SLC Hubs/ race worthy

I think you have a great idea. I'd say re-drill the upright for the new C7 hub bolt pattern (by re-clocking the new hub) and make a spacer, for the outboard side, the correct thickness from 6061 aluminum.

The only challenge will be to have a 33 spline stub shaft made the correct length to play nice with the existing axles. I guess a custom spacer could be used there as well if an existing stub shaft was in the market place but was a bit shorter.

I'd recommend ARP fasteners for bolting the hub on though as I just don't trust McMaster Carr sourced fasteners in a critical suspension part like that.
 
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Ron McCall

Supporter
Why couldn't you adapt the C7 bearing to the upright and then swap the outside CV on the current axle to the C7 Corvette style which incorporates the stub shaft as part of the axle?

Ron
 

Howard Jones

Supporter
After talking to a old friend who has a huge amount of experience with X Tracker hubs on SLC's I am pretty much convinced that for my use they are a satisfactory solution. They also have seamed to work well on corvettes raced for extended periods (in many cases full seasons) So this is the direction I am going in.

Ron, I am trying to reuse as much of the original parts on my car as possible and at the same time come up with a solution for others with the gen 1 uprights. Then, if possible, adapt the gen1 fix for the gen2 upright.

Adding the stub shaft to the drive shaft drastically increases the cost for the drive shafts should they need to be replaced and getting them custom made would more than likely be more difficult than getting stub shafts made as a stand alone and reusing the in hand drive shafts.

If it more cost effective to simply convert to a third type upright that would reuse most of the suspension parts on both gen types then that would also be a good option.

Keeping the drive shafts original is very important from a budget prospective.

However all of these need a stub shaft conversion to either 30 or 33 splines. 33 being the preferred number but only because this is the current style on new corvettes. The 30 spline X Tracker bearing itself is identical to the other newer 33 spline type. The difference being the speed sensor style. This is a secondary consideration as the speed signal can be generated using other methods such as using a gear (tone) ring and sensor placed elsewhere on the drive train.

Others running street only cars might be best served just using the C4 parts that come with the cars and time changing them as required (several years at legal speeds 90% or more most of the time) All four C4 bearings can be replaced for very little money in the big picture.
 
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Roger Reid

Supporter
Ken, I am suggesting using dowels to rigidly locate the adapter plate in place so that the hub is firmly located on the upright by its center indexing shoulder. Then the clamping force is provided by the three other hub mounting bolts that go all the way through the upright, adapter plate, and then fasten to the hub itself.

I don't propose bolting the hub to the adapter and then the adapter and hub as a sub assembly to the upright. This is possible due to the uniform outboard surface of the upright on the gen 1 version....
That's interesting. So the adapter becomes a spacer. That's fantastic as long as the inboard side of the upright has flat areas to accommodate the 3 bolt heads...

I would skip the C6 X Tracker hub and go right to a C7 hub instead due to how much cheaper they are as long as you can get a 33 spline stub shaft to fit and play nice with your existing axles.
I think you have a great idea. I'd say re-drill the upright for the new C7 hub bolt pattern (by re-clocking the new hub) and make a spacer, for the outboard side, the correct thickness from 6061 aluminum.

The only challenge will be to have a 33 spline stub shaft made the correct length to play nice with the existing axles. I guess a custom spacer could be used there as well if an existing stub shaft was in the market place but was a bit shorter...
I agree with Howard and Ken. Use the C7 SKF hub with 33 spline. Make a spacer the correct thickness. Re clock and re drill the upright giving you the option to go back for whatever reason. Use the original mounting holes for dowel pins to assure centering of the hub.
It's already been established that the original 27 spline stub shaft needs replacing to fit the SKF hub. There are 2 sources already listed on this thread capable of making the stub shafts, JBurer, and MyRaceShop.

So what you all are proposing sounds like a good solution.
 

Roger Reid

Supporter
On our second Gen rear uprights (like mine shown in this picture) it's too bad we couldn't just machine the stock protruding flange flat and get a special billet adapter created to take up the difference in depth and bolt pattern of the C7 hub. . My Pen is pointing to the protruding flange that could be machined off. You could supply us with a special adapter and new design 33 spline axle stub shaft. We could then take our uprights to a local machine shop to have the existing protrusion removed.
The Gen 2 upright appears to have been lightened by removing material on the outside except for the flange mounting area. This would require 2 different adapters. The Gen 2 being cored out for the raised flange area. The Gen 1 thinner and without the core out. No big problem. I'm not in favor of machining the Gen 2 upright to remove the flange (making it flat) because it is non reversible.
 
