Posted by Glen
on 11/7/2009, 8:06 am, in reply to "Re: Vibration"
98.77.45.121
I would get the shaft balanced before going any further; at this point it is an unknown quantity. It may be fine but, but you WILL be very upset if you chase your tail around only to find out that the shaft IS the problem after all 
.
Also realize that a lot of shops will just check the runout & calculate the amount of weight needed, and/or spin it at low speed. These shafts are long (and, depending on the shaft you have, several are large diameter), and they don't take much imbalance to get them jumping around. Eventually the tailshaft housing will crack, then the real bad stuff happens...
The "whine" may or may not be related, but if you have followed all the recommendations so far, I think you would have discovered something by now.
Hang in there, you'll get it...
Glen
--Previous Message--
: The drive shaft is refurbished but not
: rebalanced. Ouch-I had a sneaky
: feeling I should have rebalanced the
: shaft. What else could it be in the
: rear end? I do hear a bit of a whine
: when I accelerate at highway speed but
: assummed that was the engine.
:
: --Previous Message--
: Well that's actually good, it rules out
: everything from the gearbox output
: forward, but, conversely, everything
: aft is suspect...
: Which type slider is on your
: driveshaft?
: Is the replacement shaft
: new/used/rebuilt/balanced?
: Please excuse my paranoia about the
: driveshaft but I have many
: horror-stories about imbalanced
: Spit/GT-6 driveshafts...
: Glen
:
: --Previous Message--
:
: At speed on the highway, vibration is
: there but feel it more on acceleration.
: At 75+ vibration is constant and
: doesn't diminish until I coast to below
: 60- even with the engine idling.
: --Previous Message--
:
: Hmmm... how 'bout when you're running
: along in top gear, steady throttle,
: during the vibration period, or is it
: only under acceleration?
: If it is there at steady speed, does it
: go away immediately if you just pop it
: into neutral and let the engine come
: down to idle, while the car is still in
: this speed range?
: Glen
:
: --Previous Message--
: Test results from the commute this
: morning. Vibration worst in 3rd and
: 4th gear at 3-4,000 rpms when
: accelerating. Not really evident in
: 1rst and 2nd at the same rpms. It
: doesn't stop until I hit 50 mph or so
: if I push the clutch in and coast when
: the vibration starts. Seems like a
: feedback vibration so I am wondering if
: something is loose in the rear end (the
: front end is tight).
:
: --Previous Message--
: OK... is there any vibration when it is
: in neutral ie no-load, hot or cold?
: Glen
:
: --Previous Message--
: Compression was checked when we ported
: out the engine- is fine. Another
: possible clue, vibration is worse
: before the engine is warmed up.
:
: --Previous Message--
: It might be good to do a compression
: test
: if you have not done it yet.
:
: --Previous Message--
: If it pulls cleanly & makes good
: power, it's likely OK. If you were
: losing a cylinder it would make a
: vibration... but you would feel the
: loss of power.
: Glen
:
:
: --Previous Message--
:
: I don't think any questions are stupid
: when it comes to triumphs.
: (particularly-why did they design it
: that way?) Question for you- how can I
: tell if it is a missfire? The engine
: has plenty of power. It does idle a
: tad rough- RPMs move up and down a bit.
: --Previous Message--
: OK a stupid (maybe not) question...
: could
: this possibly be an engine misfire
: induced vibration that you feel?
: Glen
:
:
: --Previous Message--
: Some success, the steering rack was bad
: and has been replaced, the rest of the
: front end is tight and checked out
: fine. The "hopping" is gone.
: Vibration on the highway is down
: substanially and the car tracks well
: now. However, there still is some
: vibration, particularly when
: accelerating, that I can feel
: "through the seat" and the
: gas pedal- not so much through the
: steering wheel. The drive shaft has
: been replaced already. Anyone have any
: other thoughts? It would be nice to
: get the car vibration free.
:
: --Previous Message--
: Have you tried swapping the wheels
: front
: to rear/rear to front, see if it
: changes?
: Also is there ANY change in the engine
: "smoothness" in that RPM
: range with no load ie neutral?
: If the gear lever is not shaking, and
: there is no seat-of-the-pants vibe or
: "drone" from the rear of the
: cockpit, the driveline is likely OK.
: If there is wear in ball joints, t/r
: ends, trunnions, rack mountings, etc,
: it doesn't take too much imbalance to
: get a vibration going, ultimately
: resulting in the steering wheel
: shimmy...
: Glen
:
: --Previous Message--
: Hi Glen- It's a vibration I can feel
: through the wheel and the accelerator
: pedal. The gear shift lever is fairly
: stable. It is worse when accelerating
: at the wrong RPMs as mentioned.
:
: --Previous Message--
: Couple questions,do you get the...
: Gear lever "buzz"?
: Steering wheel shake?
: Scuttle (dash & cowl) shake?
: Also always consider the opposite
: diagonal corner when trying to isolate
: suspension issues...
:
: --Previous Message--
: Thanks to all who commented previously.
: I replaced the drive shaft in my gt6.
: Tires are balanced, new shocks,
: trunnions greased, new bearings.
: Vibration is better but still exists in
: 3rd and 4th gear at 2800 to 3300 RPMs.
: Seems to eminate from the right front
: and is worse when accelerating. May be
: connected but have an issue of the
: front end "hopping" on hard
: right turns at slow speeds when
: accelerating.
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