Torque Tube to fit 944 86-91

[Jason E]

I am wanting to source & rebuild a Torque Tube to fit my 944S2.  Apparently any of the post update 944 tubes will fit.  If you have one, know of one etc please let me know.  I am still in the diagnosis phase of finding out if the hum I can hear is torque tube related but it seems the most likely culprit.

cheers

Jason

0410 439 764

[Pauly]

describe this hum you're hearing.

[Jason E]

Thanks Pauly,

Well, first of all it is intermittent.  Comes & goes though it seems to have been increasing in frequency & volume over the last few months.  Kind of a steady hum.  Much more of a harmonic sound than anything else.  Can be loud enough to be heard distinctly.  My wife commented on it today during a drive.

If I put my foot on the clutch (& correspondingly remove my foot from the accelerator) it dies away within 1 to 2 seconds.  However if I keep my foot lightly on the accelerator while depressing the clutch the hum remains even at a stop .  It is not restricted to certain speeds or gears.  You can hear it at 10ks an hour in first or at 110ks in 5th.  You can drive without the hum & it will suddenly appear & disappear randomly.

I had a talk with Bruce Buchanan who said (& please forgive me if I get this wrong as my grasp of 944 mechanicals is rudimentary at best) that the bearings can migrate down the drive shaft due to a number of reasons causing the end of the drive shaft to bow or flex slightly causing the humming sound.  (Again I may have got this somewhat wrong so apologies to Bruce if I have incorrectly relayed his info, any mistakes are mine).

Rob said he is not entirely sure it is torque tube related until we do some further diagnosis.  He has heard the hum himself (proving that I am not mad!!).

Any thoughts,

cheers, 

Jason

[Pauly]

I'm not entirely sure it's the torque tube also. 

Does it do it at idle if you rev it? 

Under load vs no load?

TT bearings, when gone they'll always make noise when spinning. If the rubber is worn that holds the shaft in place on the bearings, then at load it can flex. 

[Jason E]

HI Pauly,

I will have to run some more tests but I can say that if I am driving & the whine is present & I am coming to a stop at a red light the whine will stop as I depress the clutch & I get under about 5 kph.  (Of course from memory the whine will also stop at 100kph if I put the clutch in).  If I let the car idle normally it will return as soon as I get above 5 or so kph.  If I am coming to a stop & I put the clutch in but continue to keep some revs fed to the engine the whine will still persist while the car is not moving forward.

If I think of something else I will add it.

[Pauly]

Your TT should still be spinning when driving with the clutch in. So i don't think it's the TT. 

Try this. 

While parked up. Leave it in neutral and rev the car to about 3000 rpm. Does it make the noise? then do the same but with the clutch in. What results do you get?

Last thing you want to do is change the TT bearings and it's not that. Not an easy job.

[Jason E]

Thanks Pauly, I will give this a go.  

I wonder though with the intermittent nature of the noise will I also have to wait until the whine begins on its own & then stop the car & run the test.  Either way I will try it today & report back.

Certainly Rob had a bit of a regime of testing planned for next time we get together.  He wanted to take the car for a run & see if we could replicate the noise then I think he wanted to put the car on the hoist & run it to again, find the noise & attempt to pinpoint it.  Certainly wise to exhaustively test before pulling the TT as it does seem by all accounts to be an involved job.

cheers,

Jason

[Buchanan Automotive]

Hi Jason , its the T/ Tube , you're 944S2 has two noise related symptoms that are noticeable & they all normal at high kms and usage dependant , meaning how hard they are driven & or flogged over the last 27 years by multiple owners and friends of owners & everyone else who has driven any car over the last 27 years

When I listened to you're car before Xmass I knew from past experience ( 40 + years ) that this car has noises ( all fixable )

The noises that Sean & I listened to , we knew they ( over time & usage ) have to get worse( more noticeable ) , they can not rectify themselves & now they are more noticeable , you can clearly hear what we heard 5 months ago , but was in the early stages then 

