BBSC drive unit noise

[WOODY]

I am getting a loud "rattle" noise from the drive unit on the bbsc. I assumed that it was the center bearing as there was a small amount of grease on the cover near the bearing mount. I sent it in to MB who replaced all bearings and seals and "realigned " the unit with his JIG. upon reinstallation the noise is still present and probably worse. there are no adjustments that can be made to the unit as it bolts directly to existing taps in the block. I also added a new spider gear to the junction with the paxton blower. The blower was gone over by paxton in july 04 (8,000 miles)and a bad bearing replaced. The noise is not present when I disconnect the belt and run the engine without the bbsc connected. The only place I can look at under the drive cover as it is running is at the spider gear with a cosmetic mirror and it appears to be spinning true. I can feel the rattle conducted through the cover if I place my hand on it when the engine is running. The paxton has no vibration when it is spinning so I dont believe this to be the problem. To remove the paxton to spin the bbsc drive without the blower attachmentwould be alot of work(aftercooler etc....) I also do not have a way to spin the paxton without the bbsc drive.
the sound seems to disappear under load (hard to tell with rm exhaust though)
sooooo.....what could it be? the only thing I can think of is a bent drive rod? if I figured out a way to spin the bbsc off of the car would I see a bent drive or even hear it? Assuming any device I rigged up to drive the pulley would be much lower RPM I may not even see or hear it. Any other ideas? There are currently no bbsc drives available from mark to buy or swap out to assist in the diagnosis.
thoughts? solutions??? :smile:
any help appreciated (or anyone with a spare?)
thanks
woody

 

[peiserg]

I too had a driveline noise. I assumed it was the novi, but mark said otherwise. He warranteed the whole thing including R&R, mark being generous as mark tends to be...

and in fact when i got the car back, it was quieter than it has ever been. I don't know if that meant there was always a slightly noise bearing that eventually gave out, or somehting on the SC that he tightened..



said it was a bearing i beleive...

 

[mikeh]

I think I have the same noise coming from my setup. Pull the intake hose/pipe off, and reach in and try to spin the compressor wheel with your finger (when the engine isnt running ofcourse, duh! ). I can feel mine rotate just a tiny bit amount forward/backward and it makes the same 'ting' type rattle that I hear from the blower at low rpms.

I think it's caused by driveline lash, as if I do it and look under the cover at the same time, i can see that tiny amount of play in the spider coupling as well. I thought about trying a new bushing, but not sure that would help as this one only has a few miles on it.

Someone mentioned that there are 2 different type/compounds of spider couplings. One is orange and the other is green (mine is green). What color is yours? I was thinking of trying to find the other one myself...

-mike

 

[WOODY]

I think it's caused by driveline lash, as if I do it and look under the cover at the same time, i can see that tiny amount of play in the spider coupling as well. I thought about trying a new bushing, but not sure that would help as this one only has a few miles on it.

According to MB there is supposed to be a little (~1mm) play from the drive shaft to the spider coupling. My original one was orange and I thought that it may be worn so MB sent me a new greeen one (green has a more rigid composition than the original orange ones and is preferable for higher HP applications) I believe that I have an acceptable fit with the spider since changing to a brand new one didnt change anything. also I would think that the constant forward motion of the drive would suck up the gap on startup and maintain constant forward pressure on the spider thus eliminating any slop.

I can feel mine rotate just a tiny bit amount forward/backward and it makes the same 'ting' type rattle that I hear from the blower at low rpms.
My paxton spins free and smooth by hand when unattached to the drive. I am familiar with the typical blower chatter from the paxton and I this isn't it. I did not have this noise when I got the car back from Devin.
If I remove the coupling from the paxton end of the drive will the shaft slide right out? Maybe then I could spin the shaft in a lathe and see if it is true?

 

[MiamieNeSeX]

I have experienced this same problem, be it becuase of the high HP or the softness composition of the "spider", On one occassion the coupling on the blower side had become loose to the point that the bolt that holds it in place was completely off. I removed it and reinstalled it using thread lock which resolved the problem. I do believe that the spider is a regular maintenance item green being the hardest.


Armando

 

[WOODY]

Everything has just been gone over by MB, and the spider is new. He specifically mentioned retorquing the coupling and I rechecked it before reinstall. Armando-did your noise sound like it came from the coupling or the center of the drive? does the drive slide out with the coupling off?
thanks
woody

 

[MiamieNeSeX]

My noise came from the coupling end. If its anywhere else on the drive check the bearing blocks. If thats the case you would need to send the whole unit to Mr.B so the bad bearings can be replaced and realigned with the shaft. The shaft will not slide out . Note The 4 allen bolts holding the drive assembly to the blower are a bear to get off.


Armando

 

[WOODY]

just got it back from MB.

 

[ANYTIME]

While I have a CTSC and am not qualified to comment on the BBSC, a suspended PRIME member asked me to post this for him.

Although a bearing on the shaft or a bearing in the blower can be a cause of
this "rattle" noise, there is another aspect to consider - both halves of
the aluminum spider coupling. The coupling halves are aluminum and the
shafts are steel. The coefficient of thermal expansion for these two metals
are significantly different. Over time, the aluminum coulping halves will
loosen from the steel shafts.....thus the noise. As MB points out, a very
small amount of "lash" is normal. In fact, it is a must because there needs
to be a little "wiggle room" (no pun intended) with this type of shaft
drive.

The coupling half on the long shft is held in place with a hex-head cap
screw, bolted into female threads at the end of the shaft. On mine, this
bolt had loosened to the point that it had completely backed out of the
shaft and was tumbling around within the coupling half and the plastic
spider insert.

The coupling half on the Paxton is fixed with only one keyway, and secured
by two very small set-screws. It does not take much to loosen these two
screws, thus more noise. BTW, these two screws are one on top of the
other.....not very efficient in my book.

This is being posted on behalf of AndyV. And in no way reflects my opinion on the subject.

 

[MiamieNeSeX]

This is being posted on behalf of AndyV. And in no way reflects my opinion on the subject.

You running for office?


Armando

 

[ANYTIME]

You running for office?


Armando

No. At least not yet! :biggrin:

 

[WOODY]

I did not check the set screws on the paxton but the sound and rattle source sure seem to be from the center of the shaft cover at the center bearing, and there is no excessive slop when I hand rotate the the pulley. How does the shaft come out? Is it unlikely it is bent?It only takes about 40 minutes to take the drive off, I would just like to make sure I have a comprehensive check list for when its off. All the help is appreciated
Perhaps andyv could get time off for good behavior?
thanks again
woody

 

[MiamieNeSeX]

I beleive there are a few set screws that hold the shaft in place, if thats not right I am sure some Moron will chime in and correct me.

Armando