Other: Vibration in gas pedal at 55mph

[Ensane13]

I don't have a lot of info yet because of not driving it a whole lot since buying the 63 Lark but when I get to about 55 I notice a vibration in the gas pedal and a humming noise as well. Without much info on this does anyone have a guess? I am leaning towards maybe loose or warn out motor mounts since I am only feeling it in the pedal. I feel like if it was tires out of balance or something along those lines I would feel it in the steering wheel. I hope to get it out on the road this weekend to try to get more information on the matter. Thanks

[52-fan]

The engine mounts would be my first guess. If they are old and oil soaked they need to be replaced anyway.

[altair]

I don't have a lot of info yet because of not driving it a whole lot since buying the 63 Lark but when I get to about 55 I notirce a vibration in the gas pedal and a humming noise as well. Without much info on this does anyone have a guess? I am leaning towards maybe loose or warn out motor mounts since I am only feeling it in the pedal. I feel like if it was tires out of balance or something along those lines I would feel it in the steering wheel. I hope to get it out on the road this weekend to try to get more information on the matter. Thanks

I don't think the engine mounts are the cause however they may ba a factor in transmitting the vibration from where ever the cause. Motors don't normally just get out of balance, one cylinder may not be fireing at that speed or I would additionally check your universal joints, check for evidence of dry needle bearings. Said vibration from a driveshaft can transmit through the vehicle and as you say it is at 55 leads me to believe driveshaft or one non fireing cylinder, best of luck Dave

[Ensane13]

thanks, I will check those out as well.

[jclary]

If the engine mounts check out OK, you can look further by checking your U=joints for wear or lack of lubrication. Another area that gets a little more complicated is if there was some past work done that required changing or removing the engine or bellhousing. For those who are not familiar with Studebaker specific quirks...those components are individually matched together (dial indicated/indexed) and will cause the symptoms you describe.

Slight vibrations can be puzzling and difficult to diagnose because of how the "harmonics" manifest themselves at various speeds. There is an entire engineering science dedicated to the subject. Several years ago, studies in harmonics and vibration resulted in a revolution in the design of tooth configuration for saw blades. It heralded a whole new round of competition among manufactures marketing them with advertising campaigns such as "New Vari-Tooth Design"...or "Mix-Tooth"...etc. It got so crazy that copyright lawsuits were threatened.

One other area to look at would be a slight miss-fire under electrical load in your ignition system. If your distributor cap has a bit of carbon build up that allows "carbon tracking," under certain conditions, you can experience an erratic condition that causes a slight vibration that will drive you nuts until you discover the problem. A small crack in the distributor cap or slight carbon tracking may operate almost normal until it gets bad enough to cause an obvious miss-fire. Eventually, it will cause the engine not to run.

[jclary]

Dave said it with fewer words. (that's what I get for walking away and doing too much Multitasking!)