FJ40 Rear Disc conversion - using late model Toyota parts.

Discussion in '40- & 55-Series Tech' started by Stubby, Feb 8, 2018.

  1. Stubby

    Stubby

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    I wanted to post this up for everyone to know about....

    I've been looking at all of the various rear disc conversions for my '73 FJ, and I just didn't like the idea of using Monte Carlo calipers (or El Dorado to keep a parking brake). Well, I have another option that y'all might be interested in....

    I installed a rear disc conversion on my 2006 Tundra from SOS Performance. They offer the typical "big brake kits", but I wanted something that I could get parts for at the local Auto Zone, if needed. They also offer a kit that uses 2005 Sequoia rear discs, with the internal drum parking brake / "top hat style" rotors. Here's a link.....

    REAR DISC CONVERSION Backing Plate Kit / TR.PS2.TU6.BPK fits 2000-2006 TUNDRA

    I contacted Tom Watts, the owner of SOS, about doing a similar kit for my FJ. After a few Facetime calls to look over the rear axle, and me taking some measurements for him, he's decided to put together a kit.

    The plan is to have backing plates that bolt on in place of the drum backing plates, and will include the necessary park brake cables, and balance bar to actuate it from either the dash mounted lever ('58-'79), or the floor mounted lever ('79-'84). The Sequoia rear discs do not need to be machined out, like the Chevy rotors, and with the exception of the backing plates, and actuating cables, everything will be late model Toyota parts, that can be purchased at any parts store.

    I'm working out the details for cable routing, length, etc..., and will be sending him my drum backing plates to measure for precise dimensions, but it shouldn't be too long before a kit would be ready for sale.

    Tom ran some numbers, and it's looking like a street price of $425-ish, shipping included. The buyer would need to either buy new Sequoia calipers, rotors, and park brake parts, or pull them off a salvage yard rig, like I did for my Tundra.

    I'll post updates and pictures once I get the prototype parts to fit up, but wanted to get this out there, so folks would know it was coming.
     
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  2. Ol Yeller

    Ol Yeller

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    Watching this....
     
  3. C6H12O6

    C6H12O6 SILVER Star

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    Any master cylinder or booster changes needed?
     
  4. Stubby

    Stubby

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    Don't know at this point. My FJ came with a twin reservoir master cylinder, so I may only need to mess with a proportioning valve if the rears lock up too soon.

    The Sequoia caliper is similar in size to the Monte Carlo, so my initial thought is that any changes needed for that kit would apply to this one as well.

    Biggest benefit I see is not having to use machined Chevy rotors, and virtually all of the parts are Toyota.
     
  5. Morse_FJ40

    Morse_FJ40

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    Sounds sweet
     
  6. 73fj40lc

    73fj40lc SILVER Star

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    I will be watching this thread. I had the same concerns with the Chevy rotors so I will be in for a kit once these are done.
     
  7. tstepp920

    tstepp920

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    I will be rebuilding the axles on my 1980 soon. Workout the bugs for the rear brakes and sell me a kit
     
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  8. Stubby

    Stubby

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    Define "soon".....LOL

    You have the floor mounted park brake lever, correct? If you don't mind, PM me your contact info. We can compare dimensions between the floor mounted, and dash mounted lever. Tom may want to contact you for some measurements....

    How about we use this thread as an informal "pre-order" roster for Tom to go by when he's deciding how many parts to do for the first production run? I know it's nothing firm, but it might give an indication of how much interest the kit would generate. :)
     
  9. tstepp920

    tstepp920

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    I do have the floor mounted park brake lever. What measurements are needed? I also have the transfercase mounted parking brake assembly from Georg
     
  10. Stubby

    Stubby

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    Mainly it will be detailed measurements on how the cable(s) mount to the lever / floor pan, and how long they would need to be for routing to the rear axle.
     
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  11. Godwin

    Godwin Resident Herpetologist SILVER Star

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    If this will work for a 40 it could perhaps be modified for a 60 with a change of backing plate and p-brake cable.
     
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  12. 73fj40lc

    73fj40lc SILVER Star

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    What would make this awesome is if there was a front and rear kit that was able to use the same Sequoia rotors, calipers, caliper bracket, and brake pads on the front and rear axles. I have a 85 front mini truck axle to do the Mini truck conversion on my 40 but I will hate having different disc brake components on the front and rear axle. Maybe this is just me being ocd but I like to keep things simple and to keep as few spare parts as necessary.
     
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  13. Stubby

    Stubby

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    Not really possible. The outside diameter is close to the same, but the inner top hat is much larger in the rear, to allow for the parking brake. Also, if you ran front calipers in the rear, you'd need a massive proportioning valve change, or you'd lock up the rears by just sneezing on the pedal.

    Now, if there was a kit that used rotors, calipers, and pads from all 4 corners of the same vehicle, that would be pretty neat, but that's just my OCD kicking in. They're naturally going to be different parts, front to back....at least this way, they're all Toyota. :)
     
  14. lelandEOD

    lelandEOD SILVER Star

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    Me wants!

    My truck loathes wearing GM calipers on the rear. I've actually been looking for a HZJ73 rear free float axle as a means by which I can upgrade to a FF axle, with discs and parking brake...
     
  15. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    Kit sounds interesting.


    When you get your total #, cut that in half, and then cut that remaining number in half, and that should be pretty close to the number of people that *MIGHT* be serious about spending money.

    :beer:
     
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  16. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    You mean like almost every modern production vehicle since the late 1960s?


    :beer:
     
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  17. Bripars40

    Bripars40 SILVER Star

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    @Stubby
    I’m planning for rear discs within the next 6-8 months. Think you’ll have the kit ready by then?
     
    Last edited: Feb 10, 2018
  18. pbgbottle

    pbgbottle Forum Lifer

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    Sounds cool
     
  19. Stubby

    Stubby

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    I'd be really surprised if it wasn't ready by then. The biggest challenge is figuring out the correct park brake cable lengths, and designing any special brackets to attach the cables at the rear end.

    Question for everyone......what's the verdict on the T-case mounted parking brake? Is it sufficient for the FJ, or should we really have it at the rear wheels?

    The entire project will be much less complex, and cost less, by keeping the stock park brake set up. The only parts needed then are the Sequoia rotors and calipers.

    If the preferred design is to incorporate the Sequoia park brake, I was thinking that it would probably be wise to keep the stock cable from the lever, and design the equalizer bar / bracket to be mounted in a location under the tub, near where the end can reach. This would also facilitate using one cable length that works for both sides of the axle.
     
  20. Bripars40

    Bripars40 SILVER Star

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    While I would love to have my parking brake at the rear axle it’s not a necessity. I’d personally go for just the rear disc setup and keep the tcase parking brake. If I really need security with parking I put it into low range, 1st gear (sm420), and cut the wheels toward the curb. All of that coupled with a welded rear axle and it doesn’t budge.

    I pretty well consider the tcase parking brake as an additional piece to everything above and I plan as though the parking brake will NOT hold.
     
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