Roger yours would be consider the Gen 3. The Gen 2 had cutout pockets on the inside for weight reduction while the Gen 3 (current production) also incorporated cutout pockets on the outside. Both Gen 2 and Gen 3 had the raised flange for the hub.
 

Howard Jones

Supporter
Ken, thank you for that. I was not aware that there are two versions of the sculpted gen2-3 upright. See, you are being very helpful!
 
Ken, thank you for that. I was not aware that there are two versions of the sculpted gen2-3 upright. See, you are being very helpful!
After the third version came out builders reported having trouble installing the hand brake caliper brackets to the side of the upright due to it now being scalloped on the outside right where the bolt holes needed to be drilled. Everyone now has to reposition the bracket further inboard to get a solid section in which to drill into. They then have to make their own spacers to space the caliper back out correctly. RCR should have just made the brackets with newer bolt holes in the correct position. Fran blamed the hand brake caliper supplier but nothing was ever done as far as I know. The error continues....lol
 
Monday I am taking my rear upright (Gen 3??) to my local machinist whom I like, to get an estimate on CNCing a new upright to accept the C7 hub. My son is a mech engineer and does design work with Solidworks 3d cad program. He can 3d image the current upright and then modify it for the new hub and brake perch.
We are going to get 2 estimates, one as basically a block and then one scalloped and relieved. If feasible we would need a new stub axle to mate to the existing axle. Havent look into that.
 
I'd be interesting if you feel like sharing the cost. I'm sure we could get others to sign up as well. This may bring the cost down.

Still waiting to hear more about John Burers design proposal as well.
 
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HCF - John

Gearbox / Brake Systems
And perhaps Gen 4 here?
Lightened with threaded holes where the script was in the Gen 3.

SLC Gen4 upright?

Ken, my proposal is to make stub axles and uprights to work with the C7 X Tracker assembly - ideally it would work across all SLC configurations. Replacing bearings becomes a $600 replacement cost at full retail vs $1400 with the earlier versions of the X Tracker assembly.

I'd need sample parts in order to pin down a cost on it.

If Paul's machinist winds up being inexpensive and can produce a good product, I'm not opposed to only making stub axles. I'd need a set and any size variances from them precisely measured to avoid introducing fitment issues from having parts made separately.
Best,
John
 

Howard Jones

Supporter
I have in hand the C4 to C6-6 adapters for the front of the car. I tried the C7 hubs and they do not fit because the large diameter bearing housing continues as the same diameter and does not step down as the C5-6 X tracker hub does. Therefor it interferes with the adapter pocket.

BUT..........the good news! I talked to Summit tech line and he read the information he has from SKF regarding the apparent similarity of two hubs in their catalog. Below are summit racing numbers. Put them into summit's search engine.

1. afe-480-401001-a

2. skf-br930544

The SKF information that is provided to Summit says that the afe number is the REBRANDED for AFE Power skf-br930544 and is exactly the same thing.

Note difference in cost. I have two skf hubs on the way. Pictures and more information when they get here.
 
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HCF - John

Gearbox / Brake Systems
Howard,
What's that all-in estimated cost for the solution using adapters and sandwich plates?

Adapters + bearings in a link posted earlier in this thread were est $1200 per side.

Isn't it slightly less expensive to just make a new upright work with the less expensive C7 hubs?
Best,
John
 

Howard Jones

Supporter
John, in a perfect world the best way to retrofit the issue would be to make new upright center sections, take the old one out and replace it with a upright center designed to accept the C7 bearing at both the front and the rear. In addition the rear will need new stub shafts of the correct spline count. To avoid replacing the drive shafts as well the new stub shafts should be close enough to the original length to work.

I think this is the best way to upgrade the later cars for sure because their more complicated sculpting.

On my 1st gen car I have designed the entire brake package, cooling ducting, etc. around the old upright and I simply don't want to redo all that work. That's why I am trying to come up with a way to adapt it to the XTracker type bearing.

