Wide body newbie?
#1
Burning Brakes
Thread Starter
Wide body newbie?
I have gotten very used to driving my C6 base I just picked up a 2017 Grand Sport and the first thing I have noticed is it doesn't have the same turning radius. Another thing is if I have the wheels turned at low speed in either forward but mostly reverse I get a shimmy in the wheel hard to describe but reminds me of an old 4x4 with the front wheels locked in. Can someone shed some light on this?
#2
Burning Brakes
Normal
#3
I don't know where you live, but on cool pavement, the OEM Michelin PSS ZPs do chatter in a tight turn. When I put all-seasons on my car for winter, that totally went away.
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Davids65 (12-06-2016),
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#4
Go Canes!
I don't know if the turning radius is any different on the GS, but my Stinray does not have very tight turning radius.
#5
Burning Brakes
Thread Starter
Thanks for the replies!
I have gotten very used to pulling my car into my garage which is a side entry on my house so I have to make a tight turn on a narrow driveway to line up. I have three cars on my driveway as I'm making the turn into the garage which makes it even harder this said in my C6 I was able to make the turn in one shot now it's takes several maneuvers to line it up. The GS is also wider making it very hard to get out of the car once in the garage. I'm not complaining this is a small price to pay for the upgrade! I can't wait until spring to enjoy the new car!
I have gotten very used to pulling my car into my garage which is a side entry on my house so I have to make a tight turn on a narrow driveway to line up. I have three cars on my driveway as I'm making the turn into the garage which makes it even harder this said in my C6 I was able to make the turn in one shot now it's takes several maneuvers to line it up. The GS is also wider making it very hard to get out of the car once in the garage. I'm not complaining this is a small price to pay for the upgrade! I can't wait until spring to enjoy the new car!
#6
E-Ray, 3LZ, ZER, LIFT
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I have gotten very used to driving my C6 base I just picked up a 2017 Grand Sport and the first thing I have noticed is it doesn't have the same turning radius. Another thing is if I have the wheels turned at low speed in either forward but mostly reverse I get a shimmy in the wheel hard to describe but reminds me of an old 4x4 with the front wheels locked in. Can someone shed some light on this?
It's the race car tire type low slip angle. Proof, the tires are the same width as my C6, Z51 (which did not have this issue to any degree with the OEM Goodyears or replacement Firestones) and posters stay the issue goes away with winter tires with the same Ackerman steering geometry.
For a technical explanation supporting my findings made this PDF: http://netwelding.com/Wheel_Chatter.pdf
It has lots of pics from references used.
Easy workaround- turn the steering wheel less when it's below 45 F and make "K" turns. It only occurs on slow speed turns so no big deal.
If you have a friend in your C7 and forget and make a full lock turn (actually have to turn at least 1/2 from a full lock) they will laugh and tell all your friends about the piece of junk you bought! At 35 F it does feel like the front end is coming apart. You can quote the ability of the tires to achieve very high lateral "g" force when warm as the trade-off!
Last edited by JerryU; 12-06-2016 at 07:58 AM.
#7
Le Mans Master
Explaining the “Ackermann Effect” in the 2014 Corvette StingrayPosted by Kif Richmann on Monday, November 18th 2013
If you take the all-new Stingray for a drive, you may notice something before you even leave the parking lot. This little something may seem like a defect, but it’s not.
It’s called the “Ackermann Effect”, and although the issue was resolved 200 years ago, Chevy left it alone on the Corvette.
The reason? It’s the same reason the Corvette has a 50/50 weight distribution and electric power steering: performance.
Explaining the Ackermann Effect:
488px-Ackermann_turning.svgWithout getting into too much geometry and mathematics, the Ackermann Effect is a skipping or lurching of the wheels when the vehicle is turning sharply. The effect is created by the inside and outside wheels traveling at different speeds and distances.
Essentially the outside wheels are traveling further, creating a skipping or jumping effect.
A system, which was patented by Rudolph Ackermann in the 1818, turned the wheels at different angles and created a smooth turn for four-wheeled wagons.
Most cars use a system to mitigate the Ackermann Effect, the Corvette Stingray, however, goes without.
If you take the all-new Stingray for a drive, you may notice something before you even leave the parking lot. This little something may seem like a defect, but it’s not.
