LaBelle

I`ve always had a small vibration in the car, and it is evident even in Park or Neutral. My mechanic has tried three different flexplates and two different torque converts in front of the FMX tranny.. and different combinations of flexplates and converters.. WE even have a new harmonic balancer on front of engine. We are scratching out heads now. The engine is not the culprit as it is newly rebuilt and runs very smooth with the tranny removed.

So,, any ideas?

69mach1377

351w or c?
Correct balance of 28 oz?
Would you think P or N would be the same as no trans attached?
Maybe post in tech section for better coverage?

Mustangdemon67

check the u joints to make sure all the pins are in there and standing up straight. also check the rear seal on the transmission tail housing where the driveshaft yoke goes in.

mechanic58

I suspect you have an engine balance issue - running it without the transmission attached isn't really a good way to make your determination. Try installing the trans without the torque converter installed (or just disconnected and slid back clear of the flex plate). The engine/trans really needs to be mounted as it would be normally in order to diagnose this properly. In my experience over the years, I have had more issues with balance on Ford engines than any other make. I think its mainly attributed to the shear number of different parts Ford made for all their engines over the years. It's very easy to build one that's out of balance when you're starting from scratch and gather parts from all over the place.

Also - if you happen to know anyone with any connections to industrial vibration analysis, you might find someone with the equipment that can diagnose this problem definitively. It would only take about a minute to find the problem with even a cheap vibration analyzer.

LaBelle

I`ve always thought it was an imbalance issue. I tried a harmonic balancer first which didn't help one little bit. Anyway,, I find out in a few days whether we fixed it or not.
Stay Tuned .............

LaBelle

Well, after several months of trial and tribulations,, we finally resolved the problem. As stated earlier, we had tried several flexplates and torque converters to get rid of the vibration. My mechanic had given up , so it was up to me to find the solution. I ordered another flexplate and torque converter from MU. The flexplate was the correct one this time but the torque converter was the right one. So I returned that one, (still waiting for the credit memo, btw ) and got a Hughes torque converter from Summit. Meanwhile, I had the drive line checked for straightness and rebalanced , replaced the new tranny mount from MU with the old one since it was still good, and a bit shorter than the one from MU. had new motor mounts installed. Then I went back to mechanic with the new torque converter and begged him to install it. Two days later,, I test drove it,, and IT`S FIXED !!!!! So, after several months of messing around with different flex plates, tc`s, and every possible combination, and several thousand dollars, I finally have a driveable car.

Gun Jam

that doesn't really make sense.....

So what it was a flex plate and torque converter issue the whole time??? But you threw 3 bad flex plates and/or torque converters at it and they were all bad in the same manner as to produce the same issue??????

It was the motor mounts the whole time then is what Im reading......

-Gun

LaBelle

Nope, not the motor mounts, tranny mount, driveline, harmonic balancer, either. I disconnected the belts to eliminate pumps, alternator., Tires were trued and rebalanced and rotated.
Getting the right parts from MU was a hit or miss deal. Summit seemed to be more accurate on their parts as they have been in the past for my chevys and mopars.
I ve been a hot rodder since the mid 60`s,, so I ve been around the block a few times, That's why this one was a bit more difficult to solve than most of my other cars.
Like my tranny guy says,, NOt all torque converters are created equal.

Gun Jam

so it really was 3 bad TCs?

bummer luck dude but I glad you finally got it dialed in.

Tracking down vibrations can be a real pain....I have a post on here somewhere that's like 30 pages long dealing with tracking down a driveline / trans vibration on a T5.

It took like 8 months but we finally more or less eliminated it.

-Gun

69mach1377

Link to this thread please?
I'm having a similar issue I think.