Rubber vs poly in front suspension?

65cpe69mach1 said:

Will be rebuilding the front suspension on the65 coupe and was wondering what the advantages/disadvantages are to using polyurethane bushings instead of rubber on some parts.

Tie rods
Spring seat saddle
Lower control arm pivot
Coil spring topper (forgot the exact name)

Will be using rubber on the strut rods, don't want to break anything.
Also, this is a daily driver that will have the Shelby drop and 225/60-15 tires. I hope.

Click to expand...

Others can and will correct me, but I think that the differences come in two categories--life and ride. I was always told that poly lasts longer, but rides harder. (They may need to be lubed occassionally, I think.)

--P

From what I've heard, if you're thinking about going poly don't, go with midolyne or polygraphite. Same life, I've heard both ways on the ride quality, but the big thing: no squeak. Yes, polyurethane WILL squeak as it begins to show signs of age, it can squeak pretty badly too. I've heard many fixes for this, haven't tried any of them (I've also not yet experienced it) but you can prevent this by just going with a newer/improved bushing!

On a side note, and I know I'm going to draw fire for this, but I find it highly unlikely that a strut rod will break only because of the poly bushing.

Why do I say this? Well first off, the stock strut rod is a fairly thick piece of metal, the force required to snap one is pretty high. Now a poly bushing is not going to help matters by not absorbing much of the force. However, if you're in a situation that puts that much force on it I doubt a rubber bushing will make much difference. Second reason: when I bought my stang it had a bent strut rod. This was an old, surface rusted strut rod. If one that old would bend before breaking...well you get the point. I'm not saying they can't break, I have no doubt they can, I'm just saying a poly bushing isn't going to induce it, you'll have to be in an activity which is conducive to this already.

skywalker said:

On a side note, and I know I'm going to draw fire for this, but I find it highly unlikely that a strut rod will break only because of the poly bushing.

Click to expand...

The 65-66 strut rods are strong enough to take a poly bushing....the 67 and up simply are not due to the two step machined end that creates a stress riser, they simply snap off right where the diameter changes. You might find it unlikely but it happens and anyone who runs poly in a 67-70 is asking for trouble. The stiffer the front spring the less likely the breakage but if you run the poly strut rods with stock springs you will snap it eventually.

I learn new things every time I log on!

The Midolyne bushings are available from Canadian Mustang or American Pony (same company). This is my favorite supplier of suspension parts since most of the suspension originally on these cars came from Canadian suppliers and the manufaturers up there are still the same almost 40 years later....it is like getting original parts for your car, they are also about the least expensive place out there.