More ?'s about vibration...
 

I started another thread since my scenario seems a bit different then what I've been reading thus far about shuddering or vibration..

My truck has a vibration after shifting to 3rd gear, at around 25mph and continues up to 35mph, but haven't gone any faster then that yet!

This was a running motor that sat for several years, I dis-assembled, checked everything out an reassembled and it started up on first try...the flywheel had been re-surfaced with new pressure plate and disc with a mark for alignment...
but I do not know for certain if it was the exact flywheel that had come off the motor, so that is an unknown as far as it being balanced...

There is nothing at idle, or up at higher rpms, no knocks from engine, and other gears have no issues...the motor mounts are stock and correctly set, so I am asking if it is possibly the universal, or what else to consider???

I do realize that the unknown flywheel is a major consideration, but would like to know if there is anything else to consider if by chance the flywheel was properly balanced with the crank...

Would like to keep this motor running while another is being rebuilt...

Suggestions, advice appreciated....

Re: More ?'s about vibration...
 

You mentioned that the pressure plate was indexed to the flywheel but was the flywheel indexed to the crank shaft? I assume you checked the weights of reciprocating components for uniformity.

Re: More ?'s about vibration...
 

No, flywheel was not marked nor was there any work done to ensure everything was balanced. This was a running motor that had sat for many years, have asked if in fact flywheel was replacement....

This was not a rebuild, it was assembled using original parts as soon as was possible to make into a driver for an ailing friend to get a ride in before his time is up...A complete, thorough restoration is pending, would just like to keep this motor usable if at all possible

Re: More ?'s about vibration...
 

If you depress the clutch while it is in the speed/vibration range does the vibration change or stop?

Re: More ?'s about vibration...
 

It very likely not the flywheel and pressure plate from running motor, this motor had been rebuilt, run for several years, then car was in an accident, motor pulled and put into another car for several more years, then removed about 15 years ago.
I acquired it about a year ago, went thru it as stated prior, and was able to get it running...



Yes it does, only happens while in 3rd gear, under power....either depressing clutch or letting off throttle will lessen or eliminate the vibration...and it does seem to be only while under acceleration, not coasting if that is any indication...

Re: More ?'s about vibration...
 

I wonder if the engine is lugging when the vibration happens . Lugging usually happens after shifting into high gear . If you are going too slow after the shift in to high gear and the engine is straining , it can lug , If it is lugging , this is something that you will need to avoid because it beats out the bearings

Re: More ?'s about vibration...
 

Purdy, it doesn't seem like lagging to me, but I've only been in one other Model A for comparison....it sure seems like everything is functioning as it should. I've even tried it out earlier today on a bit of a downhill grade, it coasts quietly in 3rd but starts up as soon as you press pedal...
Dan Partain drove it a while back and we both agreed it felt like something in drivetrain but it wasn't clear from were...haven't gotten back to finding the cause till now...

Re: More ?'s about vibration...
 

Maybe the roller bearing that supports the drive shaft? Universal?

Re: More ?'s about vibration...
 

Tires?

Re: More ?'s about vibration...
 

Will be takng it apart in a couple weeks to find the cause, both of these have been suggested as potential causes!

Tires may be a factor, however it feels more like it's under my feet or below cab after shifting into 3rd, so the universal and bearing seem most suspect....

Thanks to all for the replies, will update soon as I've had a chance to inspect further...

Re: More ?'s about vibration...
 

Definitely worth getting a knowledgeable person to take a ride with you, and/or let you ride in their car for comparison and diagnosis. There are a lot of things to look for and experienced eyes and ears will get you closer to the problem before you tear things apart. If there's a Model A Club chapter near you, try to reach out to someone. You might get some great insights, and probably make a new friend! Good luck

Re: More ?'s about vibration...
 

A loose pinion nut etc can cause vibration. I’m not sure which is which, but one problem vibrates on acceleration and one problem results in vibration on de acceleration.

Re: More ?'s about vibration...
 

I had the same symptoms with our 1930 AA stake bed. It turned out that the universal joints on the drive shaft were the problem. Replaced them and the problem was gone. The information that indicated the problem is the speed of the truck dictates the intensity of the rumble and not the speed of the motor. also by pressing on the gas, the vibration gets worse at 25 MPH and up. Our AA is the long wheel base 157".

Re: More ?'s about vibration...
 

I had just about the same preoblem in my 29 two door! it ended up being the ujoint on the transmission. you would not beleive how badly worn it was! I don't know how it stayed together! new ujoint fixed my problem!

Re: More ?'s about vibration...
 

Update
Replaced u-joint several weeks ago, old one was actually just fine...vibration was still there...
Yesterday was able to determine rear axle is the issue, although attempts to remove hubs were unsuccessful...we used the correct tools, didn't get around to using any heat however...but with axle safely supported and front wheels chocked, we ran it in 1st & reverse, noise prominent on drivers side, in axle tube, only slight noise at banjo, but a definite vibration with each rotation of wheel...
Time for rear axle rebuild!!

Thanks for everyone's input, an Dan for your help!

Any Info on NorCal shops doing axle work, pls PM me, thanks...

Re: More ?'s about vibration...
 

Some of the repo u-joints are out of alignment. I had one that I assembled on the trans with the clamshell and it locked the trans. I made a shaft to fit the ID. of the splines for the front yoke and the rear yoke. It could not fit through the pair, hence not a common centerline Snyders replaces it, after using my gauge to test alignment.

Re: More ?'s about vibration...
 

Try this: w/the axle nuts about 1/2 turn loose drive around the block, weave side to side a bit to put sideways pressure on the hub/axle connection.