another vibration problem
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another vibration problem
Posted: May 11 2004 07:59 PM
 
John Byrd (aka jcbyrd) [ View ] [ haliberty@gocats.uk.com ] [ Car Ads ] [ Blogs ]
Liberty, Kentucky
 
I have a 1939 Chevy with a 1979 305 sbc and turbo 350 trans. The car has a harmonic vibration in park, neutral or in drive going down the road. I have installed a new balancer, motor and trans. mounts and tightened the torque converter to flexplate bolts. Vibration comes in at about 2500 rpm and does not seem to get worse as them rpm's increase but just keeps a steady off and on pulse. What could it be? I have been told it may be the torque converter out of balance. Is that possible? What are the other possibilities? Thanks.
 
 
Comments
 
Posted by Crazyhorse Rod Shop  -  05/11/2004 06:04 PM
there aint a whole lot on a motor that will cause harmonics. they ar caused by rotating weight. my vote would be for changing the conveter ...after you've removed belts and sadisfied yourself it's not a pump. may even have the wrong flexplate.
dont poke the porchdog........he bites [ View ] [ Email ] [ Blogs ] [ Car Ads ] BLUFF DALE, Texas Charter Member since March 2003
 
Posted by gman0046  -  05/11/2004 12:47 PM
I once had a similar vibration in a new 67 GTO. I thought it was the water pump. The dealer said it was the torque converter. Went to pick up the car after they had changed the torque converter and they were in the process of changing the water pump. I said , I guess it was the water pump after all. They replied no, it was the torque converter but we're changing the water pump as a precaution. Yeah right. Just thought I'd mention it.
gman0046 [ View ] [ Email ] [ Blogs ] [ Car Ads ] Anchorage, Kentucky
 
Posted by jcbyrd  -  05/11/2004 07:59 PM

Thanks for all the input. I will try running engine with the belts off to see if it makes a difference. The motor and trans was out of a 1979 Malibu and were put in the car at the same time.

jcbyrd [ View ] [ Email ] [ Blogs ] [ Car Ads ] Liberty, Kentucky
 
Posted by DTW  -  05/11/2004 05:48 PM

I have seen cars where the alternator caused this - the fix was a different length belt - yes I know, I didn't believe it till I tried it either. Try running the engine with no belts for a few moments.Does the flex plate match the engine? Early 305s were internally balanced and later (86 up I think) are externally balanced and have a flexplate with a built in balance weight.



DTW [ View ] [ Email ] [ Blogs ] [ Car Ads ] MILLINGTON, Tennessee
 
Posted by REBORN55  -  05/11/2004 01:18 PM
Have you tried running the engine for a short time with the belts off--this would eliminate water pump, alternator,etc. Sometimes the flexplate and torque convertor are indexed. Have you tried rotating the convertor to a different position. Also it may be exhaust in a bind. Try loosening the exhaust a little and run the engine at 2500 and let the exhaust settle and then retighten. Hope this helps.
Ken [ View ] [ Email ] [ Blogs ] [ Car Ads ] De soto, Illinois
 
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