Driveshaft Decision. I'm torn. Advice from experienced?

[te72]

cool video, im glad i dont race cars.....lol so did i mention i have a steel 3'' one piece with standard universals and that almost every consumer car/trucks right now has either one piece steel or alum and are speed limited to 155mph.

You'd be very wrong...

You know, like the v6 Mustangs... speed limited to 155 because their driveshafts have a nasty tendency of breaking around the 138mph barrier.

I should talk to DSS today if we can catch each other. Here's to hoping a basic two piece in aluminum isn't more expensive than a one-piece carbon...

I believe the carbon has a higher threshold for critical speeds (lighter weight playing the biggest factor I'm guessing), so you would be able to get away with that if desired... plus, any parasitic loss you can get rid of safely, is a good thing, right?

 

[figgie]

I believe the carbon has a higher threshold for critical speeds (lighter weight playing the biggest factor I'm guessing), so you would be able to get away with that if desired... plus, any parasitic loss you can get rid of safely, is a good thing, right?

not weight..mass

but yes. The less mass the higher the critcal speed.

 

[3p141592654]

... and that almost every consumer car/trucks right now has either one piece steel or alum and are speed limited to 155mph.

BMW M3 series is out of production?



Infiniti G37, kaput?



Lexus IS350 terminated



Audi R8 (verboten?)



Well this could go on, but hopefully the point is made.

 

[IJ.]

Damn IJ, that thing spun him around in an instant. If that happens one a two lane highway that could easily be deadly



I dont even know what you're trying to say here...


I should talk to DSS today if we can catch each other. Here's to hoping a basic two piece in aluminum isn't more expensive than a one-piece carbon...

Perfect example of what happens when you exceed critical on a one piece STEEL shaft...

If that happens on ANY public road there's a fair chance it's going to be fatal due to the speed the failure occurs at..

"people" will think "nah never happen my car is a road car and that was a race car" well no it was "Improved Production" an an AE86 if I'm correct, shorter shaft than we run and I'm fairly sure they run a 2 piece standard (could be wrong though)

 

[1986.5supra_kid]

i was thinking domestic made consumer cars and trucks with a one piece driveshaft. but if you are building a car for illegal speeds (racing) then yes you should spend the extra money on a 2 piece.

 

[IJ.]

i was thinking domestic made consumer cars and trucks with a one piece driveshaft. but if you are building a car for illegal speeds (racing) then yes you should spend the extra money on a 2 piece.

Drop the "illegal speeds" BullShit, there's not a member here that hasn't broken the Speed limit at some time...

The way "Speed" has been Demonised by Governments just about worldwide and the population brainwashed you'd think Speeding makes you on par with Child Molesters...

 

[Poodles]

i was thinking domestic made consumer cars and trucks with a one piece driveshaft. but if you are building a car for illegal speeds (racing) then yes you should spend the extra money on a 2 piece.

I'm sorry if you enjoy comparing a high speed GT car to a POS grocery getter that can't hit tripple digit speeds.

Oh wait, you're NA...

 

[3p141592654]

i was thinking domestic made consumer cars and trucks with a one piece driveshaft.

You mean like a camaro, oh wait, that's two piece too!

 

[suprarx7nut]

Regarding the idea of replacing just the bearing: I know my power levels will be low but I'd like to lighten the shaft and eliminate the possibility of any future slip.

At this point I'm settled on a 2 piece. I've spent enough time thinking about it as being around 1000 dollars and I've come to terms with it for a really well done piece.

Still was unable to talk with dss today. meanwhile I can really notice the chatter and rough feeling that I think is coming from the drive shaft. I'm definitely anxious to get it swapped out.

On a completely separate side note I'm entering all of this text using speech to text on android. Including the punctuation. Pretty f****** cool. It even catch is my swear word and bleeps it out. What an age we live in.

Sent from my Galaxy Nexus using Tapatalk 2

 

[suprarx7nut]

Talked with Frank at DSS. He's fan of the one-piece units, but certainly not opposed to making a 2-piece aluminum. I will update pictures he sent of a recent two piece soon.

He mentioned the two-piece with the CV joint and center bearing will still exhibit the "hanger lag" as he termed it where you can feel the slight lag when stepping lightly on and off the gas while cruising. Also, he was very confident the carbon would be a quiet shaft, adding little if anything to in cabin noise.

Now, something I completely failed to consider.... Safety on the carbon. Carbon will disintegrate on a hard impact or catastrophic failure. The carbon "brooms" or frays and is not likely to pose any kind of danger. Looking at this from a safety perspective in the event of a failure... the carbon seems to win, even over the two piece aluminum. Anyone disagree?

