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So really bummed here (and pissed )....
I just started my BBK upgrade to J56 setup from my current Z51 on my 2005.Prior to this I did a ton of research and chose a set of wheels I was told by the owner of the company would clear my BBK's (J56/willwood/brembo)....I purchased these from a forum vendor as well (florida speed shop). I found C7 Z51 in my needed 18/19 sizes so i literally just swapped my tires (new PSS's) onto them.
well...guess what the first wheel I started - rim doesn't clear ! Rim makes direct contact on caliper when lugs fully seated...GRRRR
I did some research and looks like MotorSport Tech (http://www.motorsport-tech.com) makes a hub centric option so I can still get the rim on the hub to avoid vibration, etc.
Anyone with experience/other vendor, etc??
FYI - I will be adding new SS lines ?(in the image below I stopped install when I got so mad at the wheel not clearing...)
the C7 wheels I purchased in my sizes of 18X8.5 and 19X10 (same offsets of +56 and +76)
everything bolts up as it should for the caliper and rotor to my Z51 spindle
OEM rubber line is too stressed, as mentioned I have SS lines I will install
Just go with wheels spacers, nothing wrong with them and the wheels will be less tucked in, which is a good thing imo. Stock offset is WAY too conservative! A lot of guys use spacer on stock wheels! Will looks bada$$ with more agressive fitment.
Last edited by timmyZ06; Nov 29, 2015 at 08:11 AM.
So I did run up to AutoZone and got a 5 Lug 1/4' spacer knowing it won't fit, but I wanted to get it to see what a 1/4' spacer would look like on the hub..it does look like with the correct size spacer for the C6 I will still have enough meat on the hub to get the rim to sit and thus avoid any vibration...now the question is will I have enough thread engagement...I would like to not have to replace all my studs...worst cast some extended thread lugs I can live with.
I called MotorSport Tech yesterday and spoke with the owners father (he was fielding internet orders). He told me call up tomorrow and speak with his son as he's well positioned to speak to the C6 and the possibility of the studs/lugs with a 1/4' spacer.
If I recall correctly, 1/4" is the max size spacer deemed "safe enough" to use with the stock lug nuts. If you want 100% complete piece of mind, go with a new hub/lugs set up. But I have been running cheap universal 1/4" spacers on my LG GT-2 wheels for a couple of years now without issue.
NHRA and IHRA both specify thread engagement must be a minimum of the stud diameter. In the case of a C6, (12mm @ 1.5 threads per mm) that means 8 full turns of the lugnut. Extended thread lugnuts only provide false security, since the extra thread is only on the tip of the cone and amounts to about one extra turn or 1/16".
When using a 1/4" spacer, even with extended thread lugnuts, the thread engagement length is about 62% of stock.
Since changing studs is such a PITA, my choice would be to get correct fitting wheels. Hopefully, you checked this before mounting tires and will be able to return the wheels.
I used et lugs on a 5mm spacer and it had more thread engagment than stock. How big of a spacer are you planning on running? I didnt find the studs too much of a pain to change with a press. It was actually quite easy. But using a vice was hell. I pretty much broke my vice pressing in my arp studs.
NHRA and IHRA both specify thread engagement must be a minimum of the stud diameter. In the case of a C6, (12mm @ 1.5 threads per mm) that means 8 full turns of the lugnut. Extended thread lugnuts only provide false security, since the extra thread is only on the tip of the cone and amounts to about one extra turn or 1/16".
When using a 1/4" spacer, even with extended thread lugnuts, the thread engagement length is about 62% of stock.
Since changing studs is such a PITA, my choice would be to get correct fitting wheels. Hopefully, you checked this before mounting tires and will be able to return the wheels.
Not sure how you figure this. On the ET lug nuts I use the extra threads are towards the inside similar to this picture.
update here - I called and had a great conversation with Lenny Jr @ MotorSport Tech - My spaces and ET lugs are on the way, may have by Friday. I will post detailed pics of fitment, etc
well I have a great update here...the spacers from MotorSport Tech came in and they are pretty awesome. My wheels fit, the ET lugs are great and I can torque them as expected
I bought a Craigslist-ed set of C7 base rims to install on my 2011 GS, hoping they'd fit over the J56 brakes. No dice...and with some jury-rigged shimming while up on stands, I perceived to need more than 1/4" of spacing.
I was aware of rim width downsizing from 9.5" to 8.5" in the front, and from 12" to 10" in the rear - as the selection of runflat all-season tires was much better in those sizes. I do commute the ~75 mile work round trip with this car a few times per week, and the better rain performance of AS tires is desired - in case a surprise rain crops up.
Titan Wheel accessories listed AL hubcentric 1" and 1.5" spacers for a decent price that would solve this. Because they're to be used with conical lug nuts, I perceive they're both hub-centric AND lug-centric. I ended up buying:
* Hubcentric - 1 inch Wheel Spacers - 5x4.75 - 70.5mm Hub Bore 100-5475-705-1215-2
* Hubcentric - 1.5 inch Wheel Spacers - 5x4.75 - 70.5mm Hub Bore 150-5475-705-1215-2
1.5" spacer
The C7 rim's center hole ended up being about 0.010" too small to fit the spacer's raised hub...just enough interference that I judged it too much to force it on. A local automotive-focused machine shop (Quinlin Automotive) had a setup to solve this problem: they bored out just enough AL on each rim center ID to fit the spacers.
I've put about 4,000 miles on these spacers, the C7 rims, and Michelin Pilot Sport AS+ZP tires in the base Vette size (245/40/R18 and 285/35/R19), and have zero complaints. No vibrations. Spacer lug nut torques checked twice, and nothing has loosened. There is at least 3/4" of side clearance from rim spoke to caliper face, and rim face to fender spacing looks normal on both ends of my widebody GS car.
I'm not planning to Autocross on this setup...that level of additional repeated stress forces on the spacer joint sounds iffy to me. But, I have no qualms about normal commuting & highway travel on them.
I will be autocrossing the car in the 2016 season, and will be using the OEM 18x9.5 & 19x12 rims for that..obviously without the spacers. The 2nd set of lugs & nuts during tire set swaps will be annoying...but that's why I do it at home with the electric or pneumatic impact driver. I'm not sure if I'll reach up to SSR class and buy Hoosiers, or stay in AS class and hope Bridgstone or BFG releases some wider sizes.
Last edited by Conesmacker; Dec 6, 2015 at 10:38 AM.
So I got all the spacers on and used the ET lugs...torqued all to 125 with no issues
My test run with the new brakes was outstanding. I know some argue that the J56 upgrade isn't all that....I disagree, it is a very noticeable increase in stopping performance
And yes I get the added benefit of the aggressive look
grrrr...I need wheel spacers
)....