These noises are broken up into two groups 

Group A )    944S2  5 speed manual trans rattle at idle in neutral , slightly more noticeable when hot as the gear oil is less viscous , now because the massive 944S2  4 cylinder engine naturally has very distinctive firing impulses , a bit like a big V twin in a way & the manual trans layout will quite easily transmit these impulses very easily into a distinctive gear rattle in neutral any idle 
Now when these cars were new the manual transmission naturally has new bearings & all the internal bearings & input + pinion shaft pre loads ( preload of the bearings ) made the shafts harder to turn as opposed to worn out bearings preloads that are now quite loose & this allows the gear sets / shafts to move more freely ( for want of a better expression ) and with such a large 4 cylinder engine ( made worse with high compression ) shows this firing impulse as a very distinct gear rattle 

Sub note }  The above gear rattle ( quite normal 944S2 ) for high kms would not be there at all if the technology was ready in time for a dual mass flywheel , that the next generation 3.0L 944 received( the 968 ) , the dual mass masks a "loose" gear box ( rattle noise)very effectively 

Sub Note 2 } A 968 with the dual mass flywheel removed along with its dependant bell housing & a 944S2 style flywheel ( solid ) and clutch / bell housing / starter motor put in its place , the 968 gearbox Rattles like a bitch , this is how ( just in one way ) how important dual mass flywheels are in noise control

You should hear a 3.6 911 ( 964 ) without a dual mass flywheel , the gearbox rattles like crap , but with a dual mass = nothing 

This is why the 944S2 transmission set up new ( pre loads were so critical initially )and this set up masked this inherent noise ( gear chatter at idle etc )

Every time we has dismantled these 944S2 transmissions to do repairs / worn diff bearings  or upgrades like LSD fitments( we install 3 different Limited Slip diffs in these depending on what the owner needs)  , if we know that the trans is an old rattler we give the owner the option of reducing this very annoying "gear rattle" noise by the full dismantle , replacement of badly worn bearings and the EXTREMELY important and time consuming preloads" re-shimming" the pinion shaft & gear sets ( even the circlips within & on the gear sets are shims ( different thicknesses available ) in their own right 

The above can bring back the factory "as new" preloads which reduces the engine firing impulse gear rattle to near nothing at idle in neutral 

------------------------------

Group B ) Torque Tube noises 

When I mean noises I the the plural "Noises " or put another way more than one type of noise

So what are the common noises in Torque Tubes in say high Km 944 models ( all ) & high Km 928 models( all ) ? , well its interesting , in old age the" Multiple " noises become more apparent in the manual transmission versions , where as in Automatic transmission they are often in the singular range of noises ( whining bearing mainly)

To be more specific , this is what I mean }  
In the manual trans 944 / 944s /944S2 /968 / 951 there are at least two different types of noises in old age & high kms & made to happen a lot quicker/sooner if the car has been flogged over many years

Noise 1 } The traditional worn out / noisy bearing noise = bearing whine at idle in neutral & naturally goes away when you put you're foot on the clutch& naturally as time goes by the worn bearings get louder & louder

Noise 2} The less traditional , but becoming a lot more common after 25 years , this noise is a series of noises( not just one ), bumbling hums & vibrations at certain RPM and road speed & or load , this can come & go to a small degree & is very baffling to anyone who has never heard this before 

This is what you have , its mainly noise 2

Now I hear you ask , what the hell is causing this  ?

