Breaking stub shafts
Thread Starter
Instructor
Joined: Oct 2009
Posts: 162
Likes: 2
From: Midlothian TX
Breaking stub shafts
2 tracking outing's same out come.. 2yrs ago on 3rd pass I break the R/H shaft on 2-3 shift, this past weekend on 3rd pass I break the L/H shaft at the line...
Both time with aftermarket upgrade shafts!!!!
Leaving off idle except the last time I went to leave at 2500rpm
First track event car was on 305-35-19 NT05R's Second track event car was 305-45-17 M/T drag radial R's
Cars makes 716rwhp & 699tq 6 speed
At $1500 for repairs these track days are becoming expensive!!!!
Both time with aftermarket upgrade shafts!!!!
Leaving off idle except the last time I went to leave at 2500rpm
First track event car was on 305-35-19 NT05R's Second track event car was 305-45-17 M/T drag radial R's
Cars makes 716rwhp & 699tq 6 speed
At $1500 for repairs these track days are becoming expensive!!!!
AMP Racing
Joined: Aug 2006
Posts: 10,754
Likes: 589
From: Washington TWP NJ
2023 C5 of the Year Finalist - Modified
2017 C5 of Year Finalist
St. Jude Donor '09-'10-'11-'12
Problem 1 is you’re using a radial tire.
What clutch are you using? That might have something to do with it as well.
I have never broken an OEM C6Z shaft with a bias ply tire.
I have broken and/or twisted every aftermarket shaft offered.
Best of success to you with your goals.
What clutch are you using? That might have something to do with it as well.
I have never broken an OEM C6Z shaft with a bias ply tire.
I have broken and/or twisted every aftermarket shaft offered.
Best of success to you with your goals.
Last edited by C5 Pete; Mar 16, 2019 at 09:54 AM.
Pro
Joined: Sep 2017
Posts: 675
Likes: 195
From: Green Oak Township, Michigan
With drag radials, youre probably dead hooking a 3200 lb. car with those spindley axle shafts. Are you snaping the joints or twiisting the axles. ?? Aint gonna'. work. Oh,, you might get away with it for a while,, but they are a twistin''...Paint a white line on them and keep an eye on the line. Try to upgrade the axles, or like said above,,,hang a different rear end under it. 
Thread Starter
Instructor
Joined: Oct 2009
Posts: 162
Likes: 2
From: Midlothian TX
Paint a white line on what?? You can’t can’t see the stub shafts...
When they let go it’s a clean brake like you cut them in 2 on a bandsaw
Both times these have been aftermarket 300mm shafts
Frist set from DTE last set from the driveshaft shop
Plenty of guys putting way more power down & still running the IRS
Please explain why a DR would bit harder than a pair of slicks??
When they let go it’s a clean brake like you cut them in 2 on a bandsaw
Both times these have been aftermarket 300mm shafts
Frist set from DTE last set from the driveshaft shop
Plenty of guys putting way more power down & still running the IRS
Please explain why a DR would bit harder than a pair of slicks??
Last edited by te-44; Mar 16, 2019 at 05:20 PM.
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Pro
Joined: Jul 2012
Posts: 635
Likes: 54
From: Phoenix Arizona
Paint a white line on what?? You can’t can’t see the stub shafts...
When they let go it’s a clean brake like you cut them in 2 on a bandsaw
Both times these have been aftermarket 300mm shafts
Frist set from DTE last set from the driveshaft shop
Plenty of guys putting way more power down & still running the IRS
Please explain why a DR would bit harder than a pair of slicks??
When they let go it’s a clean brake like you cut them in 2 on a bandsaw
Both times these have been aftermarket 300mm shafts
Frist set from DTE last set from the driveshaft shop
Plenty of guys putting way more power down & still running the IRS
Please explain why a DR would bit harder than a pair of slicks??
What do they say?
