i have a 71 grabber with a 351w with mild upgrades (cam, intake, carb, porting). it has a new fly wheel and balancer both are 28.5 because the motor is a 73. i get a vibration when i get on the motor. around 45-55 its a pulsing vibration and you can feel it in the seat and in your back. the drive shaft is new with 1 new u-joint. i've had 2 people say some fords just vibrate. i am out of ideas so please help
Does it vibrate in Neutral when you rev the engine? Yes? then it's engine balance. When driving does it vibrate based on MPH? THen it's either Wheel balance or driveshaft issue. Put rear axle on Jackstands and remove rear wheels. Bring up to speed .. does it still vibrate? Yes ... Then it's the driveshaft ... if not then it's wheel balance. Vibration is not normal for any car ... check your Tranny and motor mounts as well ...
I guess either wheel weight or driveshaft weight. When the "new u-joint" was installed, was it overtightened? That'll do it too.
Oh, and I'll bet you make 2 types of members here happy by putting pics in your gallery! The Grabber lovers and the 351w swap lovers. Then some are like me, they just like pics of cars... Did you shave your towers? What headers did you use? These two questions are pretty much inevitable for 351w members.
when you rev the engine in neutral it does vibrate but its not thew same pulsing. if your driving and put it in neutral the vibration goes away. which im pretty sure it means its in the engine but if you look at it and rev the engine its smooth and does'nt even look like it is vibrating yes i had to cut my shock towers, i don't have headers on right now i am running 289 manifolds. all the tranny and motor mounts are good. tranny is also new.
One more avenue to check is the end play of the crankshaft. Have run into this many time's with several SB Ford's especially if they are high mileage or been hammered on pretty hard. Towing, or dropping the clutch at high rpm sometimes will hammer out the thrust surface of the bearing or crankshaft. Easy to check this, just get a pry bar and get between the flywheel/flexplate, and pry it back. Then go to the front and do the same on the balancer, should only have .006 to .008 movement. Any more than that and the engine will have a vibration until the thrust is thrown one way or the other and then will seem to go away. Just one more thing to look at.
351w is 28oz imbalance, no matter what year. 71_Maverick: Is the balancer/dampner new? If not, could the outer have slipped? If the engine has done this since the first time it was fired, then it's unlikely (but not impossible). If it started vibrating only when the balancer was changed or after the engine had run and was known not to vibrate, then the balancer may have spun.
the balancer and flywheel are new and i bought this engine for a guy that pulled it out of a van said it had about 30k on it. so i really dont know weather it has done this before or not. i was driving today and you dont feel a vibration up front its more in the back of your seat and it does it when you rev the engine. but when you go 50 or so its a pulsing vibration. i dont know how it acts under load because i haven't got my secondarys to open yet not enough vacuum. thanks all for the suggestions and help
Im gonna have to disagree....Each and every Maverick ive ever owned had some sort of vibration in the car...even my completly restored cars with EVERYTHING NEW AND BALANCED still has a lil vibration....Normal its a Maverick thing
Try flipping the DS 180 degrees .... And both my Grabber and the Yellow Maverick I had were both smooth as silk on the highway ...
i have been thinking and does the harmonic balancer have to be 28oz to along with the flywheel???? the vibration feels like it is coming from the rear??????
yes ... the damper / crank / flywheel are all a matched set .... if crank is 28oz imbalance then damper and flywheel have to be 28oz imbalance.
My '72 is closing in on 300,000 miles (43,000 on the engine and trans), and after rebuilding the front suspension and new U joints, it is completely smooth driving down the interstate... vibration is not normal for any car, period. If you have a vibration, something is causing it.
