[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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