[DeTomaso] Oscillating vibration

[Tomas Gunnarsson]

I found a web site that explains it all and has a picture.

http://www.custompistols.com/cars/articles/ts_ujoints.htm

Tomas

----- Original Message ----- 
From: "Charles Engles" <cengles at cox.net>
To: "Tomas Gunnarsson" <guson at home.se>
Cc: <detomaso at realbig.com>
Sent: Sunday, August 26, 2007 9:48 PM
Subject: Re: [DeTomaso] Oscillating vibration


> Dear Tomas,
> 
> 
>              "Half-shafts in phase"......?     I recall hearing of this in 
> the past, but I can't remember what the heck it is.   Could you refresh my 
> failing memory?
> 
> 
>                        Warmest regards, Chuck Engles
> 
> 
> 
> ----- Original Message ----- 
> From: "Tomas Gunnarsson" <guson at home.se>
> To: <Detomaso at realbig.com>
> Sent: Sunday, August 26, 2007 12:42 PM
> Subject: Re: [DeTomaso] Oscillating vibration
> 
> 
>> Mike,
>>
>> Are your half-shaft-halves installed in phase?
>>
>> Tomas
>>
>> ----- Original Message ----- 
>> From: "Mike Thomas" <mbefthomas at comcast.net>
>> To: <Detomaso at realbig.com>
>> Sent: Sunday, August 26, 2007 6:30 PM
>> Subject: [DeTomaso] Oscillating vibration
>>
>>
>>>I have about 200 miles on my new motor, and am in the debug phase of the
>>> project.  I've had an interesting issue pop up and wanted to post it to 
>>> see
>>> if there is anything I am not considering as a potential solution.
>>>
>>> When I get up to about 75-80 in fifth gear (2500-3000 rpms), I get an
>>> unusual oscillating vibration.  I've certainly felt alignment or wheel
>>> balance vibrations before in other cars, but never of an oscillating 
>>> nature
>>> that rose and fell at a constant speed/rpm.  I am pretty sure it is 
>>> chassis
>>> related as hanging in the same rev band in lower gears does not induce 
>>> it.
>>> I checked the tightness on all 16 half-shaft bolts, and they are snug.
>>> Next, I am going to have the wheels balanced tomorrow.  If that does not
>>> cure it, I am going to have the balance checked on my new half-shafts.
>>> Other than that, I know both rear rotors are slightly out of true, 
>>> dragging
>>> a bit at one point when I spin the wheel while it's off the ground, so 
>>> I'm
>>> wondering if the drag on the brakes at that particular speed sets up a
>>> harmonic between the two rear wheels to create the oscillating effect, 
>>> but
>>> that would suggest the wheels were of a different diameter and rotating
>>> different speeds.  I had the alignment recently done and no changes to 
>>> the
>>> suspension or bumps hit to knock it out, but I guess that could be 
>>> something
>>> else to check.
>>>
>>> Any thoughts from you guys would be appreciated.
>>> Thanks
>>> Mike Thomas
>>> Panteras Northwest.
>>>
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>