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View Full Version : Twisting drive shafts in two?



roybeckett13j
09-24-2011, 10:40 AM
Ok, had this happen twice now, in two weeks...I need answers! *sorry, long post*

Blew up my 355, put in a 14:1 383, with a 500 cfm carb. Had a 6.33 gear, car weighed 3504 pound. First night out ran great, stupid amounts of power.

Second night out, put about 53% wedge into the car, and 140-150 lbs of LR bite...she had some NASTY traction. I could just bury the throttle about halfway through, was carrying the LF half the time. Last lap of the heat...rear end BLEW...UP right at 6900 rpm. Broke the driveshaft. I pulled handfulls of pieces out of the housing...it was dead.

I ordered a new driveshaft from southwest speed, borrowed a set of 6.20 gears, checked for binding, clearance...everything I could think of....and went racing the next saturday.

Made it through the heat race, but had a slight vibration start on the last lap at about 6600. All bolts were tight so we went back out. Hooked HARD the first lap of the feature, then at the end of the front stretch at lap 2 it chucked the driveshaft at about 6400.

Now, my confusion. It looks like the driveshaft was held on one end, then twisted and pulled down until it was two pieces.

A few old racers said its not possible...at all! But is it possible with this big engine, a really good hooking set up and a car that weights 3504 pounds to twist a driveshaft in two?

please give me some input!

dirttrackrocker
09-24-2011, 11:21 AM
Sounds to me like your gaining too much pinion angle or something. I don't have any experience with a car that weighs that much, but, I have used Southwest Speed driveshafts for the past couple of years and had 600 + horsepower and never had a problem.

turner
09-24-2011, 11:52 AM
We had a similar issue to start the year. We put in a new rearend after about 5 years. Went out and broke driveshaft in two on the first nite.I finally traced everything that i had changed, and it ended up that i had bought a new yoke that was 1.5" longer. It fit fine on the rack, but it was to long and was causing the driveshafts to break. I dont think you are breaking them because of power. I dragrace a 3835 lb buick, and it dynos at 744 hp and 669 lbs tq, and i launch it with slicks and it has alot lower gear than you are running. I have never broken the driveshaft in it.Just have heavy duty u joints.I would make sure your fdriveshaft isnt to long. Good luck and keep us posted.

racingford
09-24-2011, 10:53 PM
if you are running trans mount make sure it is solid or at least polly type mount.I had a stock mount in street car once that had enough movement it would get the driveshaft wipping and do just what you are seeing.

roybeckett13j
09-25-2011, 02:45 AM
Solid mount on the trans.

When the new one was put in I let the rear shocks loose, and run the car through all the suspension travel it would see, and saw nothing binding up.


Could I just of got a funk driveshaft?

Egoracing
09-25-2011, 10:11 AM
Check for anything that it could be hitting. Remember your chassis is NOT rigid and is twisting and if you are lifting the LF something may be getting close enough to hit the shaft. I never had ANY luck running a solid trans mount, broke the trans or drive shaft in every car that had one. The Factory chassis can not be built rigid enough to keep it from twisting. If your car is twisting enough the front could be twisting down and away toward the LF adding a large amount of drive shaft angle.

DaveBauerSS6
09-25-2011, 01:41 PM
Urethane trans mount , it's the best of both steel and rubber.

roybeckett13j
09-25-2011, 02:46 PM
Car is build super rigid, LOTS of bracing and X's underneath the floor pans.

We were running with some 2970-ish pound cars, with one that weighs 3504. Thats a lot of weight to be moving on the same stuff the people that weigh 500+ pounds less.

Egoracing
09-25-2011, 04:46 PM
If you are using ANY part of a production chassis it is not rigid and if the chassis was solid rigid, get rid of it before you die in a wreck as a proper built car is supposed to flex and give to allow the car to absorb impact and not kill the driver. Not to mention that the more rigid the chassis the more precise the setup has to be for EVERY track condition. This is why late models are designed to flex, if not you could never keep up with chassis adjustments during a race much less a weekend. I agree on the urethane mount.

carowner73
09-25-2011, 11:08 PM
If you are using ANY part of a production chassis it is not rigid and if the chassis was solid rigid, get rid of it before you die in a wreck as a proper built car is supposed to flex and give to allow the car to absorb impact and not kill the driver. Not to mention that the more rigid the chassis the more precise the setup has to be for EVERY track condition. This is why late models are designed to flex, if not you could never keep up with chassis adjustments during a race much less a weekend. I agree on the urethane mount.