It’s called the “Ackermann Effect”, and although the issue was resolved 200 years ago, Chevy left it alone on the Corvette.
The reason? It’s the same reason the Corvette has a 50/50 weight distribution and electric power steering: performance.
Explaining the Ackermann Effect:
488px-Ackermann_turning.svgWithout getting into too much geometry and mathematics, the Ackermann Effect is a skipping or lurching of the wheels when the vehicle is turning sharply. The effect is created by the inside and outside wheels traveling at different speeds and distances.
Essentially the outside wheels are traveling further, creating a skipping or jumping effect.
A system, which was patented by Rudolph Ackermann in the 1818, turned the wheels at different angles and created a smooth turn for four-wheeled wagons.
Most cars use a system to mitigate the Ackermann Effect, the Corvette Stingray, however, goes without.
#8
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Location: NE South Carolina
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Thanks for the replies!
I have gotten very used to pulling my car into my garage which is a side entry on my house so I have to make a tight turn on a narrow driveway to line up. I have three cars on my driveway as I'm making the turn into the garage which makes it even harder this said in my C6 I was able to make the turn in one shot now it's takes several maneuvers to line it up. The GS is also wider making it very hard to get out of the car once in the garage. I'm not complaining this is a small price to pay for the upgrade! I can't wait until spring to enjoy the new car!
I have gotten very used to pulling my car into my garage which is a side entry on my house so I have to make a tight turn on a narrow driveway to line up. I have three cars on my driveway as I'm making the turn into the garage which makes it even harder this said in my C6 I was able to make the turn in one shot now it's takes several maneuvers to line it up. The GS is also wider making it very hard to get out of the car once in the garage. I'm not complaining this is a small price to pay for the upgrade! I can't wait until spring to enjoy the new car!
In the winter I make at least 1 sometimes 2 "K" turns depending on the temperature. The Chatter may not be doing any harm but don't like the feeling of the front end hopping!
When the tires get warm from driving it is almost eliminated. Backed out on the garage on a 40 degree day and used my "K" turn approach. About 15 miles later pulled into a parking slot and when I backed out, shortly thereafter, same outside temp, used full lock to see what would happen. Only very modest chatter.
Same with tire traction. It was 47 degrees the other day and a slight drizzle. When accelerating onto a 4 lane divided highway at the end of our street the back end slipped slightly sideways. Same with a turn I have to make to another street 100 yards after I enter. That was with ~1/4 throttle. No big deal and kind of fun! I was in my usual Sport Mode. Once the tires warned up ~5 miles later they did stick. When it's below 40 I switch to Weather Mode and the nannies kick in faster!
Last edited by JerryU; 12-06-2016 at 08:16 AM.
#9
E-Ray, 3LZ, ZER, LIFT
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Location: NE South Carolina
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Explaining the “Ackermann Effect” in the 2014 Corvette StingrayPosted by Kif Richmann on Monday, November 18th 2013
If you take the all-new Stingray for a drive, you may notice something before you even leave the parking lot. This little something may seem like a defect, but it’s not.
It’s called the “Ackermann Effect”, and although the issue was resolved 200 years ago, Chevy left it alone on the Corvette.
The reason? It’s the same reason the Corvette has a 50/50 weight distribution and electric power steering: performance.
Explaining the Ackermann Effect:
488px-Ackermann_turning.svgWithout getting into too much geometry and mathematics, the Ackermann Effect is a skipping or lurching of the wheels when the vehicle is turning sharply. The effect is created by the inside and outside wheels traveling at different speeds and distances.
Essentially the outside wheels are traveling further, creating a skipping or jumping effect.
A system, which was patented by Rudolph Ackermann in the 1818, turned the wheels at different angles and created a smooth turn for four-wheeled wagons.
Most cars use a system to mitigate the Ackermann Effect, the Corvette Stingray, however, goes without.
If you take the all-new Stingray for a drive, you may notice something before you even leave the parking lot. This little something may seem like a defect, but it’s not.
It’s called the “Ackermann Effect”, and although the issue was resolved 200 years ago, Chevy left it alone on the Corvette.
The reason? It’s the same reason the Corvette has a 50/50 weight distribution and electric power steering: performance.
Explaining the Ackermann Effect:
488px-Ackermann_turning.svgWithout getting into too much geometry and mathematics, the Ackermann Effect is a skipping or lurching of the wheels when the vehicle is turning sharply. The effect is created by the inside and outside wheels traveling at different speeds and distances.
