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Thread: E21/ E30 rear disc brake conversion: Some assembly required

  1. #1
    Join Date
    Jan 2009
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    Finger Lakes Region
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    '79 320/6

    E21/ E30 rear disc brake conversion: Some assembly required

    Hey Everyone!
    Just a head's up on yet another project for the Midlife Shop up here in the Finger Lakes Region. Not only am I building a new workshop but I have started on the engine swap/upgrade and have also started a disc brake conversion project for the E21's unfortunate enough to NOT be a 323i.

    I'll be posting picks soon. I've ordered parts for the project (calipers, brackets, back plates, etc.) and have 2 subframes I'm working with from other donor E21's. The approach for this conversion is to eliminate as much of the fabrication as possible, however there will be the need for a bracket mounting adapter to allow the caliper to install in a correct position.

    So, with that said the initial grocery list is: E30 loaded calipers, rear rotors and backing plates for a 1984 325e model (for the 4 lug configuration).

    With my 327cs project I really don't want to operate on drums for the rears and with no real way to get a hold of a 323i rear subframe and brake assembly I am going this route.

    Stay tuned.
    I still drive daily with no commute...
    The Hazard is All, Praise the Hazard!



  2. #2
    Join Date
    Oct 2015
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    1983 320is S52/2003 VR6T
    They sell brackets that I have seen so all you need is MK3 rear calipers, ebrake cable, and mk1 rotas and some shims to center the caliper. I will be doing this over the winter when work slows down.

  3. #3
    Join Date
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    E30M3,318is,318i,E21320
    I'll bite. So use a 1995 MK3 VW Golf set of rear calipers, and 1980 MK1 VW Golf set of front rotors, and a make a custom bracket?

    That's like $120 bucks in re-manufactured parts from any local parts place. How come this isn't popular? What's the brake bias with these with say a factory 77 vented front setup? Piston surface areas of the MK3 should be easy to find, but how to compare to the drums it replaces? Just train of thoughts here. . . back to work for me.
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  4. #4
    Join Date
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    Bayview, WI
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    1983 BMW 320i M20 Turbo
    I am pretty sure the hubs need to be turned/machined in order to run the VW setup. Someone correct me if I am wrong tho.
    1999 Z3 Coupe 2.8L


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  5. #5
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    I'm attempting to use just BMW stock parts and yes, the one item that I'll wind up fabbing is some sort of mounting bracket to secure the caliper. That's the idea anyway. I've seen Audi parts used, VW, etc. and I don't want to get into that.
    I still drive daily with no commute...
    The Hazard is All, Praise the Hazard!



  6. #6
    Join Date
    Oct 2015
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    RI
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    1983 320is S52/2003 VR6T
    I think the 2002 and e21 share the same bolt pattern for the rear disc brakes.
    http://www.classicdaily.net/product/...rake-brackets/
    Brackets - $80
    mk3 rear calipers with carriers - $340 pair including core charges.
    Pads - 45
    stainless hoses - 65pair
    VW rabbit front rotors - $60pair
    hardware - $20

  7. #7
    Join Date
    Aug 2001
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    NC
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    E30M3,318is,318i,E21320
    Quote Originally Posted by pofo View Post
    I think the 2002 and e21 share the same bolt pattern for the rear disc brakes.
    http://www.classicdaily.net/product/...rake-brackets/
    Brackets - $80
    mk3 rear calipers with carriers - $340 pair including core charges.
    Pads - 45
    stainless hoses - 65pair
    VW rabbit front rotors - $60pair
    hardware - $20
    Nice kit and I know people need to make money off others. But those prices are super high.
    A search on any online parts vendor
    MK1 Centric rotors can be found all day new for $28pair
    MK3 reman rear calipers are $100/pair no core core charge
    MK3 rear caliper carriers are $50/pair (I didn't notice at first you'd even need these)
    caliper hardware kits are $5
    Sure custom cut steel bracket ok maybe $80 to legit sell. It looks like a piece of 1/4" plate. I wish I was at this stage to make, but long ways off with the chassis.

    This is definitely on my short list now to fab up. Not trying to be a dick but reality has set

    Don't take this the wrong way. Thank you for making this available. For me pics are a 1000 words and all I needed. Thanks.


    I've no qualms using any brand manufacturer parts if they fit the application.
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  8. #8
    Join Date
    Apr 2005
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    Corona California
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    79 320/6 81320i 65malibu
    I have E30 rear calipers on my 80 with 323 arms and rotors, cannot remember what I did to make them work.

    Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link

  9. #9
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    E21 327i, E46 325iT/5
    Quote Originally Posted by OLD MAN View Post
    I have E30 rear calipers on my 80 with 323 arms and rotors, cannot remember what I did to make them work.
    I was just reading about this yesterday! You probably bored out the bracket holes, shaved down the bracket flats, and installed.

    Sorry 320i guys.

  10. #10
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    A set of E30 325e calipers should be about $140 from RockAuto. A set of rear plates is $40. and then you get into the issues of the parking brake parts, which can be more than the rest of the setup. Still, this is less than using some modified VW setup. Stock BMW E30 calipers are about $300 list for just the calipers which is insane.
    I still drive daily with no commute...
    The Hazard is All, Praise the Hazard!



  11. #11
    Join Date
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    1983 320is S52/2003 VR6T
    Quote Originally Posted by autox320 View Post
    Nice kit and I know people need to make money off others. But those prices are super high.
    A search on any online parts vendor
    MK1 Centric rotors can be found all day new for $28pair
    MK3 reman rear calipers are $100/pair no core core charge
    MK3 rear caliper carriers are $50/pair (I didn't notice at first you'd even need these)
    caliper hardware kits are $5
    Sure custom cut steel bracket ok maybe $80 to legit sell. It looks like a piece of 1/4" plate. I wish I was at this stage to make, but long ways off with the chassis.

    This is definitely on my short list now to fab up. Not trying to be a dick but reality has set

    Don't take this the wrong way. Thank you for making this available. For me pics are a 1000 words and all I needed. Thanks.


    I've no qualms using any brand manufacturer parts if they fit the application.
    Not my kit and these prices are what he sent me as a kit. But as a business owner myself, him going threw the time to piece the kit together and send it out its a very fair price. But I am resourceful and can find the parts easy. I will be using these brackets, but as someone coming from a VW I have and know a lot of friends have these parts laying around the garage.

  12. #12
    Join Date
    Sep 2015
    Location
    Massachusetts
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    E21 327i, E46 325iT/5
    Quote Originally Posted by midlifebmw View Post
    A set of E30 325e calipers should be about $140 from RockAuto. A set of rear plates is $40. and then you get into the issues of the parking brake parts, which can be more than the rest of the setup. Still, this is less than using some modified VW setup. Stock BMW E30 calipers are about $300 list for just the calipers which is insane.
    Don't buy new BMW calipers. And make sure used/rebuilt calipers include the bracket. The bracket is usually the really expensive piece if you have to buy it new. Rebuilt calipers sometimes have them, sometimes not. Here are some that I found with the bracket:

    Cheapest on Rock Auto: $58.79 with bracket (and coated!)
    http://www.rockauto.com/m/mobilecatalog.php

    $75 each with the bracket:
    https://www.turnermotorsport.com/p-3...i-325is-325ix/

    $86 each (shows the bracket but doesn't say):
    http://www.pelicanparts.com/catalog/..._pg1.htm#item0

    All prices include the core charge which you won't get back since you won't be returning a used caliper...

  13. #13
    Join Date
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    Quote Originally Posted by DougIng View Post
    Don't buy new BMW calipers. And make sure used/rebuilt calipers include the bracket. The bracket is usually the really expensive piece if you have to buy it new. Rebuilt calipers sometimes have them, sometimes not. Here are some that I found with the bracket:

    Cheapest on Rock Auto: $58.79 with bracket (and coated!)
    http://www.rockauto.com/m/mobilecatalog.php

    $75 each with the bracket:
    https://www.turnermotorsport.com/p-3...i-325is-325ix/

    $86 each (shows the bracket but doesn't say):
    http://www.pelicanparts.com/catalog/..._pg1.htm#item0

    All prices include the core charge which you won't get back since you won't be returning a used caliper...

    Hey Doug I found them on Partsgeek.com for 50ea
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  14. #14
    Join Date
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    79 320/6 81320i 65malibu
    Quote Originally Posted by DougIng View Post
    I was just reading about this yesterday! You probably bored out the bracket holes, shaved down the bracket flats, and installed.

    Sorry 320i guys.
    Pretty sure I looked it up on-line and did what everyone else had done - or a flavor of what they did, I always make things easier and better if possible.

    Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link

  15. #15
    Join Date
    Oct 2005
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    It's probably cold here.
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    ‘76 2002, ‘1
    Dusting off this old thread to mention that if anyone wants to do this conversion, I have the entire rear subframe from the euro car with everything in tact including the parking brake cables. I’ll post it in the classifieds too; p.m. me if you’re interested

  16. #16
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    Oct 2015
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    where are you located?

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