Bent wheels
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I recall routine mention of bent wheels in the write-ups of many C&D long-term test cars on low profile tires. Given their MI location, they do run many miles in their test cars year-round on some of the most pothole ridden pavement found anywhere in the US. SUVs and trucks are generally immune because of much higher sidewall profiles that provide significantly more pothole protection.
Even the strongest monoblock forged wheels on low profile tires can easily be destroyed by a nasty, deep pothole w/ jagged steep edges.
Even the strongest monoblock forged wheels on low profile tires can easily be destroyed by a nasty, deep pothole w/ jagged steep edges.
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I recently replaced the tires on my C8 and was notified a couple wheels were bent. I didn't really notice any vibration when driving the car, but the Technician showed me the wheel while it was spinning on the balancer (wheel was obviously bent).
I think these C8 wheels are weak as I don't recall every hitting any potholes (I live in SoCal so roads are decent).
I got lucky and picked up a set of take-offs from a new C8 to replace my originals.
I think these C8 wheels are weak as I don't recall every hitting any potholes (I live in SoCal so roads are decent).
I got lucky and picked up a set of take-offs from a new C8 to replace my originals.
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No, C&D is repeating itself by beating up sports cars of all kinds on nasty pavement. As I said above, it has happened on many of their long-term testers.
The bent wheel problem is common on all cars on low profile tires on streets ridden with potholes, even with fully-forged wheels.
The bent wheel problem is common on all cars on low profile tires on streets ridden with potholes, even with fully-forged wheels.
Last edited by Foosh; Dec 15, 2022 at 07:22 PM.
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Crappy roads can damage any wheel, but low profile sidewalls do not help. Haven't heard many stories about C8 wheels being damaged.
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From: Redondo Beach, California
During the class room instruction at Ron Fellows, there was the suggestion to drive the car in tour mode, with the magnetic shocks turned off, when driving on potentially pot holed roads. Keeping the car lightly sprung so as to reduce stress on the wheel rims when driving over a rough road. The tires on these cars have very minimal sidewalls and there's not much protection for the wheel rims. How tall are the side walls?....They look about 2 1/2 inches tall or thereabouts. Sure, they run the cars at max stiffness with the mag shocks on when their cars are on the track.....but their track is relatively smooth....a little whoop de do here and there though.
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Drive with the magnetic shocks turned off? How would you do that? Pull the electrical cable leading to each shock? Doubt they said that. It’s not an ON/OFF function, it’s varying levels of firmness.
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From: Lakewood Ranch, FL
Drive the car in Tour mode, as opposed to Track mode to reduce the possibility of wheel damage? Probably good advice.
Drive with the magnetic shocks turned off? How would you do that? Pull the electrical cable leading to each shock? Doubt they said that. It’s not an ON/OFF function, it’s varying levels of firmness.
Drive with the magnetic shocks turned off? How would you do that? Pull the electrical cable leading to each shock? Doubt they said that. It’s not an ON/OFF function, it’s varying levels of firmness.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
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From: NE South Carolina
I recently replaced the tires on my C8 and was notified a couple wheels were bent. I didn't really notice any vibration when driving the car, but the Technician showed me the wheel while it was spinning on the balancer (wheel was obviously bent).
I think these C8 wheels are weak as I don't recall every hitting any potholes (I live in SoCal so roads are decent).
I got lucky and picked up a set of take-offs from a new C8 to replace my originals.
I think these C8 wheels are weak as I don't recall every hitting any potholes (I live in SoCal so roads are decent).
I got lucky and picked up a set of take-offs from a new C8 to replace my originals.
I found the added band of material, see pic below, where you would expect it was needed, on the barrel near the center hub.
BTW, agree it's not the wheel construction which is flow formed, where the barrel can be as strong as "fully forged" wheels (love that marketing word, it's like fully pregnant!) The wheels on my V8 CJ5 Jeep Renegade were made from cast aluminum. They were very strong, tested often off roading and never had an issue. They were just heavy!
What I measured on my C8 Rear Wheel. As Tadge said they added a band of thicker material. Note it's not separate, it's just made thicker in the flow formed process.
My CJ5 Jeep aluminum wheels were as strong as hell and took a lot of abuse offroading. They were just heavy! Note cast aluminum, unlike cast iron is not brittle.
Last edited by JerryU; Dec 16, 2022 at 08:48 AM.
E-Ray, 3LZ, ZER, LIFT
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From: NE South Carolina
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During the class room instruction at Ron Fellows, there was the suggestion to drive the car in tour mode, with the magnetic shocks turned off, when driving on potentially pot holed roads. Keeping the car lightly sprung so as to reduce stress on the wheel rims when driving over a rough road. The tires on these cars have very minimal sidewalls and there's not much protection for the wheel rims. How tall are the side walls?....They look about 2 1/2 inches tall or thereabouts. Sure, they run the cars at max stiffness with the mag shocks on when their cars are on the track.....but their track is relatively smooth....a little whoop de do here and there though.
And BTW, there is no "magnetic shocks turned off" mode. They system is always on when the car is powered up. Even in Tour mode the MSRC shocks are making constant firmer or softer damping adjustments in microseconds. They do want you running in Track mode to reduce body roll while cornering, and to keep the chassis settled for best performance.
