I think I figured it out.

Tsunami · 05-03-2004, 02:40 PM

I have done some thinking and finally figured out why my MN12 is having trouble with the drift. It's the tires. I'm controlling around 3600lbs with only a 15" rim and 215 size tire. That would explain why I have the understeer in and why the oversteer seems to be so abrubt. I think I'm just asking too much of the tires. Also it was posted here that somebody drifted a SuperCoupe which has 16" wheels, wider tires and stiffer sway bars. (blown 3.8L V6). Although it's a V6 it's a bit heavier than my car. I think the supercoupe can control its weight better due to it's better sway bars and tires. Whatda you guys think?

MrodDrft · 05-03-2004, 02:42 PM

MN12 =

im guessing a thunderbird by ur avatar

nissanguy_24 · 05-03-2004, 02:45 PM

Yes Stiffen up that chassis, then Get your self some wider tires, and some of the more popular 'drift' type tires. something that will loose grip gradulally, might make that beast alittle easier to control.

Also are you running a staggerd tire size? i wouldnt, not for drifting, if your looking for balance.

nissanguy_24 · 05-03-2004, 02:49 PM

Also man, what have you done weight reduction wise? its not nessisary but it may be easier to control if you can shave 200 lbs or so.

Tsunami · 05-03-2004, 05:46 PM

Right now it's technically my father's car (cheaper on the insurance that way), so I really can't strip it just yet. But if I could get another car I'd definitely take out the rear seat, carpet, and stuff in the trunk. I'm also thinking of doing my own cold air intake, but I haven't had time to research the idea that much. Most likely I'll trade this car in so I'll probably just save up for an F-Body or a 5.0

soultron · 05-03-2004, 07:52 PM

foxes rule!
2.5 stroker turbo hybrids put out crazy torque.

Drift For Food · 05-04-2004, 08:17 AM

Doesn't the Thunderbird weigh more than 3600lbs? (don't know which year you're talking) It's a big car that's front heavy. It's also setup to have understeer: stiffer front suspension, softer rear, front sway bar, probably no rear swaybar.

Tire choice can affect the understeer/oversteer behavior. If you throw some cheap tires on the rear and some grippy ones on the front, you can help the situation.

A better method would be to modify the suspension. Run softer front springs/stiffer rear, take off the front sway bar and/or put a rear sway bar on. This will all help get the rear end loose. Now minor suspension changes can make a potentially big difference, so You have to be somewhat careful about what you do.

Start off with something like an aftermarket spring on the rear, something a bit stiffer than stock. This will help change the car to a natural oversteer behavior and get rid of its current understeer behavior. Second is to get a sway bar. It probably has a front one, but look for an aftermarket rear one maybe a matching set with the springs. This will help the side movement of the car. Keep the front one too. Stiffer rear springs and a rear sway bar should make a big difference.

If you want to keep it stock though, just take off the front sway bar. That's the best you can do without actually buying aftermarket parts. Along with stickier tires on the front and some cheapies on the rear, you're about as good as you're going to get stock.

foilman · 05-04-2004, 08:30 AM

Changing the tires isn't going to change the car's balance (unless you stick bigger/stickier tires on the front than the back). If it understeers now with 215s all around, it will still understeer with 235s. You need to change spring rates or sway bars (or alignment to some degree) to change the balance... focus on stiffening the rear to reduce understeer.

-Tony

Tsunami · 05-05-2004, 02:44 PM

I really don't understand how stiffening the rear of the car makes it oversteer, other than the fact that it would make the rearend want to skate around. I've always thought that stiffening the front reduces understeer and stiffening the back reduces oversteer.

For right now I've changed the plan a little. The 'Bird that I was gonna replace mine with got sold so I'm gonna just save my car and get a 5.0 when I have enough money saved up. It'll be better to have a driver and have a dedicated drift car that I don't have to worry about wrecking.

foilman · 05-05-2004, 02:54 PM

Well then do some research, find a book or good article online, maybe check howstuffworks.com for info on anti-roll bars, because you have it exactly backwards. The stiffer end will load sooner, and overload sooner, and it's overloaded tires that slide.

-Tony

Tsunami · 05-05-2004, 03:05 PM

So a stiffer anti-roll bar would decrease grip and a softer one would increase it? So would that mean that the sway bars work the oppositte way that springs do. I know a stiffer spring gives more grip and a softer one gives less grip. Maybe I've thought antirollbars work the same way when in reality they work the oppositte way that the spring rates do?

nissanguy_24 · 05-05-2004, 03:35 PM

The Roll bars, and indeed the springs them selfs dont increase grip. Only tires (and weight) do that*

The springs and the roll bars effect how the weight is transfered among the tires. Let me dig up an old SCC issue, they had a great artical on roll bars and such on there project Z car, wrote by dave colemen. I will respond again when i reread it.

never mind i found it online, heres part of it

"Now here's the magic: Put a larger bar on the rear and the bar will push down harder on the outside rear tire as it resists roll. This extra load will cause the rear tire to lose grip sooner, so a bigger rear bar promotes oversteer. Put the big bar in front and you get more understeer. Now, with front and rear bars sized to get really close to neutral, you can fine-tune the stiffness of each bar by changing how long the lever arm is between the suspension and the bar. That's accomplished by simply drilling a few extra mounting holes in the end of the bar so the end link that connects the bar to the suspension can mount in a few different positions."
- This is by Dave Coleman at Sport Compact Car magazine
it can be found at http://www.sportcompactcarweb.com/pr.../0404scc_350z/

*(yes weight increases grip, its physics, push down on a eracer and try to move it across a table, now do it with no weight on it. One reason a heavy car can score really good on the skidpad, but horrible on the slalom course)

ma71supraturbo · 05-05-2004, 11:18 PM

Quote:

Originally posted by nissanguy_24
The Roll bars, and indeed the springs them selfs dont increase grip. Only tires (and weight) do that*

The springs and the roll bars effect how the weight is transfered among the tires. Let me dig up an old SCC issue, they had a great artical on roll bars and such on there project Z car, wrote by dave colemen. I will respond again when i reread it.

never mind i found it online, heres part of it

"Now here's the magic: Put a larger bar on the rear and the bar will push down harder on the outside rear tire as it resists roll. This extra load will cause the rear tire to lose grip sooner, so a bigger rear bar promotes oversteer. Put the big bar in front and you get more understeer. Now, with front and rear bars sized to get really close to neutral, you can fine-tune the stiffness of each bar by changing how long the lever arm is between the suspension and the bar. That's accomplished by simply drilling a few extra mounting holes in the end of the bar so the end link that connects the bar to the suspension can mount in a few different positions."
- This is by Dave Coleman at Sport Compact Car magazine
it can be found at http://www.sportcompactcarweb.com/pr.../0404scc_350z/

*(yes weight increases grip, its physics, push down on a eracer and try to move it across a table, now do it with no weight on it. One reason a heavy car can score really good on the skidpad, but horrible on the slalom course)

Couple of things:

1st. Mass does not increase grip. "Weight" is simply the mass of an object times the acceleration due to gravity -- its a force. However, in the calculation for lateral G's -- mass cancels out of the equation (additional mass puts more force on the tires downwards -- but also more inertial force. (I won't go through the steps to simplify the formula here, but if you're interested see: http://www.tarorigin.com/art/Bwright/

2nd. Springs and swaybars (and alignment) *can* increase grip. Say you have a car with heavy understeer. Add a rear sway bar and you end up neutral -- all of the tires do a better job sharing the load so the outside front isn't as overloaded. Additionally, body roll can affect suspension geometry and can detract from the tire's efficiency -- preventing body roll can help increase grip... Basically anything you can do to make better use of the tire's available grip will result in more g's

I really would take what SCC writes with a large grain of salt. It is mostly correct, but usually incomplete. If you are interested in getting a better picture, might I suggest:

How to Make Your Car Handle by Fred Puhn (a bit outdated but good basics)

Tune to Win by Carrol Shelby (also outdated but still decent)

Chassis Engineering/Chassis Design, Building and Tuning for High Performance Handling by Herb Adams (most recent but a bit dry)

Drift For Food · 05-06-2004, 10:22 AM

Think of it like this. If you replace your car will a flat, square pan or bowl filled with water. The water in the pan represents the weight of the car. Underneith the pan is your suspension setup, two springs in the front left and right corners of the pan and two springs on the rear in the left and right corners of the pan. You can have your sway bars across as well. The sway bars basically act like additional springs for the side-to-side forces.

