph...just sayin.


Scottio
Posts: 104
Joined: Sun Jan 06, 2019 1:02 pm
First Name: Scott
Last Name: Lay
Location: California

Re: Vibration at higher RPMs

Post by Scottio » Mon Apr 08, 2019 9:50 pm

I have been dealing with the same thing for a couple of years now. My engine and trans. have been rebuilt with scat crank and all the good stuff and balanced. Same thing though smooth up to a about 38 mph then a vibration starts. I have just learned about a torque tube bushing right behind the u-joint that is a common wear item according to the model T service manual. I will be pulling my drive shaft out tomorrow, I hope, and checking that bushing and u-joint.


Scottio
Posts: 104
Joined: Sun Jan 06, 2019 1:02 pm
First Name: Scott
Last Name: Lay
Location: California

Re: Vibration at higher RPMs

Post by Scottio » Mon Apr 08, 2019 9:53 pm

I also noticed that after I grease that bushing the vibration is not as bad. You may want to try that.

User avatar

Henry K. Lee
Posts: 1888
Joined: Sun Jan 06, 2019 11:09 am
First Name: Henry
Last Name: Lee
Location: South Pittsburg, TN
MTFCA Life Member: YES

Re: Vibration at higher RPMs

Post by Henry K. Lee » Mon Apr 08, 2019 11:45 pm

Phillip process of elimination for sure.

Could very well be a bushing as Scott talked about.

Just trying to assist, as others have said, some do vibrate but should not rattle the teeth out of your head. Had one have a slight leak blowing between # 1 and # 2 cylinder, no popping or spudering but had vibration.

Brought the cylinders to top dead center and applied compressed air to that cylinder checking the one next to it. It told on itself.

Hope you find it,

Hank


lesvonnordheim
Posts: 35
Joined: Sat Jan 19, 2019 1:01 pm
First Name: Les
Last Name: Von Nordheim
Location: Fallbrook, CA

Re: Vibration at higher RPMs

Post by lesvonnordheim » Tue Apr 09, 2019 1:30 am

A good friend found his driveshaft was out of balance.....not bent or out of alignment. A new drive shaft from Chaffins corrected the problem. His original drive shaft did not seem to be machined the complete length. Some may find this hard to believe.....but it is true! Nothing else was changed......just the drive shaft. Something to consider.


Les

User avatar

Jugster
Posts: 101
Joined: Sun Jan 06, 2019 6:41 pm
First Name: Bob
Last Name: Coiro
Location: Commack, NY
Board Member Since: 2009

Re: Vibration at higher RPMs

Post by Jugster » Tue Apr 09, 2019 2:46 am

My car is that way too. Could be your spark linkage needs adjusting.
Meanwhile, when that happens, try retarding a spark a bit.


Humblej
Posts: 376
Joined: Sun Jan 06, 2019 12:23 pm
First Name: Jeff
Last Name: Humble
Location: Charlevoix, Mi
Board Member Since: 2006

Re: Vibration at higher RPMs

Post by Humblej » Tue Apr 09, 2019 8:00 am

Phillip, not clear from your original post, this vibration at high rpm while car is in motion, is it only when in motion or also when the car is not moving?

User avatar

Mark Nunn
Posts: 206
Joined: Mon Jan 07, 2019 8:01 am
First Name: Mark
Last Name: Nunn
Location: Bennington, NE
MTFCA Number: 50321
Board Member Since: 2017

Re: Vibration at higher RPMs

Post by Mark Nunn » Tue Apr 09, 2019 8:32 am

Do your engine pan arms have wood blocks? You can get a lot of vibration if they are missing.


Norman Kling
Posts: 498
Joined: Tue Jan 08, 2019 1:39 pm
First Name: Norman
Last Name: Kling
Location: Alpine California

Re: Vibration at higher RPMs

Post by Norman Kling » Tue Apr 09, 2019 11:09 am

One way to determine whether the vibration is caused by misfiring is to note whether it occurs when pulling or while running at constant speed or when decelerating. It takes a hotter spark to ignite fuel under high compression and the compression is raised when you open the throttle. Sometimes a weak spark or a weak spark plug will misfire when pulling but continue to spark at constant speed such as running on level ground after you reach cruising speed. When it is closed, you are running on lower compression. A knock at constant speed or when closing the throttle just slightly, is usually caused by a loose connecting rod bearing. It would not be a "vibration" but a rattling sound.
Norm


Topic author
Phillip
Posts: 24
Joined: Mon Feb 11, 2019 2:33 pm
First Name: Phillip
Last Name: Lee
Location: Nashville, TN
MTFCA Number: 50230
Board Member Since: 2018

Re: Vibration at higher RPMs

Post by Phillip » Tue Apr 09, 2019 3:19 pm

I put a tack and the vibration is slight at idle (300-400 RPM) and get pretty bad getting above 700 or so. I shorted out each plug at about 700 RPMs. I did not try getting above 800 RPMs (if my tack is right) because of the bad vibration. Would miss when plug shorted out but vibration did not lessen. I am thinking magneto or something in the transmission. I will use my GPS to get MPH when the vibration starts. I think is lessens when under load. Any thoughts on the rod caps not having dippers?


