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Thread: e30 calipers on e21 323 trailing arms?

  1. #1
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    e30 calipers on e21 323 trailing arms?

    Does anyone have any specific information on this swap? I've seen it posted like its a direct bolt on but the '89 325i calipers I have are very different from the stock 323i calipers. They mount from different sides of the bracket. Has anyone actually done this swap that can give input?
    Thanks, Steve.

  2. #2
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    I haven't done it, but it's a matter of drilling out the threads on one side to allow for the different mounting position.

    '81 320i turbo | t25, 931 CIS, 250hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  3. #3
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    My 323 trailing arms are disassembled now. I will have to reinstall the bearings, axles, hub, etc so I can see how everything lines up. But, if the 325 caliper mounts the same as the 323, the caliper bracket will need more than just drilling the threads out. It is machined to mount on the opposite side. The side to mount like the 323 bracket is just the rough casting and has a rib which is higher than the areas around the mounting bolt holes that would prevent it from sitting flush. It looks to me like the bracket will have to be machined flat for proper mounting.
    Can anyone verify this? I will try to check all this this weekend if I can.
    Steve.

  4. #4
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    I just did this conversion took pictures to do a write up, I believe I have the pictures on my digital camera that is with me, but my notes are home and I'm away on business. Below is a link for reference, that I used. I believed my calipers were from an 87 e30, holes lined up perfectly, I also believed that I drilled holes out with 13/32 drill bit. I used my drill press with 3" roloc disc to grind the carrier down, this gave me a machined like finish. I also had to cut the back-plate were the piston goes. Final touch was I bought some UUC brake lines. I'll do a write up this weekend when I'm home, I'll have access to my notes for exact size. Also I'll see if I can send pictures in the mean time.

    http://e21.tricord.be/forum/view.php?view=20106
    Last edited by dhlthr; 12-04-2008 at 04:05 PM.

  5. #5
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    [ATTACH]267874[/ATTACH

    Hope this picture can help some. My more detailed pics are on my camera at the office.
    Attached Images Attached Images

  6. #6
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    Quote Originally Posted by SRC60 View Post
    My 323 trailing arms are disassembled now. I will have to reinstall the bearings, axles, hub, etc so I can see how everything lines up. But, if the 325 caliper mounts the same as the 323, the caliper bracket will need more than just drilling the threads out. It is machined to mount on the opposite side. The side to mount like the 323 bracket is just the rough casting and has a rib which is higher than the areas around the mounting bolt holes that would prevent it from sitting flush. It looks to me like the bracket will have to be machined flat for proper mounting.
    Can anyone verify this? I will try to check all this this weekend if I can.
    Steve.
    Take pics and please document this as I need to do this conversion. I am putting the volvo calipers on the front but my rears are blow out as well.
    "..Horsepower is a measure of work done over time, or the rate at which work is done."




    http://www.cardomain.com/ride/579694/1


  7. #7
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    I'll work on sizing the pictures tonight and try to post tomorrow.

  8. #8
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    In the thread dhlthr attached it discusses vw calipers and indicated they will also fit. I have both Mk2 cast iron and Mk4 aluminum and neither come close to fitting. The bolt hole spacing on the bracket is much wider than the 323 or 325 brackets. Thats not to say a simple bracket wouldn't be able to adapt these - I will look into this also when I reassemble my trailing arms.
    What dhlthr said about machining the brackets to fit flush and to allow proper spacing to the rotor is what it looked like to me but I wanted to make sure I wasn't missing something - like wrong year 325 calipers or something.
    Thanks for all the responses, Steve.

  9. #9
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    E30 rear caliper for e21.jpg

    OK here is my attempt at photoshop. This is the rear carrier. I recommend that you drill the holes to fit first. I remember that drill bit was bigger than the 3/8" bit that I had so a trip to home depot and I bought two bits, I believe I used a 13/32" bit. I then screwed the carrier to a board jig that would keep it flat and used drill press and grinding disk to grind area flat. I test fitted with rotor on trailing arm a couple of times to make sure that I did not over grind. When I was happy that rotor was center of carrier I was close to .580 width.
    Last edited by dhlthr; 12-04-2008 at 03:47 PM.

  10. #10
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    Modified for e30 caliper_edited-1.jpg

    euro ta with e30 caliper.jpg

    Here are couple more pictures to help with installation. This shows cut out of backing plate. I will post pictures with the drilled and slotted (bavauto) rotors and uuc brake lines.

