[DeTomaso] Vibration in Longchamp
Julian Kift
julian_kift at hotmail.com
Mon May 4 09:49:19 EDT 2015
Something with the final drive, likely prop shaft would be my guess too as it's speed related rather than engine/transmission. Either as Thomas suggest 'phasing' of the u-joints or you mention a longer shaft for the new transmission. Does the output flange of the AOD transmission sit at the same height as the old C6? The distance increase alone would have altered the propshaft and u-joint working angle, is there any chance it is setting up some sort of harmonic resonance? Does the vibration disappear at higher speeds?
Even if it is phased correctly, some driveshaft shops will recommend simply clocking the propshaft 180 degrees as a first try.
Is it a fast cycle vibration or a slow cycle vibration? Place a bucket of water on the passenger’s floor and go for drive. If the vibration produces small ripples on the water this would be fast cycle it is usually a drive train; driveshaft, motor or torque converter. If the vibration puts waves on the top of the water or splashes, it's a slow cycle vibration and usually an axle or tire. You can also try putting the car on jack stands and running it up, but make sure it is very well supported if you intend to run it up to 80 mph equivalent.
Julian
> Date: Mon, 4 May 2015 09:57:01 +0200
> From: thomas at hax.se
> To: detomaso at poca.com
> Subject: Re: [DeTomaso] Vibration in Longchamp
>
> If the shaft is a two piece thing with a U-joints and a slip joint,
> check that it is clocked correctly.
>
> Mikael skrev den 2015-05-04 09:34:
> > This winter I replaced the engine, trans (C6 to AOD), propshaft, rear
> > diff, all rear ujoints and bearings. All was fine until I drove it fast
> > as a test, at 80-90 mph it has a nasty vibration. No vibration below
> > that speed, all seems fine. The vibration seems to change with load,
> > but doesn't change if I use 3rd gear, so don't think it's engine
> > related.
> >
> >
> > Any ideas:
> >
> > 1. Wheels (the easy one of course, no vibration last year with same
> > wheels though, and usually wheel vibrations start at 50 mph IMO)
> >
> > 2. Prop shaft? (Brand new, built by people that don't do anything
> > else in UK)
> >
> > 3. Angles? Could it be trans/rear diff angles? What's the name of
> > the tool that measures, inclinometer?
> >
> > 4. Or?
> >
> > Right now just looking for ideas. I plan European vacation including
> > German highways, so this has to be sorted out...
> >
> >
> > Mvh/Regards
> >
> > Mikael
> >
> >
> > !DSPAM:55472123739468702045!
> >
> >
> >
> > _______________________________________________
> >
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>
>
> --
> Real life: Thomas Törnblom Email: thomas at hax.se
> Snail mail: Banvallsvägen 14 Phone: +46 18 32 31 18
> S - 754 40 Uppsala, Sweden Cellular: +46 76 209 8320
>
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>
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-------------- next part --------------
Something with the final drive, likely prop shaft would be my guess too
as it's speed related rather than engine/transmission. Either as
Thomas suggest 'phasing' of the u-joints or you mention a longer shaft
for the new transmission. Does the output flange of the
AOD transmission sit at the same height as the old C6? The distance
increase alone would have altered the propshaft and u-joint working
angle, is there any chance it is setting up some sort of harmonic
resonance? Does the vibration disappear at higher speeds?
Even if it is phased correctly, some driveshaft shops will recommend
simply clocking the propshaft 180 degrees as a first try.
Is it a fast cycle vibration or a slow cycle vibration? Place a bucket
of water on the passengers floor and go for drive. If the vibration
produces small ripples on the water this would be fast cycle it is
usually a drive train; driveshaft, motor or torque converter. If the
vibration puts waves on the top of the water or splashes, it's a slow
cycle vibration and usually an axle or tire. You can also try putting
the car on jack stands and running it up, but make sure it is very well
supported if you intend to run it up to 80 mph equivalent.
Julian
> Date: Mon, 4 May 2015 09:57:01 +0200
> From: thomas at hax.se
> To: detomaso at poca.com
> Subject: Re: [DeTomaso] Vibration in Longchamp
>
> If the shaft is a two piece thing with a U-joints and a slip joint,
> check that it is clocked correctly.
>
> Mikael skrev den 2015-05-04 09:34:
> > This winter I replaced the engine, trans (C6 to AOD), propshaft,
rear
> > diff, all rear ujoints and bearings. All was fine until I drove it
fast
> > as a test, at 80-90 mph it has a nasty vibration. No vibration
below
> > that speed, all seems fine. The vibration seems to change with
load,
> > but doesn't change if I use 3rd gear, so don't think it's engine
> > related.
> >
> >
> > Any ideas:
> >
> > 1. Wheels (the easy one of course, no vibration last year with same
> > wheels though, and usually wheel vibrations start at 50 mph IMO)
> >
> > 2. Prop shaft? (Brand new, built by people that don't do anything
> > else in UK)
> >
> > 3. Angles? Could it be trans/rear diff angles? What's the name of
> > the tool that measures, inclinometer?
> >
> > 4. Or?
> >
> > Right now just looking for ideas. I plan European vacation
including
> > German highways, so this has to be sorted out...
> >
> >
> > Mvh/Regards
> >
> > Mikael
> >
> >
> > !DSPAM:55472123739468702045!
> >
> >
> >
> > _______________________________________________
> >
> > Detomaso Forum Managed by POCA
> > Posted emails must not exceed 1.5 Megabytes
> > DeTomaso mailing list
> > DeTomaso at poca.com
> > http://poca.com/mailman/listinfo/detomaso_poca.com
> >
> > To manage your subscription (change email address, unsubscribe,
etc.) use the links above.
> >
> >
> > !DSPAM:55472123739468702045!
> >
>
>
> --
> Real life: Thomas Toernblom Email: thomas at hax.se
> Snail mail: Banvallsvaegen 14 Phone: +46 18 32 31 18[1] Call: +46 18
32 31 18
> S - 754 40 Uppsala, Sweden Cellular: +46 76 209 8320[2] Call: +46 76
209 8320
>
> _______________________________________________
>
> Detomaso Forum Managed by POCA
> Posted emails must not exceed 1.5 Megabytes
> DeTomaso mailing list
> DeTomaso at poca.com
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>
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use the links above.
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