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89 Porsche 944 racing with vibrations HELP!!! (Read 1323 times)
944chicago
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89 Porsche 944 racing with vibrations HELP!!!
Apr 13th, 2020 at 3:36am
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OK! So i purchased a 89 Porsche 944 turned into a racing car not much updates with some pretty good vibrations so I decide to replace the old motor mounts which had 80 thousand on them still oem so the vibration stopped big difference. The engine has racing headers no cat straight down pipe to a muffler the exhaust system barely movies its pretty tight on the rubber hangers. Is this the cause why the vibrations could be coming from? also the shifter vibrates maybe bad trans mount? or worn clutch any ideas
  
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OhioTom
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Re: 89 Porsche 944 racing with vibrations HELP!!!
Reply #1 - Apr 15th, 2020 at 3:27pm
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The single biggest issue for excessive vibration is a poorly timed balance shafts. It can be tricky to get them timed properly and there are several ways to get it wrong. 

try removing it and see if it gets better....
then you will know if it was helping, or hurting....

I had the same issue on my car. I got so frustrated with it, I took my pocket knife and cut the balance shaft belt and just pulled it out one day.
I knew then that my problem was shafts out of time.
Found that someone had installed the lower balance shaft sprocket indexed wrong. So the timing marks were off. (easy to do).
Once I got that all figured out, I put on a new balance shaft belt and been smooth ever since.
  

Tom Simpson&&VW/Porsche freak.
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944chicago
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Re: 89 Porsche 944 racing with vibrations HELP!!!
Reply #2 - Apr 16th, 2020 at 2:09am
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That's the first think I checked the timing everything seems good. You still think I should just change the balancing belt ?? when I purchased the car and i replace the old ass motor mounts. Usually the trans mount they don't go bad . But something is puzzling me there is a LSD tranny in this car which I think is causing the problem with the gear ratio it doesn't belong in this car. Mostly lsd fit turbo's and 968
  
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Dave W
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Re: 89 Porsche 944 racing with vibrations HELP!!!
Reply #3 - Apr 17th, 2020 at 5:20pm
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It is EXTREMELY easy to do the balance shafts incorrectly.

If the timing marks on the shafts are the same, then it is wrong.

Read the instructions very closely and pay attention to the 2 different stamps which are used.

Then ponder why Porsche didn't just use 1 mark and move the reference tab for the lower shaft...
  

Dave - black 84 no longer exists. Sad 83 self destructed. All better now. Smiley
... Let's go hit some twisty roads! ...
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944chicago
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Re: 89 Porsche 944 racing with vibrations HELP!!!
Reply #4 - May 29th, 2020 at 4:14am
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I checked the Timing everything is freshly dont by the proper marks the engine still shake not so bad I changed the motor mounts and still. Any other idea's what else can cause this hopefully not the clutch or flywheel
  
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Re: 89 Porsche 944 racing with vibrations HELP!!!
Reply #5 - Jul 13th, 2020 at 1:17am
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Let’s start differently

When do you get the vibration? Is it at idle? 2000 rpm? 3000 rpm? 4000 rpm? 5000 rpm? 6000 rpm?
10 mph? 20,30,40
1st gear, 2nd gear, 3rd, 4th, 5th
Sitting still, going straight, left, right
Steady state speed, accelerating, decelerating
Heavy acceleration, light acceleration
Under braking
  

1988 Celebration Edition
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PierreM
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Re: 89 Porsche 944 racing with vibrations HELP!!!
Reply #6 - Aug 8th, 2020 at 9:59am
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Hi,

  I heard about that some vibrations are coming from the radiators, as the rubbers don"t make the job to limit the inconvenience. If it can help...

best regard,
PierreM
  

1988 - 944 Celebration
1989 - 911 Carrera
2007 - Cayman S
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PierreM
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Re: 89 Porsche 944 racing with vibrations HELP!!!
Reply #7 - Aug 8th, 2020 at 10:03am
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or so because of the wheel balancing, but I imagine you have already looked, another idea about a violent emergency kick that could have caused a flat on the tires
  

1988 - 944 Celebration
1989 - 911 Carrera
2007 - Cayman S
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