SLC Hubs/ race worthy

Howard Jones

Supporter
I did PM Ron. He said if Fran was OK with the spirit of this thread then it was OK with him. Another told me that he had spoken to Fran and in a nut shell he was OK with us trying to
come up with several individual promising updates to the car in this area or something like that.

In the end if I do come up with something for sale (very small possibility on my part) I will conform with the rules and find out how to do that.

So where we are now: I have asked a friend to see about getting stub shafts made of M300 and to the same dimensions as the C4 stubbie but suited to fit the C7 bearing (33 spline). This would pretty much allow for retrofitting the rear of the car with the C7 bearing and keeping the original driveshaft length BUT the three hole bearing mounting difference between the C4 and C7 bolt circle difference remains to be addressed for the later upright versions.

The earlier slab side (non sculped) upright like mine can be simply re -drilled and every thing else should fit up including the existing drive shafts. In addition, a pretty thin, 0.2 ish wheel spacer behind the rotor would be required on my car to reuse my caliper mount (my design) and have everything line up.

So...…………. watch this space.
 
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The C7 Corvette 33 spline stubshaft uses a axle nut that takes a 36mm socket. The part number for a replacement axle nut is #11611234. The torque value for installing is 184 ft/lbs.

Paul mentioned that the nut was included in the hub purchase from a GM dealership. Mine are on order and I'll further update this post if the nuts were included in the boxs as well.

Paul did mention that the three bolt holes will be countersunk for clearance of the bell section of the stubshaft. They will all be machined like that in his first revision 1.1 with the machinist. The pictures he posted was the first test upright.
My C7 rear hubs came in. The nuts were NOT included in the boxes.(purchased from Rock Auto)
 

Howard Jones

Supporter
Ken, I think whoever supplies the stubshaft would be best positioned to provide the castle nut to suit or at least point to a source.
 

Howard Jones

Supporter
My friend was unable to supply custom length stubshaft's. At this point I think I will be going with the Driveshaft Shop pieces and modify as necessary for my car. I will order them Monday and let you all in on the process to fix my as I do it.
 
My friend was unable to supply custom length stubshaft's. At this point I think I will be going with the Driveshaft Shop pieces and modify as necessary for my car. I will order them Monday and let you all in on the process to fix my as I do it.
Howard, I have ordered new axles rom the Driveshaft shop to connect my new stub shafts. As I mentioned earlier the new C7 hub setup is about an inch shorter than the original setup so I ordered axles for both sides that are 1 inch longer. The cost was a little over $500 with shipping. Should be receiving them soon. I have installed the new rear uprights and hubs. No problems. Everything fit (amazingly enough). just need my axles then I wil be good to go.
 

Howard Jones

Supporter
I decided to re use my uprights. They are the original type with slab sides and not sculped. The C7 bearing is much stronger than the C4 original bearing but is slightly different in dimensions. The bolt circle is bigger and it will not directly bolt on so I re drilled the upright to the new bolt circle diameter after I re clocked them a bit.

Then to allow for the new stub shaft being a bit shorter and interfering with the cap screw heads I counterbored the holes. You will need a 12mm cap screw counterbore tool with a 3.5mm solid pilot and a 13.5mm drill bit along with a drill press and careful setup. CAREFULLY lay out and drill the new bolt hole centers. Start with a 1/8 inch hole, then a 5/16", 1/2" and finish with a 13.5mm. Use the 13.5 mm mounting hole for the 13.5mm cap screw counterbore tool's solid pilot and counterbore to a depth the same as the cap screw head.

You do not need a expensive cobalt counterbore tool. You are working with aluminum and the cheapest you can find will work. Go for the smallest piolet diameter you can find 12mm or larger. I used a 13.5mm solid piolet type made for a 12mm cap screw. You will also need a 13.5mm drill bit if you use the tool I did. Be aware that the cap screw is a 12mm so you will end up with a 1.5mm clearance bore for it.

I have the new 33 spline stub shafts on the way so I will come back here to show you the complete setup when they arrive.

Like this.
 

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Howard Jones

Supporter

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Howard, I have no experience with the China stub shafts. BUT....if they are anything like their trailer hitch balls.....stay away! These are known to shear off. Very costly to loose trailer and horses, etc. Not to mention danger to others on the road!
 

Howard Jones

Supporter
Ya, I have a VERY personal policy of not using the cheap version of what I call "itwillkillya" parts. I have included the full range of everything I have been able to learn about this subject. The difference in price is a good indication of what the good stuff costs. I note that all the American made high strength pieces were either chromoly or M300 steel and were all in the same price range. The Chinese piece is not even half of that. Enough said.
I used the 300M driveshaft shop stubshafts. IMHO these are the best I could find. We should all remember, if that stubshaft shears in two the wheel will come off and/or the driveshaft on that side will beat the hell out of the rear of the car. Get the good stuff.
 
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Howard Jones

Supporter
Well if that is correct they don't know about them because the only ones available from the driveshaft shop when asked are the ones Paul and I have in hand. It is my understanding that the blue 25 hour car also used them, 33 spline C7 DSS stubshaft, but maybe the people I talked to at the DSS didn't know about the 27 spline custom made ones for the SLC. In any case I don't recommend using the 27 spline stubie/C4 bearings on a track car running slicks.

Good to know Will in any case.
 
Hey guys, fantastic thread. Paul, did you receive your axle shafts? Any updates to this thread? Just replacing my first set of fronts (Delaney adaptor, SKF Hubs) putting slicks on this week and from the sounds of things I better replace the rears right away as well.
 

Howard Jones

Supporter
I spent some time trying to figure out the best way to relocate the rotors due to the the C7 bearing being shorter than the C4 by about .24". In the end I decided to just remove material from the rotor hats by that amount. This approach puts the rotor right back where it was without using spacers behind them. The last three weeks have been spent finding a machine shop that would do such a limited volume.

Thank you: New Braunfels Machine.
 

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I have sent my stock rear uprights to a machine shop to be modified. Each of the three mounting holes get slotted by .0915". The large center hole of the upright then gets a thin bushing pressed in due to the slightly smaller diameter of the C7 bearing hub pilot. I then made a .190" thick spacer for each one to take up the thickness difference between the C4 and C7 bearing. The 33spline stub shafts are on order. Once I get them assembled I'll take my final measurements from the inside to see how much longer the axle shafts need to be.

The first picture shows the two spacers I cut out of .190' plate 6061 aluminum.

The second picture shows one of the spacers installed on the mounting flange (I'm pointing to the spacer on the C7 wheel hub. You can see that the C4 and C7 hubs are now the same thickness. Now the new C7 hubs will be located the correct distance from the upright when bolted up. The measurements were within .005" of each other. (2.165" vs 2.160"). I'm probably going to powder coat the spacers to help prevent galvanic corrosion.

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