Aribert,
I cannot speak for anyone else on this list but myself. The reason that I did
not post an answer or suggestion to solve your problem was that I did not have
one. You need to understand that your GT6 is a rather unique beast (I know
because I used to have one). Some problems/conditions that may manifest
themselves
in a GT6 just don't happen in Spitfires or the "larger" TRs. Rest assured that
if, in the future, you have a question that I have an answer for, I will gladly
post it.
Hugh Barber
Hollister, CA
'73 TR6
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>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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