That is some serious bullshiot right there.

Egoracing
09-26-2011, 06:35 AM
That is some serious bullshiot right there.

Please explain.

Dirtman29
09-26-2011, 04:15 PM
That is some serious bullshiot right there.I agree with ego on this one, you want the chassis to have some give to it. Build it solid in the 4 point area of the cage (in case of a rollover), but IMO the front & rear of the car should be built (braced) to take a 'moderate' hit, otherwise you can snap your neck if you have a real bad crash.

sj valley dave
09-26-2011, 06:09 PM
Professionally built Late Model manufacturer's call them crush zones..The cage is rigid and solid but the front and rear clips are designed to "crush" in a large impact so it does transfer to the driver...

roybeckett13j
09-26-2011, 10:17 PM
Car was built, like a racecar should. LOTS of bracing and cage around driver. Bracing under driver, under the floor pans like I said. The center of the car should not be flexing.

The front is built light, not dangerous, but light. The rear has good bracing surrounding the cell...

...How the car is built was not the question.

Is it possible with a heavy car, really heathly engine and a goood setup...to produce the forces necessary to break a driveshaft in two. thanks...

blncfn57
09-26-2011, 10:44 PM
Car was built, like a racecar should. LOTS of bracing and cage around driver. Bracing under driver, under the floor pans like I said. The center of the car should not be flexing.

The front is built light, not dangerous, but light. The rear has good bracing surrounding the cell...

...How the car is built was not the question.

Is it possible with a heavy car, really heathly engine and a goood setup...to produce the forces necessary to break a driveshaft in two. thanks...

NO..........

Egoracing
09-27-2011, 06:48 AM
The point was that the front and rear flexing can cause the drive shaft to hit the car in places you would never know that it would get clost to when it is on the ground and you are looking at it. This flex can also cause a large amount of driveshaft pinion angle changewhen added to the engine torque that can bind up the shaft and cause it to twist AND/OR bottom the shaft out into the trans which can cause shaft issues. Both of these issuse would be compounded when you installed an engine with more torque and got better traction.
Unless you are over 750hp on a drag car with 12 inch slicks your engine is not twisting the driveshaft into 2 without help from something.

stock car driver
09-27-2011, 09:33 AM
.

Is it possible with a heavy car, really heathly engine and a goood setup...to produce the forces necessary to break a driveshaft in two. Thanks...

no

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Ricky76
09-27-2011, 11:24 AM
I run a 600 hp metric car and the chassis is pretty stiff and have never broke or twisted a drive shaft. It may be like someone else said, the drive shaft is going into the trans too far or too much pinion angle ? Jeff (stock car) did you come to Louisiana several years back and race at ArkLaTex Speedway in an I-Stock car ? I think it was a $5000.00 to win race ?

stock car driver
09-27-2011, 12:53 PM
I run a 600 hp metric car and the chassis is pretty stiff and have never broke or twisted a drive shaft. It may be like someone else said, the drive shaft is going into the trans too far or too much pinion angle ? Jeff (stock car) did you come to Louisiana several years back and race at ArkLaTex Speedway in an I-Stock car ? I think it was a $5000.00 to win race ?

No that was jeremy christians from wisconsin in a big full body malibu like I had in 06/07/08/09. Hes in a metric car now also and has been for about the same time frame as me, 09/10/11.

Since I started looking for races like that its a factory stock race now and IMCA cars arent close to legal.

jj

Ricky76
09-27-2011, 03:12 PM
[QUOTE=stock car driver;1444501]No that was jeremy christians from wisconsin in a big full body malibu like I had in 06/07/08/09. Hes in a metric car now also and has been for about the same time frame as me, 09/10/11.

