Ken's SLC build thread

Rich - I think we'll have to agree to disagree on this point. I believe the lugs and lug nuts are plenty strong enough to take the load of the vehicle's weight in addition to whatever impulse and weight transfer is going on at that joint.

Almost every SLC running stock wheels is doing it the same way, one way or another. As I said, as far as I know, every Forgestar wheel delivered with an SLC came with a plastic insert to align the wheels. I've done this wheel installation method on a Mustang that I used to track and I've been doing it with the SLC so far. My experience with those plastic rings is they deteriorate and fail with heat and can't take any kind of load anyway. They're there strictly for alignment purposes, not load bearing.

If the vehicle's weight load is constantly orbiting around the wheel as it rotates then you've got a loose wheel.

No hubcentric wheel is an exact fit to the hub, it's a loose fit in all cases so it's semantics as to how much "loose" is. Otherwise you'd have to heat the wheels up in order to install them. Or bang them into place, neither of which is a good solution.

Not to discount your experience, but I suspect your experience with loose wheels was driven by factors other than hubcentric vs non.

For the purposes of this discussion I'm defining hubcentric as a wheel that is closely matched, but slightly oversized, in diameter to the hub.
 

Johan

Member
GT40s Supporter
I must agree with Cam, if 5 studs can’t hold he load, one plastic centering ring will not do job eighter.
I’m not using mine eighter, just pay attention when tightening the lug nuts to center the wheel.
 
Personally, after doing some investigating a few years ago on the subject I came to the conclusion that the hub centric feature of a rim supplements the 5 studs ability to retain the wheel if undue stress is applied. I've never heard of a OEM manufacturer not using a hub centric wheel. You can argue that a factory wheel isn't an interference fit to the hub so it really isn't hub centric but I believe even though there is a slight gap the feature will still help save the studs from shearing due to a high load. For street cruising I don't see an issue but for any kind of high performance/high speed use I would never use a non hub centric wheel. I kept finding instances of wheels flying off after the studs snapped on cars used on track that were multi fit wheels (non hub centric). I would definitely recommend using the rings and buying a spare set to change out in the future as they degrade. I just looked to see if aluminum rings can be purchased and unfortunately they can't be made in a less than 4mm difference between ID and OD. (72.56 vs 70.3)

Looks like I'll have to re think using Forgestar wheels for my next steet/track car.
 
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I just emailed Forgestar to ask why some are hub centric and others not.

They replied back that previously RCR put in a order for some that were made hub centric. They are currently only sold/made with hub centric rings.
 
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Drop gears (1.04) are currently being installed in the V10 Graziano at Heffner Performance. I purchased a new Audi R8 gear shift assembly and OEM cables from Bernardi Parts. HCF provided the drop gears and a Kevlar lined clutch and flywheel cut for a LS9 bolt pattern. Purchased some M16x1.5 banjo and straight fittings for 8AN hose to make a loop or to feed a Setrab transaxle cooler. Also a M12x1.5-3AN banjo fitting and bolt for the clutch. Five liters of Redline MT90 oil was bought from E Bay. Now I'm broke for the rest of the year....lol :rolleyes:

https://www.summitracing.com/int/parts/rus-r4058c/overview/
https://www.summitracing.com/int/parts/rus-r40516c/overview/
https://www.summitracing.com/int/parts/vpe-11535/overview/
https://www.summitracing.com/int/parts/vpe-16626/overview/
https://www.summitracing.com/int/parts/urr-brc287/overview/
https://www.ebay.com/itm/Red-Line-O...s/181879973897?hash=item2a58e42809:rk:24:pf:0
 
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It took some going back and forth to adjust everything by myself, a second set of hands would have been very helpful. Not sure the fancy pinor drill bit are all that necessary - just leave the gearbox in neutral, then adjust your cables so the shift lever is in the neutral position within your gate (if you're using one of the gated options). IIRC you don't really have the ability to change pivot ratios so your throw distance is whatever bottoms first, the gate or the gearbox. If you're using the RCR non-gated mechanism then you have total freedom to bias neutral wherever you want so long as you've got enough throw to engage the box without first hitting the shifter assembly. The R8 mech has a plastic piece that the lever bottoms on.

With the non-gated shifter the part I struggled with most was getting enough left/right motion to properly engage reverse and 5th/6th while still having the preferred neutral position I was shooting for. In the end I tossed all that when I went with the R8 mechanism.

My Graziano came with that funny looking plastic/rubber/spring end but I removed it in lieu of using a metal rod end at both the gearbox and shifter ends. I added a couple of washers to take up any axial slack and installed the circlip to retain everything.

I know Johan got the factory Audi cables and is probably using factory-everything, might be good to hit him up on how he installed and adjusted things if that's the route you plan to go. Procedure is probably like me - set the gearbox in neutral, adjust cables to center lever in gate, good to go!

Incidentally if you plan to stick with the RCR supplied cables (on an SLC anyway), one of the cable housings needs to be adjusted to max length and the other to min length to get it all to work well if using a simple piece of angle to hold things in place.

Deets on my mods/install here:
https://socalslc.com/2018/01/02/24-oh-shift-did-i-just-do-that/
 
Thanks for your insight Cam. I probably would have gone with the RCR gated shifter but for us guys with the higher hp engines and the need for a non stock clutch I couldn't justify buying the "completion" kit and then having to buy a second kevlar clutch and then the need to sell the OEM clutch.
 
Ken - totally agree, go with the clutch that's going to work for your application.

At the time I was calling around, the cheapest new assembly price for the R8 unit was ~$1400 from AudiUSAParts.com; prices seemed to fluctuate over time (I had been tracking for a month or two). I think Stephen located a used one from Germany at a significantly lower cost. Whichever way you go, definitely go with a gated shifter. Nice thing about the R8 unit is it's a 1-handed operation to disengage the reverse lockout. I'm guessing the RCR version requires a second hand to disengage the lockout while maneuvering the lever with the other.
 

Johan

Member
GT40s Supporter
Ken, I can just confirm what Cam says concerning cable adjustment. I have the stock R8 cables (Audi all the way) and it took 15 minutes max to adjust them, going one turn at a time until it was perfect. I would suggest to go with the R8 cables, if not you have to modify the forward cable connection since it is a small ball at the lower end of shifter.The length of the cables is also perfect.
 
I collected some parts for assembling the rear axle shafts. I bought a set of the torque washers (12) and bellville type of cup washers (24) with serrations. The bellville washers were sourced from McMaster Carr and I was suprised to see they were from the OEM Porsche supplier "Schnorr". This type of washer was used by Porsche and is superior to split lock washers.

Schnorr washers (100 for $13). https://www.mcmaster.com/93501a031

Schnorr washers from Kartek (more expensive-24 for $12) https://www.kartek.com/parts/porsch...ribbed-lock-washer-for-38-cv-joint-bolts.html

Here is a one of the cheapest prices on the torque washers. https://www.kartek.com/parts/porsch...its-any-108mm-cv-joint-sold-individually.html

IMG_2404.JPG
 
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