Front End/Steering Vibration

[JIMOCO]

I have recently began to feel a vibration in the steering wheel. I begins to appear at about 70mph and get worse as I approach 75mph. After 80mph it settles down but is still there. My first thought was a front tire out of balance. Took them to my local shop and had them rebalanced. They said they were not far off to begin with but did the balancing. I still have the vibration. When the wheels were off I checked the suspension and all looks normal, no loose bolts, worn bushings or cracking parts. Any thought on a cause/solution would be appreciated.

[Avalanche325]

Did they check to see if a tire was out of round? That is the typical speed when it shows up.

You can jack the car up and do a rudimentary check pretty easily. Find a way to mount a straightedge close to the tread and give it a spin. Also check for a warped rim. Have a good look at the sidewalls on each side of the tire to see if there is anything that doesn't look right. A dip or bulge can be s sign of separation.

[GoDadGo]

I'm no expert so take any suggestions from me with that perspective in mind:

1. When they balanced your tires did they try to play "Hide The Weights?"
.....If they did it is possible to create elipical vibrations that the balancing machine won't find.
.....I've had this happen to me when the tire installer didn't want the weights to show.
.....He split the difference hiding multiple weights behind the spokes on my old Vette.
.....Once removed and rebalanced all the vibration went away at operating speeds which were below the 100 MPH mark.

2. Could you possibly have a tire starting to shift a belt?
.....On a super stiff suspension you'd feel this pretty early and lets face it the MK-4 is stiffer than stiff.

3. Could you possibly have a front brake rotor that might be a tad off or maybe one of the internal fins got coughed up?
.....Since most rotors are cast this is an issue that does sometimes happen.

4. Have you pulled on the tie rod ends to make sure that they are as tight as they look?

Like you I hate vibrations and chasing them is a royal pain in the you pick the body part.

Good Luck From The Dark Dart Side!

Steve

[CDXXVII]

Do you happen to have the front wheel well liners from Alex’s Roadster Interiors?

[JIMOCO]

Thanks Avalanche325 and Steve, I will try your suggestions over the next couple of days and see if I can pinpoint the issue. Hopefully something comes of the tests. I do not have Alex's Roadster Interior's front wheel liners. Front end is FFR complete kit components without modification.

[tonywy]

I had the same issue even at the same speed, 73 was the sweet spot. It was on a ZR1 vette that I had. Changed everything including a steering rack. So at a last ditch effort I pulled the right front shock off, it was stuck in the extended position and would only travel about an inch. Put new front shocks on and problem solved. The shocks were Bilstein with the on the fly adjusters.

[Murd]

I have the same issue, below or at 75 mph it is fine, starts to get bad just above 75 and pretty shaky by 80. I don’t remember having this issue last season but I rarely drive on the hwy so I’m usually going max 60-70 on back roads.

I have just under 2500 miles on my car, 15” wheels with cooper cobra tires. I have manual steering with 3 deg caster. JIMOCO, do you have manual or power steering?

I’m wondering if it’s a combination of more feedback of bumps through the manual rack as well as the minimal caster starting to get unstable at that speed.

What’s the most caster anyone is running through a manual rack?

[Big Blocker]

Have that issue early in the morning, tires cold . . . but still noticeable at around 70-75 mph. I have my tires balanced every year just before I head to the Huntington Beach Cruise-In. I have them remove all weights and then balance with the generic "Hunter" balancing machine. When they are done, I have them re-balanced on their "Road Force" machine . This last step almost completely eliminates the "wiggle" in the steering wheel.

I have always thought this issue was caused by the fact that I run 275's up front - the wider tire being more susceptible to road forces.

+3° caster on a Flaming River manual rack.

Doc

[JIMOCO]

I have manual steering with 245-17s and 3 degrees caster. I dont think it is a bump steer issue. I have not noticed that bumps affect the front end beyond the normal level of twitchy I feel at speed. This is my fifth season on the road with over 11k miles. Did not notice the vibration before this spring. My next steps will be to double check torque specs and I got a recommendation to check pinion angle, upper rear control arm (3 link), tranny and diff fluid levels to rule out any drive train vibration I am feeling through the steering wheel. If all that fails I think a visit to the grand guru Mark Dougherty is in my future.

[SJDave]

Just want to let you know that I had a similar experience 8 years ago. Had alignment checked, had tires balanced twice, had driveshaft balanced, new harmonic balancer....no difference. The forum chimed in and someone asked if I had the flywheel and clutch balance checked? Flywheel was done, pressure plate assembly was not....how could it be bad, Ford Racing King Cobra purchased form Forte....made by Valeo in Korea...a respected manufacturer for many OEMs.

Ok....pull the engine, take the pressure plate to the Engine Shop, worst balance he had ever seen on a pressure plate assembly. I think it was 20#s of force radially at 3000 rpm. It's enough that it excites a drivetrain vibration of the entire system. I took off the side pipe hangers at one point and the vibration improved...and the speed at which it got worse changed, because the Mass that twists and vibrates in the rubber mounts is effectively higher now. The shop welded on some metal to the pressure plate housing, about 3 grams worth.

Put it back together...NO Vibration.

I hope it's not this same issue and just getting a good tire balance will do it for you.

HTH
Dave

[Murd]

Dave,
Was yours more rpm dependant than speed dependant I assume?

[SJDave]

Dave,
Was yours more rpm dependant than speed dependant I assume?

I would say YES....2100 to 2300 RPM was the worst range. It was worse in 5th gear, could even tell in 1st, 2nd, 3rd. Of course 2200 rpm was exactly 70 mph in 5th gear on the TKO 500 with 3:55 gears. Driving to Huntington Beach that first year, it was enough to drive me crazy, so I drove around 85 mph most of the way to avoid the bad vibration. My vibration was like a high frequency drumming that cycled every 2 seconds. Brmmmm...Brmmm...Brmmm. It was noticeable in 4th gear at 2200 rpm, but not that bad. In neutral holding it at 2200 rpm you could see some movement on the engine mounts but nothing like the vibration in 5th gear...I guess you need to transfer torque back through the running gear to get the rubber mounts on the engine and tranny excited at the system natural frequency.

[JIMOCO]

My issue is speed rather than rpm. I drove to vibration speed. Down shifted to fourth and vibration stayed the same. No change in vibration with clutch in or coasting in neutral with engine at idle.

[GoDadGo]

My issue is speed rather than rpm. I drove to vibration speed. Down shifted to fourth and vibration stayed the same. No change in vibration with clutch in or coasting in neutral with engine at idle.

Do you have any friends or neighbors that has a Mustang that you could borrow the front tires for a short spin?

If you don't then consider renting a Mustang (Base Model) for a day to borrow a couple of tires to see if swapping the fronts solves it.

Desperate Times Call For Desperate Measures!

[JIMOCO]

That is a great idea. Unfortunately, my son-in-law has a mustang but it is four lug. I belong to a car club and will track down a mustang owner and see if he will help me.

[GoDadGo]

That is a great idea. Unfortunately, my son-in-law has a mustang but it is four lug. I belong to a car club and will track down a mustang owner and see if he will help me.

Baby Go-Dad and I swapped wheels when I had a vibration in my C-4 which is how we found the "Hide The Weight Issue" that I outlined in my 06/12/2019 post....Both cars ran 17" wheel, but my fronts were 255/45's while his were 255/40's....We swapped front wheels and he picked up my vibration.

The two cars are shown below:

2017 C-4 Corvette & Camaro
https://youtu.be/svZX2BMSDEs

2018 Just His Camaro After Paint Work Was Completed
https://youtu.be/A5WUZgl6N5Q

Good Luck!