Vibration

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Jayro

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73 mustang baby blue with clevo 351
Hey guys,

So the car has so vibration issues and was told the trans support needs replacing. All good and happy to swap them over. As you can see the new one doesn’t have straight edges and instead has a big curve in the mid section stopping it from fitting.

Any ideas?
 

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73 Grande will undergo three phase build process. Phase 1 is to make roadworthy. Phase 2 is interior/exterior restoration. Phase 3 is ++ performance.
I’m old, but I remember turning the mount 180 degrees because it wouldn’t go on. But that was an AOD trans, so I don’t know. What trans are you having the issue with?
 

Jayro

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I’m old, but I remember turning the mount 180 degrees because it wouldn’t go on. But that was an AOD trans, so I don’t know. What trans are you having the issue with?
Cheers mate. Just an inexperienced mustang owner here that was doing it wrong 🤦🏻‍♂️
 
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1971 Mach 1, Grabber Blue w/Argent stripes. Original 2V 351C Auto, Tilt, rear defog, Black Comfortweave Interior. Under restoration. Original colors, 4V 351C, 4-Speed, Spoilers, Magnums, Ram Air. All Ford parts.
I found that my vibration from 50 mph up was an out of balance driveshaft. Mine actually had no balance weight on it. Getting that balanced now.

Kcmash
 

RGunter

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1971 Mach 1 - 351c 2v - FMX transmission
Hi everyone. I have a 71 Mach 1 also with a bad vibration. I just had the engine and transmission rebuilt. Before I did that I had no vibration. Now I have a significant one.
I have had the driveshaft balanced so I don’t feel like that is the issue.
But I am interested in the mention above about the transmission support. How might that cause a vibration?
I am out of ideas and it’s bad enough I worry it is damaging the transmission and/or the rear end.
Thanks for any thoughts.
 

Jayro

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Hi everyone. I have a 71 Mach 1 also with a bad vibration. I just had the engine and transmission rebuilt. Before I did that I had no vibration. Now I have a significant one.
I have had the driveshaft balanced so I don’t feel like that is the issue.
But I am interested in the mention above about the transmission support. How might that cause a vibration?
I am out of ideas and it’s bad enough I worry it is damaging the transmission and/or the rear end.
Thanks for any thoughts.
Like wise mate, mine didn’t have a vibration until new motor went in. The transmission support has certainly reduced the shaking around but still a terrible shutter through the front on the car from a stop position until i get underway at maybe 30mph 🤷‍♂️
 
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71 429CJ
I would look for metal in the oil by simply pulling dipstick and putting some oil from the dipstick on my thumb and index finger, look at it in the sun. If you see sparkles, next step is cut the oil filter open and spread the element apart.
If you don’t see obvious metal in your oil, my next step would be to pull the distributor and look at the gear wear pattern. I would double check the distributor gear was installed at the correct shaft position.
I would also double check drive shaft install and think about having the balance checked again.
A bad or improperly installed torque converter will also cause the vibration.
 

RGunter

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1971 Mach 1 - 351c 2v - FMX transmission
I would look for metal in the oil by simply pulling dipstick and putting some oil from the dipstick on my thumb and index finger, look at it in the sun. If you see sparkles, next step is cut the oil filter open and spread the element apart.
If you don’t see obvious metal in your oil, my next step would be to pull the distributor and look at the gear wear pattern. I would double check the distributor gear was installed at the correct shaft position.
I would also double check drive shaft install and think about having the balance checked again.
A bad or improperly installed torque converter will also cause the vibration.
There isn’t any metal in the oil. I checked that. But interesting thought about the torque converter because I had the transmission rebuilt at the same time. It’s the original FMX transmission.
 

InjectedMach

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2011 Grand Sport Corvette
2008 Toyota Tundra Crewmax
There isn’t any metal in the oil. I checked that. But interesting thought about the torque converter because I had the transmission rebuilt at the same time. It’s the original FMX transmission.
Yes it may be original but they use rebuilt torque converters which are sometimes bad, the converter could also not be fully engaged when bolted in and could also have the wrong flexplate or harmonic balancer. It sadly could be internal if the rebuilder used new pistons. It could also be a vacuum leak, a misfiring plug and a host of other stuff. Start with the small stuff first.
 
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73 Grande will undergo three phase build process. Phase 1 is to make roadworthy. Phase 2 is interior/exterior restoration. Phase 3 is ++ performance.
Yes, both sound like they could be a simple ignition problem, vacuum leak, etc that could cause the engine to shudder, which feels like a vibration issue. Get one of those diagnostic manuals and start from the beginning and work your way. Those are more likely than a bad torque converter, driveshaft, etc. Even something simple like two plug wires are on the wrong cylinder; don’t ask how I know. 😳
 

RGunter

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1971 Mach 1 - 351c 2v - FMX transmission
Yes it may be original but they use rebuilt torque converters which are sometimes bad, the converter could also not be fully engaged when bolted in and could also have the wrong flexplate or harmonic balancer. It sadly could be internal if the rebuilder used new pistons. It could also be a vacuum leak, a misfiring plug and a host of other stuff. Start with the small stuff first.
Thank you! That sounds like a good thought.
 

RGunter

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1971 Mach 1 - 351c 2v - FMX transmission
Yes, both sound like they could be a simple ignition problem, vacuum leak, etc that could cause the engine to shudder, which feels like a vibration issue. Get one of those diagnostic manuals and start from the beginning and work your way. Those are more likely than a bad torque converter, driveshaft, etc. Even something simple like two plug wires are on the wrong cylinder; don’t ask how I know. 😳
Thank you! I will start with the smaller things and work my way through it.
 

RGunter

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Like wise mate, mine didn’t have a vibration until new motor went in. The transmission support has certainly reduced the shaking around but still a terrible shutter through the front on the car from a stop position until i get underway at maybe 30mph 🤷‍♂️
Good luck. Thank you for letting me share your post! Have a good week!!
 

steves73

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73 rusty convertible
Is the vibration based on car speed or engine speed? Test by going a certain speed but in different gears. Mine was engine speed, the transmission mount rubber insulation was gone, so the natural V8 harmonic was transmitted directly.
 

Bill Perkins

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I suggest getting the driveshaft completely rebuilt. I had a vibration for years and it was my driveshaft that needed complete rebuilding
 
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B1
I second the DS balance. Just had a new one made from a “reputable” local company. Seemed good initially, and within 200 miles both the spot welded on, original style weights were mysteriously missing?? I thought the vib had increased and I was correct.
Had same company….(questionable logic) rebalance and replace weights. Curiously the replacement weight is of significantly larger pieces and quite a bit more…???
Unfortunately I still have a minor/annoying vibration starting around 50 and going up from there.

Not a confidence inspiring experience…….
 
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