Driveshaft critical speeds.

[Doward]

I'm doing some quick and dirty calcs, and I think a 9000rpm critical speed will be good for me for the following conditions -

7200 rpm redline
25.66" tire
3.91 rear gear
r154 tranny

http://www.markwilliams.com/driveshafttech.aspx

Looks like a 3.5" mild steel will be the way to go for me (isn't stock DS length like 45 inches? Dammit, I have to measure mine - '88 auto converting to an r154)

Will possible go to 3.73s down the line (depends on how my power band feels)

Thoughts?

 

[TurboStreetCar]

One piece i assume? I think this will need IJ's opinion......

 

[jmanbball]

http://www.wallaceracing.com/driveshaftspeed.htm

 

[IJ.]

Dow: At 7200 your shaft is turning 9600 in 5th with a R154...

I'd want at least a 1000 rpm safety margin.

 

[TurboStreetCar]

wouldn't aluminum be better for a higher critical speed?

 

[IJ.]

Right up till it work hardens fatigues and fails

 

[honestabe]

wouldn't aluminum be better for a higher critical speed?

No, steel would because it's stronger.

 

[Doward]

Dow: At 7200 your shaft is turning 9600 in 5th with a R154...

I'd want at least a 1000 rpm safety margin.

You're right, I miscalculated that.

So far, the problem has been nobody's got an r154 flange that will accept a 3.5" tube. :3d_frown:

 

[IJ.]

Try Spicer

I'm using 3" tube here in the 2 piece.

 

[Doward]

Nothing there, according to the guy I emailed

Looks like a 2 piece 3" will be what I have to run, as well. This should be fun to have built, lol.

 

[CPT Furious]

I wouldn't think it would be too bad, just use the stocker for the measurements. I guess the big problem would be convincing them to do it.

 

[Wiisass]

What about just ordering one from the Drive Shaft Shop?

http://www.driveshaftshop.com/toyota.ivnu

And unless you're using one of the driveshaft from that first place that was posted, the critical speeds and natural frequencies and all that fun stuff is going to be different for other drive shafts. Unless they use the same diameter and wall thickness.

 

[antman]

I don't know about you guys, but my car won't ever see 7200 rpm in 5th.

 

[7MGTEsup]

I don't know about you guys, but my car won't ever see 7200 rpm in 5th.

Yeh! thats like what 185mph

 

[Poodles]

depends a lot on the rear gear ratio...

if you're getting a beefier 2-piece made, what about the center bearing? it seems to be the weak link in the chain...

 

[Doward]

There are many center bearings out there... gonna look more into it.

As to why?

http://www.silverstateclassic.com/

 

[Poodles]

looks like fun

if you find a better center bearing, let us know. I went to the junkyard because I needed the part of the driveshaft that goes into the tranny (pulling the tranny, and don't want to drain it). Low milage 90 model and the center bearing was still toast...

 

[antman]

Thats insane! Have fun.

 

[IJ.]

I don't know about you guys, but my car won't ever see 7200 rpm in 5th.

Mine will and it'll be a LOT faster than 185

 

[Quin]

Mine will and it'll be a LOT faster than 185

I call BS!













A340 is a four speed :biglaugh: