Brian@BMVK
Well-Known Member
Can you please describe in automotive handling terms? Clearly the tires are staying on the road. No one is going to be able to help via the descriptions you've provided.
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NightmareMoon
Well-Known Member
I remember feeling the rear tire in that way on the stock pirellis in a slightly off camber sweeper at ~80 mph.
I wasn't looking ahead (off camber and large sweeper made it difficult), and the pirelli pzeros were not great at confidence at the limit, it felt like once you went past their peak, they'd slide fast. I was also probably past their pressure and heat limits, so they were getting greasy. The instructor wanted me to give it more throttle to plant the rear with weight transfer.. too him it felt close to a lift-oversteer situation, but any more gas and they'd really slide.
I haven't really felt that way since ditching those tires and going to better tires. So... what tire are you on? Was traction control on or off and was it kicking in?
Driving at the limit is all sorts of scary feels until you've got some experience. Was there an instructor in the car? Most new-to-track people go out with an instructor for the first many sessions.
You may have too much oversteer bias, so we're going to ask all sorts of questions about swaybars, shocks, tires, springs, tires pressures, etc.
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K4fxd
Well-Known Member
- Thread starter
- #19
I ran a Sunbeam Tiger from 78 to around 96 or so. Full on race car. Then I went Drag racing due to it being cheaper, and the Tiger got stolen.
I get this feeling long before it is anywhere near the limit. I was on I 40 through the gap in Tn/Nc and I was able to slowly pull away from a Suv that wanted to play. I should have been able to run away. The car felt wobbly and like it wanted to spin. This at around 80. It is worse when pushing it into tire squeal. I haven't been able to find the problem.
Track, traction control was unplugged.
Right now the car has Eagle F1 All seasons. I will be able to fit some slicks Wed.
I get this feeling long before it is anywhere near the limit. I was on I 40 through the gap in Tn/Nc and I was able to slowly pull away from a Suv that wanted to play. I should have been able to run away. The car felt wobbly and like it wanted to spin. This at around 80. It is worse when pushing it into tire squeal. I haven't been able to find the problem.
Track, traction control was unplugged.
Right now the car has Eagle F1 All seasons. I will be able to fit some slicks Wed.
Bluemustang
Well-Known Member
Sounds to me like something is loose in the suspension and/or the alignment is way off. The rear toe being off can cause some squirrelly effects. Other than those things not sure.
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Dana Pants
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FYI, no one should ever discuss setup with any seriousness while taking all seasons on track. Adding traction will make the car behave totally differently.
- Banned
- #23
OK, you've got enough of a driving background that we should be able to sort this out.
Logically, we know that all four wheels are actually on the ground and you're not just driving around on the outside rear. If you feel the grip doesn't match what you would expect, that's a different matter and one that makes sense. The next thing we need to sort is where in the corner you get this feeling and what seems to be the factors which provoke this response.
1. How does the car feel while braking?
2. Does the nose follow your hands with the initial turn of the wheel?
3. Does it roll into the corner and develop grip or does it feel like it stays flat and it prone to sudden sliding?
4. What's the feedback mid-corner steady state?
5. What limits your ability to go to throttle?
6. How does the car response when you do apply throttle? Does the balance shift or is wheelspin/traction control an issue?
There is a big component of a car which is fun and easy to drive fast which is not necessarily balance as much as it is stability. Imagine we put cornering balance on an 'X' axis continuum with Understeer on the left and Oversteer on the right. That's pretty standard. I also add a vertical axis which is 'Stability', which I define as the car responding in a predictable manner to the driver's inputs. This 'Y' axis is positive as it goes up, which mean an increase in stability. An excessive amount would mean the car is sluggish to change direction. As we go negative on the Y-axis, we go towards a car which wants to overreact to driver inputs, such as wanting to spin on entry or a 'nobody's home' understeer which shifts directly into a snap oversteer. Many see understeer as inherently stable and oversteer as inherently unstable. I disagree. It's plenty easy to produce a car which has understeer, but is very difficult to drive. A car which has a neutral to oversteer balance, but is stable is the Holy Grail in smaller formula cars (which don't struggle with powerdown/wheelspin), particularly on ovals. In general, though, if a car is acceptable in terms of stability, you can drive it reasonably fast with either an understeer or oversteer balance (defined by relative tire slip angles). Another rule of mine: When dealing with a 'neutral' car, a 10% increase of understeer slows lap times by 1% and a 1% increase in oversteer slows the car 10%. Never be hesitant to add understeer. It might not be the right answer, but it's unlikely to cause dramatic problems.
