Upgraded front wheel bearings - SKF X-Tracker
Cliffs Notes version: The SKF X-Tracker style front wheel bearing / hub assembly for the STS-V (part number 930537) will fit on the CTS-V, and is probably a good upgrade for those who track their cars.
Full story: Last year a guy on another automotive forum I frequent PM'd me about a upgraded front wheel bearing assembly. Apparently, SKF had a new design on display at SEMA in a 6-lug variant, so this guy had contacted SKF to find out what the story was. Their response was...
Apparently, SKF was tapped by GM to develop wheel bearing/hub assemblies that would survive on the STS-V. Here's some info from SKF's webpage about the resulting X-Tracker wheel bearings, and a PDF that has similar info. You can see there are some pretty significant improvements in rigidity of the bearing/hub assembly. While I can't say I've had any issues with pad knock-back, it certainly can't hurt to have stronger/better wheel bearings, particularly on a car that sees track time on sticky R-compounds.
Originally Posted by SKF email
At the time, I had just replaced both front hubs with Timken units, so I filed the above information away for future reference. A couple months ago, during a pre-track day tech inspection, the tech at Lindsay told me I had a just a little bit of play in the passenger front bearing, so I went looking for the SKF hubs.
I was under the impression that the STS-V and CTS-V used the same knuckles/hubs/brakes, but when I looked up the part numbers through gmpartsdirect.com and rockauto.com, they showed different numbers. I don’t have the OEM part numbers handy, but the SKF part numbers were quite confusing. They showed the CTS and STS used the same bearings (930298 front and 930081 rear), which would seem to confirm my initial impression (that the parts were compatible). Both of those parts were shown to have a “flange offset” of 1.66”.
Confusion started to set in as I looked at some of the other STS/STS-V part numbers. First, there were 2 different rear 6-lug parts listed, one for the STS-V (930539) and one for a non-V (930458). A 6-lug non-V? The non-V part had that same 1.66” flange offset, but the V hub assembly showed a 2.67” offset. Hmmm, that doesn’t make sense… Double .
When I looked at the CTS-V part numbers, I saw (as expected) the same 1.66” flange offset for front and rear (930313 and 930368, respectively). But the front STS-V bearing (930537) was listed with that same weird 2.67” flange offset. All of the pictures of the bearings looked essentially the same, so I couldn’t see where that extra 1” of flange offset was supposed to be.
In the end, I decided to just go ahead and order the X-Tracker bearings for the front of the STS-V (930537) from rockauto.com. I figured if there really was a 1” difference in any of the dimensions, it would be readily apparent, and I would just return them if they weren’t right for the CTS-V. As you’ve probably already surmised, in the end the X-Tracker hubs fit on the CTS-V just fine. I think I might have a picture at home of the SKF X-Tracker STS-V hub assembly sitting next to the Timken CTS-V hub assembly just to show that the dimensions are the same. I just sent an email to SKF through their "Contact Us" page asking what the "flange offset" measurement is supposed to be, and to clarify whether the 2.67" vs. 1.66" thing is a mistake in their catalog. We'll see if I get any response.
I don’t have any data to show that these bearings are better than the non-X-Tracker assemblies. However, the 5-lug variant is apparently the hot ticket for the Vette guys that open track or race on sticky tires. I also don't know if the rear X-Tracker bearings (930539) will work on the CTS-V, but I'm pretty sure they would.
One final note – How do you know whether a bearing assembly is an X-Tracker, say if you’re shopping for another vehicle? Well, I don’t know. When I was researching these parts just a couple of months ago, when you called up the “Attributes” for each bearing, below the dimensions it also listed “X-Tracker: Y or N”. Now that’s gone. I don’t know why that line is no longer there. Perhaps they’re transitioning all of their bearings to the X-Tracker design, so they no longer need to differentiate them?
'05 Stealth Grey CTS-V, Hyper Silver Linea Corse Venetos w/Continental ExtremeContact DWs (summer), black Team Dynamics ProRace 1.2 wheels with 275/35-18 R-compounds (track), Hyperblack Rota Torques (winter), KW Variant3s, V2 front brakes, Hotchkis rear sway bar, EPS cam, TEA-ported 243 heads, FAST92 intake w/LS2 TB, JBA Camaro/G8 1-3/4" shorty headers w/JBA cat pipes, Corsa exhaust, UUC motor and tranny mounts, UUC shifter, MAPerformance trailing arms, Specter cradle bushings, etc...