Driveshaft and center support bearing vibration

[MarkLinRacing]

Do you think you should've gone with the steel shaft?

My center bearing is pretty much dead so I need a new driveshaft too but I can't decide whether to go with the steel or aluminum one.

How bad is the noise/vibration/rumble above 70mph? Does it get worse?

I take my cars to the track and my Supra will reach speeds of 140mph or higher and I really don't want the whole car to shake because of the driveshaft.

Failure of the part at those speeds would be detrimental too.

[cre]

You definitely should put a loop around it... It'll keep the DS from hitting the ground and getting thrown through the rear seats of gas tank, or nailing the car behind you if it does come apart.

If the DS was well built it should have decent balance and vibration shouldn't be a huge issue... the issue is more noise and harmonics, IMO. There are plenty of calculators online for calculating the critical speeds; Where the shaft reaches a peak stress level (This does NOT mean it's going to fail at that speed!). It varies quite a bit, but for the MKIII DS's I have calculated for you don't want to do the majority of driving on it doing 70MPH to 90MPH. So, you'd be well advised to get a lightweight two piece DS if you commute a long distance every day and average 80MPH.

Now, with the warnings and doomsday-er BS out of the way: I've been running a steel DS for years without any problems or major swelling in the center. Just crawl under the car and check it for and signs of fractures and measure it for any significant change in diameter from time to time (like whenever you change your oil).

[MarkLinRacing]

Originally Posted by cre

You definitely should put a loop around it... It'll keep the DS from hitting the ground and getting thrown through the rear seats of gas tank, or nailing the car behind you if it does come apart.

If the DS was well built it should have decent balance and vibration shouldn't be a huge issue... the issue is more noise and harmonics, IMO. There are plenty of calculators online for calculating the critical speeds; Where the shaft reaches a peak stress level (This does NOT mean it's going to fail at that speed!). It varies quite a bit, but for the MKIII DS's I have calculated for you don't want to do the majority of driving on it doing 70MPH to 90MPH. So, you'd be well advised to get a lightweight two piece DS if you commute a long distance every day and average 80MPH.

Now, with the warnings and doomsday-er BS out of the way: I've been running a steel DS for years without any problems or major swelling in the center. Just crawl under the car and check it for and signs of fractures and measure it for any significant change in diameter from time to time (like whenever you change your oil).

Would I be ok with going with a 1 piece steel driveshaft though?

This is starting to sound like I should just get a new center bearing instead of getting a 1 piece driveshaft made.

My other concern is also loss of ground clearance when using a 1 piece.

[cre]

Honestly, I haven't heard of too many failing, but I have heard of it. Ideally a custom two piece is the way to go... it'll be a LOT lighter than stock and as the length of each segment is less than half that of the one piece the critical speed is MUCH higher. If you've got a competent shop in your area who can build you one I'd go two piece. Like I said, I'm running a one piece, but if I were to do it over again, I'd get a stock two piece rebuilt with lighter steel and a new or retrofitted carrier bearing... IIRC, the stocker is very thick and filled with rubber or some similar dampening material.