Should I buy drag radials?
05-16-08, 12:30 PM
#16
Lexus Champion
What do you run? Have you managed to break anything?
That car doesn't have anything major. I took off his front sway bar, we put the Megan Racing traction bars on it, messed with shock settings, and put a Hoosier slick on it. The two step is up north of 6000 RPM now and still dead hooks.
I might go with the full slicks, seems if I'm going to do it, I mise well do it right. I'm considering suspension upgrades, just trying to figure out what to do first. BTW, I have an LSD, does the one wheel squat problem still apply?
If you don't mind the read, here's a bit of an explanation.
There's another phenomenon common to front-engine, rear-drive cars. It, too, is an action/reaction, inertia/momentum situation, but it operates side-to-side in the car, rather than front-to-back. It is caused by the fact that the crankshaft and drive shaft rotate along a north-south axis while the rear axles and wheels rotate on an east-west axis. Actually, it is two separate problems, only moderately related. The first, of which you are probably aware, is the tendency of the engine to try to lift the left front corner of the chassis as the car launches. That's because the crankshaft is trying to turn clockwise (viewed from the front), but the car's inertia is holding it back (see illustration next page). As the engine strains against this resistance, it reacts by trying to spin (counterclockwise) around the crankshaft. Since the engine is (hopefully) anchored securely to the frame, it tries to pull the frame up on the left (passenger's) side. The more powerful the engine, and the heavier the car, the more pronounced the problem becomes
The other problem due to drive shaft rotation is less obvious, but more severe. The drive shaft rotates clockwise as it drives the pinion in the third member. When inertia holds the car from moving and the tyres are stuck firmly to the ground, the rotating drive shaft actually tries to turn the entire rear end in the same clockwise direction. This effect is usually not apparent to the eye, but it does tend to lift the right rear tyre slightly, and plant the left rear more firmly. You have undoubtedly witnessed the result of this in the typical street machine. If you sidestep the clutch in a car with a live rear axle and unlocked differential, it will smoke the right rear tyre. (A car with a chassis-mounted third member, such as a Corvette or Jaguar IRS, avoids this problem.) In a race car, any imbalance in traction, right to left, can send the car veering off the starting line at an angle. It doesn't take much when one big sticky slick hooks up more than the other does. Many race cars do tend to pull to the right off the line because the drive shaft twist on the rear end is unloading the right rear tyre slightly.
05-16-08, 01:52 PM
#18
Lexus Champion
Here's the entire article. It's about four link drag suspensions but the above quoted exceprt felt appropriate for the thread.
http://www.raceglides.com.au/TechInfo.htm
http://www.raceglides.com.au/TechInfo.htm
05-16-08, 06:11 PM
#19
Agreed, thanks again for all the info!
I kinda figured that disconnecting the sway bar links would allow more suspension travel (upward) in the front. This, I would think, would serve two purposes. Not only would weight transfer to the back to aid traction, it would take weight off the front wheels to decrease the amount of energy needed to push them down the track.
Last time I was at the track, I had a friend from work with me who raced 11-12 second Grand Nationals "back in the day". He said my car launches beautifully, but I'm sure tire spin and granny launching reduces the squating affect.
KC
I kinda figured that disconnecting the sway bar links would allow more suspension travel (upward) in the front. This, I would think, would serve two purposes. Not only would weight transfer to the back to aid traction, it would take weight off the front wheels to decrease the amount of energy needed to push them down the track.
Last time I was at the track, I had a friend from work with me who raced 11-12 second Grand Nationals "back in the day". He said my car launches beautifully, but I'm sure tire spin and granny launching reduces the squating affect.
KC
05-21-08, 08:24 PM
#20
Lexus Champion
No problem man. Let me know how it works out for you. (sorry haven't been on here in a few days)
If you disconnect the endlinks, drive it around a bit in the parking lot to get used to it. It comes down to driving styles, if you don't really corner hard in the car (and once you're driving on drag tires chances are you're probably not really gunning it until your tires are pointed straight anyway when you're headed around town) and you don't mind how it feels with the endlinks disconnected, go ahead and take the whole thing off. Saves having to attach/detach every time you want to go to/from the track, saves a tiny bit of weight, and also gives you that weight transfer you seek at the track if someone's feeling a bit froggy at a stoplight too.
If you disconnect the endlinks, drive it around a bit in the parking lot to get used to it. It comes down to driving styles, if you don't really corner hard in the car (and once you're driving on drag tires chances are you're probably not really gunning it until your tires are pointed straight anyway when you're headed around town) and you don't mind how it feels with the endlinks disconnected, go ahead and take the whole thing off. Saves having to attach/detach every time you want to go to/from the track, saves a tiny bit of weight, and also gives you that weight transfer you seek at the track if someone's feeling a bit froggy at a stoplight too.
05-21-08, 08:30 PM
#21
No problem man. Let me know how it works out for you. (sorry haven't been on here in a few days)
If you disconnect the endlinks, drive it around a bit in the parking lot to get used to it. It comes down to driving styles, if you don't really corner hard in the car (and once you're driving on drag tires chances are you're probably not really gunning it until your tires are pointed straight anyway when you're headed around town) and you don't mind how it feels with the endlinks disconnected, go ahead and take the whole thing off. Saves having to attach/detach every time you want to go to/from the track, saves a tiny bit of weight, and also gives you that weight transfer you seek at the track if someone's feeling a bit froggy at a stoplight too.
If you disconnect the endlinks, drive it around a bit in the parking lot to get used to it. It comes down to driving styles, if you don't really corner hard in the car (and once you're driving on drag tires chances are you're probably not really gunning it until your tires are pointed straight anyway when you're headed around town) and you don't mind how it feels with the endlinks disconnected, go ahead and take the whole thing off. Saves having to attach/detach every time you want to go to/from the track, saves a tiny bit of weight, and also gives you that weight transfer you seek at the track if someone's feeling a bit froggy at a stoplight too.
For now, I can't justify spending the money for a better time slip. The 275 Sumitomo's do a great job on the street so I don't see buying tires of any sort just for track use.
I will be keeping an eye out for a good deal though.
KC
05-22-08, 12:30 PM
#22
Lexus Champion
Keep an eye out for used tires too, you can usually get pretty good deals on them. I got my last set of 255/50/16 Mickey Thompsons for $200 with hardly any miles on them, a friend bought a set of wheels, drove for maybe a week, then decided to go to a bias ply. The set before that I got for free since they were getting pretty low on tread and they were just going to get tossed for a new pair.
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