924Board.org

[Britain]

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 931’s? The pictures I found online showed 4 bearings.

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



Thanks,
Britain

[Kenodog]

Not sure about the bearings but I would say a big YES on the damper going back in.
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1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

[Britain]

[Rasta Monsta]

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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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[ideola]

Don't the later torque tubes have four bearings and no damper???
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erstwhile owner of just about every 924 variant ever made

[fiat22turbo]

Strangely, my 79 NA had 4 bearings. Nothing like the consistency of German production
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[ideola]

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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erstwhile owner of just about every 924 variant ever made

[fiat22turbo]

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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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[edredas]

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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'84 944 -White, Brown interior
'84 944 -Red, Automatic
'86 944 -Garnet, Fully loaded, Koni suspension
'87 924S -Red, 300hp 951 swap
'87 924S -Red, Project Car
'88 924S -Red, Daily Driver

[ideola]

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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erstwhile owner of just about every 924 variant ever made

[v8carreragts]

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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84 944--924 Carrera GTS clone w/520HP Chevy 302 V8--RUNNING!
2015 AUDI Q7
2013 Dodge Charger R/T AWD HEMI
2013 Chevy Cruze

[Britain]

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

[Captain_Kirk]

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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1977 924na BlackSeaRD.com Torque Tube SuperBearings, Xenon air dam, 200# Weltmeister springs, Bursch header, 944 exhaust, Audi throttle body

[Rasta Monsta]

[Captain_Kirk]

Ya, I can replace the pilot and torque tube bearings, but I can't imbed a link to another page.
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1977 924na BlackSeaRD.com Torque Tube SuperBearings, Xenon air dam, 200# Weltmeister springs, Bursch header, 944 exhaust, Audi throttle body