[DeTomaso] Vibration in Longchamp, part 4

[Larry - Ohio Time]

That's good news. Very good work!!


Larry - Cleveland


-----Original Message-----
From: DeTomaso [mailto:detomaso-bounces at poca.com] On Behalf Of Mikael
Sent: Tuesday, May 12, 2015 2:39 PM
To: detomaso at poca.com
Subject: Re: [DeTomaso] Vibration in Longchamp, part 4

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 [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