FRporscheman

It doesn't need to be a luxury car for rattles and noises to pose a threat to the mechanical health of the engine. Vibrations can cause pickup tubes to crack, among other problems. Rattle sounds have to be coming from somewhere, because something is hitting something else, and you can bet there is wear being caused there.

Scott, Horizon Blue is awesome and I need to give mine more love. BTW it may look nice in my avatar but I'm sure if you could see it in person you'd be put off by all the rock chips and stuff. I'm sure your cab would blow me away!

Here's some pics of the 968 TT slot. The slot is covered by a kind of foil strip, I peeled off half of it to reveal the slot.

FRporscheman

Update. I think the remaining vibrations are due to bad motor mounts! I had just assumed that the mounts were good because the service records show they were replaced recently. But I am beginning to believe that dealerships blatantly lie on receipts and that I should not fully trust the dealer records. I'm going to measure the MMs this weekend and change them if needed.

Also, I eliminated one rattle by lowering the exhaust as far as possible on the hangers. I usually keep the exhaust as high as possible to avoid hitting the road or debris... but now I know one rattle is a heat shield.

fortysixandtwo

The slot shown in the TT will allow it to twist a little. This is probably to help absorb a torsional shock load to the TT.
This is not something I've heard of, just what I see from an engineering perspective.

FRporscheman-
What did the new S2 dampener cost? I've thought about adding one to my 968 engine thats using a 951 flywheel/clutch

FRporscheman

I ordered from sunset, and to be honest I don't remember the exact amount. I guess the brain supresses traumatic memories... but it was over $300. I think it was like $330...?

RajDatta

Ironically, that slot is not there in some torque tubes. This could be something that was on either eariler or later cars but not something that was all across all torque tubes.
I have seen and have a tt in my cab without this slot.
Raj

FRporscheman

Interesting! Your '94 has no slot while my '93 and '95 have it. Maybe it's a coupe/cab thing? I suppose the unslotted TT is "stronger" and gives the cab more "structural rigidity"... I put those in quotes because I don't really believe that but it's possible...?

RajDatta

If I remember correctly, the original turbo tt had them as well. I replaced it with a factory 968 turbo S tt.
Raj

FRporscheman

the original 968 turbo S TT had the slot? And you replaced what with a 968 turbo S TT?

RajDatta

When i bought the car, it had a standard tt and a dmf that was modified to work with 951 harness. I got rid of that setup for factory turbo S tt and clutch setup.
Raj

FRporscheman

Are you talking about your '94 turbo?
So you're saying it had a 968 TT, and you put in a 968ts TT? Sorry I'm just trying to understand.
And does the factory 968ts TT have the slot? I'm guessing it does.

968turbos2

Getting kinda thick....

RajDatta

I guess I went a little OT, sorry.
No, the factory turbo S tt does not have any slots. Its strange that some cars do and other cars don't.
Raj

C ANDERSON

MY 90 S2 HAD A SLOTTED TT BUT REPLACED IT WITH A NON SLOT THAT I REBUILT. HAD NEVER SEEN THE SLOTTED ONES UNTIL STARTED REMOVAL OF THE ORIGINAL.

ALSO HAVE THAT BOLTS IN THE COFFEE CAN RATTLE AT LOW RPM WHEN YOU LUG THE ENGINE . BEEN CHASING THAT PROBLEM FOR A WHILE CANNOT FIND ANY SHILEDS TOUCHING.

IF THE MIND REMEMBERS CORRECTLY THE RATTLE WAS THERE WITH THE SLOTTED TT BEFORE THE BEARINGS WENT SOUTH.

MY 2 CENTS WORTH

CLIFTON

FRporscheman

Who, me? DERRRR i'm samrt, really!

Thanks clifton, I mean I'm sorry you have the problem, but I'm glad I'm not the only one!

Tim968

Reading this with interest while I overhaul the TT on a '92 968 Tip, with slotted tube. [It's a Porsche patent at http://www.patentstorm.us/patents/5067582.html). See abstract from patent reading "A drive assembly for motor vehicles comprises a front power unit which is elastically supported at the vehicle body and which is rigidly connected with a rear drive unit by means of a center tube through which a drive shaft extends. The front area of the center tube has a low bending stress and is connected to the power unit. This front area of the center tube has at least one longitudinal slot which is axially limited in its length and which is arranged in a vertical longitudinal center plane of the center tube. The slot causes a reduction of the torsional rigidity while, at the same time, the bending rigidity of the center tube is maintained. As a result, the torsional natural frequency of the assembly is reduced so that torsional resonance and vibrations at the transmission line are avoided during the driving operation."

My question - what bearing centers are appropriate in the 968 Tip TT? I have them ranging from 7.5" to 19.75", as removed from the car. Any ideas? Thx/Tim.