Chris Kennedy
Member
Well, I am delighted to report that I finally solved the wheel shimmy problem with the TCP Rack and Pinion (Manual) unit in my '65 289.
To make a very long story short, what I did was a sort of "staged" test, in which I made changes/checks/corrections to separate components and then determined what the effect was before moving on. First, I checked (for the umpteenth time), the tightness of all front end components, wheel bearings etc etc etc., and also added TCP's billet tie-rod connectors. All was fine, though I set back toe-in slightly. No difference. Next, the TCP manual units place more stress on the u-joints than the power units do, and I had some play in the upper u-joint. I was pretty certain this was NOT the problem (for reasons I won't go into here). Instead, what I did was research u-joints, generally, and found that both Borgeson and Flaming River manufacture a vibration dampening u-joint. This u-joint uses a special plastic/rubber type of bushing internally which functions much the same as a rag joint in dampening vibration and kick-back through the system. Frankly, I always felt that the TCP unit transmitted far too much kickback over broken pavement and bumps, so even if this didn't help with the shimmy I figured it would help with the kicking back and sharpness. Well, the Borgeson vibration dampening u-joint was great, and it took the nasty edge off the steering kick, AND it allowed me to isolate the problem. Basically, after the Borgeson joint was installed, I noticed that the shimmy was really related to road surface: In other words, when you went along certain road surfaces, the "shimmy" was really a cyclic/harmonic type of vibration, not a balance problem, as some sections of road at same speed were fine, then as the surface changed it would start. This reminded me that I did not remember having the problem until I moved up to 225 60 15 tires on the front (I run this size on the back with no problem, and had been experimenting with moving up from 205s in the front). So, what I did was go back to the 205s on the front, and, voila, the problem stopped. I have driven the car hard a little over 250 miles this last week on all the bad surfaces in blinding Texas heat, and the most I get is an extremely mild "nibbling" feel only very rarely, not the shimmy at all, and the car has never felt this good. I am going to let TCP know of this, as I think that their unit tends to amplify road vibrations generally, and that they should consider some additional engineering work and selling vibration-dampening u-joints as part of their kit OR as an extra (I also think it is not acceptable to put customers through all this---I suspect lots more people than will admit have similar problems with these units). Also, for anyone considering buying a TCP unit, you may want to go with power instead of manual, as this should avoid u-joint wear and help absorb any vibration. One additional benefit of going back to the front 205s is less steering effort and strain on the system and the tires fit better in the fender wells (and are still plenty beefy looking). Also, get one of these vibration dampening u-joints. I got mine through Jeg's for $113.00. The entire steering system now feels much better and more "factory"----by "factory", I mean it simply feels well and completely engineered, not like the Mustang factory steering.
Regards,
/s/ Chris
To make a very long story short, what I did was a sort of "staged" test, in which I made changes/checks/corrections to separate components and then determined what the effect was before moving on. First, I checked (for the umpteenth time), the tightness of all front end components, wheel bearings etc etc etc., and also added TCP's billet tie-rod connectors. All was fine, though I set back toe-in slightly. No difference. Next, the TCP manual units place more stress on the u-joints than the power units do, and I had some play in the upper u-joint. I was pretty certain this was NOT the problem (for reasons I won't go into here). Instead, what I did was research u-joints, generally, and found that both Borgeson and Flaming River manufacture a vibration dampening u-joint. This u-joint uses a special plastic/rubber type of bushing internally which functions much the same as a rag joint in dampening vibration and kick-back through the system. Frankly, I always felt that the TCP unit transmitted far too much kickback over broken pavement and bumps, so even if this didn't help with the shimmy I figured it would help with the kicking back and sharpness. Well, the Borgeson vibration dampening u-joint was great, and it took the nasty edge off the steering kick, AND it allowed me to isolate the problem. Basically, after the Borgeson joint was installed, I noticed that the shimmy was really related to road surface: In other words, when you went along certain road surfaces, the "shimmy" was really a cyclic/harmonic type of vibration, not a balance problem, as some sections of road at same speed were fine, then as the surface changed it would start. This reminded me that I did not remember having the problem until I moved up to 225 60 15 tires on the front (I run this size on the back with no problem, and had been experimenting with moving up from 205s in the front). So, what I did was go back to the 205s on the front, and, voila, the problem stopped. I have driven the car hard a little over 250 miles this last week on all the bad surfaces in blinding Texas heat, and the most I get is an extremely mild "nibbling" feel only very rarely, not the shimmy at all, and the car has never felt this good. I am going to let TCP know of this, as I think that their unit tends to amplify road vibrations generally, and that they should consider some additional engineering work and selling vibration-dampening u-joints as part of their kit OR as an extra (I also think it is not acceptable to put customers through all this---I suspect lots more people than will admit have similar problems with these units). Also, for anyone considering buying a TCP unit, you may want to go with power instead of manual, as this should avoid u-joint wear and help absorb any vibration. One additional benefit of going back to the front 205s is less steering effort and strain on the system and the tires fit better in the fender wells (and are still plenty beefy looking). Also, get one of these vibration dampening u-joints. I got mine through Jeg's for $113.00. The entire steering system now feels much better and more "factory"----by "factory", I mean it simply feels well and completely engineered, not like the Mustang factory steering.
Regards,
/s/ Chris
