new QA1s and still wobble - need help please

[JW313]

Hey guys,

well - the new QA1 shocks did arrive in Germany and we put it on right away. Great quality and shipment - thanks to cobra valley.

however - in cruise mode at 60 until 100 (didnt go faster yet today), I still have the usual strong wobble and shaking in my steering wheel.
It does get better under hard breaking.

The old AVO shocks were bad (and I mean really bad) and I was sure to solve the issue with the new shocks. Now, I am kinda scratching my head.

Here are some facts:

15 inch wheels with Avon CR6ZZ
450# springs
Air pressure = tried with 23 and 27 psi
QA1 settings = 7 clicks from loose

We balanced the wheels for the third time - and they are within 5 gramms.

Do you have any ideas ?

thanks in advance

Jürgen

[Tommy]

General advice with wheel vibration is to swap front to back and see if the wobble moves too. If so, it could be a delaminated tread or bad tire.

[JW313]

Originally Posted by Tommy

General advice with wheel vibration is to swap front to back and see if the wobble moves too. If so, it could be a delaminated tread or bad tire.

hmm - are you saying, I should try to put the rear wheels onto the front ? - I might get into some space issues there ...

Anybody tested the balancing beads with Avons and higher speeds ?

[xlr8or]

Check them for roundness. If they are out of round the shocks won't over come that. Also try getting the "Road Force" balanced.

[JW313]

Originally Posted by xlr8or

Check them for roundness. If they are out of round the shocks won't over come that. Also try getting the "Road Force" balanced.

Thanks - I read in another long thread about steering vibrations about the road force balancing method. Need to find a shop here that offers that service.

Any ideas about the "magical balancing beads" ?

[Blas]

Alignment, wheel bearings or a warped rotor are other possibilities. You can't swap the front and rear wheels. Tie rod ends, ball joints..... Then spindles.... With braking lessening the wobble that might mean something... But I'm not sure what. Know anyone with another Superformance? You could try swapping the front wheels with them. That would either eliminate or pinpoint the problem component. Oh.. The steering box can be tightened up with an adjusting screw too....

[Chilibit]

Wasn't there a thread or two a few years back about ball joints being a trigger for a wobble (I guess this is a side to side motion on the steering wheel) on Superformance. It was at 60 MPH which is roughly your 100 kph. But I would have thought that Cobra Valley would have brought that up since it was a topic on SCOF if memory serves. Also, Dennis Olthoff suggested an approach to me when I was down there but I forget just what it was. It was an adjustment not a part. I did not have much of an issue and if it crops up I just "drive around it." You might email him at Olthoff Racing.

Edit: Blas's comment about the steering box rings a faint bell. I would follow that path. I vaguely associate that with Dennis' comment.

[Tommy]

Jurgen,
I looked at one of your earlier posts and note that these are new tires. Did you have the same problem with the previous tires? If so, it's not likely the tires that need attention. If the problem arose with the new tires, I suspect you have a bad tire and no amount of balancing will solve it. .... I've not yet heard a theory about the operation of the balancing beads that explains why they would go to the side of the tire that most needs the additional weight of the beads. I suspect they work on the placebo effect.

BTW, do you have a friend with a SPF who would let you swap wheels for a few miles?

[Shootnride]

Jurgen,

You may want to read through this thread in the Superformance forum (page 15)

"Mysterious front end shake at speed"

I have the same issue with my SPF but it's intermittent. Some days there is no shake at all and on another day under exactly the same driving conditions, it will shake. Still haven't resolved the issue.

Ted

[jhv48]

Before you do anything else, get the fronts road force balanced.

Go online and locate a shop that uses the Hunter GSP9700 balancing machine and turn it loose on your front tires. It will match the highest point on your rim with the lowest point of your tire and then will balance them. If that doesn't do it, something is out of round.

[Shootnride]

Jurgen,

Here's another thread you may want to look at. Read Randy Rosenberg's comments about his solution to this problem. I will be checking my car for the same issues he had.

Club Cobra > Club Forums > Bay Area Cobra Club
Suspension/handling

Ted

[JW313]

Originally Posted by jhv48

Before you do anything else, get the fronts road force balanced.

