HELP PLEASE!!! Vibration!

[1991RWHP]

Please help! A friend of mine bought a '92 built 306 H/C/I, All of the goodies. Around 3500RPM+ there is a crazy vibration through the shifter handle and feels like the entire car. It doesn't matter if the car is in Neutral and the car is revving, or he is driving hard and shifting through the gears. It happens in every gear, and its RPM related not MPH. If anyone has any ideas they can throw my way to look into i would greatly appreciate it. I've never ran into the problem, so I dont even know where to start.


Thanks for your time!!

 

[Repostyle]

Check the U joints in the driveline.

 

[2000xp8]

Does it do it while in neutral parked?
If it does, it's the balancer or flywheel.

If it's rpm related, it's not the driveshaft or u joints. Those are mph related, they always spin at the same speed as the rear, regardless of what gear you are in.

 

[1991RWHP]

U-Joints are in great shape.


It happens when the Car is in Neutral just sitting still in the driveway, and In all gears 3k RPM+. Gets worst as the RPM Increases.

 

[Chrome_Rust]

Check the rubber on the balancer. I had a 95 GT that did the same thing. One of the reasons I traded it for the 93 in my sig...

THe rubber ring broke away from the hub and caused a VERY bad Vibration above 3k....

 

[1991RWHP]

When it happened on your mustang, did it get worst as the RPM's would increase? Would it happen in gear, and out of gear? At Idle and while driving? I know anything that rotates can cause it, I just dont want to swap out a part if/when I dont need it. I cant really see a rubber ring on my balancer. It just has a bunch of holes in it.

 

[2000xp8]

First off, make sure it's not an engine miss.

Second, if there is even a chance it's the balancer, replace it. A bad balancer can turn a good engine into a pile of junk in no time at all, and trying to save $80 on the balancer is not a good place to save money.

If you are sure it's not a miss, or the balancer, the only other spinning part is the the flywheel.

 

[1991RWHP]

It's got bran new plugs/wires/cap etc. So i ruled out a misfire.

How can i tell what is the best fit Balancer for my car to get? I've seen numerous different brands/weights out there. Also, how difficult is it to change the balancer?

 

[2000xp8]

I've been foolin aroung with mustangs for many years.
New plugs and wires sometimes cause the miss, specifically aftermarket cap and rotor and plug wires that don't seat properly.

For a balancer as long as the engine is still a 50oz balancer, you could get the ford racing stock replacement, it's like $65 at summit.
They you have the upgraded ford racing with no rubber, but that price jumps up there, or you could goto the best, ATI, but that's really gonna cost you.

 

[lancec2c30]

Does the car have solid motor mounts? I have a brand new FRPP balancer, but with my solid mounts the car vibrates quite a bit above 3k.

 

[Chrome_Rust]

It was a 5-speed car and did just as you desribed. My buddy that I traded cars with changed it and fixed the problem. But like 2008xp8 said, even if there is a chance, you should change it. How old is it? the car is a 92, the chance that it is the stock one and the car more then likely gets the hell beat out of it. taking that into consideration the balancer is 17 years old.... stock balancers should be changed out on a serious engine build anyway IMHO....

 

[1991RWHP]

The car still has Poly motor mounts/trans mounts. The vibration was present prior to me changing the plugs/wires/cap etc. Is there any way of telling what size balancer I have? I've been looking at Professional Products or this other " rattler " style. To be honest, I want something that is good... The cost is irrelevant to me when it comes to the car ( sad huh? )

Is changing the balancer anything special? Am I going to need any specialty tools? Once again, thanks for everything!

 

[frankeeski]

I had a 93 with an auto that did the same thing. There was actually a TSB for the car back then and the dealer replaced the balancer for free.

 

[project67]

i've seen the poly trans mounts do this. swap it out for a stock one.

 

[1991RWHP]

I changed it to poly thinking that was it ... but I ended up changing parts for virtually nothing

 

[Chrome_Rust]

I had a 93 with an auto that did the same thing. There was actually a TSB for the car back then and the dealer replaced the balancer for free.

Just a puller, you can rent one from your local parts store. should not take you more then an hour to do it.

 

[1991RWHP]

Does it matter what weight i get? I've seen 28oz and 50oz. Whats the difference, and How do i know which one I should get?

 

[project67]

50 oz. also you might check your timing, if your balancer has spun the timing will look like it's way off. have you recently changed your clutch?

 

[1991RWHP]

Yea i plan on checking the timing after i swap out the balancer. The car is in pieces in the garage right now anyways so i cant do it prior to the change.


And .. No, the clutch hasn't been done recently. Thats another project i plan on jumping into over the winter as well though. Why do you ask?

 

[project67]

when i built my 331, the new flywheel pressure plate dowel pin holes were too small so i couldnt install the pins in the flywheel/. i used the pins to line up the pressure plate then bolted it in place. i had a nasty vibration that i could feel in the shifter and floorboard. i pulled the trans and turned the dowel pin heads down to fit the flywheel holes. reinstalled and voila-vibration gone.

you can check to see if they're there w/out pulling the trans-look through the clutch fork opening in bellhousing (w/flashlight) toward the pressure plate. if you look directly through the hole in the clutch fork while someone turns the engine over, you will be able to see the dowel pin holes to see if they are there.

i agree the original balancer is probably due to be replaced but if it doesnt correct the problem, this may be another cause.