Mark we have the same vibration (as determined from you your posted).
I got our 65mph vibration fixed. You still feel/hear a change just over 90mph but all the other odd-ness is gone.
In addition to the 65 mph shake, the Mustang was starting to get an odd feeling when driving.. Almost like it was loading/unloading the rear axle and the gear shift was really moving when you got on/off the throttle.
Soo, I attacked some of the issues on Friday...
I changed the Trans cross member assembly which comes with a new insulator. The new p/n works fine on the vehicles that came with the older style.
You can see the differences here. The old mount had a chunk taken out of the metal front an off-road incident but I think the real issue was 220k+ miles on the rubber.
photo (49) by
maniak_az, on Flickr
I also swapped out the rear shocks. They were worse than I thought.. Since they got bad over time I really couldn't remember how tight they were supposed to be. Once I put the new ones on I really couldn't push down on the rear of the car and make it move. We are using the Saleen shocks, springs and struts so they should really be stiff. I think this was the weird loading/unloading I was feeling in the rear of the car.
The last thing I attacked was the front strut mounts. I was trying to get rid of the clunking sound up front. The old strut mounts had way too many miles on them so I replaced them with a set for a 2011 Mustang gt500. These are supposed to be a much better mount. When I took the old ones off the struts they just fell apart and bearings went everywhere.
photo (46) by
maniak_az, on Flickr
Once I had all the work done I did a quick alignment (camber) and got the front tires set back to 1 degree of negative camber. I'll check it tomorrow and see if it moved some as I wanted to let it settle before I set them back to "my specs" of 0 toe and .5 degree of negative camber.
We took the car out last night and again today. The 65mph shake/feel is gone and the car feels nice and tight now. Good enough that when Yo was late this morning and hit amusing speeds on the freeway that the car felt nice and planted like it did right after we did the saleen suspension upgrade.
If I had to guess, I'd say the Trans Mount/insulator (p/n 8R3Z6068D) was the 65 mph shake and the other odd-ness was the rear shocks. I don't think the front strut mounts were causing the vibrations.
~Mark
