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Discussion Starter #1
Are there valid reasons why this may be, or may not be a good idea? A big one for me is the lack of destruction should I have a shaft fail. Not sure if there are reasons not to use one on the street. Thanks for any real world info you can afford. High 8 second/low 9 second 3400# automatic with brake. 5.3 LS turbo.
 

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Are there valid reasons why this may be, or may not be a good idea? A big one for me is the lack of destruction should I have a shaft fail. Not sure if there are reasons not to use one on the street. Thanks for any real world info you can afford. High 8 second/low 9 second 3400# automatic with brake. 5.3 LS turbo.


You need to figure critical shaft speed for length and shaft size to see if CM will be ok
 

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It really depends who makes the shaft and what it’s rated for, I know there’s a QA1 that’s rated for 2000hp, so really you should check with the manufacturer. Otherwise the only real-world info I have is that I know the new Alfa Romeo Quadrifoglios run CF driveshafts, high-11s at best.
 

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Mine runs one. 70 mustang. 3450lbs w/me. Mine is a small block pump gas street car with full interior and even cd player. Drive quite a bit on street. Have run 8.80's, with a 1.22 60ft. Only issue I had was on the track. I had changed 4 link settings and it squated on a launch. So much so the driveshaft hit the frame. NOT much! but it doesn't take much. Shattered it. PST replaced under their warranty and have been running ever since. (I cut a bunch of metal out and redid where it went through frame now so it has much more clearance.)
 

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Discussion Starter #5
You need to figure critical shaft speed for length and shaft size to see if CM will be ok
Doing the math is scary. It looks like CF is the only one that is safe, due to the length!
 

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I think the benefit of it shredding vs. damage to the car (or worse, you) alone is worth it. Let's also remember the overall weight/rotating mass advantage and less NVH.
 

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We run one on our BBC nitrous 67 camaro, did it mainly cause they are "safer". The weight loss was a nice byproduct also!

Nice to know that it won't destroy the car if something happens.
 

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Discussion Starter #9
Ironically, new trans is being assembled right now. Do to the trans tunnel/floor structure configuration, I need to stick with the short tail stock.
 

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Banksters Paradise
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I have the 9" tail on my t400. They seem plenty strong. I've seen long wheelbase Pontiacs etc with big blocks well into the 8's with their stock 9" th400 tail end. My driveshaft is only 37" long.. so I went 3" full chrome moly and be done with it.

I can't see how the floor would get in the way over an additional 5in of extension housing?

Since this photo was taken I've installed an S60 , so my driveshaft yoke runs much closer to the extension housing now. I also had to adjust the rear axle 1/4" back to give enough additional yoke clearance, which works out on the 4th gen as the tires run closer to the front of the 1/4 panel rather than the plastic back bumper, which i can also trim if I want to run a 28" or taller slick.

 

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Mike
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I think any kind of impact from road debris hard enough to cause some kind of defect would be scary. MW made me a 50+ inch 7075 4"(7000 RPM) for my car. like I have said, too heave to go 8s
 

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Although the car I was considering using a cf shaft in is not an 8 sec car, mechanical damage from road debris etc was the reason I went away from the cf path... personally I feel that a true street car, {thinking an 8 sec car is not really a true street car more of a licensed "racing" style car...} that risk is too great to take. but in this car the risk is greatly lessened.
 

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I think the benefit of it shredding vs. damage to the car (or worse, you) alone is worth it. Let's also remember the overall weight/rotating mass advantage and less NVH.
This was my main reason for doing a CF driveshaft.

My car isnt as fast as you are talking about(yet), but i have been 9.70's with a stick car, so the violence factor there was also a reason why i felt CF was a good idea. I have completed 2 dragweeks and many street miles, driving on roads with various debris on them with no problems. On DW2015 we had a bridge repair that was about 60 feet a pea stone, around a blind corner, so little time to slow down. I hit that at 35-40mph and sent rocks all under the car and there wasnt any damage. I feel like that was a pretty good test.

Also, PST sells a no questions asked protection plan for $100 bucks that i bought, so if there is some freak incident where the driveshaft is compromised, they will send me a new one.
 

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Discussion Starter #15
This was my main reason for doing a CF driveshaft.

My car isnt as fast as you are talking about(yet), but i have been 9.70's with a stick car, so the violence factor there was also a reason why i felt CF was a good idea. I have completed 2 dragweeks and many street miles, driving on roads with various debris on them with no problems. On DW2015 we had a bridge repair that was about 60 feet a pea stone, around a blind corner, so little time to slow down. I hit that at 35-40mph and sent rocks all under the car and there wasnt any damage. I feel like that was a pretty good test.

Also, PST sells a no questions asked protection plan for $100 bucks that i bought, so if there is some freak incident where the driveshaft is compromised, they will send me a new one.
Great info. Thanks Jeff. I did not know PST had that plan. Great idea.
 

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Discussion Starter #16
I have the 9" tail on my t400. They seem plenty strong. I've seen long wheelbase Pontiacs etc with big blocks well into the 8's with their stock 9" th400 tail end. My driveshaft is only 37" long.. so I went 3" full chrome moly and be done with it.

I can't see how the floor would get in the way over an additional 5in of extension housing?
My floorpan

 

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Discussion Starter #18 (Edited)
Looks to me like the long extension housing would fit. The last 5" of extension housing isn't any bigger than a 4" driveshaft. Just have to move your driveshaft loop back.
Exactly. I did't want to pull the interior, cut the tunnel, cut the floor, and remake the removable section of the tunnel.

 

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Although the car I was considering using a cf shaft in is not an 8 sec car, mechanical damage from road debris etc was the reason I went away from the cf path... personally I feel that a true street car, {thinking an 8 sec car is not really a true street car more of a licensed "racing" style car...} that risk is too great to take. but in this car the risk is greatly lessened.
Damn. I wish I'd known that before I drove 4,000 miles across the country back in 2012 then circumnavigated the country and covered almost 14,000 miles this last summer. :p

On a serious side, I agree that CF would not be my choice for a car driven many miles over various road conditions. Just not enough benefits to outweigh the risk of road debris taking out your driveshaft a long way from home. Even if they replaced it for free, the time waiting would ruin a good road trip.
 
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