Engine shudder/vibration

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Model T Ford Forum: Forum 2018: Engine shudder/vibration
Top of pagePrevious messageNext messageBottom of page Link to this message  By Wilf Bradbury on Wednesday, January 17, 2018 - 04:50 pm:

1914 engine in Runabout
Just after shifting into high gear, as I accelerate under normal load, I get a bad engine /shudder in a narrow rpm range, but once past that shudder rpm range the engine smooths out. This vibration/shudder whatever has caused the upper inlet fitting on the rad to cause a leak for the third time. The rad is now in the repair shop for the third time.
The shudder is so bad you can see it vibrate the rad during that short period of acceleration.
I plan to pull the engine in Apr and do a careful balance on everything possible.
Any suggestions what to look for would be appreciated


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Bourgeois on Wednesday, January 17, 2018 - 04:53 pm:

Are you sure that it is in the engine and not the tires being out of balance?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Warren F Rollins on Wednesday, January 17, 2018 - 04:53 pm:

Clutch adjustment? No shutter in low?


Top of pagePrevious messageNext messageBottom of page Link to this message  By William Dizer on Wednesday, January 17, 2018 - 04:55 pm:

Broken/loose motor mount? If everything is bolted as solidly to the frame as usual, would the engine move enough to damage the radiator?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wilf Bradbury on Wednesday, January 17, 2018 - 05:22 pm:

Motor mounts checked all OK
Warren, haven't checked that, good thought!
Steve, good thought but shudder stops if I back off on throttle!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Marshall V. Daut on Wednesday, January 17, 2018 - 05:27 pm:

Bad or loose universal joint? That causes vibration more at certain RPMs than at others. A bad U-joint will make you think your car is falling apart and the world is coming to an end at various RPMs.
Is your U-joint pinned to the drive shaft the way it should be?
Marshall


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wilf Bradbury on Wednesday, January 17, 2018 - 05:33 pm:

Motor mounts checked all OK
Warren, haven't checked that, good thought!
Steve, good thought but shudder stops if I back off on throttle!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Wednesday, January 17, 2018 - 08:37 pm:

Sometimes an ignition miss will only show up on a hard pull. Could be missing when you first shift into high and then smooth out as the engine speeds up and you back off the throttle. Check your spark plugs, the coils and the timer.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Lloid on Wednesday, January 17, 2018 - 08:50 pm:

I had a bad u joint and that was my shutter problem on up shift.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Wednesday, January 17, 2018 - 09:46 pm:

When you retard the spark going into high gear you will not have any shutter as the engine will easily pick up the RPMs due to the gear change


Top of pagePrevious messageNext messageBottom of page Link to this message  By Adam Doleshal on Friday, January 19, 2018 - 11:36 am:

Poorly re-ground crankshaft, or huge flywheel imbalance. Could also be loose flywheel to crankshaft bolts (but less likely).

I had the exact same vibration circumstances in an engine over 10 years ago. Turned out that the shop who had ground the crank centered off the worn front & rear main journals to make a quick grinding job instead of the gear area and the outside of the flange to do a quality job. When disassembled, the flange had .024 indicator runout. The installation of a properly re ground crank eliminated the vibration.

I had 2 more cranks on the shelf from the same re-grinder. I checked them and they had the same errors. Took them back and they happily refunded the grinding charge and paid for the core value.

A couple years later, one of the guys from that shop had both those cranks for sale in the swap meet at the dodge county antique tractor show. He was telling people they were cranks they ground for somebody who never showed up to pick them up. They were gone by the end of the show, so I imagine whoever bought them has the same vibration issues!!! If I remember correctly, they were both 26-27 EE cranks.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Coiro on Saturday, January 20, 2018 - 02:13 am:

I've heard this story quite a few times and, to an extent, my own car behaves the same way. -The know-nothing-newbie thinks this is the very common consequence of building a low-power car without an intermediate gear between low and high. -The symptoms appear to varying degrees depending on the individual car in question, but every Model T I've driven grumbles at least a little bit on acceleration right after up-shifting. -Retarding the spark and throttling up very gently is a common way of dealing with this annoyance, but if you're getting a very heavy, low-frequency vibration, it's possible there's something wrong with your car. -Check the easy, inexpensive suspects first.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wilf Bradbury on Saturday, January 20, 2018 - 08:51 am:

Thanks all for the input
Wilf


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