Essentially the outside wheels are traveling further, creating a skipping or jumping effect.
A system, which was patented by Rudolph Ackermann in the 1818, turned the wheels at different angles and created a smooth turn for four-wheeled wagons.
Most cars use a system to mitigate the Ackermann Effect, the Corvette Stingray, however, goes without.
Proof it's not the Ackerman geometry is folks report the issue goes away when they put on winter tires (which have more slip angle as do normal tires) and the Ackerman geometry has not changed.
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#10
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If you look at the paper tag that was around the shifter **** it states the tires will do this on slow tight turns, I believe GM calls it chatter. Much more noticeable on the GS and Z due to the wider tires. Normal as others have stated
#11
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FWIW, I got my September 2013 built C7, Z51 very early. Not much info on what you discovered and below 40 F if feels like the front end is falling apart! The GM, "Chatter is Normal" doesn't help much! Investigated and found why the Michelin's are the cause NOT Ackerman steering geometry, wide tires, sticky compound and why it's worse in the rain (as GM notes.)
It's the race car tire type low slip angle. Proof, the tires are the same width as my C6, Z51 (which did not have this issue to any degree with the OEM Goodyears or replacement Firestones) and posters stay the issue goes away with winter tires with the same Ackerman steering geometry.
For a technical explanation supporting my findings made this PDF: http://netwelding.com/Wheel_Chatter.pdf
It has lots of pics from references used.
Easy workaround- turn the steering wheel less when it's below 45 F and make "K" turns. It only occurs on slow speed turns so no big deal.
If you have a friend in your C7 and forget and make a full lock turn (actually have to turn at least 1/2 from a full lock) they will laugh and tell all your friends about the piece of junk you bought! At 35 F it does feel like the front end is coming apart. You can quote the ability of the tires to achieve very high lateral "g" force when warm as the trade-off!
It's the race car tire type low slip angle. Proof, the tires are the same width as my C6, Z51 (which did not have this issue to any degree with the OEM Goodyears or replacement Firestones) and posters stay the issue goes away with winter tires with the same Ackerman steering geometry.
For a technical explanation supporting my findings made this PDF: http://netwelding.com/Wheel_Chatter.pdf
It has lots of pics from references used.
Easy workaround- turn the steering wheel less when it's below 45 F and make "K" turns. It only occurs on slow speed turns so no big deal.
If you have a friend in your C7 and forget and make a full lock turn (actually have to turn at least 1/2 from a full lock) they will laugh and tell all your friends about the piece of junk you bought! At 35 F it does feel like the front end is coming apart. You can quote the ability of the tires to achieve very high lateral "g" force when warm as the trade-off!
Those experiencing their 1st winter with the C7 need to understand what is occurring and NOT, as many did in the winter of 2013, run to the dealer and say their car is broke! It feels that bad!
Tire slip angle causes the tire tread to move at a lesser angle than the tire carcass. This allows less than theoretical full Ackerman Steering compensation to be used for slow speed turns. That helps hi speed performance as with weight transfer less is needed. When the tire is cold and stiffer the tire tread moves even less relative to the carcass creating "Chatter" or "Hopping." Installing more normal slip angle winter tires eliminates the Chatter issue.
Race Car Tire Construction Has A Small Slip Angle. Z51 OEM C7 Tires Have Race Car Type Construction
Last edited by JerryU; 12-06-2016 at 12:16 PM.
#12
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But Michelin says tire performance deteriorates below 40 F! It should also say an easy workaround is to turn the wheel less on slow speed turns.
Last edited by JerryU; 12-06-2016 at 02:09 PM.
#13
Regardless of what Michelin says, the PSS ZP starts losing significant grip well above 40F. It is noticeably less grippy below 60F.
In my work parking garage, I don't have the luxury of turning the wheel less, and as soon as the temps got to about 60, I heard the chatter every day. As soon as I put the AS3+ tires on the car, all chatter ended.
In my work parking garage, I don't have the luxury of turning the wheel less, and as soon as the temps got to about 60, I heard the chatter every day. As soon as I put the AS3+ tires on the car, all chatter ended.
Last edited by Foosh; 12-06-2016 at 02:32 PM.