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Old 12-13-2009, 02:08 AM   #1
BillW
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Post Driveshaft and center support bearing vibration

I have a vibration around 50-70 mph. I checked, and the center of the driveshaft has a 1/2" play in the center support bearing, so I think I need to replace the center support bearing. The bearing is $257 at horspowerfreaks.com. In the TSRM it shows some special service tools to get the driveshaft apart, to replace the bearing, so it seems like it might be a bit of work and difficult to replace the bearing.

Another option I see, is to replace the driveshaft with a one piece aluminum unit. Shaftmasters sells a complete, balanced, bolt-in driveshaft for $350. I'm wondering though, if a one piece driveshaft works, why did Toyota go throught the trouble of a two piece unit? I wonder if a one piece driveshaft puts more load on the u joints or the differential bearings.

What is the best way to go with this? Are there any other options to consider? I saw a used driveshaft on ebay for $100, but I'm thinking I may still have the vibration when I'm done. Thanks for any help you can give me on this.

BTW, I did have the wheels balanced and checked the wheel bearings for play so I am pretty sure the vibration is coming from the shaft.

Last edited by BillW; 12-13-2009 at 02:13 AM. Reason: add a thought
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Old 12-13-2009, 04:21 AM   #2
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I posted a good amount about this already. Do an advanced search and search drive shaft and my name under user. If you can't find it I'll dig it out later when I have more time.

The short answer as to why is that Toyota went for longevity. I'd go with a steel one piece, not aluminum.
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Old 12-13-2009, 11:04 PM   #3
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CRE, thanks for your reply, I looked up the other threads, interesting.
My question was if a one piece drive shaft puts more stress on the differential and transmission than a two piece drive shaft, and maybe that is why Toyota uses a two piece drive shaft.

As for aluminum versus steel, I agree that steel is much tougher than aluminum. I do not plan on adding HP to my stock motor, and the Aluminum shaft is the only stock one I saw, so I though aluminum would be tough enough for my application.
Stress on the drive train from a one piece is my main concern, but it sounds like you do not see that as a problem.
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Old 12-14-2009, 02:38 AM   #4
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Quote:
Originally Posted by BillW View Post
My question was if a one piece drive shaft puts more stress on the differential and transmission than a two piece drive shaft, and maybe that is why Toyota uses a two piece drive shaft.
Well, it lessens the angle that the u-joints connect at by distributing the bend across 4 joints instead of two, thus lessening the load on the output shaft of the transmission and the input shaft of the differential. The only load it affects it the load on the bearings, if they're in good shape and the differential has the proper amount of preload the effect is negligible.

The Carrier bearing also dampens changes in torque and as a result causes some power loss... again, the effect is minimal. I went with a one piece because I'm a cheap SOB.

Quote:
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As for aluminum versus steel, I agree that steel is much tougher than aluminum. I do not plan on adding HP to my stock motor, and the Aluminum shaft is the only stock one I saw, so I though aluminum would be tough enough for my application.
As I mentioned in the other thread, Jaws Gear and any decent drive shaft shop will make you one to order in whatever material you wish. Do keep in mind also that the lighter the mass the higher the frequency of any noise the driveshaft produces... more people complain of noise from aluminum drive shafts for a reason.

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Stress on the drive train from a one piece is my main concern, but it sounds like you do not see that as a problem.
Like I said, negligible.... BUT there is also the option of having a drive shaft shop build you a lighter two piece as well.

EDIT: Shorter shafts are more reliable, but more moving parts to maintain is the trade off.
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Old 12-15-2009, 03:57 AM   #5
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I ended up purchasing an aluminum 1 piece driveshaft from shaftmasters.

CRE, I thought hard about what you said but ended up with going with an AL one piece, because I figured my stock 7mge would not put much load on it, and it seemed neat to have a driveshaft from AL. I know, dumb selection criteria. One reasons I went with AL because it was the only stock one I found listed on shaftmaster's website and I needed it by the weekend. I called shaftmasters around noon today to see when it was going to ship, and they told me that it was "almost out of the shop", as if they just made it, so I guess I could have gone with steel and still got it on time. I should have asked. Oh well, live and learn. I'll try to let you know how it turns out. Thanks for you input. I really appreciated it.
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Old 12-15-2009, 04:29 AM   #6
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Whatever you like. Let us know how you like it.

Oh, and if the stock bolts which connect it to the diff are a little short GET LONGER ONES! It's come up before.
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Old 12-17-2009, 05:44 AM   #7
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I received and installed the drive shaft from shaftmasters today. The diameter of the boss going into the differential, and the diameter of the part going into the transmission, as best I could measure with a dial caliper, was the same as the stock one, +/-.001", and by eye, the length was the same. The welds looked ok, but not great. Fit together fine.

I still have a faint vibration / rubble past 70 mph. CRE, I guess this might be the noise you spoke about. I checked the critical speed of the drive shaft at http://www.wallaceracing.com/driveshaftspeed.htm and with my guess of driveshaft wall thickness , it came back with a critical speed of around 8,000 rpms, so I guess I am below that.
I was surprised how easy it the driveshaft is to change. The nuts attaching the driveshaft to the differential were tight, but overall it was a breeze.
Is it unusual that no transmission fluid came out of the transmission when I pulled the driveshaft? I did have the rear of the car up jacked up about a foot.
CRE, thanks for the input you gave me. Really appreciate it.
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Old 03-01-2010, 08:11 AM   #8
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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.

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Old 03-02-2010, 02:30 AM   #9
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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).
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Old 03-02-2010, 06:27 AM   #10
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Quote:
Originally Posted by cre View Post
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.
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