Driveshaft options?

[te72]

Hey guys, doesn't seem like this question has been asked yet, but I'm wondering what the benefit might be of a lighter driveshaft? In my tired overworked mind, my logic seems to point toward a similar idea of a lightened flywheel, i.e. better response, less rotational mass, etc...

HPF sells a small variety of them, the options being steel, aluminum, or carbon fiber. Is replacing the driveshaft with a lighter one going to make a noticeable difference? If so, would the cf option really be worth exploring for a couple hundred more?

 

[IJ.]

Small diameter= small PMoI so a great deal of effect Brad.

Personally I always err on the side of whatever is stronger.

 

[te72]

Googling "PMoI" returns a lot about something called the People's Mujahedin of Iran... I don't think that has anything to with driveshafts, just a hunch. Explain perhaps?

As for strength, the aluminum and cf ones are sold by Titan, I would think they'd be plenty strong enough for my goals.

 

[IJ.]

"Polar Moment of Inertia"

NOT a big fan of 1 piece shafts in a Mk3 but that's more my end use of the car than the materials fault.
(I get them into the critical speed zone far too often for comfort)

 

[RockPaperSwoRD]

you get more response and feels smoother if your carrier barrier is going out. you will feel a difference, just get an aluminum ds. high speed runs (120+ mph) will put the aluminum ds at risk of breaking. so if you plan on going that fast maybe you should get the 2 piece aftermarket or a CF

 

[airhead04]

Titan Motorsports
Driftmotion
Shaftmasters
HorsepowerFreaks

All make driveshafts. =]

---------- Post added at 09:14 PM ---------- Previous post was at 09:11 PM ----------

Ive had my supra up to 147 multiple times and it has yet to fail on me. My fathers supra has seen 156 and didnt show any hint of failing. Both are aluminum. So Idk where you go the 120+ mph thing from but I dont tend to believe it. Sorry.

 

[arknotts]

I have a shaftmasters 1-piece aluminum driveshaft and it's been great so far. Time will tell whether it will hold up to lots of power though.

 

[Zumtizzle]

I might have a 1 Piece Steel Shaft Coming up FS next week.

I'll send you a PM. I'll let it go for CHEEP.

 

[arknotts]

Oh, and since I'd like to track my car (road course) quite a bit I plan on modifying a generic Summit driveshaft loop to bolt into the center carrier bearing area. This way if it does snap on me it won't be a disaster. Ever see the myth busters "driveshaft pole vault" episode?

 

[mkiiichip]

so if you plan on going that fast maybe you should get the 2 piece aftermarket or a CF

Who sells a 2 piece aftermarket DS?

 

[whitemike]

get the 2 piece aftermarket

A what?

 

[te72]

Hypothetically speaking, this motor will see something between 600-800hp, I live about 3 hours from Bonneville and would like to get a Mk3 to 180 (200?) mph someday, so critical speed is a bit of a concern. There's nothing particularly wrong with my driveshaft, but if it's gonna net me better response and if the weight reduction is worth it, I'll upgrade.

Is it going to change things the way reducing unsprung weight does? Or is it more a thing of how the engine feels?

 

[IJ.]

Hypothetically speaking, this motor will see something between 600-800hp, I live about 3 hours from Bonneville and would like to get a Mk3 to 180 (200?) mph someday, so critical speed is a bit of a concern. There's nothing particularly wrong with my driveshaft, but if it's gonna net me better response and if the weight reduction is worth it, I'll upgrade.

Is it going to change things the way reducing unsprung weight does? Or is it more a thing of how the engine feels?

Custom 2 piece, pref CroMo.

 

[te72]

I'll look into that, thanks for all the input guys!

 

[IJ.]

800rwhp/200 mph is the clincher for this one.

 

[Cz.]

There is a sticky thread if you search that talks all about driveshaft critical speed. It also includes a well put together excel sheet that shows you the driveshaft rpm based on gearing and tire diameter.
I myself bought the Shaftmasters aluminum shaft, he told me that it has a critical speed in the 13k rpm range which should be fine past 200mph. I haven't gone that fast yet, but I have had no problems with it so far.

 

[te72]

800rwhp/200 mph is the clincher for this one.

Don't think 800 would be enough for a Mk3? I'm by no means an expert, but I can't imagine it would take much more than that... Or are you referring to driveshaft strength?

 

[IJ.]

Depending on what combination you use to get the 200, if you're using low gears and lots of RPM you can easily bump critical, just NOT something I'd chance.

 

[te72]

Hmm... so basically if I were to ever get serious about trying to hit that speed at the salt flats I'd wanna put as tall a tire as would fit, to keep driveshaft rpms down as much as possible? This is more of a pipe dream than anything, but I'd rather do my homework on such a subject considering the potential consequences.

 

[Mike Morris]

Have the carbon fiber one SS used to sell which I think is the Titan. Have had it for years and beat the hell out of it. No problems. Have one on my Camaro too