Vibration Felt

Recently I have been feeling a vibration in my clutch and accelerator pedals under hard acceleration. The clutch pedal vibration is felt when I push the clutch in to shift but disappears as clutch disengages. If I rev up the engine with no load, there is no vibration anywhere. The support that goes from the rear of the car to the rear cam cover is tight with no slop at either end of the rubber portion.

I'm thinking motor mounts. The ones in the car are the originals. What do you guys think?

 

Planning on getting vehicle out tomorrow morning to see if vibration is gear dependent. There is too much traffic today for any testing. There is no unusual noise, but it could be masked by engine noise. As said, my suspicion is that I have bad engine mount(s) changing the natural frequency of the system or adding another modal vibration which is the response I'm feeling in my feet when pressing pedals connected to the engine. The vibration is slight but there and is new.

 

I'll have to dig out the receipt from when the clutch was replaced back in the early to mid 90's. I recall that I had been at a track event at Summit Point, W. VA a couple of hundred miles from home. Upon return I opened the engine cover and discovered oil on the lid. I had the car towed to a shop in NC. They replaced the badly leaking crank seal and clutch that had gotten oiled up. Vehicle has only been to a shop 3 times.

Just dug out the receipt dated June, 1995. Items involving the clutch are clutch disc, pressure plate, and release bearing ($155). Assuming the release bearing is the throw out bearing, it was replaced according to my receipt. Vehicle has slightly less than 40K miles on it and has not been tracked since 1997.

 

My clutch is OK, so I'll wait until it needs replacing and do the throw out bearing at that time. Another thing I have noticed is a difference in shifting effort at different times. I start the car in my garage and back it out. I sit there a few seconds to goose the engine to get the alternator light to go out. I use a battery cut off switch so a minute or two goes by for me to reset the radio controls. After that put it in 1st gear move forward in the driveway. Visibility is good at the driveway exit, so I shift to second gear as I slowly proceed on the driveway not having to slow the vehicle to exit driveway. The shift is very easy. I live on a hill, so I let the car idle in gear to keep the speed down going down the hill that is about 1/4 mile from a stop sign. I stop at the stop sign, shift to first, and move off slowly. Shifting to 2nd gear nearly always requires some effort at this point. Other times when I start off in 1st with hard acceleration and high rpms, the shift to second gear is smooth, but sometimes it is notchy. I am aware from reading FChat posts that engine movement can affect how much effort is needed to shift the vehicle. That is why I keep thinking engine mounts are the cause of my problem.

I'll remove the bolts from the reaction rod and check the rubber bushing. Thanks for the attention on this matter.