PLEASE HELP - 1931 Cabriolet noise identification

[293131]

Hello, everyone. I am trying to help my dad out in finding a noise he hears only at certain RPMs. I haven't heard it, but from what he said, it almost sounds like a metal to metal grinding.

He thought it was the transmission. He had it replaced and it still makes the sound. He thought it was the engine and he replaced it with a rebuilt engine. No change. He changed out the speedo cable and no change. He feels as though he is running out of things replace. He is not a mechanic, but has a knowledgeable one who at this point can't find the noise either.


Any suggestions? If you have any thoughts, I would love to hear them. You may email me at wmleiv(at)yahoo(dot)com - spelled out for all of the spammers out there. Thanks again for your help. I look forward to hearing from you.

[Jason in TX]

can he take his phone and take a video and then post it?

[293131]

I will try to do this and post it. Someone mentioned that it might a poorly positioned flywheel.?

[Aerocraft]

How about the rear axle? Gar Williams

[293131]

Thanks. He typically hears it only with certain RPMs but it is typically always under load. I don't know if that helps out or not.

He had disconnected the speedo and ran it that way and it still made the noise so he was able to eliminate that.

What specifically is the mechanic to check for in the rear axle? Is there a common weak area there? Thank you again.

[Raven]

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Does the muffler have a heat shield on it? Even though you say the noise is grinding could it be a vibration?

[Benson]

If it is a grinding noise maybe the four flywheel bolts are too long and are scrapeing on the engine block.

Also if the flywheel dowel pin retainer is missing then the correct length bolts can sometimes stick out too far and scrape on the engine block.

Flywheel dowel retainer looks like this:
http://parts.modelastore.com/show_Product.asp?ID=3739

[293131]

Thanks for all of the answers, everyone. I am fwding these to my dad so he can let his mechanic know.

Great stuff. Thanks again!

[Tom Wesenberg]

Also, too long a starter mounting bolt can hit the flywheel.

[293131]

UPDATE and follow-up question -

I rode in this Model A today and I don't think it's metal to metal grinding at all. To me, it's more like a heavy vibration. You can feel it in the steering wheel, etc... But it's still really only under load/acceration.

If this changes suggestions, I'd love to hear them

Thanks!

[Greg Jones]

Well here is the standard answer: "Could be a lot of things." Of course, that is not helpful. How is your timing? Are you sure it is timed right? Sometimes I have seen cases where timing is set too far advanced, the car will rock and roll and it feels like it is coming from the flywheel (which it is). A Model A timed right should idle with the spark lever no more than halfway down the quadrant (and that is a bit much in my opinion). For general running on the highway spark lever should advance about 2/3 of the way down the quadrant. Only when running at self-destruct speeds should the spark be fully advanced. Now, this is with Snyder and Brumfield 5.5 and 5.9 heads which require less advance. I ramble on about this just to ask if maybe your Dad is running too advanced at low speeds, such as at idle?

[293131]

Thank you. I think the timing is okay. It was idling beautifully with the spark lever all the way up. I don't know if it would help with a recording or not. I will try to do that.

Thanks again for all the help. This is a great forum.

[mebeached]

sounds more like a wheel bearing to me if you changed the motor and trans not much left

[Fred K-OR]

Bad brake situation on one of the wheels????????

[Phil]

Has it been run on jack stands?

[Pete in Michigan]

When I got my dad's Model "A", it had a metal to metal grinding sound that was caused by the " Throttle Control Assembly" pivit arm rubbing on the bottom edge of the firewall. Replaced assembly, noise gone.
Another vibration at certain RPMs was caused by a hood rod nut that bottomed out before being tight to the bracket at the firewall. Make sure nothing is loose or rubbing on firewall. The firewall is like a sound board in a piano, it amplifies noises.

[Hicktick]

If you tell us where your father is at , maybe someone is close and could run by and help .

Just a thought , you never know the power of the barn .

[1936ford64]

May be a harmonic vibration, such as a choke rod with out a bushing.

[BILL WILLIAMSON]

293131,
Dog here, havent rode the Model A yet, but smart a**ed Bill says, "Welcome to the world of Model A noises, BRR, GRUMP, BUZZ, ZIDDLE, RAORR, ETC"! Like, "What's that new noise?? I didn't hear it yesterday! Is something goin' to break?" "NAW! it's just Model A FUN"!! Buster T.

[Bruce Adams]

293131,
WHERE are you located?
There are Model A people all over the world, many of whom will be pleased to assist you.
Replacing major components without a proper diagnosis is not the most effective way to get the car running right.
Good Luck !