11-18-2018, 09:56 AM | #1 |
Senior Member
Join Date: May 2010
Location: Cape Cod Ma.
Posts: 129
|
Vibration
I just purchased a restored 31 sedan. Everything done correctly and first class.
It has Float-A Motors. It has an engine vibration sitting in neutral when bringing up the RPM's, with the clutch in or out. Also on deceleration. It seams fine when driving along at a steady speed 30-45. Any ideas........Bob |
11-18-2018, 01:50 PM | #2 |
Senior Member
|
Re: Vibration
Make sure your exhaust pipe is not touching the frame or body.
|
Sponsored Links (Register now to hide all advertisements) |
|
11-18-2018, 03:51 PM | #3 |
Senior Member
Join Date: May 2010
Location: Cape Cod Ma.
Posts: 129
|
Re: Vibration
Thank you, It's not a rattle, but a vibration. Seems to be from the engine.............Bob
|
11-18-2018, 04:18 PM | #4 |
Senior Member
Join Date: Mar 2017
Location: Connecticut Shoreline
Posts: 1,823
|
Re: Vibration
Has your Float-A-Motor allowed some sag or alining problems in your drive train?
|
11-19-2018, 05:54 AM | #5 |
Senior Member
Join Date: May 2010
Location: Cape Cod Ma.
Posts: 129
|
Re: Vibration
FAM seem OK
|
11-19-2018, 08:08 AM | #6 |
Senior Member
Join Date: Sep 2013
Location: Dighton, Mass
Posts: 1,230
|
Re: Vibration
Sponsored Links (Register now to hide all advertisements)
moment of insanity. Clutch in or out no change = that rules out drive line. So I bet a dollar to donuts its the pressure plate / flywheel I doubt, but could be. My machine shop has yet to find a new pressure plate from venders way out and I mean way out. My personal car engine all first class new a 59A V8 Findings = Flywheel ah couple grams: pressure plate almost 90 and that aint going to fly with me. New plate and we had to weld 90 + or minus grams a stack of washers on it because USA don't make nothing no more, and those who do across the pond could care less. Hate to say pull the motor A's are easy and have flywheel and pressure plate balanced.....sam been there on this. |
11-19-2018, 12:50 PM | #7 |
Senior Member
Join Date: Jun 2010
Location: Temecula, CA
Posts: 4,088
|
Re: Vibration
Make sure the F-O-M's bolt is snug, or replace them with stock mounts. I replaced mine and the engine was as smooth as before and had less clutch chatter.
|
11-19-2018, 12:54 PM | #8 |
Senior Member
Join Date: May 2010
Location: Alabama
Posts: 8,099
|
Re: Vibration
If the bolts on the float-A- motor mounts are TOO tight it can cause vibration .
|
11-19-2018, 02:42 PM | #9 |
Senior Member
Join Date: Apr 2011
Location: New Zealand
Posts: 444
|
Re: Vibration
If all else fails, try a Harmonic Balancer Pulley. It certainly transformed my motor. These are made in New Zealand "These dampers are made by Murray Horn in Levin N.Z. His Company is Engine Restorations Ltd. His email is [email protected]
Murray says this is the best way to contact him. The dampers are a straight fit to replace the standard Model A pulley. An added benefit is a shallow reverse scroll in the rope seal area to help contain oil." |
11-19-2018, 03:24 PM | #10 | |
Senior Member
Join Date: May 2010
Location: Eastern Tennessee
Posts: 11,513
|
Re: Vibration
Quote:
Bob, just to poke fun at you, I like your first sentence however the verbiage in the second sentence does not seem to agree with the next paragraph! While the above ideas all have merit, I tend to think by you saying the vibration is only happening during idle while accelerating/deaccelerating in neutral, my guess is the flywheel has been lightened a tad too much which is showing up from the impulses of each cylinder firing. When you are driving it, items such as transmission cluster, driveshaft, U-joint, wheels, etc. all are mass that adds to the weight of the flywheel which in-turn masks those impulses. |
|
11-20-2018, 06:23 AM | #11 |
Senior Member
Join Date: May 2010
Location: Cape Cod Ma.
Posts: 129
|
Re: Vibration
Brent..The car looks like it was done by a pro about 12 years ago with attention to detail. That's why the vibration doesn't make sense. Very few miles.....Bob
|
11-20-2018, 07:34 AM | #12 |
Senior Member
Join Date: Jul 2010
Location: upstate NY near Mass border
Posts: 789
|
Re: Vibration
Harmonic Balancers are on most modern engines and I thought that they reduce the twisting action on the crankshaft. Does this have anything to do with vibration which seem common in the Model A engine? Jack
|
11-20-2018, 09:07 AM | #13 |
Senior Member
Join Date: May 2010
Location: Jordan, MN
Posts: 1,411
|
Re: Vibration
From my experience: Anytime you change the mass of the rotating assembly, the rpm range where the vibration is felt will change. The Murray Horn dampers do eliminate felt vibration with some engines. I used on on a project last about a year ago with good success.
Good Day! |
01-23-2019, 03:54 PM | #14 |
Senior Member
Join Date: Apr 2013
Location: Northwest CT
Posts: 1,092
|
Re: Vibration
Gonna dig this one up. How much vibration is considered "normal"? My Fordor does tend to vibrate a bit on decel but nothing that seems too bad to me considering how the engine is mounted.
|
01-23-2019, 04:40 PM | #15 | |
Senior Member
Join Date: May 2010
Location: Oregon
Posts: 1,375
|
Re: Vibration
Quote:
|
|
01-23-2019, 07:07 PM | #16 | |
Senior Member
Join Date: May 2010
Location: Wa.
Posts: 5,408
|
Re: Vibration
Quote:
If it vibrates when idling, it has a first order harmonic. That generally means something is REALLY out of balance in the engine. |
|
01-23-2019, 07:20 PM | #17 |
Senior Member
Join Date: May 2010
Location: Wa.
Posts: 5,408
|
Re: Vibration
Just as a side note here while balancing is the subject, it is a VERY bad idea to weld weights on a clutch cover to balance it if you value your lower body parts.
The proper way is to drill the spring posts. |
01-23-2019, 08:42 PM | #18 |
Senior Member
Join Date: May 2010
Posts: 332
|
Re: Vibration
Make sure that the fan is balanced and if original check for cracks .
|
01-23-2019, 08:56 PM | #19 |
Senior Member
Join Date: Jun 2015
Posts: 1,414
|
Re: Vibration
Perhaps start with the easy stuff 1st: as mentioned, fan, front motor mount tightness and springs (if original), replace FAM biscuits if 12 years old and side frame rubbers(vendors sell new ones. See posts 2,3,4. Are engine pans attached? Check front alignment of pulley thru the radiator shell and clearance of service brake rod to torque tube, etc.
Also, check the engine in neutral thru the spark rod range and see if vibration persists. |
01-24-2019, 01:01 AM | #20 |
Senior Member
Join Date: May 2010
Location: Wa.
Posts: 5,408
|
Re: Vibration
ALL engine vibrations are caused by MOVING PARTS.
If the engine is not running, there is no vibration. Changing engine mounts, muffler clamps, brake rods, drive shafts and anything else can and does sometimes minimize or mask the problem by changing the resonant frequency of the vibration, BUT it does not address the root problem. BAD BALANCE JOB. |
|
|
Sponsored Links (Register now to hide all advertisements) |
|