Now when you accelerate, brake, and turn the water shifts around the pan and changes the weight load on each spring. The added water in one corner will compress that corner's spring and tilt the pan in that direction helping bring more water to that corner. The more weight on a spring, the more force pressing down on the tire. This means more traction. If you want traction on the front, you want the water to go to the front. This means you want softer springs on the front. Doing so will make the pan tilt easier towards the front and bring more water and weight to the front.

This is how springs and weight transfer work. The springs, dampeners, and swaybars just control how much weight shifts around or in the example, how much the pan tilts and how much water moves around. The stiffer the suspension setup, the less the pan will tilt and the less the water will move around. The softer you have your suspension, the more easily the pan will tilt and the water will flow and rush to the lower area of the pan.

In a stiff rear, soft front setup, the water will flow to the front easier, especially during braking but also when steering as well. When steering, the water will flow to one side of the pan, but because the front of the pan has softer springs, it will tilt down more under the weight of the water, thus making more water flow towards the front. This added weight on the front end will increase front traction and induce oversteer. This is how you create and change oversteer, understeer, and neutral car behaviors.

Now swaybars are special. Durning accelerating and braking, they do nothing. The front and rear suspension do all the work and resist the weight shift of the car body. Now when you steer, the weight of the car goes sideways. The problem is that the car is narrower side to side than it is front to back. It can't resist the weight shift as well as front and rear. Think of it like you tightening a bolt with a wrench. When you hold at the end of the wrench and tighten the bolt it's like the front and rear directions of the car. It's easy to apply a lot of force with a long lever arm(the length of the wrench). The suspension can easily resist the front and rear forces of thw weight of the car. Now when you turn, the weight goes side to side. This is like you trying to tighten a bold holding the wrench half way up. Now your lever arm is half of what you were previously using. It's much harder to tighten the bolt, twice as hard in fact. The same applies to the car. The same suspension that could easily resist the weight of the car front and rear now has to work twice as hard side to side. The smaller lever arm decreases the ability to resist the weight of the car. This is why you experience a lot of lean in stock cars. To assist the suspension with the side to side forces, you add swaybars. Swaybars add additional spring resistance when the car leans. The equivelant spring rate of the swaybar and spring combined helps eliminate the disadvantage of the shorter level arm side to side.

The swaybars can be used to create oversteer and understeer as well. A stiff front swaybar will act like a spring when you corner. It's like putting stiffer front springs on. This as in the water example makes the water not want to go towards the front when cornering. Instead, the pan will tilt rearward due to the added front resistance by the front swaybar and create more rear weight. This creates understeer. To create oversteer, you do the opposite, put a rear swaybar on.

All in all, it's a balance all around. To get a good car behavior both accelerating and braking as well as cornering, you have to balance both the front and rear springs as well as both the front and rear swaybars. Essentially, you use and modify all 4 to create the balance you want. Some want understeer, some want oversteer, and some want neutral handling. Playing with the springs and swaybars can create the setup you want.

Ok, that was long. Read it, it's good.

I promise, lol.

GRiDRaceTech · 05-10-2004, 09:34 PM

Right on, DFF and MA71.

In reality, there is no reason to even bother trying to drift a T-Bird. They have sloppy handling, a slushbox, and poor weight distribution. Sure, you can try... but you can only get so far because the 'box will upshift when the wheels spin. Also, the lackadasical steering and too-soft suspension will limit the feel of the pause and thus tank-slapping seems to be the order of the day. Just my two cents.

Ghost of Duluth · 05-10-2004, 10:53 PM

You might also check your tire pressure. That is something that never really gets covered much. Tire pressure is super important. When we teach stunt driving we jack the tire pressure up to keep the tire from flexing. Higher tire pressure also helps keep you from rolling the bead. It will slide easier with jacked up pressure. You can do it in the rear or front or both. Rear is what I do. I wouldn't recommend the front as you will be steering with that. But the rear is good. Try it and see what a difference it makes. We use stock cars in our instruction. You can be amazed at what you can do in a stock car when you jack that pressure up. I have done 360's, super sweet J-turns and boxed in 180's to land on camera marks in Buicks and never broke a sweat, bead or rim.

