Andrew and Lumps Folks:
In reading this post on vibrations, it coincidently was posted right as
I started to deal with my own type of vibration. I would first like to
address the trans mount issue to see if I don’t have a similar problem.
I used the JTR boilerplate for the trans mount. A nice heavy sucker
that I had fabricated locally. I don’t recall any rubber in that
construction at all. I am steel to steel at all 5 points, i.e.: 4
mounting bolts to the uni-body (along the tunnel) and the one bolt from
the trans through the trans cross member. I have always felt a little
tug that came apparent at the shift lever when I goose the Kat. And I
can feel a vibration in the shift lever itself as I motor along. Should
I be considering putting rubber bushings at all 5 points? And where
would one get such bushings?
Now on to my vibrations …
About 2 months ago, I started to get a vibration (feels like the front
end) that was reminiscent of a tire starting to separate tread. I have
been using “take offs” on my car, experimenting with tire size to get a
good feel (to me). Long story short, I went from 215X70, to 225X70,
back to 205X70 and felt the 205X70s gave me the best feel, sans a little
weak feeling on cornering. The latter tire size was on my car up until
yesterday. The vibration in question was only there around 55-70 miles
Yesterday, after having a new set of 225X60s put on the car all around,
I noticed that the vibration was still there. It was not so radical,
only slight, but had moved up the scale more towards the 65-80 mph
range. I am guessing that the difference in tire size height, has
changed my speedo readings a little and that it is the same problem that
is causing the vibration.
The front end is a relatively new rebuild. The car does need an
alignment but this vibration has only been there twice now, once when I
did have a tire tread separation issue and now with the new 225X60s.
And as additional information, I have always had a coming and going
issue of vibration when I brake. Sometimes there, sometimes not. Could
this be tied to this issue as well. I have replace front end disks,
rotors and calibers -and- brake master, but the cavitations in the pedal
seems to be still there. I have tested this back and forth and there is
not a steady pattern to the vibration on this issue, i.e.: braking from
different speeds, conditions, etc.
Any ideas folks? Where should I start looking.
The Arizona Leaper (76XJ12L - L82 build/700R4)
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