Vibration

[30Tudor]

When we rebuilt my engine, we checked through three flywheel housings to find one that would work within the specified tolerance. I think the best I could do at the time was 0.004. Les Andrews recommends 0.006 maximum. I don't have any vibrations.....so far. Intersting that one of the flywheel housings that won't work for my engine worked fine with another engine.

I also think if you are going to use the float-a-motor setup that you should use the rear mount (the one that bolts to the universal housing and transfers load to the center frame cross member). I think the rear float-a-motor mount helps to carry some of the additional loads from the radius rods that Brent is talking about.

[pat in Santa Cruz]

Louis,
most aftermarket front mounts have been found to increase vibration. The one you have restricts the floating that a stock Ford mount would have, and probably transmits more vibration to the cross member. I think Henry's original design is best.

Originally Posted by Louis

.

Im kinda new to the model A, I also have a eng. vib. that I think is to much.
I looked under the car to look at the frt. eng. mount to see if it was to loose, But the frt. eng. mount looks nothing like the one on page 1-151 in Les Andrews hand book, instead of a spring this one has a large rubber cushion, Is this Pic. the correct frt. motor mount?
Should i leave it alone, or get one like the hand book shows ?
Thanks for any advice.

[James Rogers]

OK, today I picked a random flywheel housing out of a pild and checked it. The results were, horizontally it is dead flat and measures .000 on the exact same place side to side. It measures being out .020 in the vertical plane which can be shimmed out. This housing has some wear in places I wouldn't expect it to but this didn't affect the test. I say check the flywheel housing mounting flange and if it is out, have it re-surfaced.

[Louis]

Pat in Santa Cruz,
I think you are right, orig. design on order. I will let you know. Thanks for your helpfull advice.

[Steinar]

When it comes to adding shims between flywheel housing and engine, both for understanding why, and how, I will recommend the booklet 'How to restore your model A, Volume 4'. I picked up this one, and a few shims, before I started to bolt my flywheel housing up to my rebuilt engine. The book is published by 'Model A Ford Club of America' and refers to a Ford Service Bulletine of February 1928, where the importance of adding those shims are described. But in their own writings they also add a lot of drawings and photos which makes everything easy to understand.
As James Rogers says, I'm sure this is an important step to build a vibration free engine setup!

[James Rogers]

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Originally Posted by Steinar

When it comes to adding shims between flywheel housing and engine, both for understanding why, and how, I will recommend the booklet 'How to restore your model A, Volume 4'. I picked up this one, and a few shims, before I started to bolt my flywheel housing up to my rebuilt engine. The book is published by 'Model A Ford Club of America' and refers to a Ford Service Bulletine of February 1928, where the importance of adding those shims are described. But in their own writings they also add a lot of drawings and photos which makes everything easy to understand.
As James Rogers says, I'm sure this is an important step to build a vibration free engine setup!

I agree this is a very important step and not to be overlooked but, if after all the adjustments are done and the alignment is still out, check the horizontal plane of the flywheel housing. Resurfacing it just might solve the problem.

[James Rogers]

Originally Posted by fordgarage

I am wondering how the housing mounting flange can be 'out' and needing re-surfacing?
It is the datum surface for both location and perpendicularity to the virtual centerline of crankshaft, as defined by the back of block and the block dowel pins.
If cannot be out, in my view.

Practically everything else could be 'out', but the flange surface is a small footprint and is the interface datum to the back of block, and is 'good' by definition.

The flywheel housing mounting flange would be the very last surface on the casting I would ever tamper with.

It is also interesting that this entire thread has sidestepped discussion of how the pan rail surface is related to driveline vibration. That is as big a source as warped flywheel housings in my view.

I don't know how it got out but it is or was. The one I checked today has worn spots where the bottom of the block has worn into the housing. After 80 years you might find anything.

If you have insight as to the pan rails influence on vibration, don't let someone else bring it up, let's hear your opinion about it.

[tiquer]

My freind and I tore down a Model A moror once that had one con rod that weighd 26gr heavier on the big end and 16 on the small end than all the other rods. Tink it might have had bad vibes

[jrelliott]

Guess I am extremely lucky as everyone who hears my A run says it is the smoothest they have seen. Will idle down to less than 400 rpm when spark and throttle rods all the way up. Fires up in one revolution. Engine rebuilt by Byers in Rochester, MN and bearings poured by fellow Model A'er in Rochester.

[MikeK]

Now that I've been rebuffed (and rightly so!) for an earlier comment I made in this thread, I'll throw in some thought about drivetrain alignment.

