Intense Engine Vibration — Even When Sitting Still!
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Topic author - Posts: 6
- Joined: Wed Mar 12, 2025 3:42 pm
- First Name: Rob
- Last Name: Zomber
- * REQUIRED* Type and Year of Model Ts owned: 1926 Coupe
- Location: Redwood City, CA
Intense Engine Vibration — Even When Sitting Still!
I've gotten my 1926 coupe to idle smoothly and start up without a hitch. It has new fuel, new plugs, rebuilt carb, etc. but any time I get the RPMs above probably 1500-1600 it sounds and feels like it's about to shake apart! This happens when driving and when it is just sitting in the driveway. I heard it could be the fan (new, 4 blade on there) so I disconnected it with no difference. What should I check next??
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- Posts: 4872
- Joined: Fri Feb 12, 2021 12:24 pm
- First Name: john
- Last Name: karvaly
- * REQUIRED* Type and Year of Model Ts owned: 14/15 wide track roadster. 23 touring, 27 roadster pickup, 20ish rajo touring
- Location: orange, ca
- Board Member Since: 2020
Re: Intense Engine Vibration — Even When Sitting Still!
Its a balance issue. Every part needs to be balanced.
Pistons, wrist pins, rods, crank, flywheel, triple gears & each drum plus the output & flywheel must run true.
I have seen a mix of lite & heavy rods.
Pistons, wrist pins, rods, crank, flywheel, triple gears & each drum plus the output & flywheel must run true.
I have seen a mix of lite & heavy rods.
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- Posts: 90
- Joined: Sat Jan 12, 2019 12:01 pm
- First Name: Dave
- Last Name: Eddie
- * REQUIRED* Type and Year of Model Ts owned: 1926 Tudor, 1926 Touring, 1931 Plymouth PA, 1952 Hudson Hornet
- Location: Lillooet BC. Canada
Re: Intense Engine Vibration — Even When Sitting Still!
What was done to the engine recently? Or did it always shake?
I have experienced this, in my case it was caused by a tight piston wrist pin.
I have experienced this, in my case it was caused by a tight piston wrist pin.
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- Joined: Mon Jan 07, 2019 2:42 pm
- First Name: Frank
- Last Name: van Ekeren
- * REQUIRED* Type and Year of Model Ts owned: 1916 touring, 1916 pick-up, 1924 coupe, 1926 touring, 1927 touring
- Location: Rosedale Vic Australia
Re: Intense Engine Vibration — Even When Sitting Still!
Worn main bearings are another source of vibration.
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- Board Member Since: 2020
Re: Intense Engine Vibration — Even When Sitting Still!
Have you done a plug short out test @ different speeds? You will find if you have a dead or weak cylinder. Even compression #'s?
Any knocks/noises? as in loose rods or mains. A loose flywheel can make her run rough.
Run spec is 1800 rpm =45 mph.
@ higher rpms, say over 2k you can get a harmonic imbalance point. Been there.
Retarding the spark & slowly advancing can get you thru that imbalance.
Try varying the spark. If you are running on battery, advance adjustment is infinite. If you are running on magneto, there are 3 or 4 nodes. Best to be centered in the node.
Any knocks/noises? as in loose rods or mains. A loose flywheel can make her run rough.
Run spec is 1800 rpm =45 mph.
@ higher rpms, say over 2k you can get a harmonic imbalance point. Been there.
Retarding the spark & slowly advancing can get you thru that imbalance.
Try varying the spark. If you are running on battery, advance adjustment is infinite. If you are running on magneto, there are 3 or 4 nodes. Best to be centered in the node.
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- Joined: Sun Feb 14, 2021 10:08 pm
- First Name: Pat
- Last Name: McNallen
- * REQUIRED* Type and Year of Model Ts owned: 1926-7 roadster
- Location: Graham, Texas
- Board Member Since: 2021
Re: Intense Engine Vibration — Even When Sitting Still!
Check for loose motor mounts, loose generator, front spring clamp nuts loose, loose or cracked front cross member, etc.
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- First Name: John
- Last Name: Kuehn
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Re: Intense Engine Vibration — Even When Sitting Still!
You mentioned that you’ve got the car to idle smoothly but was that after you worked on the engine, after it was rebuilt, added new parts or ?
Did it just start the rough running recently ?
Did it just start the rough running recently ?
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- Posts: 61
- Joined: Wed Mar 16, 2022 2:09 pm
- First Name: John
- Last Name: Delamater
- * REQUIRED* Type and Year of Model Ts owned: 1927 Depot Hack
- Location: Huron, Ohio
Re: Intense Engine Vibration — Even When Sitting Still!
I had a similar experience with my T.
I could get it to idle but had no power and a lot of vibration after going to high gear.
Also had extreme shuddering or bucking going from low to high gear.
Did a short test of cylinder plugs and found #4 cylinder no change and #3 cylinder questionable.
Next did a compression test on #4 cylinder and found no pressure. Did the same test to #3 and got a result of
several psi.
Pulled the head and found the head gasket blown between #3 and #4 cylinder.
Replaced the head gasket and fired her up and found a NEW car.
This might help.
Johnr
I could get it to idle but had no power and a lot of vibration after going to high gear.
Also had extreme shuddering or bucking going from low to high gear.
Did a short test of cylinder plugs and found #4 cylinder no change and #3 cylinder questionable.
Next did a compression test on #4 cylinder and found no pressure. Did the same test to #3 and got a result of
several psi.
Pulled the head and found the head gasket blown between #3 and #4 cylinder.
Replaced the head gasket and fired her up and found a NEW car.
This might help.
Johnr
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- First Name: Norman
- Last Name: Kling
- Location: Alpine California
Re: Intense Engine Vibration — Even When Sitting Still!
Even the spark timing of the coils can vary if they are not tuned to spark at she same amperage for each coil. if you have some other coils which have been tuned up or if not, substitute coils from a T which runs smoothly and see if it makes a change. if it smooths out, the problem is your coils.
Norm
Norm
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- First Name: Jerry
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Re: Intense Engine Vibration — Even When Sitting Still!
Rob,
Did it ever run smoother, or has it always done this? In other words, is this a new thing?
Did it ever run smoother, or has it always done this? In other words, is this a new thing?
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Re: Intense Engine Vibration — Even When Sitting Still!
So the question is was the car running and shaking before you changed the plugs and etc or was it doing it before the work was done.
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Re: Intense Engine Vibration — Even When Sitting Still!
Plug wires on wrong? (firing order) Gaps set improperly?
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Re: Intense Engine Vibration — Even When Sitting Still!
I had identical symptoms. The vibration was horrible. My problem was that one of my connecting rods was the old heavy version. It weighed 42 grams more than the others. I replaced all four rods and balanced the rod-piston assemblies. That made a huge improvement.