[DeTomaso] Vibration in Longchamp, part 3

[Mikael]

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 [mailto:mikael_hass at mail.tele.dk] 
Sendt: 5. maj 2015 20:55
Til: 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

mikael_hass at mail.tele.dk

 

-------------- next part --------------
   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 [mailto:mikael_hass at mail.tele.dk]
   Sendt: 5. maj 2015 20:55
   Til: 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

   [1]mikael_hass at mail.tele.dk

References

   1. mailto:mikael_hass at mail.tele.dk