S197 Spring and Sway Bar Rates

[twistedneck]

I'm trying to find replacement front sway bar bushings for a 13 boss 302. It has the 34.6mm bar. All I can find is the 35mm bushings. Anyone know where to find the correct size bushings? Ford discontinued them. All of the aftermarket selection is 35mm.
Thanks.

Edit: Check the old bushings on pre 2010 cars.. looking now there was a 34mm bar back then, meaning that 34mm bushing should fit just fine and its not bonded so rate will be 7% less than the 2010+ bonded ones. But you will also need to get the matching brackets.. the cross section shown is the 2010-2014.. the first gen were slippy and had a different hump.

I'm pretty sure those were bonded on to the bar and they are not for sale without the front bar. The front assembly is made by Mubea, an excellent German company with plants here in the USA. Its not a great design with the open ears on the bracket so the rubber can squirt out and it has hysteresis when the outside of the bonded bushing slides against the inside of the bracket.. we fixed all those issues on S550. Back in 2003 when the S197 was getting designed nobody could do full rubber assemblies with preload and all that to see what was going on. I think in 2010 they started bonding them to stop noise. I remember doing research on this back in 2003 and i was able to pull data from like the 77 Tbird and some other crazy old cars that had noisy bushings, there was no fix at all for 50years! until 2013 when we designed the 2015 S550 setup.. thanks Ansys!

 

[stevbd]

@twistedneck interesting stuff, thank you. On my 2011 GT I’ve removed the oem front bar but I’ve always been interested, how much does the bonding affect rate?

 

[twistedneck]

@twistedneck interesting stuff, thank you. On my 2011 GT I’ve removed the oem front bar but I’ve always been interested, how much does the bonding affect rate?

you are welcome stevbd, bonding is about a 7% rate increase from slippy.. however slippy can wear out the center hole very fast and the bushing rate falls off a cliff.. You are allowed up to 35% rate loss after the full vehicle durability if that tells you anything. Usually you want 20-25% deg max but that's a lot more than 7% bump you get by bonding. The other stange thing about bonding is its called a parasitic rate because its not increasing the effectiveness of the bar its reducing it..example over speed bumps a normal slippy racecar system has no affect but with bonded bushings all of a sudden you are adding the wind up of bushings to spring rate!