Here is a perfect example of why this CV driveshaft is needed. I was running this guy in Q4 this weekend in TD when his drive shaft came apart in the lights. #1 he should not be running an aluminum driveshaft in TD but looks like the U-joint is what failed not the driveshaft itself.

Ouch

Can't see the other strap. But any chance that it deflected enough to rip the corner off the cap? I'm using a similar strap on mine right now. And man that is a short driveshaft. Mine is not that short.

As stated...safety in mind innovation is a reason for the change as the technology is presented.

Its expensive...its more costly upon failure of u joint or driveshaft it self.

quote:

Originally posted by Bucky:
Can't see the other strap. But any chance that it deflected enough to rip the corner off the cap? I'm using a similar strap on mine right now. And man that is a short driveshaft. Mine is not that short.

The other strap was still on and looked tight. The one showing is missing the nuts. I am thinking the nuts came loose and the cap fell off but that's only speculation..
For what its worth this in a nitrous car and just ran 4.11 on this run so not a super fast car

quote:

Originally posted by Big Steve:
Here is a perfect example of why this CV driveshaft is needed.

Steve, be careful of what you wish for or it's liable to be a new requirement to run TD.

That said, 99.99% of all cars drag racing have a u joint driveshaft and a fraction of 1% have a driveshaft related failure every season and you can be certain that when they do fail, it was because of the wrong shaft for the application and/or lack of maintenance.

quote:

Originally posted by 1320racer:

quote:

Originally posted by Big Steve:
Here is a perfect example of why this CV driveshaft is needed.

Steve, be careful of what you wish for or it's liable to be a new requirement to run TD.

That said, 99.99% of all cars drag racing have a u joint driveshaft and a fraction of 1% have a driveshaft related failure every season and you can be certain that when they do fail, it was because of the wrong shaft for the application and/or lack of maintenance.

Hard to say with 100% certainty what caused it but just proves it does happen and isn't pretty when it does.

I have a CM steel shaft in my car but after seeing this first hand it will have a CV shaft in the near future, you can take that to the bank. Damage to his car will far exceed the $1600 cost to possibly prevent it not counting the danger of running over the pieces and crashing from a cut tire

Anyone running Top Dragster should be running this style strap.

https://www.markwilliams.com/u-joints-bolts-caps.html

quote:

Originally posted by Big Steve:

quote:

Originally posted by 1320racer:

quote:

Originally posted by Big Steve:
Here is a perfect example of why this CV driveshaft is needed.

Steve, be careful of what you wish for or it's liable to be a new requirement to run TD.

That said, 99.99% of all cars drag racing have a u joint driveshaft and a fraction of 1% have a driveshaft related failure every season and you can be certain that when they do fail, it was because of the wrong shaft for the application and/or lack of maintenance.

Hard to say with 100% certainty what caused it but just proves it does happen and isn't pretty when it does.

I have a CM steel shaft in my car but after seeing this first hand it will have a CV shaft in the near future, you can take that to the bank. Damage to his car will far exceed the $1600 cost to possibly prevent it not counting the danger of running over the pieces and crashing from a cut tire

Agreed!

3 Years ago We had an Aluminum Drive shaft on our 4 link T/D come apart right after the burn out. It was about 20 runs after we put on the Procharger. That aluminum shaft had been on the Car for 8 seasons with our Nitrous motor and I closely inspected the u-joints every time the drive shaft was out..which was many times !! as we have changed our share of converters. It wasn't the U-Joint that let go but the ears on the driveshaft. Russ Farmer said there is a finite life to Aluminum Shafts, much like an aluminum connecting rod. We cycle those out, hopefully before they break..When our shaft broke, it broke the safety hoop and did damage to the wishbone and supports. everything was re-inforced and a steel drive shaft installed..I was always grateful the shaft didn't break further down track, my son said he felt a severe
vibration just after the start of the burn out and lifted immediately, but it broke and that was it..
I wonder what the driver felt and when, during the run we are discussing now? On a fast car stuff happens, TOO Fast...Thankfully that driver is okay..

these type failures can always be traced back to the knucklehead wearing the brain bucket.

most cars running top dragster today, weren't built specifically to run top dragster and therefore the components used in the build usually aren't up to the performance levels the cars are running now, no mind in many cases these components have thousands of passes on them,
and many years if not decades of service and more often than not, have never gone back to the manufacture for inspection and service.

Is a CV driveshaft needed on every dragster? of course not. Is it required equipment on every TD? NO but maybe it should be.

If I were planning to run TD with my car or building a car to run TD, I would follow Mark Williams recommendation as to what driveshaft to use.

quote:

Originally posted by S/S Dart:Russ Farmer said there is a finite life to Aluminum Shafts, much like an aluminum connecting rod. We cycle those out, hopefully before they break..

Hmmm, someone said this before in this thread.......... Oh, wait, it was me!

Nothing last forever. That said, I've never had a steel/CM aftermarket driveshaft in any of my race cars and have been running aluminum driveshafts for 20 years and I ain't ever had a u joint or shaft failure. If you buy the right driveshaft for the performance level you are running and have it inspected and service periodically, you've got nothing to worry about.

That one pic looks like the ear split. Can't see the underside tho.

Worthy included an aluminum shaft when I bought the car. He warned me that when I got close to 1000 hp that I should change it. Didn’t listen, shaft broke, now it has a chrome moly shaft from Front Range Driveline in Colorado. Been great so far.

A couple more pix of the driveshaft. If anyone is wondering the other U-Joint was still in the transmission yoke.

Most people over tighten the absolute begeezes out of the U strap style bolts because they think tighter is better and have no idea how things work. Which causes u joint failures.

The main cap style ones Mark Williams sells fix that issues.

I have to agree with Ed, 99.9% of failures are self induced, whether it be tire shake, wrong shaft all together, or ovetightened U bolts

Last year my aluminum drive shaft let go about 40 ft into a pass. It looked like it had been put into a lathe and cut both end caps off right in the center of the welds. The front cap u-joints was still attached to the yoke and in the transmission. The rear cap and u-joints were still bolted to the pinion yoke. The "tube" was split open like a biscuit can and laying between the transmission and frame.
I called Mark Williams and ordered a CM shaft and using their website ordering diagram the new shaft fit perfect. At the time they weren't offering the CV shaft or I would have got one.

FYI my car runs 4.40's so many bracket cars today run that fast or faster so take a good look at your aluminum shafts if you have one and think about replacing it if its older. Most of us continually make our cars go quicker and quicker and might not consider this part of the equation.
One more thing, my car ran exactly the same with the CM shaft as it did with the aluminum so the extra weight did not matter.
David

quote:

Originally posted by Will Harrison:
Most people over tighten the absolute begeezes out of the U strap style bolts because they think tighter is better and have no idea how things work. Which causes u joint failures.

agreed, 15-20 ft./lbs that's it!

https://www.markwilliams.com/servicebull/sb0049.pdf



not important who stated this but this is why driveshaft/u joints fail and this is most bracket racers and many class racers.

quote:

I have a MW alum driveshaft from 1995 still in car, I've looked at the u-joints once in the 16 yrs

quote:

Originally posted by DragRaceResults:
Goethe use to work at MW. I'm sure they did a deal.

According to MW, no. Upwards of 3 weeks to get one.