Both the flywheel and clutch house castings flex under stress. Not all castings are created equal, their rigidity varies. One may flex only a few thousanths under the load of the drivetrain, another from a different heat of cupola iron may flex a great deal. Is it flexing in a way that is additive or subtractive to the static variance from 'zero'? It may run smooth on a stand and vibrate when installed with everything seemingly "in spec".

There are really two castings, not one that need consideration for the final transmission alignment. BOTH the flywheel casting and the clutch housing casting do warp from stress, heat cycles, and age. Even if both are seemingly within spec, the assembly of tolerances can either be additive or subtractive. That is, if each is 'off' 10 thou, the assembly of tolerances can be anywhere between zero (perfect) and 20 thou off. That would account for the same housing working differently in different builds.

Henry addressed some of this in the 'B' by making the clutch housing an integral part of the trans case.

[Rowdy]

I will add one more intersting note that has been discussed before. Sometime in post production these extra ribs were added. Did this have more to do with flexing or cracking? Rod

[JoeWay]

Lots of discussion about shims in this thread.

Some assemblers/builders, myself included, deliberately delete the shims on occasion. I do a trial fit of the flywheel housing without the gasket or shims, and if it dials in well I use RTV in place of gaskets and shims.

I started doing this after I noted that the gaskets supplied in different sets vary from 0.008" to 0.022" in thickness. This means that OE type 0.010" shims are only rarely the correct size. Using RTV to seal the camshaft, with a matching application at the housing ears, eliminates the difficulty of trying to match random gasket thicknesses.

I've since read and heard of other people doing the same. Don't be too quick to assume a problem if there are no shims in your assembly.

Joe

[eystein]

Originally Posted by James Rogers

Well, this is not really going where I figured it would. I figured someone would mention the flywheel housing which, I think, is the source of most vibrations in the Model A drive-train. Many don't check it or don't know it needs adjusting because I find so many motors that don't have any shims under the throttle assembly mounts. I checked one last week and found the run out was in an unusual place. The flange was out .005 and the flywheel was out .003 at the outer diameter but, the housing was out .020. The unusual part was it was out at the motor mounts. There is no adjustment for this run out and most would not expect cast iron to flex and warp that much but, this did. I figure it was because of being run for years without shims in the top mounts and the frame bent. I don't know about this but it sounds as good as any explanation. I had the housing resurfaced and it was warped .016 from one mount to the other. This would throw the engine to transmission out of line a couple of inches from crank pulley to the universal joint. This, IMHO, would be a cause of vibration if all other sources are in spec. Might pay to check this on the next removal.

Unusual ?

Is that really so, that it is unusual for the flywheel housing to be out at the engine mounts ?

Of the two housings that I tried for my engine, both the one that I discarded, and the one that I used was out at the engine mounts.

Had to use an uneven number of shims L-R, which of course makes the adjustment more complex.

[James Rogers]

Originally Posted by eystein

Unusual ?

Is that really so, that it is unusual for the flywheel housing to be out at the engine mounts ?

Of the two housings that I tried for my engine, both the one that I discarded, and the one that I used was out at the engine mounts.

Had to use an uneven number of shims L-R, which of course makes the adjustment more complex.

And it is probably still out. There is no way to shim the housing in the horizontal plane. If it is out there, it has to be surfaced to correct the problem.

[James Rogers]

Originally Posted by James Rogers

Well, this is not really going where I figured it would. I figured someone would mention the flywheel housing which, I think, is the source of most vibrations in the Model A drive-train. Many don't check it or don't know it needs adjusting because I find so many motors that don't have any shims under the throttle assembly mounts. I checked one last week and found the run out was in an unusual place. The flange was out .0005 and the flywheel was out .003 at the outer diameter but, the housing was out .020. The unusual part was it was out at the motor mounts. There is no adjustment for this run out and most would not expect cast iron to flex and warp that much but, this did. I figure it was because of being run for years without shims in the top mounts and the frame bent. I don't know about this but it sounds as good as any explanation. I had the housing resurfaced and it was warped .016 from one mount to the other. This would throw the engine to transmission out of line a couple of inches from crank pulley to the universal joint. This, IMHO, would be a cause of vibration if all other sources are in spec. Might pay to check this on the next removal.

This is how it should read. I found this mistake myself.

[BILL WILLIAMSON]

Originally Posted by 30Tudor

When we rebuilt my engine, we checked through three flywheel housings to find one that would work within the specified tolerance. I think the best I could do at the time was 0.004. Les Andrews recommends 0.006 maximum. I don't have any vibrations.....so far. Intersting that one of the flywheel housings that won't work for my engine worked fine with another engine.