Thread Starter
Instructor
Joined: Oct 2009
Posts: 162
Likes: 2
From: Midlothian TX
I haven’t had time to call them, broke the car last Sunday and then left town on Monday. I will call them Monday and see what they say plus these are their latest and greatest. Probably put less than 500 street miles and then 3rd pass snap still shocked it was the drivers side
AMP Racing
Joined: Aug 2006
Posts: 10,754
Likes: 589
From: Washington TWP NJ
2023 C5 of the Year Finalist - Modified
2017 C5 of Year Finalist
St. Jude Donor '09-'10-'11-'12
A drag radialis designed to dead hook and has a stiffer sidewall so it shocks the drive train harder. A bias ply is designed to spin a little at the hit and the sidewall is more flexible so it softens the hit.
Most often when a shaft breaks, it breaks clean, like you’ve described. I’ve used 300M, 500M, and the trick ones from Eaton that come with their posi unit. I’ve snapped them all.
The only ones ones I haven’t snapped, are the OEM C6Z shafts. Not saying they can’t break, but this is just my experience with hundreds of passes in both manual cars and auto cars.
Again, bias tires are your friend.
Most often when a shaft breaks, it breaks clean, like you’ve described. I’ve used 300M, 500M, and the trick ones from Eaton that come with their posi unit. I’ve snapped them all.
The only ones ones I haven’t snapped, are the OEM C6Z shafts. Not saying they can’t break, but this is just my experience with hundreds of passes in both manual cars and auto cars.
Again, bias tires are your friend.
AMP Racing
Joined: Aug 2006
Posts: 10,754
Likes: 589
From: Washington TWP NJ
2023 C5 of the Year Finalist - Modified
2017 C5 of Year Finalist
St. Jude Donor '09-'10-'11-'12
What clutch are you using? That also plays into how hard you can launch the car.
Being cautious, start at 2000rpm and work your way up to 3500 or so depending on your comfort level. 18psi in your slicks. That’s typically way too much pressure, but when getting used to a slick, it’s always better to have them spin too much vs not enough.
This video shows a relatively weak launch for the combo. This car is using OEM C6Z shafts ($80) on both sides. 27” tall slicks with about 900rwhp.
Being cautious, start at 2000rpm and work your way up to 3500 or so depending on your comfort level. 18psi in your slicks. That’s typically way too much pressure, but when getting used to a slick, it’s always better to have them spin too much vs not enough.
This video shows a relatively weak launch for the combo. This car is using OEM C6Z shafts ($80) on both sides. 27” tall slicks with about 900rwhp.
Last edited by C5 Pete; Mar 16, 2019 at 08:31 PM.
AMP Racing
Joined: Aug 2006
Posts: 10,754
Likes: 589
From: Washington TWP NJ
2023 C5 of the Year Finalist - Modified
2017 C5 of Year Finalist
St. Jude Donor '09-'10-'11-'12
The McLeod RXT is a great clutch. That’s what is in the C5Z in the video. It takes a beating and keeps going. He launches at 4000 and 60’ in the high 1.3s.
You’ll get there. Gotta creep up slowly.
You’ll get there. Gotta creep up slowly.
AMP Racing
Joined: Aug 2006
Posts: 10,754
Likes: 589
From: Washington TWP NJ
2023 C5 of the Year Finalist - Modified
2017 C5 of Year Finalist
St. Jude Donor '09-'10-'11-'12
Cool. I’d love to try out the 7x sometime, but this 900EASy is getting the job done for us.
Racer
Joined: Mar 2008
Posts: 457
Likes: 52
From: Elkhart, Texas
What clutch are you using? That also plays into how hard you can launch the car.
Being cautious, start at 2000rpm and work your way up to 3500 or so depending on your comfort level. 18psi in your slicks. That’s typically way too much pressure, but when getting used to a slick, it’s always better to have them spin too much vs not enough.
This video shows a relatively weak launch for the combo. This car is using OEM C6Z shafts ($80) on both sides. 27” tall slicks with about 900rwhp.
https://youtu.be/iRoPoAH4HaU
Being cautious, start at 2000rpm and work your way up to 3500 or so depending on your comfort level. 18psi in your slicks. That’s typically way too much pressure, but when getting used to a slick, it’s always better to have them spin too much vs not enough.
This video shows a relatively weak launch for the combo. This car is using OEM C6Z shafts ($80) on both sides. 27” tall slicks with about 900rwhp.
https://youtu.be/iRoPoAH4HaU
Pro
Joined: Apr 2017
Posts: 590
Likes: 134
From: Hanover Maryland