Answer = Its a combination of two things , both important 

First one }  The Vulcanised nylon/steel inner insulation sleeve between the T Tube quill shaft too the high speed bearing /s was worn away , causing a gap to occur in this area & its this gap is not allowing a smooth transfer of Torque through the quill shaft ( the shaft is flexing & vibrating within the gap area )we are seeing more & more of these 

Second one } The( factory implemented) Stupid longitudinal split( cut) in the front lower section of the 944S2 T tube outer tube opens up( widens ) at high kms or if the car has been flogged a lot or both & this allows the first two sets of T Tube bearing sets to migrate forward ( nothing to hold the outer insulator to grip within the outer tube now that the tube is bigger than it should be  , this gap  is a mini disaster & can be fixed back to spec , but it takes more than 5 minutes after the total dismantle , it has to be carefully heated & pressed back into the correct gap ( diameter ) with a series of lathed machined dollies we place inside the tube while we are putting back into shape , then in this position , the custom made steel ofter half moon straps are Tig welded into place & remeasured & if perfect then cleaned & painted ( permanent fix ) & the T Tube internals are installed with new high speed bearings & insulators , all custom made 

When the sets of T Tube bearing / insulator sets migrate forward , this allows the unsupported shaft ( quill shaft ) to vibrate even more ( more vibration/ noise )

We have been fixing these for years & naturally new high speed high internal clearance bearings and custom made insulators on the inside & outside of the high speed bearing encapsulator/s

All simple time consuming engineering ( when one has the correct parts & knowledge )

Regards

Bruce Buchanan

Buchanan Automotive

 

[Jason E]

Thanks Bruce,

Comprehensive as always.  This will give us a fair bit to ponder.  Cheers Jason

[michel]

Great detailed response Bruce.

These custom inner outer insulators you are producing I'm assuming they are a replacement for the bearing carrier (outer)  and the inner bush. The inner appears from factory to be some form of nylon/Delrin or similar?

Bruce/Sean in lieu of not taking on rebuilds of non customer car TT's, are you willing to sell these parts so others can rebuild their Torque  tubes.

cheers michel 

[Kelly]

Must be Torque tube week, I'm going to refurb my TT in the next few weeks as well.

[michel]

Gruppe buy And build weekend @Kelly

[Jason E]

Must be Torque tube week, I'm going to refurb my TT in the next few weeks as well.

Very interesting Kelly.  Please keep us informed re your progress.  I would be very interested to see what you do & what you use please,  We are thinking the best thing to do at this stage is to try & source a donor tube (non S2 preferably to avoid dealing with the split seam issue) & rebuild it on the bench then fit it to the car once it is done.  Should reduce down time as my car is my daily.  That's the plan anyway....sourcing the tube is another matter............

cheers, Jason. 

[Kelly]

Gruppe buy And build weekend @Kelly

Probably a bit late for that I'm afraid. I'm waiting for an invoice in my inbox so I can send payment and get the bearings on the way.

Very interesting Kelly.  Please keep us informed re your progress.  I would be very interested to see what you do & what you use please,  We are thinking the best thing to do at this stage is to try & source a donor tube (non S2 preferably to avoid dealing with the split seam issue) & rebuild it on the bench then fit it to the car once it is done.  Should reduce down time as my car is my daily.  That's the plan anyway....sourcing the tube is another matter............

cheers, Jason. 

I'm sure there will be some photos as I do the job The split TT sounds like a design that was asking for trouble in the long run.

[Jason E]

Probably a bit late for that I'm afraid. I'm waiting for an invoice in my inbox so I can send payment and get the bearings on the way.

Kelly,

are you buying the Black Sea Super bearings?  Would be very interested in how you find them if that is so.  I had a long phone conversation with Constantine from Black Sea re the bearings, torque tubes etc.  Nice bloke.

[Kelly]

Kelly,

are you buying the Black Sea Super bearings?  Would be very interested in how you find them if that is so.  I had a long phone conversation with Constantine from Black Sea re the bearings, torque tubes etc.  Nice bloke.

Yes

[Jason E]

Probably a bit late for that I'm afraid. I'm waiting for an invoice in my inbox so I can send payment and get the bearings on the way.

I'm sure there will be some photos as I do the job The split TT sounds like a design that was asking for trouble in the long run.

