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Old 05-05-2020, 08:39 AM   #1
Bob Bidonde
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Default Misnomer - Front Engine Support

This is a quote from a reprint of Dyke's Automotive And Gasoline Engine Encyclopedia, Model "A" Passenger Car And Model "AA" Truck: Engine Chassis Manual,

"The Model "A" Ford car is equipped with a flexible front engine vibration absorbing support for the engine, which greatly reduces the transfer of engine vibration to the chassis. It is simple in design and operation, and frees the car from unpleasant vibration periods.

The support bracket is bolted to the front engine cover and rests on two flexible coil springs which support the front engine weight. The stud at the lower end of the bracket has a large foot. This foot comes almost in contact with the top of a stiff, flat, horizontal spring which rest on the frame cross member. This arrangement gives the front end of the engine a very large free range of vertical motion, yet holding it within definite limits. It thus permits the engine mass to move in response to the unbalanced inertia forces, yet the vibrations are absorbed or dissipated before they are transmitted to the chassis.

The flat spring and a lower coil spring used where the bracket stud passes through the frame, serve to cushion the engine against downward and upward road shocks."


The misnomer is our emphasis on the word "support." It is not a structural attachment that reacts engine power transmission to the rear axle, it is a vibration damper, similar to a shock absorber. The damper is adjustable by loosening or tightening the nut at the bottom of the stud.

Ford specifies that the space between the spring coils should be no less than 1/64" and no more than 1/32". This was the production and maintenance setting for original springs in new condition. However, the reproduction coil and flat springs do not have the stiffness of the original springs. Additionally, used original springs do not behave as they did when new. So I suggest we tune the front engine damper to get the least transfer of vibrations by iterating the nut tightness. This has been my practice for many years of driving my Model "A" cars.

By the way, the nut tightness also will reduce clutch chatter as is a common annoyance when converting to a V8 / tractor clutch. Also, all of the push and pulls of the rear axle go through the rear engine mounts to the frame, not the front damper.
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Old 05-05-2020, 08:54 AM   #2
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Default Re: Misnomer - Front Engine Support

Bob, mine probably has the original springs, do you have a set guidline how I should go about this? I've never got my head around this entirely. I know with semi automatic pistols and rifles the springs can make a huge difference in felt recoil, ejection, reloading, jams,,,,,,,. If you watch videos of competitive shooters they seem to keep the weapon flat and on target for follow up shots. There's more that than just springsnbut they play a big role.

Just curious what you recommend in my case as it seems similar as to yours. Just reread and maybe you have newer springs?

Thanks
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Old 05-05-2020, 10:09 AM   #3
Bob Bidonde
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Default Re: Misnomer - Front Engine Support

History,

My cars have reproduction springs in the front damper, and I suspect that the reproduction springs are not as stiff as new originals. I do not have access to the drawings for the original springs, so I do not know their spring constants.

Using the reproduction springs, I tighten the nut just enough to engage the coil springs. Then I drive the car sensing vibrations and clutch chatter. I continue tightening the nut and test driving the car until I get what I feel is the preload on the damper that is best for my driving style. If there is no tuning I can live with, I would replace the coil springs with stiffer ones and continue testing. Such is the case with my Victoria, it needs stiffer springs in the front damper.

Here's another thought. Running a high compression head increases the reciprocating force which adds to the vibratory force. Lightening the flywheel and clutch changes the rotating unbalance, and the seesaw effect about the rear engine mounts. The seesaw would have more unbalanced engine weight for the damper to balance.

The bottom line is that the vibrations don't go away, they just change their amplitude / frequency. We seek small amplitude and high frequency in the Model "A."
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File Type: jpg Engine & Driveline Freebody Diagrsm.jpg (10.3 KB, 136 views)
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Old 05-05-2020, 10:45 AM   #4
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Default Re: Misnomer - Front Engine Support

Here is a drawing from Marco's site.
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Old 05-05-2020, 11:02 AM   #5
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Default Re: Misnomer - Front Engine Support

I have the radiator off mine at the moment, I'll look at the springs, they may be constantly compressed together, as in no spring at all.
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Old 05-05-2020, 11:23 AM   #6
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Default Re: Misnomer - Front Engine Support

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Here is a drawing from Marco's site.
We truly do miss Marco! A walking, talking encyclopedia !
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Old 05-05-2020, 01:10 PM   #7
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Default Re: Misnomer - Front Engine Support

Bob, Please go back to your original post and insert the final quotation mark at the end of the quote from Dyke's Automotive And Gasoline Engine Encyclopedia. I began reading the quote and could not discover where the quote ended. It only leaves me speculating as to where the quote ended and your input started.
Thanks

Request honored. Thanks Bob!