  11. #11
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    Where did you get the 325i calipers and is there any difference between the eta, and I in terms of rear brakes.

    I talked to Rob at Bav Auto about this swap and he says its as easy as pie,
    and a great upgrade. You have to drill only a little bit.
    "..Horsepower is a measure of work done over time, or the rate at which work is done."




    http://www.cardomain.com/ride/579694/1


  12. #12
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    Nice Work !!!

    Quote Originally Posted by dhlthr
    Here are couple more pictures to help with installation. This shows cut out of backing plate. I will post pictures with the drilled and slotted (bavauto) rotors and uuc brake lines.
    Great pics and a very clean job. Guess it might be time to go play with those trailing arms

    Bimmerod

  13. #13
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    Quote Originally Posted by jjgbmw323 View Post
    Where did you get the 325i calipers and is there any difference between the eta, and I in terms of rear brakes.

    I talked to Rob at Bav Auto about this swap and he says its as easy as pie,
    and a great upgrade. You have to drill only a little bit.
    I picked mine up from junkyard, was told they were from an 87 eta. Don't know if there is a difference, but I believe all e30 caliper carriers are the same and have a 2.25" bolt spacing which is what our trailing arms have. I bought a rebuild kit and rebuilt my calipers as well (cheap and easy). I would upload more pics but keep getting excessive quota error, though pics are less than 100KB
    Last edited by dhlthr; 12-06-2008 at 03:11 PM.

  14. #14
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    Quote Originally Posted by dhlthr View Post
    I picked mine up from junkyard, was told they were from an 87 eta. Don't know if there is a difference, but I believe all e30 caliper carriers are the same and have a 2.25" bolt spacing which is what our trailing arms have. I bought a rebuild kit and rebuilt my calipers as well (cheap and easy). I would upload more pics but keep getting excessive quota error, though pics are less than 100KB
    use photobucket.com or imageshack.us to upload pics
    -Josh


  15. #15
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    Quote Originally Posted by wayfast View Post
    use photobucket.com or imageshack.us to upload pics
    Here you go!

    http://s37.photobucket.com/albums/e53/dhlthr/

  16. #16
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    Looks great.





    What rotors and brakelines are colorful are they stainless steel. What type of new bushings on the trailing arms? Can the emergency brakes be seperated from the trailing arms, if I want to get new ones to powdercoat the new trailing arms and install the emergency brakes.

    How much is the rebuild kit and who makes it? Is this hard to do.
    I am wondering If I should powdercoat them before I rebuild them.

    PS: I heard the the 323i rear rotor = the e30 325i rear rotor.
    Rob says they are identical.
    Last edited by jjgbmw323; 12-07-2008 at 05:21 AM.
    "..Horsepower is a measure of work done over time, or the rate at which work is done."




    http://www.cardomain.com/ride/579694/1


  17. #17
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    To answer jjbmw323's questions:
    1) Rotors are from Bavauto and yes the rears are the same as the E30.
    2) The brake lines are from UCC they are the 6 line stainless with blue sleeve. This is suppose to protect the stainless from fraying. Bimmerworld also sells these.
    3) Yes everything can breakdown and you can have the arms powdercoated. I did break mine completely down but used Eastwoods chassis black, instead of powedercoat (wish I powdercoated). I added new bearings and tumbled the parking brake parts and painted them.
    4)Rear bushings are KMAC adjustable urethane.
    5)Caliper rebuild kit was bought at local parts store $10ea. comes with new boot, seal and retaining ring. I also bought new rubber bushings but can't remember price.

  18. #18
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    OK. Thanks I am going to work on my car this winter and do this rear brakes conversion along with the rear DINAN Adjustable subframe. I also am going to do the front brakes.

    Does UUC or Bimmerworld sell a kit for the 323i or do you have to order the right length lines to make up the kit?

    I have never seen stainless with blue sleeve the lines I have are regular stainless steel, for a 320i. Thats all Bav Auto had at the time I ordered them.

    What do you do to tumble something - this is a process that cleans it somehow?
    "..Horsepower is a measure of work done over time, or the rate at which work is done."




    http://www.cardomain.com/ride/579694/1


  19. #19
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    Quote Originally Posted by jjgbmw323 View Post
    OK. Thanks I am going to work on my car this winter and do this rear brakes conversion along with the rear DINAN Adjustable subframe. I also am going to do the front brakes.

    Does UUC or Bimmerworld sell a kit for the 323i or do you have to order the right length lines to make up the kit?

