[DeTomaso] Vibration in Longchamp, part 4
marshall smith
marshallgsmith at sbcglobal.net
Tue May 12 15:03:54 EDT 2015
Congrats Mikael!
Marshall
--------------------------------------------
On Tue, 5/12/15, Mikael <mikael_hass at mail.tele.dk> wrote:
Subject: Re: [DeTomaso] Vibration in Longchamp, part 4
To: detomaso at poca.com
Date: Tuesday, May 12, 2015, 11:39 AM
I put the IDB
(In-Denmark-Balanced) propshaft on. That used to take me
2-3 hours, but now I can do it without
removing p-brake and using small
power tools I can do it in well under an
hour, including a small nap
when laying there so comfortably looking
at the rear suspension.
And the roads got dry enough to test just
now. And the vibration is
100% gone. So the UK vendor didn't balance
it properly. That cost me
hours of work, sleepless nights, and
several $100 for balancing of
wheels, propshaft and inclinometer. I'll
write them an email...
Since my test stretch is a bit short for
80-90 mph test runs, I had to
accelerate more than usual, not full
throttle, but maybe 3/4. It spun
its wheels briefly when shifting from 2nd
to 3rd. Thanks Dan and Dave
and Monster Transmissions J
Mvh/Regards
Mikael
Fra: Mikael [mailto:mikael_hass at mail.tele.dk]
Sendt: 12. maj 2015 14:57
Til: detomaso at poca.com
Emne: SV: Vibration in Longchamp, part 3
Got wheels back, very off balance before
according to the shop, but no
change, vibration still there. Did find
out that the vibration is only
at 80-90 mph, just have to go 100 mph,
then it's fine. A bit scary
testing on 50 mph max country roads.
So took the prop shaft off to have it
balanced. It's brand new custom
made in the UK. Took it to the only shop
in Copenhagen area. The guy
immediately said: "It's a Ford yoke but
not rear a Ford flange?". They
seem to know what they're doing! We'll
see. Maybe a waste of money, but
have to keep trying.
Today I had it back. They added 30 grams
to the rear and 15 grams to
the front. And then they told me that in
the UK the balancing was not
done as well as at their shop. Well,
maybe, we'll see. Can't test until
I get dry roads, the speeds I need to get
to is for dry roads only.
Mvh/Regards
Mikael
Fra: Mikael [[1]mailto:mikael_hass at mail.tele.dk]
Sendt: 5. maj 2015 20:55
Til: [2]detomaso at poca.com
Emne: Vibration in Longchamp, part 2
So wheels are sent to get balanced (won't
leave my entire car at any
shop). And the newly bought inclinometer
arrived. Seemed like an
accurate one, $150, and very consistent.
At the diff I measured at the
flange, 0.00 degrees. At the trans there's
always a bit of looseness.
Measured with propshaft just hanging (on
yoke), 0.00 degrees (is it
"on"? J) and then with the yoke pushed up
by hand, 0.40 degrees. So
trans must be 0.20 degrees up. Does
anybody here do this for a living,
can 0.20 degrees produce a vibration?
So let's do some math here, and let me
know if I got it wrong. There's
about 115 cm from rear of trans to pivot
points (engine mounts). So a
full circle of the rear of the trans would
be "pi" x 115 x 2 = 722 cm.
With 360 degrees round, that would be 2 cm
per degree. And I would have
to lower the rear of the trans 0.20 x 2
cm= 4 mm. That I've done. Can
that really make a difference? Looking at
the old trans and mount
versus new, it looks like the new trans is
between 4 and 8 mm higher,
so maybe that's it?
Also took the chance to turn the propshaft
on the rear diff 180
degrees.
Will not be able to test for a few days,
not too optimistic.
Mvh/Regards
Mikael
Hass Consult ApS
+45 31770747
[3]mikael_hass at mail.tele.dk
References
1. mailto:mikael_hass at mail.tele.dk
2. mailto:detomaso at poca.com
3. mailto:mikael_hass at mail.tele.dk
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