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higher rev vibration
Posted: Sun Oct 13, 2024 2:00 pm
by Barteldes
24 coupe
two problems.
Mine is the only Model T I've ever listened to or driven so my experience is very limited. When i get up to about 30, or the high end of first it has some vibration. I know this description is really vague but that's really all i have. Also, there is a slight tick i can hear if the hood, cowling, or bonnet (whatever you call it) is up but not a knock its just a tick. i wouldnt think these two are related I guess its time to take off the head and take a look this winter when i wont be driving it anyway.
I have no history of the car. I'm just hoping the vibration it isn't babbit bearings or something like that i cant fix myself. My skills and knowledge are limited to say the least.
thoughts?
Re: higher rev vibration
Posted: Sun Oct 13, 2024 2:29 pm
by speedytinc
30 mph in low is really wicked up.
Model T's have a point @ a certain speed of a harmonic imbalance. Mine hits around 54 with 3:1 gears.
It can be severe enough to keep the motor from reving more. I find, I have to retard the spark some & slowly advance thru the rough spot, then she will be able to speed up.
Re: higher rev vibration
Posted: Sun Oct 13, 2024 2:50 pm
by speedytinc
speedytinc wrote: ↑Sun Oct 13, 2024 2:29 pm
30 mph in low is really wicked up.
Model T's have a point @ a certain speed of a harmonic imbalance. Mine hits around 54 with 3:1 gears.
It can be severe enough to keep the motor from reving more. I find, I have to retard the spark some & slowly advance thru the rough spot, then she will be able to speed up.
That vibration cant be good for the life of a stock crank.
Re: higher rev vibration
Posted: Sun Oct 13, 2024 3:50 pm
by Jerry VanOoteghem
As mentioned above, 30 mph in low is WAAAY too fast. It would have to vibrate at that speed. In normal situations, 15 mph in low would be considered near the top end. Ten mph is usually about right. These are low speed/high* torque engines. You don't wind them out like you would a Mustang.
Don't remove the head "just because." Try driving it differently first. The tick noise can be as innocent as valve lifter noise.
*High torque considering you can drive them as low as 5 mph, or even less, in high gear when they're tuned right.
Re: higher rev vibration
Posted: Sun Oct 13, 2024 4:06 pm
by John kuehn
You have to remember that average driving for a T low speed is around 10-15 mph and maybe less. Low speed was meant to get a T going but not passing cars. T engines aren’t a high rev engine. Sooner or later you lessen the engine life. Probably sooner. Theses days we expect them to be like the modern cars we drive but they aren’t. When rebuilding a T engine some spend the time to balance the engine and that’s a good thing to do. It does extend engine life but a T is still not a hot rod as we think of that today.
Re: higher rev vibration
Posted: Sun Oct 13, 2024 4:21 pm
by RecklessKelly
Maybe you mean you are in high when you hear the tick at those speeds. Try running with the hood off to rule out a loose hood. You may want to check the bolts on every part for tightness and lube the entire chassis to rule out squeaks and rattles. I found alot loose ones on mine and alot of lube points that went untouched for decades.
Re: higher rev vibration
Posted: Sun Oct 13, 2024 6:33 pm
by Norman Kling
You don't state how fast the engine is running when you get the "tick" Usually a tick is heard at slower speeds and is harmless. It could be the valve lifters hitting the valves. Or if it is at idle, could be the pin which goes through the front pulley and is also the pin which the crank ratchet uses to push the crank. If it is loose in the front of the crankshaft it will move up and down at idle making a tick.
Norm
Re: higher rev vibration
Posted: Sun Oct 13, 2024 6:40 pm
by speedytinc
An intermittent tick can also be a triple gear bushing seizing. That will happen @ high rpm's when the gears are working their hardest if a bit tight. I have heard that noise running the engine up in neutral. For such running, I lift one wheel & run in high gear.
Does the noise go away in high?
Re: higher rev vibration
Posted: Mon Oct 14, 2024 9:45 am
by Mark Nunn
The harmonic imbalance in my '26 Runabout is between 32-35 mph. The vibration at that speed will make the fillings fall out of your teeth. I have heard one other T in a video that sounds like mine. I, too, have never driven another T and wondered if the vibration is normal.
Re: higher rev vibration
Posted: Mon Oct 14, 2024 10:19 am
by Moxie26
Mark.... Could be too much bearing clearance in the center main
Re: higher rev vibration
Posted: Mon Oct 14, 2024 11:09 am
by 1925 Touring
I dont think he is going 30mph in low. Is that even possible without blowing up the engine?
I think he means that it is rough when he is at the high end of first gear (8 to 10mph)? And around 30 in 2nd. Rpms wold probably be about the same at these speeds in both gears.
