Message text written by "Mercier, Murry J"
>Tony,
>I have been reading the exchanges on the subject and offer the following
>FWIW. The value is less than desired since my TR6 is a hybrid with no record
>to trace origins.
I know that problem with my white one!!!
>After purchase I found a collection of drive-train parts contributing to a
>sizable speedo error (~20% fast).
I know that problem too!!!
>Speedo: 1000, SN 6411/10
>Car: '73 TR6 CF10027U
>Engine: circa '70 TR6 CC53550E
>Trans: circa '64 TR4A CT57639 with OD
>Diff: ?? TR? CD19302, 4.1?(calc from Tach RPM and radar meas. speed, @ 1,500
>rpm(OD off): Radar= 35 mph/Speedo= 42 & Radar= 29/ Speedo= 35)
>Tires: 205/70/15
>If you like I will send the Lotus123 .wk4 file with my calculations and
>assumptions which led me to believe that the rear end was a 4.1.
Yes, please do send the file. Use the oldest format possible as my spreadsheet
is an ancient version of quattro.
>After counting the number of speedo cable revs I had Bob Nisonger
>recalibrate/rebuild (odometer was broken) to closest gear (1165). I have
>yet to check by radar but a partial check with 5 mile-markers at 60 mph for
>60 sec* 5 indicates a slightly higher/fast reading.
Hmmmm. I guess you did a reading on a run on a measured road. How far did
you drive for the calibration? What measurements did you give them? The
calibration they gave you was only a 16.5% improvement. It looked like you
needed
around a 1200 calibration, and they ought to have been able to get closer
if you told them 20%. Even a "standard" 1184 would have worked better!
I wonder what gearing they used to recalibrate! 1165 is only evenly divisible
by 5..... Strange. Is 1165 correct?
>Great work on the speedo article and pictures on your web site. If I pick
>up a used speedo I will be tempted to try my hand at a rebuild, especially
>if I must change the differential. Something is vibrating and thumping. I
>will start with drive shaft u-joints and a balance then to half shafts.
No, don't change the differential! Unless you need to for something other
than the calibration. I had the same vibration. It was a nasty combination
of factors. The main thing was the drive shaft was bent and out of balance.
To reduce the vibration, I think somebody re-indexed the drive shaft yokes so
they were "misaligned", but that vibration somewhat counteracted the intrinsic
vibration. Nevertheless, there was still bad vibration that destroyed the
U-joints.
When they got loose, the vibration was very bad. I found that the drive
shaft was indexed wrong and fixed it. WHOAH!!! When I got to 60, I thought
something came apart the vibration was so bad. I fixed the ujoints and found
that the vibration was still present but reduced. I had the drive shaft
balanced
and straightened and that cured it! I think there MIGHT be s slight vibration
in one half shaft (possibly bad u-joint), but I will live with it for now.
Take your drive shaft to a "shop" with 2 new u-joints and let them
straighten and balance it, as well as do the joints. My cost was $60 for the
entire job.
I removed/reinstalled it myself.
>
>This was an interesting puzzle for a novice LBCer (never owned/drove/worked
>on any TR before Sep 97 when I went to the Summer Party to take pictures of
>cars and talk to folks... came home to buy my TR6... that is another tale)
>We are starting a new all Triumph club, Buckeye TRIUMPHS, in central Ohio
>and would appreciate permission to reprint your speedo article. We have 39
>paid members from a Dept of Motor Veh. List membership mailing (>300
>registered Triumphs in the 5-county area, >2,300 in all Ohio) and will meet
>the new members at a reception on the 20th of March.
GO ahead and print it. Just give me credit! Mainly, I want whatever
feedback they will give so I can improve the article. Also, give my
email and webpage address. That way if there are any questions I can help.
-Tony
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