[Ubie78]

I have a 66 mustang V8 289 that starts shaking when I hit 60mph but settles fine when I hit 70mph or higher. It is only from 60 - 70 that it starts shaking. Might it be one of the cylinders? Any suggestions as to how to fix it or what it might be? Thanks

 

[PencilPro]

I'm guessing it's the engine that's shaking??:?:

 

[Ubie78]

Yes, it's the engine thats starts shaking. It rides smooth except when at 60 - 70mph.

 

[PencilPro]

If it's not doing it at the same RPM's when sitting still then it probably in the front end and not the engine.
I would start with having the front tires balanced and/or checked for a bad one.:bigthumbsup

 

[kyle67289]

I had that happen on an old truck of mine and it turned out to be the idler arm. So yea, I agree with the front end not the motor.

 

[Keving]

I agree with them. If it was an engine issue, it should shake at the same rpm range in other gears or at idle. And to second what they said, start with balancing your tires first, and check the front end.

 

[buzzboy]

I've had similar issues at different speeds. Once it was toe'd too far in and once too far out. I would put money on that being the issue.

 

[rodbender]

Just drive 70 everywhere!:rollgrin: I would check your wheel bearings too.

 

[Ubie78]

HAHA . . I wish i could just drive 70 everywhere. Ok, so i'll check and see The RPM ranges at idle and see if any shaking, then try to rule that out. A couple of months ago I had gotten the front end aligned and they put it a new idler arm. After that I purchased the tires from craigslist, it could be that they were not balanced properly. So if the car doesnt shake at idle, i'll go get the tires balanced first then rule that out. . . . . . But what if the engine does shake at the same RPM range at idle, Any suggestions?

 

[rodbender]

Well if the engine drops out at a certain rpm I would look at plug wires first or perhaps a faulty plug second. It is very doubtful it's the carb. Especially if the engine runs fine at idle and off idle.

 

[Lizer]

could it be a bad harmonic balancer in the event it's shaking at all RPMs? I remember Pockets had an issue like that and everyone kept telling him to go back and check the timing, check the wires, check it all again, and then it turned out to be a bad balancer.

 

[PencilPro]

could it be a bad harmonic balancer in the event it's shaking at all RPMs? I remember Pockets had an issue like that and everyone kept telling him to go back and check the timing, check the wires, check it all again, and then it turned out to be a bad balancer.

At all RPM's--Sure!
It can also be a engine miss from some mechanical/electrical failure too!:bigthumbsup(according to the year)

 

[Ubie78]

Well the car doesnt shake while at Idle at any RPM, so I guess my next bet is to check the tires are properly balanced.

 

[camaney]

im almost 100% sure is tire related. same thing i had couple months ago when change to diferent rims/tires.all it needit was balancing