Re: higher rev vibration
Posted: Mon Oct 14, 2024 12:08 pm
by Jerry VanOoteghem
1925 Touring wrote: ↑Mon Oct 14, 2024 11:09 am
I dont think he is going 30mph in low. Is that even possible without blowing up the engine?
I think he means that it is rough when he is at the high end of first gear (8 to 10mph)? And around 30 in 2nd. Rpms wold probably be about the same at these speeds in both gears.
You may very well be correct. It would make better sense. Would be nice if the OP would come back for replies/comments.
Re: higher rev vibration
Posted: Mon Oct 14, 2024 1:06 pm
by Craig Leach
I would think the vibration in low @ 30 mph is the crank flexing & the pistons hitting the head
I have a 3:1 rear & I don't think I could do
20 mph in low maxed out & boxed out with the ears pulled down. I would look @ main bearings, triple gears, crank bolts & flywheel that's
the parts turning @ the same speed under both circumstances?
Craig.
Re: higher rev vibration
Posted: Mon Oct 14, 2024 5:24 pm
by Kerry
How can one make out that the poster is saying that he's doing 30mph in low? he posts that 30mph or the high end of first it has some vibration.
Re: higher rev vibration
Posted: Mon Oct 14, 2024 6:24 pm
by Jerry VanOoteghem
Kerry wrote: ↑Mon Oct 14, 2024 5:24 pm
How can one make out that the poster is saying that he's doing 30mph in low? he posts that 30mph or the high end of first it has some vibration.
It's the comma after "30" that implies a meaning of "When I get up to about 30, or [
in other words] the high end of first...". But, as has been pointed out, this is most likely not what the OP intended to state.
Re: higher rev vibration
Posted: Mon Oct 14, 2024 7:11 pm
by Kerry
that could be so Jerry, but I was educated with the kings English, and the use of a comma is to separate independent clauses.
Re: higher rev vibration
Posted: Tue Oct 15, 2024 1:29 pm
by Craig Leach
Let's eat grandma Let's eat, grandma Punctuation saves lives.
Craig.
Re: higher rev vibration
Posted: Mon Oct 28, 2024 9:46 am
by Susanne
Had to search for it, but back in 2009 Seth Harbuck posted the chart of speed vs rpm, low is like 8.9 to th 1000 RPM, High is 24 point something to the 1000. Angel would cruise on stock gears at 50 all day (as do the Montana 500 cars), so yeah, 2000 + or - RPM. I did have it up to match freeway speeds one time, I also had larger valces, a good intake, and an excellent carb (Go Winfield!!) but it was pretty scary to think had something gone wrong... well, yeah, 30 in low is 3300 RPM which on a stock T is pretty "toasty". THo the car IS a roadster, so higher speeds ARE possible,,,
Whats the vibration? Out of balance flywheel, Magnet(s) trying to decide they want to go airborne, Transmission balance... at 3 grand, it's gonna be hard to nail down but you should be HEARING something along with FEELING it.
Re: higher rev vibration
Posted: Mon Oct 28, 2024 10:01 am
by RecklessKelly
By now he found his answer in the bottom of his oil pan.
Re: higher rev vibration
Posted: Mon Oct 28, 2024 10:57 am
by John Codman
1925 Touring wrote: ↑Mon Oct 14, 2024 11:09 am
I dont think he is going 30mph in low. Is that even possible without blowing up the engine?
I think he means that it is rough when he is at the high end of first gear (8 to 10mph)? And around 30 in 2nd. Rpms wold probably be about the same at these speeds in both gears.
I agree. I wouldn't dare rev my T to 30 in low.
Re: higher rev vibration
Posted: Mon Oct 28, 2024 12:28 pm
by Mark Nunn
Re-read the first post. He never said that he was in first gear at 30 mph. He said "...or the high end of first".
Re: higher rev vibration
Posted: Mon Oct 28, 2024 12:50 pm
by TXGOAT2
For reference: 25 MPH in high is 1,000 RPM.
In low, the engine speed is about 3 times faster. 8 to 10 MPH is about all you can do in Low, and about 45 MPH in High.
A T engine in good shape will handle up to about 1800 RPM, though 1600 is better.
A T engine should operate without severe vibration up to or beyond 40 MPH in High, and about 8 to 10 MPH in Low.
If you have severe vibration, there are a number of possible causes. Some things to check are motor mount fasteners and all chassis and driveline attachments. All T engines vibrate, but severe vibration within the normal engine speed range indicates a problem. Having an experienced person drive the car, or ride with you, is a good way to determine if the vibration is abnormal and what a likely cause is.