Too right.  I've had a few conversations with Bruce Buchanan on the subject & my interpretation of his thoughts were that the Porsche Engineers were trying to make it so perfect, chasing gremlins that were almost nonexistent that they introduced an absolute timebomb if the car was not strictly maintained.  It's a bit of a shame really.  

[Kelly]

Too right.  I've had a few conversations with Bruce Buchanan on the subject & my interpretation of his thoughts were that the Porsche Engineers were trying to make it so perfect, chasing gremlins that were almost nonexistent that they introduced an absolute timebomb if the car was not strictly maintained.  It's a bit of a shame really.  

Unfortunately it's one of those things that falls into the category of ''just has to be dealt with" in the course of ownership, it's a pity but part of the journey. ... On the plus side the S2 ring and pinion rocks

[Jason E]

Yes

Ahh very nice.  I can't wait to hear what you think of them.  Lot of money but allegedly the cats whiskers of bearings.  Are you fitting 3 or 4 bearings to your tube?   You're ahead of the game with your 951 TT not needing the extra work securing the seam in the S2 TT.  I've got to find me one of those!!

Unfortunately it's one of those things that falls into the category of ''just has to be dealt with" in the course of ownership, it's a pity but part of the journey. ... On the plus side the S2 ring and pinion rocks

Yes, I am just loving my car.  It's a cracker for my first Porsche & it's definatly given me the bug. I've been amazingly lucky to find a member up here who has generously helped me with lots of work.  My car was in a pretty sad & sorry state when I bought it, had been neglected for a lot of years.  Spent a month at Buchanan's getting the major jobs sorted so I could daily drive it & I have been working through the rest at a steady clip.  The torque tube is stacking up to be the next big job it would seem so I am very interested in your progress.

[Kelly]

Ahh very nice.  I can't wait to here what you think of them.  Lot of money but allegedly the cats whiskers of bearings.  Are you fitting 3 or 4 bearings to your tube?   You're ahead of the game with your 951 TT not needing the extra work securing the seam in the S2 TT.  I've got to find me one of those!!

4 Bearings. I'm on a bit of an anti vibration trip at the moment, so I've taken to addressing a few contributors, primarily because the vibrations in a bare track car seem more pronounced.

[Kelly]

Ahh very nice.  I can't wait to hear what you think of them.  Lot of money but allegedly the cats whiskers of bearings.  Are you fitting 3 or 4 bearings to your tube?   You're ahead of the game with your 951 TT not needing the extra work securing the seam in the S2 TT.  I've got to find me one of those!!

Yes, I am just loving my car.  It's a cracker for my first Porsche & it's definatly given me the bug. I've been amazingly lucky to find a member up here who has generously helped me with lots of work.  My car was in a pretty sad & sorry state when I bought it, had been neglected for a lot of years.  Spent a month at Buchanan's getting the major jobs sorted so I could daily drive it & I have been working through the rest at a steady clip.  The torque tube is stacking up to be the next big job it would seem so I am very interested in your progress.

Yeah, there is always something to do. I had the engine and transaxle out of my car a few weeks ago, kind of wishing I'd done the TT then.

[Jason E]

4 Bearings. I'm on a bit of an anti vibration trip at the moment, so I've taken to addressing a few contributors, primarily because the vibrations in a bare track car seem more pronounced.

My thoughts exactly.  Given you pay about 580us for 3 & 680 for 4 I say go the extra mile.  Plus Black Sea's blurb state that 4 bearings will assist in vibration dampening.   

Yeah, there is always something to do. I had the engine and transaxle out of my car a few weeks ago, kind of wishing I'd done the TT then.

Same same, we just did the clutch a couple weeks ago & it would have been the perfect time.  Of course as my car is a daily it starts to get hairy the longer the car is off the road.  And the last thing I wanted to do was tie up my mates shed with my half dismembered car so I took some holidays to do the job so we could do it in a couple days & I wouldn't be desperate for the car to get to work.