Shock Experts, Please Weigh in, is this complete BS?

[Wayne 962]

See this thread:

Is this mechanic full of BS?

-Wayne

[Moses]

The list of issues that cause premature or uneven tire wear include:

1) Poor alignment
2) Improper Camber/Caster
3) Over/underinflation
4) Driving habits.

I have never heard of, nor can I imagine, bad shocks causing uneven tire wear. In order for the shocks to cause that problem, I would think they would have to be so bad that the car would be undriveable.

My guess is the customer discovered a different set of shocks he wants but can't afford.

[Tyson Schmidt]

Bad shocks can cause tire wear. A very specific kind of tire wear. It's called "Cupping"

It won't make them "out of round" though.

The cupping is caused by the undampened tire basically bouncing up and down at a specific frequency, causing wear in very spotty areas on the tire. It's a very weird wear pattern.

But, it takes a pretty dead shock to cause "Cupping". So, it should be pretty obvious that the shocks are dead if they are indeed the culprit.

[jpachard]

Wayne, I concur with Moses points and for the record, I have had a shock go bad. It did not cause any excessive tire wear and my mechanic told me to return the shock to Koni for a refund. In response, Koni asked me to send BOTH the shocks back and they shipped me out a pair back in return. Maybe there is some miscommunication between the mechanic and the customer regarding both being bad. Koni required that I send both back in order to get the warantee. Hope this helps.

Cheers, James

[Tyson Schmidt]

I should have added to the above, that tire imbalance combined with a dead shock will cause cupping.

But the customer never mentioned that. He mentioned that the mechanic told him the tire was out of round. That is a tire problem.
I've seen plenty of brand new tires mounted on perfectly straight wheels that were significantly out of round. Had to send them back. The customer may have gotten a bad tire, and that may have killed the shock!

[makaio]

I think the shop is trying to pull an "Appleton Snow Job" on this poor soul. Probably trying to get him/or her to spend extra $ with their shop.

[HawgRyder]

If the tires were switched left for right during the shock change...yes..you can get an out of round tire....in fact the cords inside the tire twist and create the weirdest look to the tire.
Bob

[avi8torny]

Wayne,
The consumer is in a tough spot. He has his mechanic telling him one thing, and you telling him another. It is easier for you to deal with Sachs than the consumer. IMO...send him a pair as goodwill....it doesn't happen all the time and you will most likely secure his future business along with his friend's business.

On a side note, I had a front tire go bad after one track event. Called Tire Rack and told them what the installer discovered and a replacement was FedEx'd the next day. Guess who gets tire business from now on?

I have bought many things from Pelican....I don't shop around because your customer service has been excellent. Now if you only carried Orange Pagid's for my 87....you would have all my business.

[john walker's workshop]

i concur with what tyson posted.

[Zeke]

I am not an *expert.* I did work in a tire shop in my college days and then I had the fortune of meeting a man who had 2 patents on wheel balancing devices. He explained a lot of tire balancing theory to me.

Let me correct one thing.

Bad shocks can cause tire wear.

Bad shocks can allow tire wear. As memtioned, the shock is a reactive device to input. On its own, it doesn't produce any signal before receiving one. Even on active suspension this is true, but the signals are acted on in a real time environment which is faster than the tire dynamics can react, so you get control. To the same extent, a regular shock produces latent control. Good enough for most of us, but not a cause of anything.

Most tires are out-of-round from the manufacturer. They have set tolerances and they are not zreo. Still, many tires are more OOR than others. The computer balancer cannot recognize OOR. My patent man trues each tire before balancing. After a preliminary balance on the computer, he then balances the entire tire, wheel, hub and brake assembly on the car.

None of the systems take into account the deflection that the tire sustains under various loads. All of the balancing that I have seen is done with the tire off the ground. So there is a lot going on and the shock is trying to dampen the results.

The shock is not the cause of tire wear, but it can certainly contribute to it if not working properly, but something else has to be wrong first.

[Superman]

JW gets the Pelican Award for providing the most information overall, with the fewest words. I'm going to agree with him and Tyson. Tyson's two posts provide EXACTLY the same information I would contribute.

In other words, I disagree with the mechanic who is trying to blame high-quality two year old shocks. Even so, I would also consider sending him a new pair and dealing with Boge for him. For goodwill purposes. Sometimes, a maneuver like that gets you one loyal lifetime customer, and he tells several of his friends as well.

[Oldporsche]

I'm not a shock expert.

I have experienced out of round tires and "cupping" and bad shocks.

I do agree with Tyson and Zeke.

I have sent back tires that were out of round when they were delivered from the mfg. Out of round can not be corrected by balancing. Truing the tire will take the out of round out of it however it may produce an out of balance situation. This is because the tread may be thinner in one area. If the new tires are out of round, send them back.

Bad shocks, I believe accentuate balance and out of round problems.

When ever I have encountered a suspect new shock, I have always been asked to send in both shocks.

Good luck,
David Duffield

[Zeke]

That's the trouble with the language. We are all saying the same thing. It's not the shocks. There is no disagreement here. And I further agree that the vendor has to at least lead the customer to the solution even though the vendor did not make the shock or the problem.

[tobluforu]

I agree with tyson. This happened on my saab. I had this noise coming from the right rear shock area. Was not sure what the heck it was. But, it did it when going over bumps. More so when going slow and over small imperfections in the pavement. Almost like a rattle I looked everywhere for the problem. Then that one tire started wearing like I have never seen. Drove to shop to have someone look at it-something i really never do, and the guy said-shock. Yea right I said. Well 2 months later I replaced the shocks in the rear along with tires. Problem solved. Not sure if this coincides with the original topic. Saab with old shock and all, compared to BMW.