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  1. #1
    FEP Power Member LTDScott's Avatar
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    Default Rear disc options with narrow track width

    My '85 LTD LX currently has '95 Cobra front brakes and SVO/Mark VII rear brakes, including the longer axle shafts (1.25" longer per side than std Fox width). Overall I'm very happy with the braking performance of the car (including parking brake), but the wide axle plus limited wheel well openings on the LTD mean my wheel/tire selection is very limited. I'm currently running 17x9 +45 wheels (practically a FWD car fitment) with 245/45/17 tires, and they barely fit, even with the rear fender lips and inner quarter panel "massaged" for more clearance. I plan to bolt a supercharger onto my car in the near future, which means I need more rubber under the rear end to get power on the ground. Ideally I'd run a 275/40 or something similar.

    So I'm looking into what my options are to keep rear discs but narrow the rear track width. Here's what I've come up with, along with pros and cons. All three would end up with similar sized rear rotors.

    SN95 Cobra rear axles/brakes:

    Pros:
    -.50" narrower per side than my current setup
    -Good parts availability
    -Can use OE components that aren't modified or custom
    -Wheel spacers are easier to find for the '94+ hub bore size
    -Lighter calipers than SVO
    Cons:
    -.75" per side wider than Fox
    -Parking brake cable options are mostly unknown for my car since it uses a foot operated brake and has a different wheelbase than Mustang. I've heard talk of '90s Taurus cables working since they basically use the same calipers as the Mustang, but it'd take some trial and error.
    -Unknown braking performance, meaning I may have to alter other parts of my setup (including master cylinder).

    SN95 Cobra rear brakes with Fox length axles:

    Pros:
    -1.25" narrower per side than my current setup
    -Good parts availability
    -Wheel spacers are easier to find for the '94+ hub bore size
    -Lighter calipers than SVO
    Cons:
    -Will require either modification (cutting) of stock caliper brackets which make them weaker, or pricey North Racecar brackets
    -Parking brake cable options are mostly unknown for my car since it uses a foot operated brake and has a different wheelbase than Mustang. I've heard talk of '90s Taurus cables working since they basically use the same calipers as the Mustang, but it'd take some trial and error.
    -Unknown braking performance, meaning I may have to alter other parts of my setup (including master cylinder).

    SVO/Mark VII rear brakes with Fox length axles (using the "flip" trick that changes the orientation of the caliper bracket):

    Pros:
    -1.25" narrower per side than my current setup
    -Known braking performance that I'm happy with
    -I already have all needed parts except the axle shafts
    Cons:
    -Must permanently modify (grind/weld) stock components
    -Parking brake options are unknown because the parking brake bracket on the caliper will interfere with the lower control arm mount. I've read posts about people being able to modify this, but they're old threads with no photos so I don't know the solution.
    -Older style heavier components
    -Parts availability not great - Hawk doesn't make rear pads for these brakes, but thankfully Porterfield does.

    Am I missing any obvious options?

    I'm inclined to stick with the SVO/Mark VII set up since it's a known quantity and I already have all of the needed parts except the axles, but I realize it's an older setup which isn't supported as well as the SN95, and it'd be nice to have all of my brake parts at each corner come from the same donor. The parking brake cable is an unknown with all of these options, but at least I'm already familiar with how it works on the SVO setup.

    Any advice or thoughts?
    Last edited by LTDScott; 10-30-2017 at 03:43 PM.
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  2. #2

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    I have the same parking brake setup that you would have with the SN95 set (foot operated). You simply used a full late Mark VII cable setup. Mark VIIs switched to a SN95 style rear caliper in the last couple of years. '90-92 I believe. Further, I don't think the North Race Car brackets are that bad, really, when you consider what you spend on wheels and tires.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  3. #3
    FEP Power Member LTDScott's Avatar
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    Damn, how did I not think of that? I knew the last couple years of Mark VII used the SN95 (and Taurus) style Varga rear calipers. I just did some research and it appears that the front cables were the same across all years of Mark VIIs - only the rear cables are different. My current cables are from an older Mark VII. So this may work out.

