Rear Disc brake conversion info needed

Discussion in 'Suspension/Chassis' started by Bronchogg, Jan 4, 2017.

  1. Bronchogg

    Bronchogg Member

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    I've been working on my 1971 since winter grabbed Utah by the nuts. I sourced an MKIII Supra LSD which is in the process of a rebuild (Weir Performance plates and springs) and figured I would hit wheel bearings and rear discs while everything is apart.

    After destroying a backing plate (which seem to be impossible to source) and reading anything I could find on the subject of a rear disc conversion, I feel like too much of the info is incomplete.

    These are the options I've read about.

    Option 1 - Buy a Littleshop/Tre5 kit
    Pros: Install and go.
    Cons: Their kits are listed as 1979 and up. I still may need to fab stuff to get it to work.

    Option 2 - piece together a kit using a 4wd conversion bracket, 90-95 V6 4Runner calipers and a rotor that'll fit (haven't found anything in print to tell me exactly which rotors I need).
    Pros: I already have most of the parts. The clamping force of those huge calipers.
    Cons: I don't have a definitive anser as to what rotor will work and Ill have to upgrade the master cylinder to push enough fluid for those massive calipers.

    Option 3 - piece together a kit using a SKY Manufacturing type bracket, late 70's - early 80's calipers and a rotor that'll fit (again, haven't found any concrete answers on this one).
    Pros: Uses GM calipers so parts can be had at any shop in any town. I could upgrade to Wilwood calipers at a later date.
    Cons: I don't have any of those parts currently and I would still need to track down rotors and would still have the same master cylinder problem as option 2.

    Option 4 - Swap over ma70 Supra calipers, rotors and make a bracket to mount the calipers.
    Pros: Other than making a bracket for the calipers, it's all Toyota stuff. E-brake can be integrated. I can run 14" wheels (yeah, I like the old JDM stuff).
    Cons: Not many ma70 Supras show up in these parts. I'd still have to make a bracket to mount the calipers.


    So far, I've started option 2. I have the brackets and have rebuilt the calipers that I picked up. The problem is the rotors. Lots of 5x114.3 bolt patterns out there but very few that'll fit over the axle-to-wheel mounting pad.

    If you're still reading, thank you. If you have any info on what rotors option 2 would use, please comment or if there is another option I haven't covered, feel free to post.

    Thanks everyone.
     
    Last edited: Jan 4, 2017
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  2. Sk1dmark

    Sk1dmark Enthusiast

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    Edit: Nevermind I'm retarded, you said you had a mk3 axle, I read it as mk2. Sorry
     
  3. jetas

    jetas Grand Toyotaholic

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    Hit up TRUCKACTION about his set up.
     
  4. Bronchogg

    Bronchogg Member

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    I'll do that. Thanks for the lead.
     
  5. yotarip

    yotarip Veteran

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    I'm glad I looked at this thread. Found a set of brackets on ebay for the v6 brake conversion on the rear. Will figure out the best rotor / brake pad combo for this conversion.

    Thaks
     
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  6. Bronchogg

    Bronchogg Member

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    From what I understand, the brackets allow the V6 calipers and rotors to be used on the rear of just about any 7.5" or 8" toyota rear end - providing that its 4wd. The problem with trying to use it on 2wd is the obvious 6 lug vs. 5 lug difference and the center bore of the rotor. 4wd rotors have a huge center bore compared to the 2wd.

    The other problem is the booster/master cylinder size. I bought a T100 booster and its huge - to the point of not fitting with the intake manifold/Weber carb I have. The master cylinder on the 1st and 2nd gen. trucks pushes enough fluid for a front disc swap but adding the V6 calipers to the mix and it just isn't big enough to push it all.

    Just some food for thought.
     
  7. Bronchogg

    Bronchogg Member

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    In an effort to consolidate any info I find on the conversions, here are a couple of links for some of the options I've found. Again, the are relatively incomplete for 2wd info but info nontheless.

    Brackets for Option 3 above
    http://www.tsmmfg.com/Rear Disc/2493.html

    General info concerning Option 3 above
    http://www.mindspring.com/~jayk3/toyota/discs.htm

    ma70 swap thread. Option 4 above. Tons of good info here.
    http://www.toymods.org.au/forums/threads/18913-How-to-Supra-MA70-rear-discs-to-Hilux
     
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  8. yotarip

    yotarip Veteran

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    Yeah. It's just a factor of finding the right 5x114.3 pattern rotor and the pacer size needed to center the caliper. I'm not too worried about the mastercylinder issue on my 87 mini. I dont think it will be an issue. A first gen 4runner master will bolt up and a 89-92 cressida master will bolt up also.
     
  9. nnywg

    nnywg Member

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    Might be worth a call to Wilwood - their pricing isn't so different from Option 3, above, and comes with new callipers. They have so many options and staff to find something that fits. Right now they don't list the axle flange (3-7/16" square) on their site, but maybe that's the only issue? It would certainly make finding a front pair of brakes that are balanced with the rear much easier too.

    EDIT: I picked up a set of callipers and a brake master/booster from a mkiii supra today at the junk yard. Suspect that's the route I'll go eventually, for now I've got another long-running mkii supra project to actually finish.
     
    Last edited: Jun 24, 2017
  10. nnywg

    nnywg Member

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    My Hilux is stripped down, and I did a test fit of the Mk3 brake booster. It's way bigger and fouls with the wheel well panel severely. Boltup patern to the firewall is different but that's not really a big deal in the grand scheme.
     

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