Last edited by Dave in MN; 05-07-2020 at 02:03 PM.
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Old 05-06-2020, 09:06 AM   #8
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Default Re: Misnomer - Front Engine Support

Dave,
I edited the post and made the quote from Dyke's in a bold font.
Bob C,
I cannot read the spring drawing because it is too small. I tried enlarging it, but it became too fuzzy. Perhaps someone on this forum can lead us to larger size file of the spring drawing.
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Old 05-06-2020, 02:10 PM   #9
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Default Re: Misnomer - Front Engine Support

Maybe this link works


https://web.archive.org/web/20140609...shop/mount.htm
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Old 05-06-2020, 02:45 PM   #10
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Default Re: Misnomer - Front Engine Support

If I am reading the drawing correctly, the unloaded spring is 1-5/8" - 1-11/16" long. 60 lbs will compress it to 1-1/8". So the spring rate is 107-120 lb/in?
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Old 05-06-2020, 03:14 PM   #11
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Old 05-06-2020, 10:38 PM   #12
Jack Shaft
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Default Re: Misnomer - Front Engine Support

The modern style front mount uses rubber biscuits and spreads the load outside the timing cover bolts instead of centering it.I believe any clutch chatter issue is amplified by the original front mount design,with only a single spring to dampen upward force on the front of the engine.
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Old 05-07-2020, 12:21 AM   #13
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Default Re: Misnomer - Front Engine Support

Quote:
Originally Posted by Jack Shaft View Post
The modern style front mount uses rubber biscuits and spreads the load outside the timing cover bolts instead of centering it.I believe any clutch chatter issue is amplified by the original front mount design,with only a single spring to dampen upward force on the front of the engine.
Has anyone used the "modern style" front mount with the stock rear mounts?
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Old 05-07-2020, 03:58 AM   #14
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Default Re: Misnomer - Front Engine Support

I am using fams in the rear and front with a 6.1 and v8 clutch.

https://www.snydersantiqueauto.com/P...earchByKeyword
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Old 05-07-2020, 08:36 AM   #15
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Default Re: Misnomer - Front Engine Support

I have been reading a lot about front mount and clutch chatter. Why not fix the clutch problem instead of trying to band-aid it.
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Old 05-07-2020, 08:54 AM   #16
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Default Re: Misnomer - Front Engine Support

I agree in principle with you,always find the root cause of an issue.That being said,engine mounting has a lot to do with smooth clutch operation,when applying the engines torque to the driveline the more support the engine has the smoother the application will be.Centrifugal pressure plates ,like the V8 plate use rpm to assist engagement,the A pressure plate relies solely on the driver..when the clutch application is successful in moving the engine it changes the application force of the driver,as the engine goes up,the clutch pedal cross shaft goes down..also creating the condition for chatter..
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Old 05-07-2020, 09:24 AM   #17
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Default Re: Misnomer - Front Engine Support

Spring rate, also known as spring constant, is the constant amount of force or spring rate of force it takes an extension or compression spring to travel an inch of distance or, in the metric system of measurement, a millimeter of distance. The units of measurement of rate in the English System are, lbf/in (pounds of force per inch) or N/mm (newtons per millimeter) in the Metric System.


A-6032 is the part number for the 2 coil springs on top of the damper. According to the drawing, the spring has a length of 1-5/8" to 1-11/16", and should take a force of 60 pounds to compress the spring to a length of 1-1/8".



The Spring Constant is k= F/x where k is the constant, F is the force and x is the amount of spring compression.
k= 60/0.5 = 120 lbs/in. So a reproduction A-6032 Spring should have a length of 1-5/8" to 1-11/16", an inside diameter of 1/2", ground flat on both ends and be heat treated to achieve a spring constant of 30 pounds per inch of compression. Are there drawings of the lower coil spring and the flat spring available? I am curious to learn their spring constants.



Once the spring constant is known, the coil spring wire and heat treatment can be defined. Is there a kind soul out there that will test a set of reproduction coil springs to determine their spring constants?


As I mentioned in a prior post, I likely will be installing coil springs with a higher spring constant in my Victoria. Perhaps the camshaft plunger spring will work?



Joop, Alexiskia,
Thanks for the drawings.
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Old 05-07-2020, 09:27 AM   #18
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Default Re: Misnomer - Front Engine Support

Fundamentally, I view clutch chatter as a slip-stick engage of the disk onto the flywheel which sets-up a vibration. I agree this is not the cause of the chatter.
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Old 05-07-2020, 10:09 AM   #19
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Default Re: Misnomer - Front Engine Support

If the following parameters are met, engine angle @3 deg, alignment of front pulley viewed at radiator shell, etc. , then the close 1/64 to 1/32" coil spacing per the Service Bulletins adjustment may be challenging to fine tune with the nut and cotter. Also, assume the front yoke condition may be a variable.

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Old 05-07-2020, 11:56 AM   #20
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Default Re: Misnomer - Front Engine Support

Quote:
Originally Posted by Bob Bidonde View Post
...k= 60/0.5 = 120 lbs/in. ...spring constant of 30 pounds per inch of compression....
Where did the 30 lb/in come from? I agree with your first number,120 lb/in.
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