    Does your car have Fox or SN95 rear axles? I figured you could probably get away with either due to the SVO wheels.

    I don't disagree about the North Race Car brackets, but given that I'll need to buy nearly all of the parts (including 31 $$pline axles), another $150+ on a couple chunks of metal kinda stings.
    Last edited by LTDScott; 10-30-2017 at 09:07 PM.
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  4. #4

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    I'm using SN95 axles. That combined with 1/2" spacers is the formula for my rear stance.

    Sent from my XT1650 using Tapatalk
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  5. #5
    FEP Super Member erratic50's Avatar
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    Default

    Lots of companies make fox length axles with SN95 style flanges now. That plus north racecar brackets is a winner with SN95 style brakes if your goal is 5 lug.
    Last edited by erratic50; 04-22-2019 at 09:32 AM.

  6. #6
    FEP Power Member LTDScott's Avatar
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    To be clear, I already have 5 lug, I just want to go to a narrower rear track width.

    I did some calculations and in order to fit 275s in the rear and have the same tire clearance I have now (with 245s), I'd have to move the wheel in about 15mm (half of the 30mm tire width difference). Using Fox length axles would bring the wheels in from their current location by about 32mm, or using SN95 axles would bring the wheels in about 12mm. So going to SN95 axles + 275 tires would net the tires being about 3mm closer to the outside than they are now (12mm inwards + 15mm outwards). That's pretty small, but my tires already rub on bigger dips or if I have passengers in the back, so I think I'd rather go Fox width and have the option to play with fitment, or go with different wheels altogether.

    The only catch is that in order to maintain the same amount of clearance I have now, I'd need 16mm spacers (approx 5/8") and all Maximum Motorsports offers in slip-on style is 1/2" or 3/4", whereas in bolt-on style the smallest they have is 1". I wonder if it's kosher to stack spacers together?
    Last edited by LTDScott; 10-31-2017 at 01:47 PM.
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  7. #7
    FEP Power Member conmech's Avatar
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    Scott,
    In box full.
    Text me 619-850-5433
    conmech - aka Marshall
    Pending build-1983 Mercury Capri RS NOT staying as it left the showroom floor......
    Sonic blue pearl, sand beige, netted halos, FR500 wheels and shiny under the hood.

  8. #8

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    Quote Originally Posted by LTDScott View Post
    To be clear, I already have 5 lug, I just want to go to a narrower rear track width.

    I did some calculations and in order to fit 275s in the rear and have the same tire clearance I have now (with 245s), I'd have to move the wheel in about 15mm (half of the 30mm tire width difference). Using Fox length axles would bring the wheels in from their current location by about 32mm, or using SN95 axles would bring the wheels in about 12mm. So going to SN95 axles + 275 tires would net the tires being about 3mm closer to the outside than they are now (12mm inwards + 15mm outwards). That's pretty small, but my tires already rub on bigger dips or if I have passengers in the back, so I think I'd rather go Fox width and have the option to play with fitment, or go with different wheels altogether.

    The only catch is that in order to maintain the same amount of clearance I have now, I'd need 16mm spacers (approx 5/8") and all Maximum Motorsports offers in slip-on style is 1/2" or 3/4", whereas in bolt-on style the smallest they have is 1". I wonder if it's kosher to stack spacers together?
    If you can get a slip-on spacer in a larger size than you're looking to have, i would think stacking would be okay. If you did a 1/2" one combined with an 1/8" (for a total of 5/8" ), the 1/8" one should fit on the lip like my MM spacers have with room for the wheel center bore to spare.

