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  1. #1

    Default '83 front caliper confusion

    My '83 is a 4 lug V8 car that needs some new calipers. I can't find the original build date so I was unsure if it was pre 11/82 or post 11/82 since they used different calipers according to parts stores etc. So I finally found some photos of the calipers online and decided to see if I could match mine to one of the photos. Seems the pre 11/82 calipers have roughly rectangular holes at the top of the casting whereas the newer post 11/82 units have rounded holes on one end of the castings. Also the older pre 11/82 unit photos show raised round and half round casting marks on the piston housing side with cast letters and numbers as well. The newer post 11/82 caliper photos don't show any of those easy to spot casting features. So I ordered some reman AutoZone units that matched what I have installed - namely the pre 11/82 calipers with raised casting letters etc. They look the same as the originals and bolt right in BUT they fit very loosely when dropping them into the spindle leaving about an 1/8" gap on both sides between the spindle and the caliper castings. The original calipers had no gaps and were snug enough they had to be coaxed out with a screwdriver etc. So these new calipers only have the wimpy retainer bolts and plastic sleeves inside the caliper to take the load when the caliper tries to spin in the direction of the brake disc upon applying the brakes. This seems way wrong since the caliper will likely rotate 1/8" taking up the gap until it makes contact with the spindle casting edge. Seems dangerous to me.

    The car has passed through many hands and could possibly have different spindles / different calipers than stock I suppose - '84 stuff maybe? Or the post 11/82 calipers might be the correct ones for this car - but the pictures of them look quite different than what was on the car? So if anyone has dealt with this before or has wisdom to pass along I sure could use the help. I am close to finally getting her back on the road and this is one of the last "major" mechanical issues to overcome (I think).

  2. #2

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    I'm thinking I can make some 90 degree steel shims to bridge the gaps that bend around the front and have a hole for the caliper bolts to pass through to hold them in place if all else fails. They would have to be bullet proof though IMHO. Brakes come in real handy at times!

    If local parts stores had the post 11/82 calipers on hand (they don't of course) I'd grab one and see if it fit better. At $22 apiece it's not overly pricey for rebuilts. That could solve the issue if they do.

  3. #3

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    Name:  pre11-82.jpeg
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Size:  36.5 KBName:  pre11-82top.jpeg
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Size:  50.3 KB This is the caliper I have on my car and it matches the look of the rebuilt units I bought.

    Note the area where gaps appear when I assemble them to the spindle (in red). Name:  pre11-82topred.jpg
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Size:  109.3 KB
    Attached Images Attached Images
    Last edited by Solow302; 06-15-2019 at 10:50 AM.

  4. #4

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    Name:  12-82+.jpeg
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Size:  31.2 KBName:  12-82+TOP.jpeg
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Size:  50.4 KB This is the later version used after 12-82 according to Oreilly's website. My original units do not look the same but maybe they fit my spindles better. Who knows?

  5. #5
    FEP Senior Member Patrick Olsen's Avatar
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    Can you show a picture of one of your originals on the spindle vs one of the new ones on the spindle? Having not had that sort of brakes (well, the '87-93 style in my case) in many, many years, I can't really recall how they mount up.
    '89 GT convertible - not a four-eye
    '82 Zephyr Z7 - future track car

  6. #6

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    Finally got photos. First one is the new caliper installed where you can see the gaps on each side. Name:  DSC_0865.jpg
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    Then a photo of the original caliper set in place - no gaps here! Name:  DSC_0866.jpg
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Size:  43.4 KB

    Finally a photo of the back side of the original caliper - notice the raised casting marks & numbers etc. Name:  DSC_0867.jpg
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  7. #7

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    You can't use the gap ones. The pins only hold it in position, they are not meant to take the pressure of braking. Have you considered having your rebuilt by Karp's or someone else?

  8. #8

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    Thanks Mudge' I pretty much thought the same thing - no way the pins carry the loads of braking. I'll grab a pair of the post 12-82 calipers and see if they fit first. Surely someone has rebuilts that fit available somewhere - I just have to figure out which ones do. This is an odd thing for sure.