Since I started looking for races like that its a factory stock race now and IMCA cars arent close to legal.

jj[/QUO Yeah they stopped running that class around here. Now they're called Super Stock or Southern Stock. The factory stocks are the ones that are having all the "big" money races. There's a $5000 one coming up, a $2000, and a $2500 coming up. They also run factory stocks for $1000-$1500 several times a year around here now.

carowner73
09-27-2011, 09:46 PM
The crush zones are not built into the chassis, they are built to keep the chassis and driver from bending in the event of an impact.the chassis can be super rigid and still have plenty of crush for a short track. the chassis that is rigid is very consistent and setup dependant, some flex is desirable for touring type cars because you can get the setup closer quicker with less precision. the rigid racecar is preferable for the weekly racer competing at the same venue, once you hit the setup the car repeats week after week, but it may take longer to find that sweet spot.

All my cars are built with 12 to 14 sticks of tubing and are super rigid and setup dependant, I can race my car at a track 1 time and then go back a year later with the same setup and get the same results. I let my shocks and springs do the work, not twist my chassis all to pieces. I have yet to build a racecar that didnt make 10 seasons.

Egoracing
09-28-2011, 06:53 AM
The crush zones are not built into the chassis, they are built to keep the chassis and driver from bending in the event of an impact.the chassis can be super rigid and still have plenty of crush for a short track. the chassis that is rigid is very consistent and setup Dependant, some flex is desirable for touring type cars because you can get the setup closer quicker with less precision. the rigid racecar is preferable for the weekly racer competing at the same venue, once you hit the setup the car repeats week after week, but it may take longer to find that sweet spot.

All my cars are built with 12 to 14 sticks of tubing and are super rigid and setup Dependant, I can race my car at a track 1 time and then go back a year later with the same setup and get the same results. I let my shocks and springs do the work, not twist my chassis all to pieces. I have yet to build a racecar that didn't make 10 seasons.

The more a chassis flexes the larger "Sweet Spot" it has for setup and is less forgiving of track conditions. A rigid chassis is harder to get setup and MUST change with track conditions. This is why the GRT computer car failed. They designed and built a car that would not flex and you could not keep the car setup for the track as is changed from the beginning of the race till the end.

A top dirt late model chassis builder several years back built a chassis that was built to flex so much they planed it to only race about 10 events before it would need to be replaced due to flex/stress cracks.Only put one setup on it and ran it at 9 events and it was first or second every event and then they swapped out the chassis and did it again for another 10 events.

Crash zones are built and designed into a car to allow the car to absorb impact by bending during a crash rather than transmit the force to the driver. The are SPECIFICALLY built into the chassis to allow the chassis to bend.

bushracing67
09-28-2011, 08:18 PM
somewhere around 01-03 rocket made some cars out of a different tubing (i believe it came from a different supplier or something along those lines) and the cars wouldn't flex, most drivers hated them, a quick fix was to cut the cross bar out of the center of the halo to try and add some flex, anyone that ran the cars on bullrings struggled, some people had luck with them on big momentum tracks... and further proof of the lack of flex... it is easier to find a used 01 rocket than an 04 lol cause they are still around

carowner73
09-28-2011, 09:46 PM
We arent talking about a late model, a late model has absolutely zero influence on a street stock builder. The two have no comparison as to the way they are designed and built. Noone racing a street stock should give a crap what a late model has or hasnt done, period. If you want to race a throwaway car in street stock then you better have a big bank account or enjoy building new cars every year. I race against wanna be late model guys all the time, most just get tired of getting there asses out ran and move on up to late model, this is just before they go broke and quit.

My point is if you know setup, you will make it a lot longer with a rigid street stock than a throwaway car. If you reread my earlier post, you will see I said the touring guys prefer a car that flexes, this would be referring to most late model guys and a only a few street stock racers. I have yet to see a late model weigh 3200 lbs and run a street stock race, so it is hard for me to compare.

Oh yeah I almost forgot, the bigger sweet spot is bull. The sweet spot is about domination, you cant dominate a track if you are touring.You guys love to get on here and compare apples to oranges, tell everybody what you got is the way to go.

I like my cars stiff, you like your throwaway, we will probably never race, so what does it matter. My reputation speaks for itself were I am from, yours probably does too.