    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  9. #9
    FEP Power Member LTDScott's Avatar
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    Quote Originally Posted by conmech View Post
    Scott,
    In box full.
    Text me 619-850-5433
    Try again. I really hate that we don't get a full inbox notification until someone actually tries to send a message.
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  10. #10
    FEP Power Member LTDScott's Avatar
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    Zephyr, out of curiosity, does the center hub "lip" on your spacer taper down? I figure it has to be the same ID on the backside of the spacer (where it sits against the rotor) and OD on the lip since they have to be the same size.
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  11. #11
    FEP Super Member erratic50's Avatar
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    Fox vs SN95 diameter flange hub.

  12. #12

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    Quote Originally Posted by LTDScott View Post
    Zephyr, out of curiosity, does the center hub "lip" on your spacer taper down? I figure it has to be the same ID on the backside of the spacer (where it sits against the rotor) and OD on the lip since they have to be the same size.
    Yes, the inner diameter gets larger on the rotor flange side to fit over the lip on the axle shaft. I wondered about that too when i first ordered them, haha.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  13. #13
    FEP Senior Member Patrick Olsen's Avatar
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    Quote Originally Posted by ZephyrEFI View Post
    I'm using SN95 axles. That combined with 1/2" spacers is the formula for my rear stance.
    A little bit off topic, here, but just to clarify... You've got SN95 axles, 1/2" spacers, and SVO wheels? And those are 16x7" +40mm, from what I've read here. What size tires? Any fender rolling?

  14. #14

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    Quote Originally Posted by Patrick Olsen View Post
    A little bit off topic, here, but just to clarify... You've got SN95 axles, 1/2" spacers, and SVO wheels? And those are 16x7" +40mm, from what I've read here. What size tires? Any fender rolling?
    Yep, SVO wheels, 16x7. Tires are 225/60. The fenders are sort of rolled, but it's not needed. I had actually swapped from the SVO/Mark VII rear axles/brakes to SN95. It pulled my rear wheels in so far, I wanted that back. So that's why i got the spacers. This was the end of a loooooooooong journey of fighting with wheel fitment.

    I had rolled the fenders back when I'd had 17x8 30mm offset Bullitt wheels on the SVO/Mark VII axles/brakes. Bigtime rubbing.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  15. #15
    FEP Power Member LTDScott's Avatar
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    Why did you opt to go from the Mark VII to SN95 axles, if you ended up with the wheels in the same place they were before? Just more options/flexibility for wheels/tires?
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  16. #16

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    Quote Originally Posted by LTDScott View Post
    Why did you opt to go from the Mark VII to SN95 axles, if you ended up with the wheels in the same place they were before? Just more options/flexibility for wheels/tires?
    Mostly, I was trying to address a concern with braking performance. I got the idea the SVO/Mark brakes might not be well matched to the rest of my system. I went to a full '94-98 Mustang GT system. Secondly, I'd had a lot of problems with the SVO/Mark calipers sticking. I was tired of dealing with that, so it all had to go, haha. And then, options, yes. SN95 stuff is much more common, so there's more choices of pads, as well as not having to worry about parts availability. As for wheels, I'm happy with the SVO wheels, but it IS nice to know i'd have less fitment issues if I decided to go a different direction.

    I'd only recently found out that SVO/Mark axles are longer than SN95. I'd be telling guys they can't have 30mm offset wheels on their F/Zs with rear disc brakes (I thought they were all the same), only to have them come back and tell me they fit fine with their SN95 rears.

    Scott, I know you had '99 Cobra wheels on your car for a while, did you have rubbing?
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  17. #17
    FEP Power Member LTDScott's Avatar
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    Gotcha. I've been happy with the braking performance of the SVO rear brakes (other than limited brake pad selection) and never had any caliper issues. But I'm with you in that it'd be nice to have a fully matched system with SN95 Cobra brakes front and rear.

    Yes, I had rubbing with the '99 Cobra wheels and 245 tires. It was fine with 225 tires, but that's not enough rubber on the ground for me.
    85 Ford LTD LX: Four eyes and Four doors

    EFI swap, AFR 165 heads, 5-speed conversion, Cobra brakes, etc.

  18. #18
    FEP Senior Member Patrick Olsen's Avatar
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    Thanks for the additional details.

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