Go online and locate a shop that uses the Hunter GSP9700 balancing machine and turn it loose on your front tires. It will match the highest point on your rim with the lowest point of your tire and then will balance them. If that doesn't do it, something is out of round.

Well - good point with the hunter locater. In fact, I did find a dealer here in Germany (actually not too far) that has one of the GSP9700 road force balancer. I begged for an appointment today and 14:00 it is.

I always had some sort of vibrations and wobble in the car. But after replacing the shocks it is somwhat different. No clunking noises after going over uneven surfaces but continous steering vibs.

The AVOs were totally shot, especially the mount rubber - dangerous.

True is, that the vibrations did get more intense with the Avons.

So - first, I'll try the road force balancing and then I start replacing stuff like ball joints etc.

Keep you posted - thanks again

[ha_pe_1968]

Hi Jürgen!

Had the same problem with my first set of Avons - the back tires were not round - after changing it was a lot better. If they are not round you can balance whatever you want and will have no sucess. I am driving with 28 psi.
When the car is not moving some days i have a shaking at the steering wheel at the first miles - then it goes back to normal. So it seams Avons tend to flat spots. At lower speeds i have some light vibrations and shakings at my steering wheel too...thats not perfect but i am living with it :-)

Greetings from Austria
Peter

[JW313]

That doesn't look good - just as an FYI for all, that still use the AVOs (I guess there aren't too many).

[JW313]

Originally Posted by Shootnride

Jurgen,

Here's another thread you may want to look at. Read Randy Rosenberg's comments about his solution to this problem. I will be checking my car for the same issues he had.

Club Cobra > Club Forums > Bay Area Cobra Club
Suspension/handling

Ted

Good point - read through the thread. Mine is #1385, so the design issue after 1250 was solved. However, I do suspect a different root cause than just he tires. Not sure how I can work this issue from overseas, since there aren't many cobra shops around.

I am getting my hopes up with the road force balancing - we'll see.

[Tommy]

Jurgen,
I don't think you'll need a Cobra specialists to help solve your problem. I suspect any shop that deals with modified or race cars could help. You just need someone who understands how suspensions work, not some guy who only knows how to replace parts. Good luck.

[Mark IV]

Originally Posted by ha_pe_1968

Hi Jürgen!

Had the same problem with my first set of Avons - the back tires were not round - after changing it was a lot better. If they are not round you can balance whatever you want and will have no sucess. I am driving with 28 psi.
When the car is not moving some days i have a shaking at the steering wheel at the first miles - then it goes back to normal. So it seams Avons tend to flat spots. At lower speeds i have some light vibrations and shakings at my steering wheel too...thats not perfect but i am living with it :-)

Greetings from Austria
Peter

28 PSI is high for the street. Somewhere in the 21-24 range would be preferred for street use.

[ha_pe_1968]

Originally Posted by Mark IV

28 PSI is high for the street. Somewhere in the 21-24 range would be preferred for street use.

After some reading and different opinions i started on 21 and ended at 28psi. Tire wear looks ok for me and the feeling is in my opinion better - mostly i am driving spirited on small montain roads - but thx for the info...i was testing it 2 years ago...think i will make this test again :-)

Thanks,
Peter

[vatdevil]

Light car, big tires, manual steering with no rag joint...... all this makes the car very sensitive to flat spotted tires, out of round tires, and balancing that's not quite on. I run NT01s that flat spot and shake the car until warmed up. Road force balancing has helped on my car.

[Blas]

That red bushing in the photo of the AVO below from JW313 does not appear to be standard issue. It looks like the bushing had 2 additional red inserts added to it somewhere in time. Probably due to failure (elongation) of the original bushing. The failure commonly seen on these shocks is the bushing collapsing and the steel ring surrounding the bushing making contact with the A-Arm - leading to a weld or bushing ring failure on the shock and a corner suspension collapse. AVO's shocks on early SPF chassis due date back quite a few years now. The bushings can be replaced if you are so inclined. But since you would need to remove the shocks to replace the bushings and the availability of new ot "take-off" Bilsteins, replacement units make sence. More a matter of age than of bad design anywhere. 12+ years on shocks on a performance car? NO..... 12+ years on a bottle of Scotch? OK.......