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    Results 1 to 10 of 10
    1. #1
      Join Date
      Apr 2021
      Posts
      8

      18's don't fit need to go bigger

      Yes you read right! I have a 72 cutlass supreme with an ls engine 6 speed t56 full UMI suspension set up for protouring. I have raced the car a hand full of times now at willow spring raceway and its AWSOME!!!! I had issues in the beginning of course. Power steering pump, suspension set up, rear sway bar. But I was able to really dial the car in and had a great time. Shes not a show car by any means (plenty of dents and rust with all red primer) but I still get complements at the track.




      Ok so to the point, the car seems plenty fast with about 470hp to the wheels but the brakes need to be upgraded. Mind you I have 2002 Camaro calipers front and rear with drilled and slotted rotors. I came up on a set of CTS V brakes 6 piston calipers and 4 piston rears. So I made it work with my set up. Had to open up the center bore of the rotors to slip over the hub. An had to drill out the mounting hole for the calipers to 9/16. Front calipers and rotors now fit. So to my problem. My current wheel is the ridler 650 18x9.5 0 offset which should be 5.25 backpacking. I was under the impression they would work.😣😣😣😣 but the wheel contacts the caliper. Just barely! But I dont want to grind down the caliper to make it work. Plus I would have maybe a 1/8 of clearance. I dont like that idea.


      So bigger wheels it is! I would like a 19in wheel but I feel like there is a better tire selection for 20's. I see alot of 20in wheels and was planning on just going to the same ridler 650 in a 20x10 and I would like the same wheel on all four corners for front grip and ease of tire rotation.


      Any other track guys or gals running large wheels??? What size and backspacing? Again I currently have a 18x9.5 with 275/40-18 square. I'm thinking 20x10 with 275/35-20 or a 295/35-20 if I wanted to go wider. I'm asking for anyone's help or input. Thanks in advance, oh and I am literally waiting on responses before I make a purchase for new wheels and tires but no rush.

      I just looked at my car and I swear I have a lot of room I think I could fit a 20x10 with 6 in back spacing. I think the only contact issues i might have would be with the rear part of the inner fender (Plastic) well at full lock but it was just be grazing it..... maybe im wrong your thoughts


    2. #2
      Join Date
      Oct 2016
      Posts
      206
      Where are u located?? If your in SoCal I can go by and look at what u have and help u that way.

    3. #3
      Join Date
      Aug 2015
      Location
      charlotte
      Posts
      848
      Country Flag: United States
      It seems like you're set on new wheels regardless. I run the 4-piston version of those brakes and have run into similar issues, I managed to get 18x9.5 to fit because Boze can make them with extra clearance to cover the calipers but I do have limited options in tires like you mentioned.
      IMO opinion, 19's would be a wise and safe choice, 20's, as common as they are on modern cars, are a little too big for me on a cutlass. but again, just personal opinion.

    4. #4
      Join Date
      Apr 2021
      Posts
      8
      I'm in the high desert area Palmdale Lancaster not far from willow spring.... I did some more research and found someone with the 6 piston brakes on 18s but they were weld racing wheels and forged wheel apparently have more clearance than cast wheels. I wonder If it's safe to grind out some clearance on the rim????

    5. #5
      Join Date
      Aug 2015
      Location
      charlotte
      Posts
      848
      Country Flag: United States
      Quote Originally Posted by cutlass11 View Post
      I'm in the high desert area Palmdale Lancaster not far from willow spring.... I did some more research and found someone with the 6 piston brakes on 18s but they were weld racing wheels and forged wheel apparently have more clearance than cast wheels. I wonder If it's safe to grind out some clearance on the rim????
      Weld S71 have great brake clearance options and are surprisingly cheap. They don't come in 19's unfortunately

    6. #6
      Join Date
      Apr 2021
      Posts
      8
      Ok I currently have the 18x9.5 if I find a wheel with a inner diameter of 16.2 or more the caliper should work.. sounds like cast wheels are thicker and are about 16.1.
      #1 I could grind out or mill out just enough room for the calipers and keep my wheels and tires.
      #2 I could sell my wheels, keep my tires and and go to a 18x10 on a forged wheel, which should have JUST enough clearance. I would only be out of pocket $ for the rims but I get to stay with 18s.
      #3 i sell my rims and tires and go with 20s plenty of clearance but will be out $for rims and tires and might not be able to have a square pattern. I think the 20s do look good but I agree with 18s would be better for track use.

      Lock to lock I have plenty of clearance with a 9.5 I'm sure I can go with a 10 wide up front no problem. The only issue I had at the track is slight fender rubbing at the top during hard G turns. I have since rolled the lip of the front fenders. But if I go with more backspacing it "SHOULD" give me more clearance from the fender lip. I'm at 5.25 a 10 inch wide would be at 5.5 but if I go to a 6 in backspace I think that might work for both front and rear. So far looking at rocket wheels attack, weld RTS and S71 S72 wheels, forgestar D5 wheels. It all come down to the inner diameter. I think I should post a how to or more of a how not to video to really show everyone what I'm talking about so the next person can to it right lol.

    7. #7
      Join Date
      Dec 2008
      Location
      Detroit
      Posts
      2,454
      Country Flag: United States
      A lot of the one piece cast wheels will not have the clearance you require for those wheels in 18". You will likely be looking for a forged wheel. A wheel manufacturer could possibly tell you if the wheels you're interested in will clear the CTS-V spec caliper.
      Big dreams, small pockets....

      Chris--
      '72 Cutlass S LS2/T56 Magnum
      Bowler Performance, Rushforth Wheels, SC&C, ATS, Street Rod Designs, Speedhut, KORE3, Ridetech

      Project Motor City Madness

    8. #8
      Join Date
      Feb 2021
      Location
      SoCal
      Posts
      4
      Country Flag: United States
      What rotor / caliper mount are you using with the CTS-V calipers? IE: caliper to hub face clearance?

      I'm only in mock up stage on my 64 Skylark and using 4 piston Brembos from a 18" Camaro

      http://bigbrakeupgrade.com/product-c...indle-1964-72/

      I test fit a Ridler 650 18X8 with 4-1/2" backspace and would need a 1/4" spacer for the spokes to clear the caliper. I was able to borrow a Rocket Attack wheel, 18x8 / 5'' B.S and it had much more caliper clearance due to the design of the wheel spokes.

      https://www.rocketracingwheels.com/r...ck-series/c332

    9. #9
      Join Date
      Apr 2021
      Posts
      8
      I started out with 12in disk brakes from an 02 camaro. I have seen where others upgrade to the 6 piston setup with little modifications on camaros. So I thought it should work for me.
      http://www.brphotrods.com/mm5/mercha...ry_Code=BRK12F

      I'm using the 6piston with 14.6 rotors. I will have to measure the caliper height I'm not sure what it is. I think 1.77 from what I read somewhere.. will check

    10. #10
      Join Date
      Oct 2015
      Posts
      48
      Country Flag: United States
      I run a ridler 650 wheel 20x8.5 in front and 20x10 in the rear with z06 calipers. I have to run a spacer to clear the calipers. I thinks it's more of the design of the wheels than the diameter of the wheels.