With the one piece carbon being lighter, cheaper, presumably safer, more solid and having a shorter lead time... I'm struggling to conclude the two piece aluminum to be a better option.

 

[Poodles]

Carbon is safer when it fails, but it will fail easier as they're quite fragile Road debris can and will scratch the driveshaft, and that will cause a failure of a carbon unit.

I dunno about the "hanger lag" since there's a ton of performance cars running 2 piece driveshafts...

 

[te72]

You mean like a camaro, oh wait, that's two piece too!

Huh... that is a new design then. The 4th gen cars had a one piece, but it was quite short, not to mention thick. I wanna say it was a 3.5" from the factory in my SS...

On a completely separate side note I'm entering all of this text using speech to text on android. Including the punctuation. Pretty f****** cool. It even catch is my swear word and bleeps it out. What an age we live in.

Sent from my Galaxy Nexus using Tapatalk 2

That really is something. I'm still quite content with a "dumb" phone, but that is pretty badass.

 

[3p141592654]

5th gen Camaro... he did say "right now" production cars.

 

[suprarx7nut]

Carbon is safer when it fails, but it will fail easier as they're quite fragile Road debris can and will scratch the driveshaft, and that will cause a failure of a carbon unit.

I dunno about the "hanger lag" since there's a ton of performance cars running 2 piece driveshafts...

I've read about this fragile carbon fiber driveshaft syndrome but I've seen almost 0 cars with actual street driven failures. I'm also reading that the 350 z comes from the factory with the carbon fiber driveshaft. And I haven't seen anybody with problems with that.

Sent from my Galaxy Nexus using Tapatalk 2

 

[Poodles]

http://www.350z-tech.com/forums/190-drivetrain/69347-drive-shaft-replacement-help-opinions.html



And theirs is far less exposed than ours.

 

[3p141592654]

Hanger lag! LMFAO.

 

[suprarx7nut]

http://www.350z-tech.com/forums/190-drivetrain/69347-drive-shaft-replacement-help-opinions.html



And theirs is far less exposed than ours.

He also broke it after a clutch dump on a regularly raced and abused car. Not exactly a similar situation to me. I don't plan in a single clutch dump in this car.

Also, notice how most all responses were "wow I've never seen that!"

Nevertheless an example of a failed carbon OEM unit, so I tip my hat.

Hanger lag! LMFAO.

Yeah, kinda dumb term, but I definitely have a relate-able sensation. My car has a little "give" while cruising on and off throttle and I know my bearing has a ton of radial play. Not sure if its from the hanger, but I could believe it. :dunno:

Sent from my Galaxy Nexus using Tapatalk 2

 

[3p141592654]

I had no idea the driveshaft business was so full of snake oil and outright BS. Free-up horsepower, really? Does the stock DS get hot from all the HP its absorbing. Hanger-lag! How about instead fixing your worn out drivetrain so you don't have so much slop.

 

[suprarx7nut]

I had no idea the driveshaft business was so full of snake oil and outright BS. Free-up horsepower, really? Does the stock DS get hot from all the HP its absorbing. Hanger-lag! How about instead fixing your worn out drivetrain so you don't have so much slop.

Err... horsepower yes. I know youre a smart guy, so I'm confused by your comment. Lowering the rotating inertia results in less energy required to increase rotational speed. Drive train loss is real and can certainly be lowered by reducing the rotating mass/inertia. I would assume just the driveshaft to be a small enough difference in the overall drive train that it'd be tough to notice, but I'm not sure how you could argue lowering rotational mass is not beneficial. :dunno: the heavier shaft has more kinetic energy at speed. It doesn't need to get hot to contain more energy, lol.

Regarding the slop: I'm unaware how much the stock shaft bearing should have. Regardless, mine has roughly 1/2-1 inch of radial play. I can't imagine that's what toyota had in mind. I don't notice any other slop, but that's not to say the rest is perfect. The hanger in my car needs to be replaced or eliminated after 325k miles. Axles seem to be fine, no slop obvious there. Diff also seems slop free. There's a small amount of rotational slop in the wheels when jacked up but that's been typical of every single car I've ever worked on.

If you've got other suggestions I'm all ears.

I'm curious to hear Ian's take on the single piece carbon option...

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[IJ.]

You're talking PMoI, I doubt you could measure the difference as it would be within the +- error of most Dyno's.

I build/drive my cars in the real world and unless you can figure out a shoud to enclose the Carbon Shaft I wouldn't use one in a street car, Duane destroyed one a few years back.