So let's get a little deeper into your particular situation. If you go out and are sliding all over, the first question to ask is what are the track conditions? If the track is dirty and green, then you're going to be sliding around, regardless of the car. It seems as if your alignment settings are reasonable, so I doubt if that's a big contributor. What are the other runners saying? Ask them. It's always good to get a sanity check. Did you make any changes which might effect the car? What were your pressures? Is this a new feeling with this car, or has it always been like this? Are you generally comfortable in the car or do you have trouble with your fitment? Sliding around in the seat is never helpful.
All of this is just some ideas to get your noodle going before the next time out. See if you can define your issues in way which are easier to understand, and I think you'll find a lot of people interested in talking it through with you.
Logically, we know that all four wheels are actually on the ground and you're not just driving around on the outside rear. If you feel the grip doesn't match what you would expect, that's a different matter and one that makes sense. The next thing we need to sort is where in the corner you get this feeling and what seems to be the factors which provoke this response.
1. How does the car feel while braking?
2. Does the nose follow your hands with the initial turn of the wheel?
3. Does it roll into the corner and develop grip or does it feel like it stays flat and it prone to sudden sliding?
4. What's the feedback mid-corner steady state?
5. What limits your ability to go to throttle?
6. How does the car response when you do apply throttle? Does the balance shift or is wheelspin/traction control an issue?
There is a big component of a car which is fun and easy to drive fast which is not necessarily balance as much as it is stability. Imagine we put cornering balance on an 'X' axis continuum with Understeer on the left and Oversteer on the right. That's pretty standard. I also add a vertical axis which is 'Stability', which I define as the car responding in a predictable manner to the driver's inputs. This 'Y' axis is positive as it goes up, which mean an increase in stability. An excessive amount would mean the car is sluggish to change direction. As we go negative on the Y-axis, we go towards a car which wants to overreact to driver inputs, such as wanting to spin on entry or a 'nobody's home' understeer which shifts directly into a snap oversteer. Many see understeer as inherently stable and oversteer as inherently unstable. I disagree. It's plenty easy to produce a car which has understeer, but is very difficult to drive. A car which has a neutral to oversteer balance, but is stable is the Holy Grail in smaller formula cars (which don't struggle with powerdown/wheelspin), particularly on ovals. In general, though, if a car is acceptable in terms of stability, you can drive it reasonably fast with either an understeer or oversteer balance (defined by relative tire slip angles). Another rule of mine: When dealing with a 'neutral' car, a 10% increase of understeer slows lap times by 1% and a 1% increase in oversteer slows the car 10%. Never be hesitant to add understeer. It might not be the right answer, but it's unlikely to cause dramatic problems.
So let's get a little deeper into your particular situation. If you go out and are sliding all over, the first question to ask is what are the track conditions? If the track is dirty and green, then you're going to be sliding around, regardless of the car. It seems as if your alignment settings are reasonable, so I doubt if that's a big contributor. What are the other runners saying? Ask them. It's always good to get a sanity check. Did you make any changes which might effect the car? What were your pressures? Is this a new feeling with this car, or has it always been like this? Are you generally comfortable in the car or do you have trouble with your fitment? Sliding around in the seat is never helpful.
All of this is just some ideas to get your noodle going before the next time out. See if you can define your issues in way which are easier to understand, and I think you'll find a lot of people interested in talking it through with you.
- Banned
- #24
There's a lot to this. All-season tires generally have you wiggling around on the tread blocks so much that it's hard to figure out what the hell the damned car is doing. Further, they're Goodyears, which are potentially the worst tires made. At the very least, they make an annual run for the title.
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Brian@BMVK
Well-Known Member
The new Goodyear Supercar 3 and Supercar 3R are bucking this trend significantly, and are among the best for 200+ tw street tires and max effort street tires, respectively.
Norm Peterson
corner barstool sitter
Norm Peterson
corner barstool sitter
It might be time for some IRS bracing.
The only time I've experienced something that could be described anywhere near like what you have noted was when I took a tire pressure staggering test sequence to a truly foolish level, where the tail was loose under both leading throttle and trailing throttle. In that case, it was rear tire pressures too low. In your case, maybe you're running the rear tires at too high of a cold pressure, or perhaps they're gaining an unusual amount of pressure for some reason. Not enough rim width for the tire size could be at play here as well. Street tires aren't built like cantilever race tires to get around class restrictions on wheel width.
Norm
The only time I've experienced something that could be described anywhere near like what you have noted was when I took a tire pressure staggering test sequence to a truly foolish level, where the tail was loose under both leading throttle and trailing throttle. In that case, it was rear tire pressures too low. In your case, maybe you're running the rear tires at too high of a cold pressure, or perhaps they're gaining an unusual amount of pressure for some reason. Not enough rim width for the tire size could be at play here as well. Street tires aren't built like cantilever race tires to get around class restrictions on wheel width.
Norm
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