Sprint Car pic showing no tranny
 

A while back some people asked me how it was that a Sprint car didn't have a transmission, so I took some pics last Saturday night at the last race of the season.
http://homepage.mac.com/pkrwud/.Pict...1/engine1.jpeg
This picture is just for reference for the picture further down.

http://homepage.mac.com/pkrwud/.Pict.../cockpit4.jpeg
Inside the black tube is the driveshaft, which goes from the crank to the rear end. Just above it, you can see the power steering pump, which is driven directly off the back of the camshaft.

There are more pictures on this page on my website.

Take care,
-Chris

Nice pics there :)

:D :D yep. thats a sprint car and you are right racecar spelled backwards is racecar...love that. we have a late model that we run on asphault. {on a 1/5 } mile track uaually qualify at around 13.2 to 14.0 of course our setup isn't as elaborate as some people after all he is a ONE MAN SHOW. and i'm the cheerleader, he won't let me drive it think he is scared i might actually be able to do the figure 8. hahahahahahah

Thats cool Chris. So is there some type of hydraulic device with a proportioning valve that will send the power to the driveshaft? Maybe you could give a further explanation? I dont know the first thing about these, but it would be neat to learn!
thanks
andy

andy-
There is a u-joint coupling that bolts to the crank where a flywheel normally would, and the driveshaft attaches to the u-joint at the engine end and the rear end at the other end. Inside the rear end are a 4.86 ring and pinion, which are driven through two more gears that can be switched quickly at the rear end cover. We usually run either 6.76 or 6.86 gears.

dani-
That's so cool! There aren't a whole lot of women who know their way around a Sprint Car. I'm very impressed! We also run on a 1/5th mile dirt oval (if you don't have mud in your beer, you aren't racing!). 13.2 is an excellent qualifying time, too! Our best was 13.49. Not bad for a wingless 360, but not as good as a 13.2! Our track was averaging 40+ cars per week last year, so to make things easier, they created a second division this year for drivers 45 and older (Senior Sprints). They figured this would lighten the load. WRONG!!! The last week we had both classes running we had 62 cars! 40 regular and 22 Seniors! My boss is 62, and last year was his rookie year in Sprints, although he's been racing everything else since he was a teenager! Anyway, we won the Senior Sprint championship this year, which was pretty cool. Keep pushing, and maybe you'll get behind the wheel!

Take care,
-Chris

Cool Chris, I didnt realize it worked that way. So when you start this thing up with the wheels on the ground it moves. Kinda reminds me of a go-cart I had when I was a kid. I had the idle way too high and when I pulled the rope the thing took off cause the centrifugal clutch engaged....lol....
I remember now seeing the hydraulic setup on an open wheel modified. If I remember right it had a tranmission with only drive remaining.
andy

Hmmm. Thanks for the added knowledge PKRWUD. That is interesting...

andy-
Because there is no flywheel, there is no starter. There is a cable that goes from the drivers side to the rear end that engages the gears. The way they start is to put it in gear with the cable, and then push start it with a push truck. Once the speed overcomes the engines compression, the rear wheels start to spin, along with the engine. Then, the driver flips the ignition switch on, and the engine fires. Starters do exist, but are mounted to the rear end, and are used for starting the engine in the pits. In order for it to work, the rear cover is removed, along with the quick change gear that slides onto the driveshaft. The starter bolts to the rear end, and engages the driveshaft. When voltage is applied to the starter, it spins the driveshaft, and thus, the engine. Once the oil pressure is up to 80psi, you turn on the fuel and then flip the ignition switch. Really pretty creative, all things considered.

Fox Body-
No problem! I love to explain Sprints to anyone who asks! They're a blast!

Take care,
-Chris

Thanks for the lesson Chris. That is really cool. Care to explain the starter any further? Im trying to picture a starter that could turn over a high compression engine from the rear axle. Is the starter on the wheel side of the gears? Just curious.
andy

andy-
Below is a drawing I put together to try and better explain how the rear end works. As far as the starter goes, you remove the quick change cover and the lower gear, which mounts to the mid shaft inside the rear end that couples to the driveshaft at the front of the rear end housing. It's a straight shot from the lower gear to the engine. The starter is a hi-torque Chevy starter bolted to a case that fits neatly in place of the quick change cover and has a splined connector that slides over the mid shaft where the smaller gear had been. Since it has no external teeth, it doesn't interfere with the larger top gear, which normally turns the pinion/ring gear/axle. The starter then spins the mid shaft, which is coupled to the driveshaft, which spins the engine, etc., etc.

http://homepage.mac.com/pkrwud/.Pict.../complete.jpeg

Take care,
-Chris

Thats awesome Chris! Cool drawing too! I have always heard of quick change rearends, but I never really knew how they worked. I have other questions but I dont want to take up all your time.
Thanks though!
andy

I've got no family here to eat turkey with, so go ahead, ask away.

So you get to work on your car all day tomorrow without anyone bitchin', huh?..lol... Well first of all I was curious what the difference between a sprint and a midget was. Second, is the chassis of your car chromoly? It looks like it is TIG welded. The reason I ask is, the guy helping me with the cage in my 88 used to drive sprints (or midgets I cant remember) He wants to MIG my cage is cause its easier, and because some of the chromoly cars he used to drive were migged. Unfortunately NHRA wont certify my cage if it is migged. Kinda dumb I think.
thanks
andy

PKRWUD,
Those sprint cars look like lots of fun! I never knew they didn't have transmissions. Allways learning something!

Gotta question, not about sprint cars though... It looks like you really like kitty cats. I went to your site a while back and saw all of your pets. I had a little calico and a huge part Maine Coon part ? a while back that were two of the best cats on earth. Had to give them away after I moved to PA though. :( I miss the little beggars!

TXinPA-
I will always be a "cat person". Dogs are cool, but cats are the best. I currently have 7 of the little monsters, ranging in age from 3 to 13.

andy-
Midgets are mini Sprint cars. They are the same basic design, but smaller They usually have a max weight limit of 850 pounds, and they use 4 cylinder engines (all kinds, even motorcycle engines). Sprint cars weigh in at 1325 pounds, and have two different engine classes; 360 and 410. The 360's are cast iron with aluminum heads, and usually make between 700 and 800 horsepower. The 410's are all aluminum, and make over 900 hp.

Take care,
-Chris

andy-
The frame is seamless Chromoly, and must be TIG welded.

Take care,
-Chris

Thanks Chris. See, everyone Ive ever talked to says that chromoly MUST be tigged, except for the guy whos helping me with my cage. He says that chromoly can be migged as well. I hate to doubt him seeing how he's a welder by trade. I guess it doesnt make much difference though, NHRA wont certify it if I mig it, and it will need to be certified if I go 9.99 or quicker. Thanks for the help, I was just wanting other opinions.
andy

A good welder can get by with a MIG on Chromoly for very small items, so it is possible, just not advisable.

Take care,
-Chris

Thanks for the advice (and the lessons on sprints)
andy