I am not a race fan, but I swore in footage I saw early on, the cars would “skid” through the curves allowing their back ends to slide out. I was told they have no differential gear to improve their race time. Now, my son is watching a video on race cars (both Formula One and stock car), and they handle curves normally.
Has there been some shift in philosophy? …Was I misinformed?
might be true in the “drifting” sport. No other road- or oval-course racing series would benefit from the lack of a differential. At least none that I can think of.
Sprint cars might do that, but they frequently run on dirt courses.
In any race you want your outside wheel to travel at a higher rpm than your inside wheel on a turn to maintain static friction with the surface. Sometimes some sliding is OK but to get the fastest lap time possible you want your tires sticking to the pavement.
In Karting races the go karts do not have differentials. Instead during a turn the chassis twists to allow the inside rear wheel to go light so it will carry little to no weight so the rear wheels can turn at the same speed but not lose traction.
I’ve always heard that the sprint cars (and mabe all the dirt track race cars) don’t use transmissions. They use differentials, though, and they can put different gears in them to select a final gear ratio best suited for the track conditions.
Many race cars and sporty street cars use something called a “limited-slip” differential that allows for the outside wheel to travel a bit faster than the inside wheel on a curve. It’s very effective.
All differentials allow the outside wheel to travel faster than the inside wheel.
The limited slip does just what the name implies. It allows the outside wheel to travel a bit faster than the inside wheel but will lock the wheels together if the difference in RPM between the outside and inside wheel is too great. Of course the difference in speed has to be greater than would be achievable in any turn that you would find in a race. The purpose of the limited slip is so when you are starting off in a race or making a tight turn one wheel does not turn ALOT faster than the other. It also helps if you are stuck in the mud (just like it was described in My Cousin Vinny).
Also the type of limited slip will change the characteristics of the car. A Torsen will react differently to one that uses clutches.
In NASCAR stock car racing the cars can use a (Detroit) “locker” rear end. It is also called a “ratchet”
When the driver is on the throttle there is no differential action. This can allow the cars to get through turns better (limiting the effects of oversteer or understeer)because they are set up with a certain amount of “stagger”.
Stagger is different sized rear tires. The difference depends on the track and is more pronounced on short tracks that have more turn than straights. The more stagger you have when locked the more you are dragging the slower tire down the straight. When coasting the locker unlocks and there is conventional differential action.
Dirt track cars usually have rears that are fully locked.
There is a lot of science and a certain amount of art to setting up a racecar for a particular track. There are many variables that are juggled and professional crewchiefs have lots of notes and data for each track and car.
I believe on super-speedways an open rear (conventional) is more likely to be used for efficiency.
True, they don’t use transmissions in Sprint cars. Just a dog clutch. Not sure that the differential statement is correct about Sprint cars. 15 years or so ago when I was more familiar with them they did not have differentials. One piece axles or a Ford rear end with the dif guts replaced with a spool to lock the axles. Hence the need for stagger (rear tires of different diameters) on Sprint cars.
Maybe the technology has changed in the intervening years, but searching around a bit, it doesn’t seem so.
Yes, I should have been more clear. Sorry.
Thanks for correcting my misunderstanding. So, dirt track racers going sideways thru the turns is simply due to traction (or lack of) and has nothing to do with differentials?
I’ve heard the technique is called “throttle steering”, is that a descriptive term? Sprint car races used to be televised here, that was my only contact with the sport.
In rally car racing drivers intend to get sideways on turns. They use the throttle and brake(sometimes at the same time) to achieve this.
The reason they do this, however, is because the sliding essentially clears the surface debris and allows them to actually grip the road more effectively. If they could grip the dirt as well as they could grip pavement, they would do so, because it is always faster to grip the road than to slide across it.
Bootleg turn anyone?
We do this in ice racing as well. You fling the car sideways before you get to the turn and try to time it so that when your tires actually find something to dig into, you are right where you want to be. It’s a lot faster that tiptoeing through a turn on a slippery surface.
Webpage on differentials in Formula 1. Current rules are pretty strict on what a team can do with the settings on the diff, but in the past diffs were exploited to the fullest to get the cars around corners quickly.