Front end wobble

[jstinson]

I purchased a Superformance (633) recently and discovered a wobble in the steering wheel that was slight a low speeds but became stronger at 70 mph - went away at 80 mph. It felt like a front wheel out of balance. I needed some new tires anyway so I put them on got them balanced, new alignment, and the wobble is still there at 70 mph. I'm thinking its still an out of balance problem where a brake rotor or other part of the rotating spindle is out of balance.

Does this happen often in Cobras? Do I need to replace the rotors? I am looking for a place that will spin balance the mounted wheels the way it was done 30 - 40 years ago but have had no luck.

Suggestions?

[spdbrake]

I had a similar issue I chased for quite awhile. Turned out it was the Pin drive hub adapters were out of balance. Balancing the wheels with with the Pin drive adapters attached and making note of the indexing to wheel location for re installation on the car is critical.

This thread details it further. BDR vibration issue finally fixed

[jstinson]

Interesting! Was it easy to remove the Pin drive hub adapters?

[lnfletcher]

I fought with this for years until I read an article on "match mounting" wheels. I used this information and have not had an issue since.
In short, it is mounting the wheel/tire combination and finding the high spot on the tire, then removing and rotating the tire one lug/pin at a time until the high spot is at minimum. Then the lug/pin can be marked along with the wheel to enable easy matching afterwards when removing the wheel.

This technique made mine as smooth as glass. The light weight and the wide tires on these vehicles seem to exacerbate the problem.

This was all after balancing multiple times on various machines "road force etc..." and new tires and wheels without success. Had a wobble that would come and go depending on when I went around a curve. It was worse at speed. At times it was almost gone but would come back after going around a corner. The tire place told me it was one of my wheels. It wasn't until I bought new wheels (which were perfect) and tested runout without tires that I realized the hubs have a small amount of runout along with the tires that was causing the problem. In my case it wasn't really the hub, but the studs were slightly off center.

[spdbrake]

The Pin drive lug nuts on mine are 12mm Allen key. Easy to remove

[Danr55]

I had a similar problem with my CCX. Turned out the spindles in the rear were 1/4 inch smaller than the inside of the hub. I had spacers made to compensate and problems solved.

[jhv48]

Find a tire shop that has a Hunter Road Force tire balance machine and has a trained tech that knows how to properly use it.
I chased the same problem you have for years. Finally found a guy that mounts and balances tires for race cars using the Hunter Road Force Elite machine. Smooth as glass now.
Start here. Most Discount tire stores have the machine, but few employees really know how to use them properly. Ask the manager if anyone is an expert on the machine, if not, find one that is.

[Blas]

In addition, balance the tires at your normal inflation pressure not the normal recommended pressure. I run 22 to 25 lbs max depending on the type of driving I’m doing.
Blas

[Dwight]

if you can find a shop that can shave the tires that should solve the problem.

We have chased the wobble problem on several Cobras. We've had driveshafts rebalanced, tires balanced (several times) checked rotors, you name but it was always the tires were out of round and not balanced correctly.

We have one shop in two counties that can shave a tire and only two people that know how to do it.

[saki302]

One of my front Avons was so bad Sasco swapped it out for another- wobble instantly cured.

-Dave

[undy]

Slipped belt on a front tire.

[jstinson]

Thanks for all the advice. It worked!

I took the front tires back to the tire store had them re-balanced with a more experienced tech who found a difference in both tires. Then back at my shop I created a jig to measure the diameter of each tire finding the "high point" and then with my Cobra still on the jack stands, I rotated each hub finding the low point and match mounted the tire/wheel combo high point with the hubs's low point. I now have a smooth ride!

[Cdog427]

If you need an alignment, I would highly recommend Thalmann Alignment in Northbrook. They did a great job on my car.

[HUBBELL RACING]

It’s only warped rotors if it happens under braking.

Check tire balance first then other stuff

[CHANMADD]

A good wheel shop should have a balancer that can balance the wheel whilst on the car....

[scootter]

Sounds like you figured it out. I had mine forced balanced etc. It was always the same shimmy at higher speeds. I just rotated mine tires one pin at a time, one tire at a time till it was gone.