Depends on the length. Many cars that use torque tubes to transfer
power to rear-mounted transmissions have no bearings in them at all.
Basically, it's a hollow tube rigidly fixed to the engine block in
front and the tranny in the rear. This means that there is NO relative
movement between the engine and the transaxel. They are connected
together as a unit, and therefore when the engine moves, the transaxel
moves, so the drive shaft CAN be a solid shaft with no splines and no
U-joints and no guibos. The drive shaft is affixed to the crank shaft
(or the clutch plate if the clutch remains at the engine end of the
driveline) on the engine end and the input shaft to the clutch or
tranny (again, depending on whether the the clutch is in front with
the engine or in the rear in-unit with the Transaxel as on the
Alfettas) in back. If the distance between the engine and the
transaxel is short enough, the actual drive shaft doesn't need to be
supported between the two with bearings at all. However, if you ever
want to get the thing apart for service, the shaft does need to be
splined on the clutch end (like the pilot shaft on any manual clutch
auto) and the other end as well. This will require that either the
transaxel or the engine be disconnected and moved away from the other
in order to uncouple the two in order to perform maintenance. Yes,
it's more trouble, but there's no rubber doughnuts to fail (and
eventually become unobtanium somewhere down the line) either.
George Graves
'86 GTV-6 3.0 'S'
On Feb 2, 2010, at 9:56 AM, Jerry in Arizona wrote:
Not knowing anything about torque tubes I did a google search. In
one discussion group the following statement was made;
"The biggest drawbacks to the TT solution are weight, complexity and
expense. They aren't as light as a standard driveline. They are
fairly complex in their manufacture and are difficult to repair when
the bearings fail. They are expensive to build or repair as well.
A torque tube is just a steel tube with a series of bearings inside
and a set of mounting flanges on each end. An extension shaft runs
the length of the tube and rides on the bearings. The shaft fits
into the splines on the clutch at the front and attaches to the nose
of the transaxle at the rear with a splined coupler."
I don't know if the Alfa engineers considered a TT, but they were/
are pretty smart guys. Too bad the book kind of glosses over the
details of the proposed vibration solutions.
Jerry
----- Original Message ----
From: George Graves <[email protected]>
To: Jerry in Arizona <[email protected]>
Cc: "<[email protected]>" <[email protected]>
Sent: Tue, February 2, 2010 9:54:58 AM
Subject: Re: [alfa] Those Troublesome Guibos
That's interesting. I believe David Owen as I have several of his
books and I know that he does his homework. Possibly, the problem
with the resonances was caused by the length of the driveline in the
Alfetta series, I don't know. What I do know is that Ferrari used
torque tubes as does the current C6 Corvette to transfer power to
the rear-mounted transmissions, so it is possible.
George Graves
'86 GTV-6 3.0 'S'
On Feb 2, 2010, at 8:32 AM, Jerry in Arizona wrote:
George Graves wrote;
"If you're building a car from scratch that will have
a shortened drive
shaft, why use the Alfetta drive shaft and Guibos AT ALL?
I'd fabricate a
torque-tube (which Alfa SHOULD have done with the Alfetta
design in the
first place) and dispense with the troublesome guibos."
I
have seen many other references to this issue, so going to my
extensive
library of Alfa related items made up of one book, given to me by
my once
teenage son, I took out my copy of Alfissimo by David Owen. Owen
discusses
the myriad of problems brought about by the decision to move the
trans and
clutch to the rear in the Alfetta. The original and traditional
Alfa prop
shaft design used in the models no had severe destructive resonance
problems
cause by caused by differing rotastion massses and the prop shaft
always
turning at engine speed. The original prototypes could not manage
more thas
6000K without the likelihood of the overloaded crankshaft being
shaken to
pieces by the vibration. Through a slow and patient development
process: the
rear prop shaft was ultimately split into two seperate sections,
linked by 3
rubber couplings to damp out the vibrations. My point being the
decision was
made rationally and for sound engineering reasons.
Not to pick on George,
but hs remarks just kind of reminded me of this discussion in Owens
book.
Using the Alfetta DeDion in another application could, of course,
change the
vibrational dynamics of the vehicle (different masses, size, weight
or
materials of the prop shafts) allowing a different configuration.
Jerry in
Phoenix
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