The good news is when I get the next set of bearings to confirm it all works together I (we) will have a demonstrated solution and cost in hand very similar to Ken's for the front.

By the way I sent his source for the C4 to XTracker adapter a email requesting information on his adapter and as yet not received a response.

At the rear, the C7 bearing does fit in the big hole. I tried that myself. So a simple plate with holes in it will work for me. Having said that I am pretty sure a simple flat adapter sandwich plate is a more difficult solution for the newer gen uprights with their sculpting. In addition in my case I cannot use the new upright caliper mounting style because it will not work with my caliper adapters.

At the front the adapters cost a bit less than $500 for both. The difference in cost between the C7 and the SKF xtracker looks like about $146 each or about $300 for both. So if the upright could be made for right at $400 each it would be a wash.

The rear is a bit more difficult because you don't have the differential in cost between the C7 and the SKF XTracker to work with. So if the plates can be made for the same $500 for a pair then that would be the bogie for the uprights. That's pretty tight for uprights I would think. This estimate would be for my car with the older uprights.
 
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I got a ballpark price for making new rear uprights from a local mom and pop machine shop here in Houston. Around $300 each for a simple slab upright with no pocketing. To reproduce the RCR upright similar to what we have with excess material removed (pocketed) he said around $360. A one caveat is that the estimates we got do not include the 4 tapped holes on the bottom and 3 three on top to secure the control arms. I told him we would do that but it occurred to me after that others may want that done and so it will be more for a totally complete upright. My car was delivered in 2015 and has the Camaro SS Brakes. For those with earlier uprights we would have to ascertain that the caliper mounting holes and surface are the same.

I intend to install the 33 spline c7 hub bearing which is the essentially the same as the ZR1/2009+xtracker hub. I ran a C7 Z06 over 18000 very hard track miles on the stock c7 bearing with no failures. You can find this bearing for around $100!

I havent dug into the fronts yet but the upright costs will be in the same ball park. I am also looking at the c7 hub for that setup. With hub the fronts could be around $500 each. I am also looking at the possibility of redesigning the upright to accept the c7 Z06 6 piston brembo caliper with the 370mm two piece rotor.
 
I'd be in for a set of the pocketed uprights. I'd even pay extra to have the tapped holes done. I'd need to buy the correct taps/drill bits anyways so it would be a wash.

My understanding is that the C7 hubs position the rotor out about 1/16" to 1/8" farther than the C6 hubs. The point being they are not identical.

Keep in mind Paul that upgrading to the C7 six piston caliper and rotor in the front might require new wheels for clearance.
 
On the rear uprights (and on the fronts also for that matter) since we are making a new upright we can position the hub really anywhere we want in 3d space. If we use the c4 hub face plane as the reference plane then we will design the mounting flange surface on the new upright to accommodate the difference in hub flange to mounting flange distance between the c7 and the c4. No sweat.

The Corvette ZR1 which appeared in 2009 had a 33 spline SKF bearing (same as the x tracker from which it was designed from) which was a change from the previous c6 bearings which were 30 spline. In 2010 this bearing was also used in the c6 Z06 and then used in the c7 corvettes beginning in 2014. The sensor changed from passive to active and on some c7 none, but to the best of my knowledge the basic hub bearing assembly is the same. I have a ZR1 hub and a C7 hub in my hands right now and there is no noticeable difference except a sensor on the ZR1 hub and no sensor on the C7. They are both stamped SKF and are dimensionally the same. The C7 is considerably cheaper. Again the x tracker bearing that goes in the pre 2010 c5 and c6s is a slightly different animal with 30 spline input.

I am working on getting a new 33 spline hub to work with the c7 hub.

Brakes in front. I am looking at the 6 piston brembo caliper and the 370mm two piece rotor.. These will fit in 18 ccw wheels. I had this same setup on my C7 Z06. Calipers are $280 on amazon for the Cad CTS version part number 25912477. Rotor is $282 also on amazon #20795300. I will keep the Camaro ss Brembos in back.
 
I went with Stoptech 6 pistons on mine. I tried the C6Z Corvette brakes but I had a mounting problem. I think it was the off set.
Ed
 
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