Vibration under higher rev
Thread Starter
Instructor
Joined: Mar 2017
Posts: 111
Likes: 7
Vibration under higher rev
i feel vibration in my 69 350 when I accelerate hard. I'm not sure where it is coming from. No noise from engine or trans. Anyone have ideas what to look for? Could a harmonic balancer cause this?
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Did this just start? What was changed recently? Are the trans and engine mounts in good shape? Are all of the u-joint angles in limits? No binding anywhere in the driveline?
Racer
Joined: Mar 2013
Posts: 423
Likes: 25
From: Boca Raton Florida
Also does it vibrate sitting in park? or if a 4 speed does it do it with the clutch in our out? Narrowing down when it does do it and doesnt do it is key in trying to figure out where to start.
Thread Starter
Instructor
Joined: Mar 2017
Posts: 111
Likes: 7
I just bought the car and haven't pushed it much. I will check the mount but what are u joint angle limits and how do I check? I did notice when the car is jack up in the rear that there is a thump as the wheels spin. I thought it was just due to extended angle on axle shafts
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
The thump when the rear wheels are hanging is the binding of the half shafts. Too much angle on those U joints.
Go to TREMEC's website- they have a smartphone app that measures and calculates driveline angles- handy thing to have.
If you look at the driveshaft with the car level and the driveline looks like it's not really centered in the tunnel it might be worth looking closer. Take a look at the front differential mount too- the rubber gets old and soft.
Go to TREMEC's website- they have a smartphone app that measures and calculates driveline angles- handy thing to have.
If you look at the driveshaft with the car level and the driveline looks like it's not really centered in the tunnel it might be worth looking closer. Take a look at the front differential mount too- the rubber gets old and soft.
Thread Starter
Instructor
Joined: Mar 2017
Posts: 111
Likes: 7
Sorry for the delay in replying to this post. Life got in the way. Coming back to the vibration. It happens with trans in neutral and clutch out (so not drivetrain). The vibration comes in around 3-3500rpm. I am not sure what updates have been done to the engine. Its a 350/350hp but the heads were swapped for a lower compression version from 72. I just bought a new harmonic balancer and belts and I will be installing these this weekend.
