The Stovebolt Site Forums The Shop Area Engine Shop Vibration Felt in Steering Wheel

I took my last run of the season in my ‘52 3100 with a ‘59 235, and have had an annoying vibration since I first installed this engine in December 2019. This vibration is similar to the vibration felt on a vibrating sander. Felt mostly in the steering wheel, but throughout the truck at speeds above 40 MPH. If I push the clutch in, it disappears. If it put it in neutral with the clutch in or out, it also disappears. While maintaining 40 plus MPH , in neutral, revving the engine duplicates this vibration and disappears as the RPM’S come down.

So it’s definitely the engine up to the clutch that’s producing this vibration. Any thoughts on what the cause may be?

Take the fan belt off & try it. It could be in the fan or pulleys. Check the Harmonic balancer. It might be loose or the rubber has deuterated. If not one of these, remove the flywheel cover & see if something might be broken off. Be shure the trans. to bell housing bolts are tight.

George

Another source of vibrations in the AD are the engine mounts. Especially, the front engine mount. If the front engine mount is too tight it can transmit vibrations from the frame to the steering wheel and the cab. The 1948 to 1951 Chevrolet Truck Shop Manual outlines the engine mount inspection process in Chapter 6.

So the vibration goes away when you coast in neutral at 40 but will come back when you gun the engine in neutral?

I'd look at your flywheel along with the other things mentioned.

Also check your pressure plate, Phil. I had a bad one in a GTO in the 70s that acted the same way. I could get the same effect by putting the car in neutral (sitting still) and raising the rpm to about 2500. Once I replaced the pressure plate all was Jake. Good luck.

Yes, that is correct.

That was my first thought. Shortly after installing the engine, I removed the front mount and machined extra clearance in the mounts to insure they weren’t hitting. I don’t believe that is the issue.

Also look at The rear mounts under the bell housing. Often they have been soaking in oil all these years & there is no rubber left in them.

George

The rear engine mounts are new.

"New" used to mean something. Not any more.

The most likely source of an RPM-specific vibration would be the flywheel and/or clutch cover. An inline six is inherently balanced, due to the 120 degree separation of the connecting rod journals and counterweights. When machine shops spin-balance those crankshafts they don't even have to use "bob weights" to simulate the weight of the piston and rod assemblies like a V8 crank needs.
Jerry

I put a new clutch assembly in a 1967 chevy C10. It had no vibration when driving before the work and after almost shock my teeth loose after the install. I took it all apart and had the flywheel and clutch assembly balanced, they removed 43 grams off the flywheel, after that smooth as glass. That's after trying two different clutch assemblies. Thankfully it was only about an hour to remove everything.

Thank you all for your suggestions. I think this one will have to waIt until spring. Running out of time as we fly (actually drive ) south for the winter after the holidays. I will remove the fan belt though, as that would be a simple elimination.