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  1. #1

    Question Need advice on unique problem -Not much room for a rear caliper on my 9" axle -ideas?

    Hello everyone,

    After driving my modern car regularly, I'm not very happy with how my 86 mustang stops. So, I've decided to upgrade the brakes all the way around. Unfortunately, about 25 years ago, I had a custom 9" axle made with a narrowed width to have a 'deep dish' wheel look that I really want to keep.

    I really want to keep it simple so my initial plan was to use SN95 (non-cobra) rear disks so I can keep my current 15" wheels but, based on the pictures I see of SN95 rear calipers, I'm concerned that I won't be able to fit the calipers without interference with the shocks.

    So today I started taking a good look and taking some measurements - see pics. The distance from the end of the housing flange to the outside edge of the spring is 3.70" (assuming I mount the caliper in the forward position).

    Does anyone have some caliper dimensions or have an illustration that provides some dimensions - or maybe you're in the middle of the conversion and you can take some measurements for me? Any suggestions are appreciated as well - you won't hurt my feelings with constructive criticism either - lay it on me.

    Thanks,
    Howard
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  2. #2
    FEP Senior Member E2ZZGLX's Avatar
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    Simplest solution is get a weld on bracket from Speedway...it uses a GM caliper and Jeep/Ford rotors..Name:  38D5FD86-D372-4D19-A182-8AB7DDE7C077.jpg
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  3. #3
    Moderator wraithracing's Avatar
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    The stock SN95 rear brakes mount further away from the backing flange. They require longer axles than stock Foxes and would require different rear wheels most likely.

    North Race Cars has some options for moving the calipers inboard and using stock length Fox axles. Not sure if you have enough clearance for that to work or not. Might be worth giving them a call or email. http://www.northracecars.com/Brakes.html

    If you haven't already, you might consider the simple 87-93 V8 front spindle and brake swap to your 86. That in addition to this kit from Maximum Motorsports might be a simple solution that fixes your braking issues. https://www.maximummotorsports.com/B...7-93-P676.aspx
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

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  4. #4

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    Thanks for the responses guys.

    E2ZZGLX: Unless I have to resort to it, I'd prefer not to weld on a bracket - I can't weld and I've heard that it can distort the axle shaft tubes (but that might just be a story I was told). However, I'm sure a bolt on version could be fabbed up to use the GM caliper you're describing. I'll have to look into what the caliper looks like.

    Trey: I'll try giving North Race Cars a call and see what they suggest. I think I need the calipers to move outboard, but I know there's a limit as it might contact the wheel. Also, I forgot to state that I already 'upgraded' to the 87-93 spindles, calipers and rotors so that's why I'm mostly focusing on the rear for now. I'm wondering if I can rotate the bracket from the 2 O'clock position to the 8 O'clock position and used the opposite side caliper, if that would be low enough to clear the spring?

  5. #5

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    Problem with swapping calipers to the opposite sides is that it might put the bleeders at the bottom.
    i called North Race Cars a few months ago and found that they were very knowledgeable and helpful. Itís definitely worth a shot imho.
    79 Zephyr, 4v/4r70w swap planned, with team z front and rear suspension, 8.8 and upgraded brakes and coil overs.

  6. #6

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    Have you considered a setup off an explorer? Lot's of those in the pull and save lots. Also, the hat on the rotor always looks very shallow.

    Kenny

  7. #7
    FEP Senior Member OX1's Avatar
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    Quote Originally Posted by twinturbohow View Post
    Thanks for the responses guys.

    E2ZZGLX: Unless I have to resort to it, I'd prefer not to weld on a bracket - I can't weld and I've heard that it can distort the axle shaft tubes (but that might just be a story I was told). However, I'm sure a bolt on version could be fabbed up to use the GM caliper you're describing. I'll have to look into what the caliper looks like.

    Trey: I'll try giving North Race Cars a call and see what they suggest. I think I need the calipers to move outboard, but I know there's a limit as it might contact the wheel. Also, I forgot to state that I already 'upgraded' to the 87-93 spindles, calipers and rotors so that's why I'm mostly focusing on the rear for now. I'm wondering if I can rotate the bracket from the 2 O'clock position to the 8 O'clock position and used the opposite side caliper, if that would be low enough to clear the spring?
    Weld on bracket is no issue with 9" housing. Here is Mk VII brakes I put on the rear of my 70 bronco.
    I used this setup specifically as I did not want small drum emerg brake (bronco might see some mud here and there)
    and it HAD to be Ford. Could look at 14ish mustang rear caliper also, as it uses cable emerg brake right on caliper.




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  8. #8
    Moderator wraithracing's Avatar
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    I guess I didn't fully catch the 9" rear end, for some reason or another I was thinking the 9" ends on the 8.8. Anyway, maybe this kit would work for you.

    https://www.jegs.com/i/JEGS/555/630600/10002/-1

    The pictures aren't great of how the kit actually installs, but based upon the bleeder screw location, it appears they might install at between the 4 and 8 o'clock positions in order for the bleeder screws to the high point on the caliper for bleeding. So might work to clear your spring and shock. Who knows!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Ongoing RestoModification
    1984 SVO Awaiting Restoration
    1986 GT Wrecked by PO, but still want to save!

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Underway
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  9. #9

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    Rich from North Race Cars responded to my email and (assuming I understand correctly) he said that the distance from the inside surface of the disc to the furthest inside surface of the caliper is about 5". He wasn't sure how far from the inside surface of the disc to the mounting hat surface (axle flange) is, but I don't think it matters because 5" would be too much. A very important point he made was that I should never mount the caliper under the 4 or 8 O'clock position for safety reasons in case of a wheel failure.

    I appreciate everyone's ideas and I'm going to look into some of these kits, but so far everything 'visually' looks like the caliper will contact either spring or the shock. Wilwood makes a rear brake kit and it looks like the narrowest calipers I've seen - but wow, that's gonna cost some lunch money.

    Other than the price, does anyone have anything negative to say about going with a Wilwood on the rear? (I will probably use SN95 11" GT/V6 on the front).

    Thanks again guys - I really do appreciate the help!

  10. #10

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    If you don't have the room for discs in the rear what about a 10x2.5 drum from a Ranger or Aerostar? Also I think F150's had 11x2 or 2.5 rear drums that fit under 15" wheels, assuming you are 5 lug.
    Just a thought.
    Mike
    85 GT - owned since 87

  11. #11
    Moderator wraithracing's Avatar
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    I am not a huge fan of the under mount disc arrangement for the same reasons, but that was about the only option I could see for your setup currently.

    The larger rear drums might help if there are no other options, but the F150 bolt pattern is 5x5.5" and not the 5x4.5" that most likely you currently use FYI.

    As for Wilwood, they make good products and as long as you buy the correct application for what your car is used for you should be fine. They have tons of race applications, but many don't have all the same "weather/dust" seals that the standard street applications have so that can be a maintenance issue if you aren't careful and/or drive your car in inclement weather. Good Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Ongoing RestoModification
    1984 SVO Awaiting Restoration
    1986 GT Wrecked by PO, but still want to save!

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Underway
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  12. #12

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    You should start by deciding on a front brake system. Once that is done, you will know which rear brakes can be used from a hydraulic balance standpoint. Many Wilwood calipers will be too large. Forget anything made for a GM chassis.
    Jack Hidley
    Maximum Motorsports Tech Support

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