Last edited by Foosh; Dec 16, 2022 at 12:34 PM.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
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From: NE South Carolina
During the class room instruction at Ron Fellows, there was the suggestion to drive the car in tour mode, with the magnetic shocks turned off, when driving on potentially pot holed roads. Keeping the car lightly sprung so as to reduce stress on the wheel rims when driving over a rough road. The tires on these cars have very minimal sidewalls and there's not much protection for the wheel rims. How tall are the side walls?....They look about 2 1/2 inches tall or thereabouts. Sure, they run the cars at max stiffness with the mag shocks on when their cars are on the track.....but their track is relatively smooth....a little whoop de do here and there though.
There was a period of time during the C7 era where some instructors at Spring Mt. were providing that advice (stay in Tour on the street), but not all. They aren't saying that anymore to my knowledge.
And BTW, there is no "magnetic shocks turned off" mode. They system is always on when the car is powered up. Even in Tour mode the MSRC shocks are making constant firmer or softer damping adjustments in microseconds. They do want you running in Track mode to reduce body roll while cornering, and to keep the chassis settled for best performance
.
And BTW, there is no "magnetic shocks turned off" mode. They system is always on when the car is powered up. Even in Tour mode the MSRC shocks are making constant firmer or softer damping adjustments in microseconds. They do want you running in Track mode to reduce body roll while cornering, and to keep the chassis settled for best performance
."As wheels get wider to accommodate wider tires, all these challenges are increased. For these reasons we spend a huge amount of engineering resources on optimizing wheels. We design wheels to withstand extreme pothole loads and test them on high speed laboratory equipment that can simulate the entire life-cycle of the vehicle. I have heard from some people that there is a theory that running the car in sport or track can contribute to damaging a wheel. That is not true."
Tadge had no reason to bring it up as he was overall saying it's bad roads and wider wheels in today's Vettes that cause the issue. Fact is he is an engineer, knows the max loads MRC can cause and they are probably much lower than what causes a wheel bend or break. I bottomed my 2017 Grand Sport suspension and tire/wheel hit the bump stop, which is no doubt a much higher load than Max stiffness for ferrofluid passing thru a hole in a MRC shock. I was fortunate it did not bend/break my wheel. When I sold my Grand Sport with its 12-inch-wide OEM wheels they were fine. But in NE SC we don't have frost caused potholes!
He also said at a C8 BASH they increased the design loads for C8 wheels and added a thicker band to the barrel. Found that as shown in pic below.
For the C8 they added what Tadge called a band where you would expect at the hub barrel interface. Note it's NOT a separate piece they leave the barrel thicker in that area in the flow form process.
BTW, when racing or tracking aggressively it's common to use the Track curbing to increase a turn radius. Cars, wheels can hit pretty hard! At times you have no choice!
Last edited by JerryU; Dec 16, 2022 at 01:58 PM.
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From: Redondo Beach, California
Drive the car in Tour mode, as opposed to Track mode to reduce the possibility of wheel damage? Probably good advice.
Drive with the magnetic shocks turned off? How would you do that? Pull the electrical cable leading to each shock? Doubt they said that. It’s not an ON/OFF function, it’s varying levels of firmness.
Drive with the magnetic shocks turned off? How would you do that? Pull the electrical cable leading to each shock? Doubt they said that. It’s not an ON/OFF function, it’s varying levels of firmness.
And BTW, there is no "magnetic shocks turned off" mode. They system is always on when the car is powered up. Even in Tour mode the MSRC shocks are making constant firmer or softer damping adjustments in microseconds. They do want you running in Track mode to reduce body roll while cornering, and to keep the chassis settled for best performance.
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The MSRC system is never actually off and the current supplied constantly varies in microseconds and independently in every shock with every bump in the road. It's neither "binary," nor "trinary." It's linear, and likely different in each of the 4 shocks at any given microsecond based upon sensor input at each corner.
Even in Tour, it's firming things up if that is what needs to happen to stabilize the chassis.
Even in Tour, it's firming things up if that is what needs to happen to stabilize the chassis.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
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From: NE South Carolina
I was assuming the magnetic shocks were a binary system, as I believe they are in my C6. For the C8, it appears they are a trinary system. Anyhow, when the magnetic shocks are "off," no electrical current flows through them, the microscopic iron particles in the damping fluid do not experience a magnetic aligning field, and the damping force is entirely due to the viscosity of the damping fluid. For my C6, I believe that when I turn my ride control switch to 'Sport," current flows through the shock absorber electromagnetic coils, aligns the iron particles to effectively increase the damping force of the fluid. This corresponds to "On." It appears the C8 has three damping settings, Tour/Sports/Track. I assume Tour corresponds to no current through the shock absorber magnetic coils, Track corresponds to a maximum amount of current and and Sports to a medium amount of current. My assumption is that in the softest setting, Tour, there is no current flowing through the electromagnet in each shock; i.e. off. Correct? Or is there nevertheless a bias current flowing even in the Tour mode? I'd certainly be interested in learning more of the technology of these shocks.
As you say on a smooth road there is still fluid going through an orifice just with low current, minimal resistance. The ferrofluid increases viscosity with current. As with conventional shocks (which have multimple valves actuated by rate of movement) on smooth roads still want all oscillation to stop with the 1st bounce.