Can someone tell me what's the difference in a sway bar thickness do?

 

Sure. When you go around a curve, the car has a natural tendency to lean out, as though you would fall over. The bar uses downforce on the outside wheel to create upforce on the inside wheel, keeping the car more flat in the turn. A thicker bar increases the ability to do so.

 

That makes senses, thanks for the information. So what would be a good sway bar 1"?

 

Yeah, on a 64-66, if you go beyond 1", the suspension probl'y gets harsh. I have a 1" on mine, and it's still a pretty decent ride.

 

Listen to 2+2GT........ I have the 1 1/8" front and 7/8" rear and it handles great like its on railroad tracks but sure is a harsh ride!

 

I put a 1" on my 64.5 and I really like it. Really cuts down on body roll and the ride is not noticeably harsher. The 1" was supposed to be temporarily on 64.5 until 67 painted. Now I am torn because I like it so much on the 64.5. My 67 does not roll much because it has higher spring rates.

 

Stick with the 1"!!!!!! I don't get ANY roll and its great for the track but a little hard on the street.

 

I didn't find the 1" hard at all w/ standard 65 mustang springs.

I guess you are running GT or stiffer springs.

 

So if i get a 1" front sway bar is there any type of new springs, shocks that I should get as well or just some performance onces will work?

 

Unless you have something specific in mind, just get the stock GT springs, and something like KYB GR2 shocks. I use the Gas-A-Just, but some find them too stiff. I removed a set of Konis when I installed them, so they feel pretty soft to me.