I also suspect this is why Mr. Fair had issues with his previous design UCA Systems. He claimed the factory '11 has a 14mm bolt, IIRC, in his blog....but that is simply not true. Somehow he ran into some incompatibility issues with the components he chose to run - and I feel his opinion of aftermarket pieces is slightly flawed due to this - as our parts fit like a glove.
BMR is right in what he said - we
did have some mis-matched parts, and noticed the front UCA bolt size mismatch on other brands of UCA mounts and UCA arms/bushings, and knew that had to be the cause of the clunk that would ALWAYS develop with everyone else's parts. We chased it for many months and it was intolerable. A completely redesigned system that has the holes in the UCA mount and the bolt/sleeves in the UCA bushing that actually MATCH, and don't rely on the clamping of the mount to make up the difference in the slop? Well yes, that IS the right way to do it.
And what I wrote was a little misleading on the bolt sizes...
I just went out in the shop and measured these bolts properly, just to make sure I wasn't crazy and that there WAS an M14 bolt in there somewhere. The
rear UCA bolt is indeed an M14 bolt (that goes through the axle side bushing) but the front UCA bolt is an M18, which is the one that was causing all of the problems we ran into (not matching the mounts or bushings for several other brands stuff).
We tried to modify another company's UCA mount and yet another company's UCA arm to work (mixing brands here was a bad idea), and with custom machined adapter bushings, a modified mount, a new bolt, and some other machine work it
sort of worked. Eventually it would still clunk, and we traced that to the Del-Sphere bushings themselves (we kept tightening that 2-piece Delrin/metal bushing assembly but it was a huge PITA). And somewhere along the way we tore up the OEM bushing on the axle side (which we replaced with a new OEM unit). Any bind in the front UCA bushing is going to make the rear rubber bushing have to deform more, which can cause this tearing.
Eventually we just broke down and got the $700 assembly (mount + arm + spherical + properly designed bolt and bushings) from MultiMatic and it has been silent and trouble free for a long time. But $700 for an UCA assembly is a little nuts, and most people won't want the long term maintenance hassles of sphericals.
I just really liked the long bushings and how they mounted to the UCA mount, adapted to the supplied UCA arm through-bolt perfectly, and slid into the spherical bearing with less than .002" clearance. A very well engineered, but
expensive kit. The BMR UCA mount and arm might be a better alternative for more folks - the pictures they provided are promising. The fact that they make a mount and arm and bolt
that work together, and make them specific to the 2011-14 rear suspension, is good.
