How have you decided the vibe is coming from the driveshaft and not the
halfshafts? Driveshaft vibe is usually present below 60 mph. How about
taking off the halfshafts (at the diff) and just running up the driveshaft
to 60 mph? Or, better yet, take everything down to the driveshaft shop
where they can rebalance everything. Have you done a runout test on the
driveshaft to see if the diff explosion put a corkscrew curl in the
driveshaft? ( have seen it happen ) Exchange front and rear tires, see if
ANYTHING changes. Check the runout on the trans output shaft flange. same
for the diff input and output flanges.
Don't be pissed with the list. You have a tough problem here, as
'vibration' can be caused by almost anything. You've done some of the
investigation already, but you will have to design some experiments to
isolate the offending component(s)
Good luck.
Bob Westerdale
-----Original Message-----
From: Aribert_Neumann@magna.on.ca [mailto:Aribert_Neumann@magna.on.ca]
Sent: Wednesday, April 05, 2000 10:21 AM
To: triumphs@autox.team.net
Subject: I have a small bone to chew with the list
On Sunday I posted a question about the driveline vibration in my car that
occurred after I swapped diffs. I have been under-whelmed by the quantity
of
responses. Considering the depth of responses to what type of water to use
in
the radiator a few days ago, I am a bit miffed. I understand and accept the
fact that no one is obligated to respond to any posting. Maybe, because I
listed the type of vehicle in the heading, other listers with different
types of
vehicles deleted the message without reading or did not bother to chime in
for
lack of specific knowledge. Or because my posting was long (I tried to list
all
the actions and self diagnoses to date) some just ignored it. I am certain
that
the depth of mechanical knowledge on this list is sufficient to diagnose and
propose solutions. Public thanks to: "Toad" who responded to my posting
(yes
the yokes are aligned correctly) and to Dave T. who commented that his GT-6
suffered the same problem when using a 4.11:1 LSD diff, unable to resolve
the
vibration with a rebalanced shaft and the vibration went away with the
substitution of a 3.27 diff.
I am reposting in hopes that others can provide some insight. One final
thought, after I posted the first time, I plan on dropping the front of the
engine and raising the rear trans mount as much as possible to reduce the
non
parallelism between the mounting flanges of the trans (OD actually) and the
diff. I hope to reduce the non parallelism by 2 or 3 deg - that still
leaves me
with up to 6 deg on nonparallelism.
FWIW, I use TAP water in my radiator (and also in the battery - but let's
not
start a thread on this)
I have a severe drive line vibration. Vibration starts at about 60 mph
> and becomes severe at 65+. I have tried to drive thru the vibration,
> speed wise I got up into the low 70s but the vibration kept on getting
> more intense and I was concerned that I might be heading to a
> catastrophic failure if I continued to increase speed to drive thru the
> vibration.
>
> Background: I blew apart my GT-6 diff last Fall and installed one from
> a Spit parts car. While I had the diff out I also replaced the u-joints
> in the driveshaft. While replacing the u-joints I noticed that the
> driveshaft was one spline out of phase at the slip yoke. I had had a very
> minor, subtle driveline vibration and I expected the phase correction
> would improve my car. The severe driveline vibration manifested itself
> after the reassembly.
>
> I have removed the driveshaft from the car and checked the u-joints for
> binding or play and there is none (I put about 500 miles on the new
> u-joints last Fall). I rechecked the driveshaft for phase - u-joint/yoke
> alignment - using a straight edge to make certain that the slip yoke end
was
> aligned with the shaft yoke. I also compared the phase alignment with the
> shafts of two other cars to make certain that my memory of u-joint/yoke
> alignment was correct. I have checked the shaft for missing weights
> and any sign of handling damage when I had it out of the car - none
> observed. Finally I put an angle indicator on the two driveshaft mating
> flanges on the trans and the diff. THe axis of both are pointed
> downward (approx. 4 deg) when looking at the car in side view. From
> memory are not the two mating flanges required to be parallel (in other
> word if one is down 4 deg then the opposite surface would have to be up
> 4 deg)? Unless the Spit diff uses a different front mounting bracket,
> there is no way that I could shim either the trans mount or the front
> diff mounts (up) to get the two driveshaft mating surfaces
> parallel. One final observation, I had installed the driveshaft
> backwards with respect the the slip yoke end (when compared to the
> illustration in my Bentley's manual) but it had been installed backwards
> for the previous 6 or 7 years (ever since I converted over to an OD
> trans) without a problem.
>
> Last thought, I previously had a 3.27:1 diff and now I am running a
> 4.11:1 ratio. The driveline now has to spin approximately 25% faster to
> achieve the same road speed - could it be that the vibration was there
> all along but I never got up into that rotational speed? Fastest that I
> have ever driven the car (with the 3.27 diff) was in the low 80s mph.
>
> HELP (please).
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