[Supras] [Bulk] Help! New vibration MKIII Supra Turbo - at 72mph+ post mechanical work

[Bob Shapton]

Sure sounds to me like a driveshaft issue. I would try to find/borrow a good 
used driveshaft and swap it out to see if it makes a difference. If it were a 
front tire issue you would feel it in the steering wheel and it would improve 
by swapping tires front to back.

Bob

> A new problem has appeared after my new mechanic 'fixed' my car:
> 
> 
> (a $9k repair including intake manifold gasket replacement, new
> hoses, new
> struts, balljoints, 4 new Goodyear Eagle tires, AND a drive shaft
> rebuild):
> 
> Now has a new Vibration that is worst above 72MPH that causes the
> front
> seats to vibrate more than the rear seats (judged subjectively by
> placing my
> hand lightly on the seat behind and comparing it to the driver's
> seat.
> 
> Noisy humming sound reminiscent of that of a slightly muffled ship's
> engine
> room.
> 
> Shifting the Automatic overdrive off/on  does NOT affect vibration
> frequency
> (although engine RPM changes between 2500 to 3000RPM+)
> 
> The full story:
> 
> As some here may or may not recall, I am the lucky original owner of
> a 1990
> Supra Turbo which I plan to keep indefinitely.
> 
> After researching repair shops here and elsewhere I found a repair
> shop here
> in Northern California with a ASE certified mechanic that appears to
> be
> top-notch and with whom I quite happy: honest and fairly meticulous,
> the
> rare kind.
> 
> "While I was there" they replaced the struts and front ball joints
> (said one
> balljoint was dangerously loose) and bought four new tires because
> they said
> the bad strut and balljoint had caused uneven tire wear and I didn't
> want to
> replace just two.  Also had them check the driveline because a
> Toyota dealer
> had previously told me I needed a new U-joint.  My mechanic had the
> drive
> shaft rebuilt at an outside shop.  I had the mechanic check the
> compression
> and it was fine (No blown head gasket = good, I've already had two
> in the
> past).
> 
> When I picked up the car, it now idles fine, but I immediately
> noticed an
> excessive vibration which worsened about 72MPH. This was a new
> finding. I
> immediately called them but I had to meet an appointment so I
> returned the
> Supra the next day.  The shop admitted that the mechanic had not
> driven it
> at freeway speeds after the repair, and was very apologetic for
> letting it
> out of the shop with this vibration.
> 
> The mechanic removed the driveshaft and sent it back to the
> rebuilder.
> When it came back, they put it back in, the mechanic drove it again
> but it
> still vibrated so badly they sent it back. This time, the shop owner
> states
> that the driveshaft rebuilder (for $100) 'cut the rubber out' and
> replaced
> it (or something to that effect) and when the driveshaft was
> replaced, the
> mechanic drove it again and said it was "about 80% better".
> 
> I spoke with the owner of the shop this afternoon, but the mechanic
> was not
> available.  The owner explained that the mechanic thinks it might be
> the
> rear bearing of the (automatic) transmission which is a little loose
> (which
> would fit with where I noticed that the vibration appears to be
> coming
> from), and that it might require a whole section to be replaced if
> the
> individual part is not available.  Reading between the lines it
> sounds like
> the shop owner thinks my mechanic is too "anal" (his words). Now the
> shop
> owner wants me to drive the Supra to see if it is 'good enough' or
> at least
> back to what it was prior to the repair.
> 
> I had never noticed a vibration before, the car was quite smooth
> before and
> I regret letting them mess with the driveline, although I have no
> reason to
> doubt that the rear bearing was indeed bad and that the U-joints
> needed
> replacing.   And I know from experience with a prior old clunker car
> that
> vibrations seldom get better with time and in fact, like an
> ill-fitting
> shoe, become more and more annoying.
> 
> Within the last 4 years I have had the tranny rebuilt so I am loath
> to do
> more than it needs unless I have to, but I don't want this
> vibration.  I
> asked him if the driveline rebuild shop they patronize does not
> warrantee
> their work, and he explained that my mechanic was "anal" and they
> wanted my
> opinion before they pursued it further.  I let him know that I am a
> very
> picky customer and unlikely to be satisfied with 80%, as the car did
> not
> vibrate before, in fact it ran smoother at speed than it did at idle
> (due to
> the intake manifold leak causing over-rich fueling).
> 
> I did a quick search of my saved Supras.com list postings and found
> very
> little on this subject, but there was a post about U-joint phasing,
> which I
> know from experience with another vehicle that this can happen, but
> I doubt
> that is the case with my mechanic because he is compulsive and a
> perfectionist and unlikely to have got that wrong.
> 
> Currently, I plan to test drive it but I already warned the shop
> owner that
> I am unlikely to be satisfied with a 20% increase in vibration.
> 
> Any advice regarding front drive line vibration appearing after a
> driveshaft
> rebuild is welcome.
> 
> Thanks in advance,
> 
> Dell
> 
> PS - the shop did a nice courtesy detail and had the rear tinting
> replaced.
> Now if I could just stop the mid-front vibration and the rear
> hatch
> squeaks....
> 
> PPS Also would like to discuss possible causes of decreased power
> (catalytic
> converter clogged from over rich fueling?) and best possible way to
> convert
> AC to R134 system which DOES NOT LEAK!!!  I'm tired of every spring
> having
> to recharge my system or worse.
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