Weld Racing recommended backspacing

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by Ls3rs, Jan 3, 2019.

  1. Ls3rs

    Ls3rs New Member

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    I am looking to order some 18x8 front and 18x10 wheels for my 72. They will be used in conjunction with wilwood 6 piston/14” rotor front and 4 piston/14” rotor rear, which aren’t installed yet. Weld’s application guide is suggesting a backspacing of 4.2” front and 6.2” rear. From reading in the forums, it seems like 4.75 front and 5.75 rear seems to be what guys are running. A guy I follow says his were 4.65 front and 6.1 rear. Due to the build time of 6-8 weeks, I’d like to order now, and get the brakes installed during that time. Should I go with Weld’s recommendation? Will the brake hat thickness change the offset required?
     
  2. Ls3rs

    Ls3rs New Member

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    Here is the application guide
     

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  3. badazz81z28

    badazz81z28 Veteran Member

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    The offset is measured from the hub mounting surface. Beyond that where the face of the wheel is can interfere with brake calipers. Depending on how they create offset...longer hub or moving the entire centers can gain face clearance for calipers.

    I would call them and discuss their wheels since they are custom. I wouldn’t assume
     
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  4. G72Zed

    G72Zed Veteran Member

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    FWIW Wilwood does supply a clearance "spec" sheet you can print off their website and send it to Weld Racing to be sure. Also note, Wilwood gives the OE hub offset spec, in my case, it said it was .00 difference when it was in fact +0.125. (wider track), no big deal, but every fraction of an inch counts when pushing width and lowered applications.

    An 8" front rim with only 4.200 bs is pushing it out there, unless your using smaller (H & W) front tires and regular ride height.

    For reference, I used kit #140-10485 (6P/12.88) with a 17x8 TT2 rim with 5.00 BS. I have enough radial caliper clearance for a 13.500 rotor, and over 0.750 caliper face clearance, my car is a 1972 Z/28.

    Been down this road, hope it helps you out.
     
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  5. Ls3rs

    Ls3rs New Member

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    I am working on installing my rear Wilwood’s and I am having an issue fitting the parking brake assembly onto the axle housing. The axle has a raised lip on it and the diameter on the parking brake assembly is smaller, so it will not slide all the way on. I’m wondering if I should just enlarge the hole on the parking brake assembly? Curious if you encountered this as well. I will call wilwood tomorrow
     

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  6. G72Zed

    G72Zed Veteran Member

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    No, I did not encounter that issue as I used the Wilwood kit (4P/12.19) for the 12 bolt Camaro with new "big Ford" axle ends, and could not use the C-clip eliminators with the internal parking brake setup. I,m sure some slight massaging would be OK, what did Wilwood say?.
     
  7. camaro71/holland

    camaro71/holland Veteran Member

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    Have you powder coated the axle? It can add enough to cause this. Nothing some emery cloth can handle...
     
  8. Ls3rs

    Ls3rs New Member

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    Wilwood basically said that the lip that the factory backing plate sat on is extremely rare and that is isn’t isolated to any specific year or model, but it is so rare that they don’t account for it in any of their product data. They said they have heard of people grinding the lip off. I opted to enlarge the hole in the parking brake mounting plate. It was simple enough to do. I ordered a braided rear hose from kore3 that has the Tee installed on it. I was planning on using hard line from the tee to each caliper, however now I am thinking that if/when I need to replace rotors, I would need to remove the caliper and have to re-bleed the system. Should I use flex line instead? If so , should it be flex all the way to the tee, or should I use a hard line with a short piece of flex to the caliper (like a 12” piece). Kinda seems like an extra joint that may not be needed to use a hard and flex combo...
     
  9. G72Zed

    G72Zed Veteran Member

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    A 12" long (or about) braided flex line is a good idea just as you mentioned. I did this as I change out pads styles for the track, easy and no need to disconnect and re-bleed.
     

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