I also think if you are going to use the float-a-motor setup that you should use the rear mount (the one that bolts to the universal housing and transfers load to the center frame cross member). I think the rear float-a-motor mount helps to carry some of the additional loads from the radius rods that Brent is talking about.

Yes, Model A's vibrate, you can't make a purse out of a Model A crank!! Even counter balanced crank engines sometime vibrate. Old Henry, (bless his soul), mounted crap as if he was building a stationary power plant.
My '30 coupe vibrated progressively worse and worse above 45 M.P.H.
I installed Float a Motor rears, complete with rear trans bracket and rubber block, rubber mounted the tail pipe hanger, Installed full Float A Motor front mounts (much like a Model B) The SECRET IS, when you drill the front crossmember bolt holes, enlarge the holes to 1" so the rubber from the lower pads can squeeze through the holes to insulate the long through bolt from crossmember. Otherwise, you have metal to metal contact from the engine mount plate direct to the crossmember, which makes it WORSE than the stock mount.
Mine was like a different car!! Very smooth at all speeds, and yes, it will run a true 80 M.P.H. top speed.
I would like to hear a response from the Float a Motor manufacturer, as they need to revise their installation instructions. Float a Motors are a great product if installed properly.
Conclusion: we probably won't correct engine vibrations, we just find ways to insulate those "power pulses" from the chassis and body in order to make the car more pleasant to drive. REMEMBER, this 80 something year old technology!
By the way, removing the clutch disc springs DOES NOT allow side to side movement of the disc on the splined hub and throw it out of balance. But it would shurely RATTLE AND CLACK!!

[Kohnke Rebabbitting]

Originally Posted by JoeWay

Lots of discussion about shims in this thread.

Some assemblers/builders, myself included, deliberately delete the shims on occasion. I do a trial fit of the flywheel housing without the gasket or shims, and if it dials in well I use RTV in place of gaskets and shims.

I started doing this after I noted that the gaskets supplied in different sets vary from 0.008" to 0.022" in thickness. This means that OE type 0.010" shims are only rarely the correct size. Using RTV to seal the camshaft, with a matching application at the housing ears, eliminates the difficulty of trying to match random gasket thicknesses.

I've since read and heard of other people doing the same. Don't be too quick to assume a problem if there are no shims in your assembly.

Joe

Joe, I would say as you, we have put more A's togather, that did not need shims, then did, and not always even on both bolts, and always leave the housing at least 24 hours, or longer, as when you have got it as close as you can, it most always changes with warpage in that time. Herm.

[MikeK]

Another concern is the spring center of the clutch. If you removed the springs how much radial slop/runout or off-axis side movement is possible between the hub and the friction disk? Any runout would allow clamping engagement under load that flexes the springs to throw the disk off-center from the hub and it will vibrate like mad. Those springs give the false impression that the disk stays true to the hub centerline.

If you took a cutoff wheel and removed the springs, how much off-center can the disk move? Does this vary between manufacturers?

Has anyone ever checked the balance of the clutch disk itself? Every time it engages it seats in a random place.

I once saw a HUGE mistake being made in a local shop. A flywheel/ pressure plate assembly was being balanced with the clutch disk in place. As soon as the clutch is actuated, balance is gone.

[Louis]

Originally Posted by pat in Santa Cruz

Louis,
most aftermarket front mounts have been found to increase vibration. The one you have restricts the floating that a stock Ford mount would have, and probably transmits more vibration to the cross member. I think Henry's original design is best.

Pat in Santa Cruz,
You were right, I removed that rubber donut that had a washer on both sides and was put on so tight that it had compressed the two top springs to where it might as well had been welded to the frame, After removing the hard rubber donut I then put on a spring and the brass support bushing that goes on the underside of the cross member and snuged it down, I could tell when i started it that their was a lot less vib. now 40-45 MPH, very smooth, Thank's for the helpfull advice.
Buy the way, removing that org. frt. motor mount by just jacking up the frt. of the eng. and removing the two bolts from the eng. and the one underside is impossible [for me anyway].

[RHD]

I fitted counterweights to my 30 Phaeton's crankshaft and it was as smooth as silk. The engine, clutch, crankshaft and flywheel were balanced by the engine reconditioner. I installed at the time, new rear engine mounts with fresh live rubber. (A repro set.) A lot of vibration can come through the rear mounts as previously said. Fan blade was a new Al repro. I know some engine reconditioners don't take much care with Model 'A' blocks as they should do, especially when they know it is not going to travel very fast. Many engines could be balanced a lot better with a little more care and consideration by the engine shop. They all charge enough.