Drift For Food · 05-11-2004, 09:48 AM

What kind of tires/pressures are you talking about? One question that comes with that is tire life and wear. Low pressures are not good cause of heat build up and wearing the outsides more. High pressures would wear the center and maybe explode as well. I've heard stories from a cousin of mine when he was working at tires plus about how many psi they put into some of the tires, think 80psi plus on normal tires, lol. But, I don't think it could be good for continuous driving. Correct me if I'm wrong here. Otherwise, yes, I'd agree tire pressure can change things a bit.

05-03-2004, 02:40 PM	#1
Tsunami Registered User Join Date: Dec 2003 Posts: 670	I think I figured it out. I have done some thinking and finally figured out why my MN12 is having trouble with the drift. It's the tires. I'm controlling around 3600lbs with only a 15" rim and 215 size tire. That would explain why I have the understeer in and why the oversteer seems to be so abrubt. I think I'm just asking too much of the tires. Also it was posted here that somebody drifted a SuperCoupe which has 16" wheels, wider tires and stiffer sway bars. (blown 3.8L V6). Although it's a V6 it's a bit heavier than my car. I think the supercoupe can control its weight better due to it's better sway bars and tires. Whatda you guys think?

05-05-2004, 02:54 PM	#10
foilman Registered User Join Date: Dec 2003 Posts: 104	Well then do some research, find a book or good article online, maybe check howstuffworks.com for info on anti-roll bars, because you have it exactly backwards. The stiffer end will load sooner, and overload sooner, and it's overloaded tires that slide. -Tony Last edited by foilman; 05-05-2004 at 03:40 PM.

05-10-2004, 10:53 PM	#16
Ghost of Duluth Sixgun Join Date: Nov 2003 Location: Neverland Posts: 2,280	You might also check your tire pressure. That is something that never really gets covered much. Tire pressure is super important. When we teach stunt driving we jack the tire pressure up to keep the tire from flexing. Higher tire pressure also helps keep you from rolling the bead. It will slide easier with jacked up pressure. You can do it in the rear or front or both. Rear is what I do. I wouldn't recommend the front as you will be steering with that. But the rear is good. Try it and see what a difference it makes. We use stock cars in our instruction. You can be amazed at what you can do in a stock car when you jack that pressure up. I have done 360's, super sweet J-turns and boxed in 180's to land on camera marks in Buicks and never broke a sweat, bead or rim. __________________ Team SIXGUN, Don't whine about the food chain, be the top of it. Tokyo Pimps, Godzilla is coming. Lorin, oh Lorin, where have you gone?? If you're in the stands warming the bench, don't whine about the guys in the drivers seats.

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05-03-2004, 02:42 PM	#2
MrodDrft Dorifto Pic King Join Date: Jan 2004 Location: Boston, MA Posts: 1,559	MN12 = im guessing a thunderbird by ur avatar

05-03-2004, 02:45 PM	#3
nissanguy_24 Guest Join Date: Jan 2004 Location: bakersfield, CA Posts: 3,197	Yes Stiffen up that chassis, then Get your self some wider tires, and some of the more popular 'drift' type tires. something that will loose grip gradulally, might make that beast alittle easier to control. Also are you running a staggerd tire size? i wouldnt, not for drifting, if your looking for balance.

05-03-2004, 02:49 PM	#4
nissanguy_24 Guest Join Date: Jan 2004 Location: bakersfield, CA Posts: 3,197	Also man, what have you done weight reduction wise? its not nessisary but it may be easier to control if you can shave 200 lbs or so.

05-03-2004, 05:46 PM	#5
Tsunami Registered User Join Date: Dec 2003 Posts: 670	Right now it's technically my father's car (cheaper on the insurance that way), so I really can't strip it just yet. But if I could get another car I'd definitely take out the rear seat, carpet, and stuff in the trunk. I'm also thinking of doing my own cold air intake, but I haven't had time to research the idea that much. Most likely I'll trade this car in so I'll probably just save up for an F-Body or a 5.0

05-03-2004, 07:52 PM	#6
soultron Registered User Join Date: Dec 2003 Location: The Willy NC. Posts: 1,059	foxes rule! 2.5 stroker turbo hybrids put out crazy torque.

