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Torque Tube Bearings and Vibration Dampener

 
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Britain  



Joined: 26 Nov 2013
Posts: 176
Location: Hillsboro, OR

PostPosted: Mon Dec 16, 2013 4:21 pm    Post subject: Torque Tube Bearings and Vibration Dampener Reply with quote

I have a 931 and I pulled the bearings from my torque tube today to replace them.

First thing is there were only 3 bearings, do you know if this is normal on the 931ís? The pictures I found online showed 4 bearings.

Also, is it necessary to reinstall the vibration dampener on a racecar?



Thanks,
Britain
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Kenodog  



Joined: 25 Jun 2003
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Location: Vancouver,B.C.

PostPosted: Tue Dec 17, 2013 6:42 am    Post subject: Reply with quote

Not sure about the bearings but I would say a big YES on the damper going back in.
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Britain  



Joined: 26 Nov 2013
Posts: 176
Location: Hillsboro, OR

PostPosted: Tue Dec 17, 2013 7:23 am    Post subject: Reply with quote

Kenodog wrote:
Not sure about the bearings but I would say a big YES on the damper going back in.


Not to doubt you...but why? It doesn't even come in contact with the shaft.

-Britain
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11378
Location: PacNW

PostPosted: Tue Dec 17, 2013 7:27 am    Post subject: Reply with quote

Undoubtedly there to protect the gearbox, if not the TT itself. Can you imagine a harmonic vibration building in the tube on the track? BAM!
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ideola  



Joined: 01 Oct 2004
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Location: Woodstock IL

PostPosted: Tue Dec 17, 2013 7:33 am    Post subject: Reply with quote

Don't the later torque tubes have four bearings and no damper???
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fiat22turbo  



Joined: 18 Jan 2006
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Location: Portland, OR

PostPosted: Tue Dec 17, 2013 7:47 am    Post subject: Reply with quote

Strangely, my 79 NA had 4 bearings. Nothing like the consistency of German production
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ideola  



Joined: 01 Oct 2004
Posts: 15493
Location: Woodstock IL

PostPosted: Tue Dec 17, 2013 7:52 am    Post subject: Reply with quote

The NA torque tube has smaller diameter drive shaft...don't know if that has anything to do with the bearing arrangement...

I believe Britain's car is an S1 (???), so I wonder if the G31 torque tube had the 3 bearings + damper, and the later style Audi torque tube (same as 924S/944) went back to 4 bearings???
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fiat22turbo  



Joined: 18 Jan 2006
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Location: Portland, OR

PostPosted: Tue Dec 17, 2013 7:57 am    Post subject: Reply with quote

Uh, yeah I know its an S1 (actually he's using an NA chassis with the majority of S1 parts in it).

I was the one holding the damned tube down while he was reefing on the puller to try and get all of that crap out of it.
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edredas  



Joined: 09 Dec 2004
Posts: 861
Location: Charlotte, NC

PostPosted: Tue Dec 17, 2013 8:18 am    Post subject: Reply with quote

The vibrations from the crank get transferred through the torque tube shaft where they vibrate the transmission. This design of the solid shaft essentially makes the engine 'larger'. Since the shaft is solid, there is no way to keep the vibrations from reaching the transmission, however that damper does help keep those vibrations from reaching the cabin where they become irritating and can make some people car sick.

"This then sets up vibrations in the drive line which is felt by the driver and occupants. "

A quick description of their job:
http://www.blackseard.com/site/index.php?option=com_content&view=article&id=5&Itemid=7
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Last edited by edredas on Tue Dec 17, 2013 9:01 am; edited 1 time in total
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ideola  



Joined: 01 Oct 2004
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PostPosted: Tue Dec 17, 2013 8:19 am    Post subject: Reply with quote

Point being, the G31 torque tube would have been the first in the series with the larger diameter (25mm) drive shaft. The 79 NA is not necessarily a basis for comparison since it had the smaller driveshaft (even though the outer tube is identical as far as I know for all "snailshell" equipped cars).

I'm pretty certain the 25mm setups in the 944/951 had four bearings and do not have the vibration damper. I'm also pretty certain based on other posts here that the 1980-onward Audi-based 19mm tubes had four bearings and no damper, as well as the S2 931 Audi-based 25mm tubes.

It would be interesting to know if any of the G31 tubes had four bearings and no damper (particularly 81-onward Euro 931s). It seems unlikely that there would be anything particular to the S1 931 motor that would require the damper, while the later S2 motors and the 2.5L setups with nearly identical power and torque characteristics would not have needed it.
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v8carreragts  



Joined: 05 Sep 2003
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PostPosted: Tue Dec 17, 2013 12:41 pm    Post subject: Reply with quote

The G31 and 016Y & Z TT has 3 bearings with a dampener. The 4 spd AUDI TT had 3 bearings with a dampener.The 5 spd AUDI (incl.944/968) TT had 4 bearings without a dampener.

My G31 now has 4 bearings and a dampener. With the additional torque of my v8 I figured the extra bearing would help keep the driveshaft from flexing as much. The dampener will not hurt anything and will help with harmonics but it does add weight.
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Britain  



Joined: 26 Nov 2013
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Location: Hillsboro, OR

PostPosted: Tue Dec 17, 2013 2:14 pm    Post subject: Reply with quote

Well, based on the condition of my inserts and the age of all the rubber on the bearing carriers and the dampener, it looks like I will be going with a set of SuperBearings. Trying to decide if 3 bearing will be sufficient or if I should just go ahead and do 4 while I am there.

-Britain
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Captain_Kirk  



Joined: 17 Dec 2009
Posts: 243
Location: Colbert, WA

PostPosted: Thu Dec 19, 2013 9:00 am    Post subject: Reply with quote

I went from four down to three SuperBearings. The new bearing holders and bearings are thicker/longer. My original bearing was 1/2" and the new ones were 1" so the bearing area touching the driveline went from 2" (4 x 1/2") to 3" (3 x 1").
Three SuperBearings also cost less. Check out the topic "Driveline and TT advise" just down from this one.
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Rasta Monsta  



Joined: 12 Jul 2006
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PostPosted: Thu Dec 19, 2013 3:58 pm    Post subject: Reply with quote

Captain_Kirk wrote:
Check out the topic "Driveline and TT advise" just down from this one.



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Captain_Kirk  



Joined: 17 Dec 2009
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Location: Colbert, WA

PostPosted: Fri Dec 20, 2013 5:01 am    Post subject: Reply with quote

Ya, I can replace the pilot and torque tube bearings, but I can't imbed a link to another page.
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