Egoracing
09-29-2011, 06:51 AM
We arent talking about a late model, a late model has absolutely zero influence on a street stock builder. The two have no comparison as to the way they are designed and built. Noone racing a street stock should give a crap what a late model has or hasnt done, period. If you want to race a throwaway car in street stock then you better have a big bank account or enjoy building new cars every year. I race against wanna be late model guys all the time, most just get tired of getting there asses out ran and move on up to late model, this is just before they go broke and quit.

My point is if you know setup, you will make it a lot longer with a rigid street stock than a throwaway car. If you reread my earlier post, you will see I said the touring guys prefer a car that flexes, this would be referring to most late model guys and a only a few street stock racers. I have yet to see a late model weigh 3200 lbs and run a street stock race, so it is hard for me to compare.

Oh yeah I almost forgot, the bigger sweet spot is bull. The sweet spot is about domination, you cant dominate a track if you are touring.You guys love to get on here and compare apples to oranges, tell everybody what you got is the way to go.

I like my cars stiff, you like your throwaway, we will probably never race, so what does it matter. My reputation speaks for itself were I am from, yours probably does too.

A chasiss is a chassis and good design basics fit if it is a 4 cylinder, streetstock, modified, latemodel or Nascar. A proper built car can flex and NOT be a throw away, there are MANY late 90's late models and modifieds still running and winning.

I worked for several years building cars for a company in Florida that won championships on dirt and asphalt from 4 cylinders to Hooters cup Sportsman and modifieds and they ALL had built in crush areas and they all had built in flex points.

The "sweet spot" I was refering to was what the chassis likes as a setup for a track. Oh and you can Dominate if you are touring. We won at a specific track EVERY time we showed up at a track even against the locals so even if you are touring if you can show up and win every time you pull in, that is domination.

stock car driver
09-29-2011, 09:56 AM
My old green car was a battle tank, it may have still flexed but WAY less than most and it was good to go on ALL tracks all the time with my set up.

My new car I bought was lacking in a lot of bracing departments and with the same set up it was marginal at best and as Ive added bars in the middle to tie the x to the petty bar to the halo and added a engine bay cross bar etc. The car has gotten much much better. It still doesnt transfer weight like my old car or tip up on the rf like my old car but its much more rigid now and I could tell the difference each time I added another brace.

I think the flex it has now comes down to the lack of welded seams on the frame other wise the two cars are almost identical now.



LAST POST on this by me. I speak of my experience as its going on with me right now.

car 73, Ego doesnt race, NEVER has driven or owned a car in any class.

Egoracing
09-29-2011, 08:24 PM
My old green car was a battle tank, it may have still flexed but WAY less than most and it was good to go on ALL tracks all the time with my set up.

My new car I bought was lacking in a lot of bracing departments and with the same set up it was marginal at best and as Ive added bars in the middle to tie the x to the petty bar to the halo and added a engine bay cross bar etc. The car has gotten much much better. It still doesnt transfer weight like my old car or tip up on the rf like my old car but its much more rigid now and I could tell the difference each time I added another brace.

I think the flex it has now comes down to the lack of welded seams on the frame other wise the two cars are almost identical now.



LAST POST on this by me. I speak of my experience as its going on with me right now.

car 73, Ego doesnt race, NEVER has driven or owned a car in any class.

You are an Idiot and have proven it over and over, you have No idea who I am and what I have done. I have not posted one time on your post in weeks which you asked, so you have to try post and try to start by showing your lack of knowledge about me. Again you have zero knowledge about anything I have ever done in racing and I am not here to try to prove myself to anyone so quit trying to start something you are kinda like Hemorrhoids, you think they are taken care of and then you flare up again!

stock car driver
09-29-2011, 09:08 PM
You are an Idiot and have proven it over and over, you have No idea who I am and what I have done. I have not posted one time on your post in weeks which you asked, so you have to try post and try to start by showing your lack of knowledge about me. Again you have zero knowledge about anything I have ever done in racing and I am not here to try to prove myself to anyone so quit trying to start something you are kinda like Hemorrhoids, you think they are taken care of and then you flare up again!

bahahaha

Have a good weekend Ill be racing friday and saturday at the Jackson Nationals, where are you racing?