05-04-2004, 08:17 AM	#7
Drift For Food OMG the ground's white! Join Date: Feb 2004 Location: Minnesota Posts: 676	Doesn't the Thunderbird weigh more than 3600lbs? (don't know which year you're talking) It's a big car that's front heavy. It's also setup to have understeer: stiffer front suspension, softer rear, front sway bar, probably no rear swaybar. Tire choice can affect the understeer/oversteer behavior. If you throw some cheap tires on the rear and some grippy ones on the front, you can help the situation. A better method would be to modify the suspension. Run softer front springs/stiffer rear, take off the front sway bar and/or put a rear sway bar on. This will all help get the rear end loose. Now minor suspension changes can make a potentially big difference, so You have to be somewhat careful about what you do. Start off with something like an aftermarket spring on the rear, something a bit stiffer than stock. This will help change the car to a natural oversteer behavior and get rid of its current understeer behavior. Second is to get a sway bar. It probably has a front one, but look for an aftermarket rear one maybe a matching set with the springs. This will help the side movement of the car. Keep the front one too. Stiffer rear springs and a rear sway bar should make a big difference. If you want to keep it stock though, just take off the front sway bar. That's the best you can do without actually buying aftermarket parts. Along with stickier tires on the front and some cheapies on the rear, you're about as good as you're going to get stock.

05-04-2004, 08:30 AM	#8
foilman Registered User Join Date: Dec 2003 Posts: 104	Changing the tires isn't going to change the car's balance (unless you stick bigger/stickier tires on the front than the back). If it understeers now with 215s all around, it will still understeer with 235s. You need to change spring rates or sway bars (or alignment to some degree) to change the balance... focus on stiffening the rear to reduce understeer. -Tony

05-05-2004, 02:44 PM	#9
Tsunami Registered User Join Date: Dec 2003 Posts: 670	I really don't understand how stiffening the rear of the car makes it oversteer, other than the fact that it would make the rearend want to skate around. I've always thought that stiffening the front reduces understeer and stiffening the back reduces oversteer. For right now I've changed the plan a little. The 'Bird that I was gonna replace mine with got sold so I'm gonna just save my car and get a 5.0 when I have enough money saved up. It'll be better to have a driver and have a dedicated drift car that I don't have to worry about wrecking.

05-05-2004, 03:05 PM	#11
Tsunami Registered User Join Date: Dec 2003 Posts: 670	So a stiffer anti-roll bar would decrease grip and a softer one would increase it? So would that mean that the sway bars work the oppositte way that springs do. I know a stiffer spring gives more grip and a softer one gives less grip. Maybe I've thought antirollbars work the same way when in reality they work the oppositte way that the spring rates do?

05-05-2004, 03:35 PM	#12
nissanguy_24 Guest Join Date: Jan 2004 Location: bakersfield, CA Posts: 3,197	The Roll bars, and indeed the springs them selfs dont increase grip. Only tires (and weight) do that* The springs and the roll bars effect how the weight is transfered among the tires. Let me dig up an old SCC issue, they had a great artical on roll bars and such on there project Z car, wrote by dave colemen. I will respond again when i reread it. never mind i found it online, heres part of it "Now here's the magic: Put a larger bar on the rear and the bar will push down harder on the outside rear tire as it resists roll. This extra load will cause the rear tire to lose grip sooner, so a bigger rear bar promotes oversteer. Put the big bar in front and you get more understeer. Now, with front and rear bars sized to get really close to neutral, you can fine-tune the stiffness of each bar by changing how long the lever arm is between the suspension and the bar. That's accomplished by simply drilling a few extra mounting holes in the end of the bar so the end link that connects the bar to the suspension can mount in a few different positions." - This is by Dave Coleman at Sport Compact Car magazine it can be found at http://www.sportcompactcarweb.com/pr.../0404scc_350z/ *(yes weight increases grip, its physics, push down on a eracer and try to move it across a table, now do it with no weight on it. One reason a heavy car can score really good on the skidpad, but horrible on the slalom course)

