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Thread: Using 13" rotors with stock '88 calipers

  1. #1
    Senior Member Mr355's Avatar
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    Using 13" rotors with stock '88 calipers

    Westcoast Fieros is selling large rotors to be used with stock calipers. I figure if the measurements and clearances aren't a problem and it fits, then the braking performance should be somewhat better than stock due to better heat dispersal from the increased rotor area. Any input on safety issues with this set-up; i.e. relocation of the calipers etc.?

    Rob

  2. #2
    Senior Member GSXRBOBBY's Avatar
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    Re: Using 13" rotors with stock '88 calipers

    A larger caliper would make the braking better, like using Camero brakes. Mounting them there is just a custom bracket that is made to mount the Camero Brakes on the 88 Fieros which is needed either way with a larger disc.
    I am in Lowell, Indiana<br />Building an 88 Fiero GT with a 93 STS Northstar and 5 speed Getrag. <br />Custom Mr. Mikes interior, Norms fiberglass nose and custom paint.

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    Moderator FunnyWheels's Avatar
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    Re: Using 13" rotors with stock '88 calipers

    The 11.25" Chrysler rotor conversion is very popular brake upgrade for '84-88 Fiero’s. It has been fairly well documented elsewhere on the internet, so I will not provide much detail. One thing I will suggest is that you use the stock cable mounting brackets and actuator arms that came on the rear calipers. Using the Fiero arms and custom boomerang shaped brackets will result in the cables being too short when the car is at normal ride height and completely useless if the car is lowered.

    The conversion uses four rear rotors for a Chrysler Le Baron. Two of them need to be slightly modified for the rear of the Fiero by enlarging the center hole to fit over the drive axle bolt flange on the rear hub. The stock Fiero front rotors need to be cut on a lathe to make a hub that the new rotor will slide over. The front calipers are from an '85 Camero, rears are from an '85 Cadillac Seville with the cables for the parking brakes. The calipers have many other applications, a complete list is shown below. Stock length hoses can be used. The stock 15" wheels will fit if you grind off four machine bosses from the inside of the wheels and have them rebalanced.

    The 11.25 inch brake is a lot of brake and will generate a large amount of torque on the suspension components. You may need to reinforce the lower “A” arms to prevent them from twisting under the loads of big brakes on your Fiero.

    Hope this helps,

    Dave

    If you're not confused, you're not paying attention.

  4. #4
    Moderator FunnyWheels's Avatar
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    Re: Using 13" rotors with stock '88 calipers

    12" Corvette rotor conversion

    This is a fairly simple conversion for '88 Fiero’s only. I have used '88-95 Corvette front 12" rotors. They are the same thickness as the '88 Fiero rotors which allow the Fiero calipers to be retained. The first step is machining a concentric rings to center the rotors on the Fiero bearing hub. The rings are press fit into the rotors. The second step is to drill the rotor hats with the Fiero 5 on 100mm pattern unless you want to use the 5 on 4.75 bolt circle, that is. Now the rotor will fit over the Fiero hub. The Corvette hat is 3/8" taller than the Fiero hat, which in theory means the caliper must be moved inward 3/8". On the Fiero, the caliper needs to be moved outward racially for the larger diameter rotor. A bracket made from 3/8 " steel is all that's needed. I decided to make the brackets from 1/2" steel to give the caliper mounting bolt holes more thread depth. I then machined the area where the bracket bolts to the spindle down to 3/8" thick. Then the bracket bolted to the spindle with M12-1.75 bolts. The outer holes are tapped M12-1.75. Note that the caliper also needs to be moved upward so that it will clear the bolt heads.

    Another $.02 worth, but a front 12 inch brake option for an 88 Fiero involving very little cash. The rear brakes on an 88 seem to function just fine unless your going to AutoCross your car and need additional cooling of the brake surfaces.

    I haven't done any 13 inch rotor conversions but someday I might give them a try on FunnyWheels. Today I have a Wilwood package on the car using 12 inch replacement rotors for a Corvette and 4 piston calipers. They seem to work really well.

    Dave
    If you're not confused, you're not paying attention.

