I've replaced the spherical bearings on my ADS coilovers several times now. I only really mentioned it the first and second times, but its become regular maintenance every 10,000 miles or so - generally about 3-4 trips and ~2 oil changes. I chalked it up to normal maintenance required on higher end shock components, but that doesn't mean it's an enjoyable process or that I like dropping the extra $60 or so each time I do it.
After talking to quite a few folks, it seems that there are several experiences and opinions as to their longevity and the right bearings to run. I don't know if any of these are "the truth," but I'll list them here in my ongoing mission to better understand my truck, and how its various parts work.
- Some have said that they see results similar to mine - replacing bearings every 15K miles or so. My thoughts: 15K miles is 50% more than I'm seeing, and generally takes others a year or so to rack up; for me, it's just a few months.
- Some have said they see wear, but that their bearings last on the order of 30K miles. My thoughts: This seems quite reasonable to me; I'd be happy with 30K miles on a set of bearings - for me, that'd be about a year of driving.
- Many have said that the brand/quality of the spherical bearing makes a difference; not all COM10T bearings are the same. My thoughts: this is likely true, and I assumed that the bearings I purchased from ADS were high quality, but who knows. My original bearings from them lasted 25K miles, but maybe they got a new supplier when I ordered the replacements. Maybe I got a bad batch.
- A few have said that the tightness of the spherical bearing makes a difference. My thoughts: I didn't even know that tightness was a thing, but apparently it is. Tighter bearings mean that the ball is sandwiched in the race more tightly, making it harder for contaminants to get in there and tear up the Teflon.
- A couple have suggested that the composition of the bearings makes a difference, and that hardened steel or stainless steel might work better than the mild steel variants I've been using. My thoughts: I'm not sure about the hardened steel, but since I think rust plays a factor in deteriorating the Teflon, it makes sense that stainless steel versions might not rust and allow it to last longer.
With all those things in mind, I started with brand. FK Bearings is by far the most reputable brand, and they have three lines of bearings that were relevant to my consideration:
- COM10T - Commercial Series, low carbon steel race, metal-to-metal, PTFE liner.
- FKS10T - Heavy Duty Precision Inch Series, alloy steel race, PTFE liner.
- FKSSX10T - Heavy Duty Precision Series, stainless steel race and ball, PTFE liner.
Further, they had three different tightness specifications as well: F1, F2, and F3, and they kindly sent me a description of these different tightness's:
I decided that if I was going to experiment, I might as well go all the way and give stainless steel a shot the next couple of times I replace them on the Tacoma. And, based on the descriptions, it was clear to me that the F1 tightness was what I should be using.
So, I ordered four (4) FKSSX10T-F1 bearings (to cover two bearing changes) while I waited for the currently installed generic (or at least unmarked) COM10T bearings to wear out. And now they have.
Note: I've since found a new (better) supplier in 303 Shock Services. I'm ordering from Tim from now on. If you don't see the bearings on the site - usually he only stocks the non-SS variants - just email or call and he can get any version to you that you're looking for. Good guy!
Replacement of the COM10T bearings with the FK stainless steel variants was straight forward - as one would expect - since these are the same part, just in a different material and from a different manufacturer. The first order of business was to pull the shocks from the Tacoma and bring them into the shop where I could pull the clips and press out the worn bearings.
A quick comparison of the new bearings in the foreground to the rust worn ones that are out of focus.
A quick cleaning of the bearing race in the shock eye, and a bit of lube to make bearing insertion easier, and it was time to press in the new bearings. Having done this several times now, it was reasonably easy and soon enough I had two new stainless steel bearings gleaming in the bottom of my coilovers.
With the shocks reinstalled, time will tell whether these higher end bearings are worth the cost difference (about 3x) or whether the harsh environment to which the bearings are subjected are simply too much for any bearing to withstand. Stay tuned!
Update: The links below for "More on Spherical Bearings" covers the ongoing saga with these little buggers. For the my "final" analysis of the stainless steel vs. non-stainless, this Rig Review is a good place to start.