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400 TH trans mount

Old September 24th, 2015, 08:55 AM
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400 TH trans mount

Noticed a high speed vibration in floor board behind drivers seat. Nothing spectacular but noticeable. Checked bushing in trans mount on cross member and sure enough compressed and beat up. Was going to replace with original type but am looking at the after market poly units also. Are they that much better than original type ?
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Old September 24th, 2015, 10:05 AM
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I imagine the used-up one is original to the car. An aftermarket stock replacement rubber trans mount probably won't last as long as OEM, but it'll do the job. I don't see any advantage to the poly units in a typical street driving environment.
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Old September 24th, 2015, 01:47 PM
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Check your u joints too while you are under there.
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Old September 26th, 2015, 12:55 PM
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I have a polyurethane mount and have had zero problems. The material itself is just better from what i have observed. There are also cushions on the end of the trans cross mount ,by the frame ends.that break down and can cause some vibration check them also.
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Old September 26th, 2015, 07:35 PM
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2nd on checking the driveshaft, too

Mine had a slight vibration at certain speed, 65mph or so.
When I had the TH400 rebuilt I installed new tranny mount as the old one was oil soaked. I also had the driveshaft "rebuilt" with new spicers and a high-speed balance. That driveshaft work was about $150.

Now no more vibration, and I've gone slightly more than 65.
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Old September 28th, 2015, 08:56 AM
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Thanks guys . Decided to stay with OEM type. All is fine now.
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