Harmonic Vibration

So, back to my car troubles. I have a car shaking vibration above about 60 mph...it's most noticeable on a smooth road like I-35 in Norman. Not a rattle...a tight, car shaking vibration. Low frequency.

I have had the wheels/tires balanced and rebalanced multiple times. I'm not sure they are the issue. For one thing, the vibration lasts a second, goes away a second, comes back, goes away. I can take it out of gear and coast...does not change the vibration frequency.

I"m kinda thinking it is my driveshaft. That would make sense that it only occurs at higher speeds, and shakes the entire car. It's like a mini earthquake that propagates across the whole car.

I can't afford a new driveshaft, but I"m concerned it might hurt something.

Also, sometimes when I first start up my car, one of my pulleys down below is screeching really loud, not belt, but metal. It usually goes away, but sounds annoying.

One last test I need to do is "borrow" some front wheels off someone elses car, just to make sure it's not my wheels causing the vibration. It's not my engine or else I"d feel it revving it up in my garage. What are your guy's thoughts? Maybe my TVS is too much for the stock one. Maybe I tweaked it a little bit and it's just off balance? I wonder if you can get them checked somewhere.

You need to let Mike take a look at the car. Vibration sounds like your driveshaft, which doesnt mean you need a new driveshaft...just that you may need to adjust your pinion angle.

Pulley noise I would get checked out....give Mike at Pinnacle Performance a call in Owasso and see what you need to do moving forward.

Is it still under the factory warranty? If so they should fix it no charge. Both the pulley and DS (assuming that is what is wrong)

I'd guess driveshaft is not perfectly balanced or the pinion angle is off....

I doubt they'll honor my warranty. I've got a TVS and an MGW shifter.

Shelby10' wrote:You need to let Mike take a look at the car. Vibration sounds like your driveshaft, which doesnt mean you need a new driveshaft...just that you may need to adjust your pinion angle.

Pulley noise I would get checked out....give Mike at Pinnacle Performance a call in Owasso and see what you need to do moving forward.

I think I'll do that! Thanks!

Have you checked the U joints?

Bringing it into the Cobra Doc TOMORROW! Have to be back in Norman by 3:30 to go to work...anyone wanna do lunch or something?

Gonna be cold tomorrow though...ouch! no traction!

Mike looked at my car today. Thanks Mike! Would have liked to stayed longer but had to get back for work this evening.

Turned out MOST of the vibration was due to unbalanced wheels...and in one, the TPMS sensor was loose rattling around inside! I guess most places just can't balance wheels properly...which is what I suspected but nice to know someone can do it right.

Still a very slight vibration left over. And...if I'm not imaging things, the car actually decelerates a very small amount during every vibration cycle. I"m almost wondering if my squeaky pulley somewhere up front might be slowing down and speeding up a bit?

I'm very happy, the car is much more enjoyable without the back massage at 70 mph! But I would still like to investigate what's still causing a bit of rumble (still harmonic...just much lower amplitude now). Almost seems like my out of balance wheels were exacerbating the underlying problem, perhaps.

Good to hear. I passed you on 169 this morning a little before 9:00 am. I was headed south and you were going north about 36th st north. I was in my mountaineer so I'm sure you didn't see me. Lol.

Oh you were that guy gawking at my car so hard! J/k.

That was about the time I got there. Grabbed a chicken biscuit at McDonalds first.

hehe...on the way home, I was crusin at about 80 mph on the turnpike, when this white challenger cruised past me at about 100. I could not resist showing him who was boss by dropping into 4th (after making sure there were no cops around of course!). I felt guilty afterwards. I guess I'm hopeless.

Corepuncher wrote:Oh you were that guy gawking at my car so hard! J/k.

That was about the time I got there. Grabbed a chicken biscuit at McDonalds first.

hehe...on the way home, I was crusin at about 80 mph on the turnpike, when this white challenger cruised past me at about 100. I could not resist showing him who was boss by dropping into 4th (after making sure there were no cops around of course!). I felt guilty afterwards. I guess I'm hopeless.

Glad you got some resolve

I don't blame you for picking on an obese Mopar (not that I condone off track illegal actions). There's risk and reward. I (maybe much like you and others **cough Hector cough**) tend to always bet against the house and risk playing the odds. Otherwise, what is the point? The track isn't open 24/7......



(again, I do not condone off track illegal actions. But "spirited, sprinted" driving is okay IMO)

Live by the sword, die by the sword. Or something like that.

It's just so easy when all you have to do is flex your big toe to beat up on someone who thinks they are fast.

Had a little rice can behind me on 71st St today. Traffic was insane and this little high school kid and his buddy in the passenger seat thought it would be cool to floor it up to my butt....drift back 50 ft....then floor it back up turning the wheel left to right acting as if traction was an issue....then repeating the cycle.

As soon as he saw and opening he did the fast N the furious fly by and starting weaving through 3 lanes of traffic. I dont know how in the world he didnt kill himself or someone else.

What is it with rice? I mean I respect tuner cars, but when its a beat up POS primered crap mobile with a giant wing.... Its just pathetic.

You forgot to add the that the wheels were worth more than the car itself :-)

Sadly I think they were stock wheels with the hub caps taken off....

Glad you found most of what the issue was. DS certainly can be your source of the problem or simply the pinion angle. Can't remeber if your car was lowered. Was that checked?

Have a CF DSS DS coming soon along with a MGW. Looking forward to seeing the improvements.

Would love some feedback on the DS and MGW after install Chad

Shelby10' wrote:Would love some feedback on the DS and MGW after install Chad

I will do that.


Ryan, do you have a DS loop installed? Figure you are at 650rwhp or there about I would hate to see your OEM two-piece DS give up the ghost and do damage or worse launch your car.

No...I have not had my car lowered and I do not have a DS loop. I figure whats the point when all my tires do are spin like they are on ice lol.

I'd like to get a 1 piece at some point though. Also talking with Mike at Pinnacle, would love to change the control arms and change centers of gravity and stuff like that. Also bigger rear brakes, etc. I'm totally out of money for now...gonna be a while!

Suspension mods will make a big improvement. You should be fine with spinning tires just don't throw on a set of stickies until you get at least a DS loop.

I simply cannot imagine how much pull this car will have with slicks. I can easily see how it would stress my stock parts though! I'm not even sure drag radials would be a match for 630 rwhp. Somehow I doubt it.

It certainly won't dead hook but will hook enough to trash that OEM two piece DS in a short period of time.

Chad, is there a HP rating that a DS loop is needed? Im at 535rwhp, if I have some drag radials is a DS loop a must or can I get away without?

I keep hearing anything north of 600rwhp but it is really cheap insurance though and the mid DS loop BMR tunnel brace is really easy to install. Not necessary to remove the DS to install. Currently I would guess I am around 560rwhp but getting everything ready for a Whipple.

cjgt500 wrote:I keep hearing anything north of 600rwhp but it is really cheap insurance though and the mid DS loop BMR tunnel brace is really easy to install. Not necessary to remove the DS to install. Currently I would guess I am around 560rwhp but getting everything ready for a Whipple.

Info is much appreciated!

Loops are cheap insurance,new drive shaft this spring. I pucker every time
I nail it.

D/S loop is cheap insurance on any car that will see track time. Don't be the guy that regrets it when his car is totalled by shaft failure. I have seen it, it's not pretty.

Will definitely look into purchasing one, definitely would rather be safe than sorry.

Atta boy. Metco makes a bolt in for your car.