SLC Hubs/ race worthy

Rob:

Yes, the webbing for the upright (for the top bolt only) needs to be clearanced slightly for the M12 bolt (built-in flange) on the back side of the upright. Addtionally, the upright webbing needs to be clearanced slightly for the spacer (top bolt) on the front side. I simply used a high speed inline grinder with a straight burr for this process. The parts needed are the two-(2) spacers, two-(2) hub adaptor plates and six-(6) bolts. The bolts are shown below.

My chassis is from 2013 and I'm using the Camaro SS style Chevrolet brakes which were common with the SL-C at the time...

NOTE: Just because they fit with my hub parts doesn't mean that they will fit with yours... :)


BOLTS, M12-1.75 X 75 MM LONG10.9 METRICBELMETRIC.COMBFI12X75YLW
 
Tonight I started the conversion to C7 hubs for the rear of my SL-C. It’s more work / cost than the front hub swap for sure. This is what I found thus far:

I purchased the 33 spline to Porsche 930 CV joint stub axles from the driveshaft shop. These arrived with the securing nuts and also bolts for securing the CV joint to the stub shaft.

The following items have to be addressed with the RCR rear upright to modify it. You must remove the uprights for machining because the following problems exist:

1). A 0.205” thick spacer must be used between the upright and the hub bearing assembly. This is because there is a difference in total thickness of the C4 versus C7 hub assembly.

2). The outside diameter of the C7 hub is 0.030” smaller in diameter. Therefore an adapter ring or shim stock must be used to make up the difference in hub diameters.

3). The backside of the upright needs to be modified to create more clearance to the flange of the stub axle. I plan to do this in my lathe.

4). The backside of the upright needs to be modified so that the securing bolts for the hub are recessed into the upright. Otherwise the heads of the bolts will hit the flange of the stub axle. Based on my measurements you can use an M 12 x 55 mm long bolts for this.

5). Additionally the axle shafts are going to be approximately 1 inch too short. I’m going to consult the driveshaft shop on this tomorrow.

It appears that this modification will cost between $1200 and $1500 as well as a bit of time on the mill and the lathe.
 
Aaron,

# 1 & 2 can be accomplished with one part.


Ron
Yes, it can be depending on how much machining you want to do to the upright as well as adding a shoulder to the spacer / adaptor.

Ron:

This is exactly why I'm not forthcoming with my comments on this site. It's because everyone has to chime in with their $0.02. It's like Facebook for people that primarily trailer their cars. :D
 

Howard Jones

Supporter
Aaron, Thanks for adding your experience to this page about converting C4 to C7 style hubs on early generation cars. My initial reason for starting it was to group think this project. Everyone have been very helpful to one extent or the other and that's why I asked you to add your pictures etc. to the discussion.

On my car I simply ignored the very slight difference in rear hub OD ( just a bit more than your .030) after quite a bit of thinking about load paths and concluded that the important and major loads were side to side when the car corners and that the clamping forces provided by the three large diameter bolts were more than enough to cope with fore/aft bump/droop loads generated by acceleration and braking. I have seen NO issues related to this on my car to date. Frankly, the hub being just a bit smaller in OD is helpful considering that if it was significantly larger it would have created a difficult machining operation (need a mill) to enlarge it.

I used electricians' tape to wrap the OD of the bearing body to locate it before using the hub itself as a template for the reclocking drilling operation. This worked very well for me.

For others contemplating doing something like this to their car, I would add the following. As a rule, the various upright types up to the current production SLC standard C7 uprights do vary somewhat and much of the individual modifications are upright driven with different minor changes required depending on the version. Nothing I have seen so far is exceptionally difficult but may require some careful thought and possibly finding a machine shop to do some work for you if you can't do that part yourself. The rear suspension geometry is sound and none of these modifications alter it so its just a straightforward conversion but a bit more than a bolt-on.

Or you can order the current production uprights and associated parts from RCR.

Again, thanks Aaron for your input. And yours as well, Ron.
 
OK, I can finally add to this thread. I am doing the conversion to c7 hubs on my rear right now, and I think I have a generation of upright not shown in this thread yet. See pics bellow. Sorry for not rotating them, posting from my phone.

What I have looks like the flat upright with an pocket engraved in it for the raised perch the bearing sits on. This perch is removable and looks a hell of alot like the adaptor I was going to make. Bolt pattern is of coruse just off for the c7 hub, but I can make a one or two piece adaptor that sits right in that pocket, has the right diameter for the c7 hub, and clock the bearing 90 degrees.

Has anyone seen this before, or am I just blind.
 

Attachments

I thought of that, but none of the information I have shows that as a option for his order. The hub has a mark of WBI 513020 AN615/201/10 on it. 513020 googles to a timken wheel bearing. https://www.sixityauto.com/timken-513020-wheel-bearing-hub-assembly-for-400-62004-2024-2045-513020-730-0206-713020-b20x24-3096100169.html

On amazon these bearing have poor reviews...failing after 1000 miles, ect.

So if this is a racing bearing, did I just blow 550$ on c7 bearings and new stub shafts? Or should I continue with the swap.

I'm not complaining here, I really like the pocket design to the upright, makes adaptors really easy.

Bob
 

Ken Roberts

Supporter
That cross references as a C4 corvette bearing. The C7 bearing is far superior. Plus the spline count of the C4 stub shaft should be 27. The C7 stubshaft is much thicker and has a 33 spline count.
 
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Brian Kissel

Staff member
Moderator
Lifetime Supporter
For the most part from what I’ve read,MI bearings don’t seem to last long in a performance application. I bought several sets of genuine GM’s. They appear to hold up much better. I also purchased some of the C7 bearings. I am looking into another alternative also. I plan on getting a RCR T70 in the near future. Trying to plan ahead. I appreciate Thanatos Howard started this thread and it continually gets updated.

Regards Brian
 
The SKF X-Tracker C7 wheel bearings were on sale on Rock Auto last month. I thought I mentioned this when I was doing my conversion. Maybe not.. All four hubs were roughly $450 total.
 

Ken Roberts

Supporter

This company now makes a 33spline C6 hub that has a passive sensor installed. Usually the 33 spline C6 hub sold by SKF has a active sensor. MPI claims their hubs are on par with the X Tracker hub but at a lower cost.
 

Ken Roberts

Supporter
I reached out directly to Fran instead of using the [email protected] email address and have my parts on order!

Updated uprights for the Superlite SLC are $395 per corner. The new stub axles are $795/pair when ordering from RCR. Now I need to order the C6 hubs and new axles.
I may be interested in purchasing your original front uprights if you have upgraded to the new style.
 
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