Rich Bingham
Posts: 852
Joined: Sun Jan 06, 2019 11:23 am
First Name: Rich
Last Name: Bingham
Location: Blackfoot, Idaho

Re: Vibration at higher RPMs

Post by Rich Bingham » Tue Apr 09, 2019 3:44 pm

Ts weren't made with rod dippers. They're not a bad idea but it depends on the dipper. I've seen some pressed-metal dippers fail.
"Get a horse !"

User avatar

Ruxstel24
Posts: 1657
Joined: Sun Jan 06, 2019 11:25 am
First Name: Dave
Last Name: Hanlon
Location: NE Ohio
MTFCA Number: 50191
Board Member Since: 2018

Re: Vibration at higher RPMs

Post by Ruxstel24 » Tue Apr 09, 2019 6:08 pm

Yeah, shouldn't be shaking at that rpm.
Don't recall you saying if there's any noise.
And I believe you said it is there while driving or sitting still. If so, I would be leaning towards the flywheel or something related.

User avatar

jagiven
Posts: 103
Joined: Mon Jan 07, 2019 8:13 am
First Name: Jason
Last Name: Given
Location: St. Paiul

Re: Vibration at higher RPMs

Post by jagiven » Tue Apr 09, 2019 6:41 pm

You say "under no load", I assume that means your parked, and just revving the engine. If that is true, the issue is not with the 4th main nor the drive shaft bushings, as no power is being transmitted, past the clutch.

I suspect a transmission issue, hard to say what. But I suspect a loose part, or a highly out of balanced transmission.


Jerry VanOoteghem
Posts: 131
Joined: Sun Jan 06, 2019 4:06 pm
First Name: Jerry
Last Name: VanOoteghem
Location: S.E. Michigan

Re: Vibration at higher RPMs

Post by Jerry VanOoteghem » Tue Apr 09, 2019 7:55 pm

Mark Nunn wrote:
Tue Apr 09, 2019 8:32 am
Do your engine pan arms have wood blocks? You can get a lot of vibration if they are missing.
Phillip,

Answer Mark's question, it's a good one.



Also, try running without a fan belt. Fans can be grossly out of balance and make lots of vibration. An often overlooked source!


Topic author
Phillip
Posts: 24
Joined: Mon Feb 11, 2019 2:33 pm
First Name: Phillip
Last Name: Lee
Location: Nashville, TN
MTFCA Number: 50230
Board Member Since: 2018

Re: Vibration at higher RPMs

Post by Phillip » Wed Apr 10, 2019 1:18 pm

No wood blocks for engine mounts. Some really great suggestions. Look like it is now down to flywheel or transmission.

Phillip


Jerry VanOoteghem
Posts: 131
Joined: Sun Jan 06, 2019 4:06 pm
First Name: Jerry
Last Name: VanOoteghem
Location: S.E. Michigan

Re: Vibration at higher RPMs

Post by Jerry VanOoteghem » Wed Apr 10, 2019 8:22 pm

Phillip wrote:
Wed Apr 10, 2019 1:18 pm
No wood blocks for engine mounts. Some really great suggestions. Look like it is now down to flywheel or transmission.

Phillip
Try putting in the wood blocks and side bolts. It has ceased vibration in several cases that I'm aware of. At the very least, it's an easy thing to try. Do you know what wood blocks I'm referring to?


Topic author
Phillip
Posts: 24
Joined: Mon Feb 11, 2019 2:33 pm
First Name: Phillip
Last Name: Lee
Location: Nashville, TN
MTFCA Number: 50230
Board Member Since: 2018

Re: Vibration at higher RPMs

Post by Phillip » Wed Apr 10, 2019 9:50 pm

I do not know about the blocks you are referring to.
The motor mounts I saw are one in the front under the hand crank and one on each side. Driver side by the starter. Should there be wood blocks somewhere on this.
Attachments
Front of engine
Front of engine
By the starter
By the starter
from under the starter area
from under the starter area


Humblej
Posts: 376
Joined: Sun Jan 06, 2019 12:23 pm
First Name: Jeff
Last Name: Humble
Location: Charlevoix, Mi
Board Member Since: 2006

Re: Vibration at higher RPMs

Post by Humblej » Thu Apr 11, 2019 7:58 am

Yes, wood blocks should be in the frame cavity at the rear pan mounting brackets. Cannot tell from your picture taken at that angle, yours might be there. There should also be a bolt going through the side of the pan ear through the wood blocks horizontally, again, cannot see from those pictures if you have it or not.

From the pictures you posted I would rule out the left ear and front motor mount as being a cause of excessive vibration.

Post Reply Previous topicNext topic