pulsating vibration

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Corno
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Joined: Tue 10 Mar 2015, 08:27

pulsating vibration

Post by Corno » Mon 08 Jun 2015, 10:37

Hi

There is a pulsating vibration on my bakkie in second gear at about 70 km/h. If the transmission
(C4) change over to 3rd gear at 80 km/h the vibration in gone. The driveshaft was balanced, the transmission mounting is new and the engine and transfercase mountings still look good. The vibration is there even with the rear wheels of the ground. Any suggestion where and how to start looking?

Thanks

bmwmaniac
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Re: pulsating vibration

Post by bmwmaniac » Mon 08 Jun 2015, 19:41

has the propshaft got a centre bearing? if it does, try keep the centre bearing the same height as the yolk/coupling on the centre bearing. sometimes this requires it to be spaced.
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FPT
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Joined: Wed 21 May 2008, 09:30
Location: Bloemfontein South Africa

Re: pulsating vibration

Post by FPT » Mon 08 Jun 2015, 21:00

Check flexplate/torque converter assembly and pullyes up front.
Is it at a certain revs or only at that speed in that gear? Then it sounds drive train ie gbox propshaft related.
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Mopar 440
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Location: Roodepoort, Gauteng, South Africa.

Re: pulsating vibration

Post by Mopar 440 » Tue 09 Jun 2015, 15:45

Hazard a guess and say the prop-shaft is not balanced properly. I can tell from experience, most prop-shaft manufacturers can't balance shit.
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kavesh
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Re: pulsating vibration

Post by kavesh » Tue 09 Jun 2015, 16:32

Mopar 440 wrote:Hazard a guess and say the prop-shaft is not balanced properly. I can tell from experience, most prop-shaft manufacturers can't balance shit.

I can second that comment. I messed around doing various things to fix my vibration including having my completely overhauled and balanced prop rebalanced only to have no improvement.

Eventually a friend told me to take the prop to a shop that he trusted and guess what problem gone.

By the way it was like almost 2 or 3 years of pain and much cash parted trying to fix a simple issue. No good tradesman around anymore.

Corno
Posts: 18
Joined: Tue 10 Mar 2015, 08:27

Re: pulsating vibration

Post by Corno » Wed 10 Jun 2015, 08:24

Hi

Thanks for all the assistance. The vibration is most noticeable between 2000 and 2200 rpm while stationary or driving. It seems that the vibration match the engine speed. The problem is therefore from the torque converter forward. If I understand correctly the torque converter would cause the vibration from start up. That means that the problem is most likely the flex plate. How does it happen that the flex plate became off balance? Can it be balanced without taking it out?

Thanks

Doug Hirkham
Posts: 700
Joined: Fri 11 Jan 2008, 21:20
Location: Cape Town

Re: pulsating vibration

Post by Doug Hirkham » Thu 11 Jun 2015, 12:26

Hi Corno

If it vibrates when stationary, you can look somewhere else. Have you checked the exhaust - maybe a loose baffle in the silencer, or the exhaust manifold is not tightened properly?

Doug Hirkham
Posts: 700
Joined: Fri 11 Jan 2008, 21:20
Location: Cape Town

Re: pulsating vibration

Post by Doug Hirkham » Fri 02 Oct 2015, 15:14

If it vibrates when stationary, you can look somewhere else. Have you checked the exhaust - maybe a loose baffle in the silencer, or the exhaust manifold is not tightened properly?[/quote]

Come Corno - what was the vibration?

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