05-06-2004, 10:22 AM	#14
Drift For Food OMG the ground's white! Join Date: Feb 2004 Location: Minnesota Posts: 676	Think of it like this. If you replace your car will a flat, square pan or bowl filled with water. The water in the pan represents the weight of the car. Underneith the pan is your suspension setup, two springs in the front left and right corners of the pan and two springs on the rear in the left and right corners of the pan. You can have your sway bars across as well. The sway bars basically act like additional springs for the side-to-side forces. Now when you accelerate, brake, and turn the water shifts around the pan and changes the weight load on each spring. The added water in one corner will compress that corner's spring and tilt the pan in that direction helping bring more water to that corner. The more weight on a spring, the more force pressing down on the tire. This means more traction. If you want traction on the front, you want the water to go to the front. This means you want softer springs on the front. Doing so will make the pan tilt easier towards the front and bring more water and weight to the front. This is how springs and weight transfer work. The springs, dampeners, and swaybars just control how much weight shifts around or in the example, how much the pan tilts and how much water moves around. The stiffer the suspension setup, the less the pan will tilt and the less the water will move around. The softer you have your suspension, the more easily the pan will tilt and the water will flow and rush to the lower area of the pan. In a stiff rear, soft front setup, the water will flow to the front easier, especially during braking but also when steering as well. When steering, the water will flow to one side of the pan, but because the front of the pan has softer springs, it will tilt down more under the weight of the water, thus making more water flow towards the front. This added weight on the front end will increase front traction and induce oversteer. This is how you create and change oversteer, understeer, and neutral car behaviors. Now swaybars are special. Durning accelerating and braking, they do nothing. The front and rear suspension do all the work and resist the weight shift of the car body. Now when you steer, the weight of the car goes sideways. The problem is that the car is narrower side to side than it is front to back. It can't resist the weight shift as well as front and rear. Think of it like you tightening a bolt with a wrench. When you hold at the end of the wrench and tighten the bolt it's like the front and rear directions of the car. It's easy to apply a lot of force with a long lever arm(the length of the wrench). The suspension can easily resist the front and rear forces of thw weight of the car. Now when you turn, the weight goes side to side. This is like you trying to tighten a bold holding the wrench half way up. Now your lever arm is half of what you were previously using. It's much harder to tighten the bolt, twice as hard in fact. The same applies to the car. The same suspension that could easily resist the weight of the car front and rear now has to work twice as hard side to side. The smaller lever arm decreases the ability to resist the weight of the car. This is why you experience a lot of lean in stock cars. To assist the suspension with the side to side forces, you add swaybars. Swaybars add additional spring resistance when the car leans. The equivelant spring rate of the swaybar and spring combined helps eliminate the disadvantage of the shorter level arm side to side. The swaybars can be used to create oversteer and understeer as well. A stiff front swaybar will act like a spring when you corner. It's like putting stiffer front springs on. This as in the water example makes the water not want to go towards the front when cornering. Instead, the pan will tilt rearward due to the added front resistance by the front swaybar and create more rear weight. This creates understeer. To create oversteer, you do the opposite, put a rear swaybar on. All in all, it's a balance all around. To get a good car behavior both accelerating and braking as well as cornering, you have to balance both the front and rear springs as well as both the front and rear swaybars. Essentially, you use and modify all 4 to create the balance you want. Some want understeer, some want oversteer, and some want neutral handling. Playing with the springs and swaybars can create the setup you want. Ok, that was long. Read it, it's good. I promise, lol.

05-10-2004, 09:34 PM	#15
GRiDRaceTech Opposite Lock Join Date: Jan 2004 Location: SoCal Posts: 1,096	Right on, DFF and MA71. In reality, there is no reason to even bother trying to drift a T-Bird. They have sloppy handling, a slushbox, and poor weight distribution. Sure, you can try... but you can only get so far because the 'box will upshift when the wheels spin. Also, the lackadasical steering and too-soft suspension will limit the feel of the pause and thus tank-slapping seems to be the order of the day. Just my two cents.

05-11-2004, 09:48 AM	#17
Drift For Food OMG the ground's white! Join Date: Feb 2004 Location: Minnesota Posts: 676	What kind of tires/pressures are you talking about? One question that comes with that is tire life and wear. Low pressures are not good cause of heat build up and wearing the outsides more. High pressures would wear the center and maybe explode as well. I've heard stories from a cousin of mine when he was working at tires plus about how many psi they put into some of the tires, think 80psi plus on normal tires, lol. But, I don't think it could be good for continuous driving. Correct me if I'm wrong here. Otherwise, yes, I'd agree tire pressure can change things a bit.