I enjoyed re-reading the 944 article. One question, though -- how is a "torque tube" (which, as described in the article, connects the engine to the rear-mounted transmission) any different than a "driveshaft"?
Rob
-
July 14, 2008 10:16 a.m. ZOOMiata Dork
-
July 14, 2008 10:34 a.m. racerdave600 New Reader
The driveshaft runs through the tube, a ridgid metal tube of about 4 inches or so in diameter. It has bearings in it which support the drive shaft. I'm sure it helps sfiffen the chassis, but it makes the bearings supposedly unserviceable, although there are ways around that.
I probably should start another thread with this, but I just changed the throttle cam on my 944, and it is the single best mod I've made to any car ever. Totally transforms it!
-
July 14, 2008 10:37 a.m. JG Pasterjak Production/Art Director
They essentially do the same thing, which is to transfer rotation from the engine to the wheels, but since the 944 shaft is upstream of the trans, it's rotating at engine speed. It's also enclosed in a tube so it's not exposed to the elements. So "torque tube" is just a fancy name for "engine speed synchronous fully enclosed power transfer shaft." or some such thing.
jg
-
July 14, 2008 10:38 a.m. JG Pasterjak Production/Art Director
racerdave600 wrote:
I probably should start another thread with this, but I just changed the throttle cam on my 944, and it is the single best mod I've made to any car ever. Totally transforms it!
Yes, that too. Never would have believed it if I didn't do it myself. I never though that something that doesn't make a car faster could make it so much better.
jg
-
July 14, 2008 10:51 a.m. amg_rx7 New Reader
what article?
-
July 14, 2008 10:55 a.m. Tim Baxter Online Editor
From the online articles section of the site: http://grassrootsmotorsports.com/articles/porsche-944-profile/
-
July 14, 2008 12:00 p.m. 16vCorey Dork
racerdave600 wrote:
I probably should start another thread with this, but I just changed the throttle cam on my 944, and it is the single best mod I've made to any car ever. Totally transforms it!
Sweet! I was thinking of getting one of those, but I wasn't sure if it really did that much.
-
July 14, 2008 1:06 p.m. ZOOMiata Dork
I'm not an engineer, so forgive me for my ignorance. Does that mean that the shaft in a torque tube spins faster than a driveshaft at any given RPM (that is, the engine RPM equates to the speed of the tube's rotation)?
-
July 14, 2008 1:50 p.m. mistanfo Dork
The shaft would spin at the same speed as the engine. So, in non-overdrive gears, it would be spinning faster than a driveshaft. In OD gears, it would be spinning slower.
-
July 14, 2008 2:21 p.m. bludroptop Dork
mistanfo wrote:
The shaft would spin at the same speed as the engine. So, in non-overdrive gears, it would be spinning faster than a driveshaft. In OD gears, it would be spinning slower.
I thought it was before the transmission??
-
July 14, 2008 3:04 p.m. Nashco Dork
It is bludroptop, he's comparing it to a standard trans/driveline setup...sometimes it will be spinning faster, sometimes it will be spinning slower, depends on the gear when comparing standard to 944/torque tube setups. Another way of saying it is that a torque tube driveshaft will never spin faster than the engine, while a driveline will spin many times faster than the engine in service.
Bryce
-
July 14, 2008 4:38 p.m. Dan G Dork
Torque tubes are serviceable. The bearings are just ordered from a bearing supply house and the plastic/delrin spacer thingys are made in group buys occasionally.
http://www.clarks-garage.com/shop-manual/trans-05.htm
The reason for the torque tube is to rigidly connect the engine w/the trans without using the chassis. Methinks if you relied on the chassis you'd be going through engine and tranny mounts pretty often. Think of the torque tube as just a really long and skinny bellhousing, and the driveshaft as a really long transmission input shaft.
-
July 14, 2008 4:43 p.m. AngryCorvair HalfDork
the shaft inside the torque tube spins at engine rpm. it's just a really long transmission input shaft. the outer tube itself has three functions:
- component locator
- torque reactor
- amputation preventor
when a car with a traditional driveline is at rest, the driveshaft is not spinning. when a 944 is at rest, if the engine is running and the clutch is engaged, the input shaft is spinning, which is one good reason why it is inside a tube.