  5. #5
    Senior Member GSXRBOBBY's Avatar
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    Re: Using 13" rotors with stock '88 calipers

    I thought the 11.25" Chrysler brakes upgrade was for the 84 - 87's

    Does anybody know a detailed website for this brake upgrade?
    I am in Lowell, Indiana<br />Building an 88 Fiero GT with a 93 STS Northstar and 5 speed Getrag. <br />Custom Mr. Mikes interior, Norms fiberglass nose and custom paint.

  6. #6
    Moderator FunnyWheels's Avatar
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    Re: Using 13" rotors with stock '88 calipers

    Quote Originally Posted by GSXRBOBBY
    I thought the 11.25" Chrysler brakes upgrade was for the 84 - 87's

    Does anybody know a detailed website for this brake upgrade?
    It is just an issue of fitting the rotor over the cut down hub on the 84-87. A similar process is used for the 88. One of the biggest differences in the 88 v: the 84-87 is the size of the bearing and hub assembly. Both can use the Chrysler upgrade.

    Dave
    If you're not confused, you're not paying attention.

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    Senior Member Mr355's Avatar
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    Re: Using 13" rotors with stock '88 calipers

    Quote Originally Posted by FunnyWheels
    Another $.02 worth, but a front 12 inch brake option for an 88 Fiero involving very little cash. The rear brakes on an 88 seem to function just fine unless your going to AutoCross your car and need additional cooling of the brake surfaces.
    Dave: Are you saying that the 12" Corvette rotors are just for the Fiero front end and not for the rear brakes? If I can recall the '88 fiero rear rotors are the same as the front so the proceedure for the rear 12" conversion should be more/less the same as for the front.

    Thanks,
    Rob


  8. #8
    Moderator FunnyWheels's Avatar
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    Re: Using 13" rotors with stock '88 calipers

    Rob:

    I never put big brakes on the rear of an 88 so I can't confirm your information. I have only done it on the front of an 88 with great success.

    My chassis under FunnyWheels is an 86 chassis and I used the Corvette brakes strategy on it with a Ryane Slalom front suspension. That suspension accepted either the 12 inch Corvette brake rotors or the 12 inch Wilwood option. The hubs were custom drilled by Ryane Motor Sports for a 5/4.75 bold circle so either set went right on. The rear was modified to fit the 12 inch Wilwood brakes by using 89 Olds Cutlass Ceria uprights (more meat and would accept larger bearings and axles) and front wheel hubs from an S-10 4X4 with the larger 5/4.75 bolt circle. I did have to trim out some material on the inside of the rotor hat to get it to line up properly. The Corvette hat is thinner than the Wilwood rotor hat and that made the bracket from Ryane misalign by 1/8 inch. It has been on there since 1998 and works very well. I also think a 13 inch rotor looks great but it is over kill for my car. It is all about rotor pad surface pressure. The 13 inch uses the same caliper as the 12 inch so the ratio should, in theory, remain the same.

    Dave
    If you're not confused, you're not paying attention.

  9. #9
    Senior Member GSXRBOBBY's Avatar
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    Re: Using 13" rotors with stock '88 calipers

    Is there a brake upgrade out there that uses a rotor from another car that would give us a larger disc and than a larger rotor and would fit without any mods. other than the mods. bracket to mount the rotor? I would like to have a set up such as this so if a new rotor, or pad is needed it can be pick up from just about anywhere.
    I am in Lowell, Indiana<br />Building an 88 Fiero GT with a 93 STS Northstar and 5 speed Getrag. <br />Custom Mr. Mikes interior, Norms fiberglass nose and custom paint.

  10. #10

    Re: Using 13" rotors with stock '88 calipers

    Quote Originally Posted by GSXRBOBBY
    Is there a brake upgrade out there that uses a rotor from another car that would give us a larger disc and than a larger rotor and would fit without any mods. other than the mods. bracket to mount the rotor? I would like to have a set up such as this so if a new rotor, or pad is needed it can be pick up from just about anywhere.
    Check out this site.

    http://www.fortunecity.com/skyscrape...h/67/id215.htm

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