  9. #9

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    So the post 12-82 calipers arrived and they too are too narrow to fit properly in the spindle (about the same as the pre 11-82 calipers). I am beginning to suspect the spindles are 4 cylinder parts even though this is a V8 car. A previous owner may have swapped parts etc. The part numbers for 4 cylinder calipers are different than for V6 and V8 calipers which are the same. I'm tired of ordering calipers so I am going to use all the new seals, pistons, dust covers, bolts, and sleeves from the pre 11-82 rebuilts to rebuild my original calipers. I blew the pistons out with shop air and the castings are in great shape. After a thorough cleaning they should be easy to rebuild with all new parts since internals are the same. BTW you can buy new seals for $1.75 from rockauto still and they are all the same for these early Fox bodies. I probably will come out cheaper stealing the new parts from the rebuilts than ordering all the other stuff new.

  10. #10
    FEP Super Member erratic50's Avatar
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    This is odd

    my recollection is the spindles except early 79 are the same for all through 93.

    87-93 V8 and SVO had a different spindle

    4 cyl and V6 and pre-87 V8 cars were the same

    I’ve been wrong before but that’s my recollection

    There were thicker V8 rotors. My 86 originally had them. Braking wise the problem with them is they retain more heat and the pads with backing is thinner.

    Parts stores except NAPA silently started swapping early V8 cars over to 87-93 4cyl brake parts long ago

    Once the asbestos brake pads were no longer available ..... the thick rotors were totally wrong

    Caliper wise the 87-93 4 cyl and the stuff for my 86 interchanged just fine

    My car stopped better with the 4 banger parts.

    I eventually went 5 lug on my car.

  11. #11

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    All 1979-86 Mustang spindles are the same, except SVO models.
    Jack Hidley
    Maximum Motorsports Tech Support

  12. #12

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    Yup it's odd alright. Not knowing the history of my old '83 I can only guess at the combination of pieces it is composed of. I do know the 4 banger calipers are a different part number at the chain stores and I can't tell by the parts house photos if they differ at all from the V8 calipers. I suppose my car could have spindles from any number of Fox body cars including the SVO. Regardless I stole the pistons out of the rebuilt units I bought and they match the ones from my old calipers so I used them to rebuild the old ones. Other than getting the dust boot back on and the rubber bolt sleeves out it was a piece of cake. Thanks for the reply!

  13. #13

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    Quote Originally Posted by Jack Hidley View Post
    All 1979-86 Mustang spindles are the same, except SVO models.
    Woa! I might have super racey SVO spindles! Woo hoo!

    Thanks Jack for the info.

  14. #14
    FEP Super Member erratic50's Avatar
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    Inspect the balljoint. SVO spindle is larger and needs an adapter MM sells or an 82-83 Continental / 84-86 SVO specific balljoint long since discontinued.

    Also measure the brake rotor diameter. SVO were the same size as 87-93 V8.

    Also measure the strut attachment point. 79-86 all except SVO and 87-93 4 cyl vs SVO and 87-93 V8 the 4 cyl style were thicker at the mount point for the strut.

    Also measure the strut attachment holes. The SVOs are offset a little bit from the 79-86 or 87-93 spindles of all other flavors. You have to ream holes or use camber bolts to make them fit with a normal strut.

    SVO and 87-93 V8 share the same bearings. The outer is the same as the others but the inner bearing and seal are larger than 79-86 all others or 87-93 4cyl. tell us which bearings you are using.

    If it’s back on the ground and you are driving it, go into a cement parking lot. Turn full lock left and full lock right while driving a few miles per hour. If you feel the tires fight against one another this mystery isn’t over because you still have the Ackerman problems these cars had from the factory. If it turns smoothly that also supports the suggestion that it is SVO spindles.

    but hey — they could also be 87-93 V8 spindles too. I’ve give enough tests above to tell the difference

    The 87-93 4 lug V8 rotors will fit on V8 Mustang or SVO spindles for what it’s worth

    These will help you confirm what you have.

    This info is based upon the homework I did before trying to fit SVO spindles on my 85 Saleen build, and the details Trey uncovered when he did the work. They are on and will definitely work.

    For what its worth, I found NO documented cases of anyone trying an SVO spindle on a non-SVO car before I published the idea in my 4 lug brake upgrade thread as a way to improve Ackerman

    One person posted that they’ve used the info and reported positive results
    Last edited by erratic50; 06-23-2019 at 12:02 PM.

  15. #15

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    Thanks Erratic50 for the wealth of SVO spindle info! It'll be awhile before I get back to working on the suspension since I'm trying to clean out my clogged up carb etc. to get it running decently. At least it is on the ground and will move under its own power again - and it will stop too! My guess knowing a bit about the guy who used to own this car is the spindles are not SVO units. Probably 87-93 from the junkyard. Not much is stock on this ole girl anymore.

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