    I have never seen stainless with blue sleeve the lines I have are regular stainless steel, for a 320i. Thats all Bav Auto had at the time I ordered them.

    What do you do to tumble something - this is a process that cleans it somehow?
    http://www.uucmotorwerks.com/ss_brake_lines/

    Here is a link, I ordered the e36 (6-lines). I still have to verify complete fitment. I have the girling front calipers but that should not matter. The teflon sleeves are the newest trend, I have seen them in clear and red but don't remember if they were for BMW. I don't know of anyone making the teflon coated for 323i because of the banjo bolt. I had a set of bavauto with the 323i calipers.

    http://www.harborfreight.com/cpi/cta...emnumber=93252

    This is the tumbler. It is used to clean parts, I went with the resin abrasive and it sucked, will try walnut next time. You can also use a brass wire wheel and drill to clean up parts quick and easy. everything looks new now.

  20. #20
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    I reassembled one of my trailing arms and modified the e30 caliper bracket along the lines of what dhlthr stated earlier. I used a 25/64" drill (couldn't fine my 13/32") and the bolts just fit - its smaller than the stock 323 caliper bracket holes. I 'machined' mine to about .580" and the bracket is still off ~.030" - .040" but I have not torqued the axle nut and this may pull everything in a little bit. I will wait till I reassemble the arms for good after I modify them and install new bearings and seals and torque the axle nut before I cut anymore off the brackets.
    I also looked at the vw calipers and neither the Mk2 or Mk4 brackets look to be adaptable by a simple bracket. I believe it would require welding on the 323 arm to widen it where the caliper brackets mount and I don't believe the vw calipers would gain you that much.
    Overall, the e30 conversion is relatively easy and I believe a very good upgrade. The sliding mechansim for the e30 caliper is much better than the e21 caliper and pads selection is much better.
    My e30 calipers came from a junkyard also and are from a '89 325i.
    Steve.

  21. #21
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    anyone of you guys know if it's possible to re-use the E21 banjo bolt/fitting on the E30 rear caliper?
    e21: 1981 2.5L sleeper
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  22. #22
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    While we're on the subject. Besides availability of parts - what is the performance difference?
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  23. #23
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    little to none, the pad surface area is a tad bigger, but hardly. The main issue here is getting your hands on e21 323i rear calipers. Walloth & Nesch has them for viele Euros, or you can get a rebuild kit from them for not that much. The sliding mechanism in the E30 calipers works much better, so they are less likely to sieze up on you.

    But when you have a stripped bleeder screw hole, you don't have much choice.

    I answered my own question by re-reading the Tricord thread, it appears that the E30 calipers will use the same brake line fittings. I was just concerned after looking at the line connections in the pics that dhlthr posted.

    EDIT: I went to the bone yard today & picked up a few pairs of e30 rear calipers, went home & modified a pair & got them mounted. These really are a much better designed caliper than the e21. The pad surface area really isn't much bigger, but rather than being a rectangle, the pads a are shaped in a trapezoid, so the outside edge is much bigger (more torque where it's needed). I found that I didn't need to modify my backing plate at all as long as you modify the caliper correctly.

    I started to modify the other two pairs that I have & will offer them up if anyone is interested. I also have a near new set of pads, pins, seals, boots, etc from a recently rebuilt pair of e21 323i rear calipers for cheap if anyone needs a set. As well as a driver's side caliper. The passenger side just has a stripped bleeder screw hole, otherwise is a very recently rebuilt caliper.
    Last edited by Jester323; 07-11-2009 at 02:01 AM. Reason: Automerged Doublepost
    e21: 1981 2.5L sleeper
    e21: 1982 323i Baur TC 1 # 4210
    e21: 1980 323i project or parts car, can't decide
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  24. #24
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    Alright i'm resurecting this from the dead I'm a newbie on the e21 stuff so I can see the e30 calipers can be moded to fit the 323 rear arms, what about 320? what would I need to make my rear disc?


  25. #25
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    Quote Originally Posted by DocDuvi View Post
    Alright i'm resurecting this from the dead I'm a newbie on the e21 stuff so I can see the e30 calipers can be moded to fit the 323 rear arms, what about 320? what would I need to make my rear disc?
    I'm in the process of doing this on my 320i. Although I have 323i trailing arms. I'll post up the results.

    Quick update. The ebrake cable end is different. I'm guessing you'll need an 323i/e30 cable.
    Last edited by Twelvizm; 03-10-2011 at 07:58 PM. Reason: Automerged Doublepost

    Bucket

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