rear disk brake conversion

[BoomerDJ]

On the 2002 rear disc conversions you use Golf/Jetta calipers/brackets from MkII's. I would think the Mk III's would also work. I used calipers from an Audi as they were the same. You can also use Golf/Jetta Mk IV calipers (they are aluminum) with the Mk II brackets. Not exactly sure of the years but the Mk IV calipers I have are off a '99 Jetta. The all have the emergency brake built into the calipers so it is just a matter of adapting your emergency brake cables to fit. Mk II stuff is very common in the local pick-n-pull.
By the way the 2002 conversion uses the Mk I (Rabbit) front rotor and it is 9.6". Mk II and later fronts are all vented discs and will not work with the rear calipers.
Hope this helps.
Steve.

looks like its time to go to the pick n pull and make a write up


i just need money

[braol]

I guess going all VW would allow someone to use a wider choice of wheels. I also wonder how much lighter a disc setup is compared to the drums????

[autox320]

Depends on what you do with your car. Tell me that next time you're going 115 down the back stretch of your local track.

+1, especially after a few hot laps of tripple digit speeds

-drums work but need adjustment often with track use cause they fade away with the high heat
-adjusting track temp hot drums sucks a giant phat one

Audi/VW (same same) calipers work, but even putting kit together yourself with all rebuilt calipers costs about the same as the kit. For street or autox I'd never even think of disc, it's a waste when you can get awesome shoes from carbotech.

[DubChub]

On the 2002 rear disc conversions you use Golf/Jetta calipers/brackets from MkII's. I would think the Mk III's would also work. I used calipers from an Audi as they were the same. You can also use Golf/Jetta Mk IV calipers (they are aluminum) with the Mk II brackets. Not exactly sure of the years but the Mk IV calipers I have are off a '99 Jetta. The all have the emergency brake built into the calipers so it is just a matter of adapting your emergency brake cables to fit. Mk II stuff is very common in the local pick-n-pull.
By the way the 2002 conversion uses the Mk I (Rabbit) front rotor and it is 9.6". Mk II and later fronts are all vented discs and will not work with the rear calipers.
Hope this helps.
Steve.

You guys don't get to see me on here too much... let me start by stating that I am only trying to help, not be a dickbag... here goes...

VW Brake-Down [= (Basic Version)

...specs and part numbers to follow.

MkIIs 1985-1993.5
Front: two varieties: Solid and Vented Discs
Rear: Same discs used, solid, through MkIII

MkIIIs 1993.5-1999.5
Front: Depends on Engine (i.e. ABA came vented, while diesels came solid... 4x100 anyway, VR6s are a different pattern 5x100)
Rear: As mentioned, same as MkIIs

Note: Keep in mind, VW used many different part numbers because of different manufacturing locations (i.e. Germany, Mexico etc.) and many markets (i.e. Europe, US etc.)

Also, for Audi cross-references, I don't know much... Just the A Chassis.

There are, like I said a lot of part numbers for similar parts, so I'll just post a few. If you know of a donor, and know what will work for the rear swap, please just let me know the year, model, and trim... VIN is best.

Rear Calipers:
MkII -
535 615 423 X - left
535 615 424 X - right
MkIII -
1H0 615 423 DX - left
1H0 615 424 DX - right
MkIV -
1J0 615 423 D or G - left
1J0 615 424 F or H - right

Rear Caliper Carriers:
MkII and MkIII -
1H0 615 425 - left
1H0 615 426 - right
MkIV -
6Q0 615 425 A or C - left
6Q0 615 426 A or C - right

Rear Pads:
MkII and MkIII -
1H0 698 451 E or F
MkIV -
1J0 698 451 R

My personal advise, without attempting to calculate and compensate for proportioning valves...

Use the MkII or MkIII caliper carriers with MkIV calipers and pads.


I don't know what will be needed specifically but it may help to know that a typical MkIII Jetta with four wheel discs weighs about 2800lbs curb, plus you. And the diameter of the disc in all cases in the rear is 226x10mm.



I am also looking to do this to my poor E21, but not soon.. I don't think...

Thank you for your time... As mentioned... if you need VW part numbers quick, just let me know...

[zbmwguy]

My buddy in Europe is looking at putting rear disc brakes on a car equipped with drums. He can fabricate a mounting bracket for the caliper but he had a few questions:

1. Can the hub be used from his current drum setup?

2. Assuming he is using a Mk III VW caliper from a Golf with integral emergency brake, what rotor should he use (assumed non-vented Mk I Rabbit rotor)?

3. Does the hub diameter need to be "turned down" on a lathe to fit within the rotor specified above?

4. The VW rotors use a small screw to retain themselves to the hub face. Does this need to be done on the BMW hub?

5. Does anyone have the bolt hole spacing of the backing plate for mounting and the centerhole diameter to make the bracket?

[BoomerDJ]

bump for answers to post above me...

[Twelvizm]

Wish I would have seen this thread before going the 323/E30 route.

[MrGumby]

I'll be hitting the pick n pull yard this week after class gets out. I'll bring my digital calipers & take as many measurements as possible. I'll probably go Wednesday or Thursday, so if we can come up with a list of measurements needed, I'll post up my findings with pictures. I've got the 4 wheel disc bug now, especially since I lost out on a full set of Porsche 944 Turbo calipers.

[EauRouge2002]

Another potential source of rear calipers with integrated parking brakes for those who want to do a big brake upgrade are the Corvette c4 rear calipers. They are also aluminum.

For those doing non vented rotor conversions in the rear, the rear calipers from the 84-87 Pontiac fiero may also work. These are single piston aluminum calipers with integrated parking brake as well.

[Boosted20th2886]

I know this is an old thread, but I figured I would just add to this rather than create a new one. But I have some questions that can hopefully be cleared up.

I was at the junkyard today and picked up the rear spindle, rotor/hub and bearings from a MK2/3 rear beam. I also got a pair of MK4 rear calipers, just need to track down some MK2/3 carriers and pick up some proportioning valves. I haven't had the chance to dig into the rear brakes on the E21, but does the whole VW rear spindle swap over? If it does I would imagine it would alter the track of the rear end as well?

Thanks for any help.

[semperjim]

boosted20th, if those are for a rear brake conversion,the only thing that will be usable from that list is the mk4 calipers, unless you're planning on making your car front wheel drive

[Boosted20th2886]

boosted20th, if those are for a rear brake conversion,the only thing that will be usable from that list is the mk4 calipers, unless you're planning on making your car front wheel drive

wow, super stupid on my part...im going to just go off into the corner now. I can't believe non of that crossed my mind. hahaha

Ok, lets scratch that and toss it up as a life lesson to stop and think. Good thing it was cheap.

So I have the rear calipers, I need a pair of carriers and some non-vented rotors. Now do the rotors simply replace the whole drum assembly? What am I missing? Was there ever a detailed write up done?

[jjgbmw323]

wow, super stupid on my part...im going to just go off into the corner now. I can't believe non of that crossed my mind. hahaha

Ok, lets scratch that and toss it up as a life lesson to stop and think. Good thing it was cheap.

So I have the rear calipers, I need a pair of carriers and some non-vented rotors. Now do the rotors simply replace the whole drum assembly? What am I missing? Was there ever a detailed write up done?

I have done the swap on my MK2 - and I have converted it to disk from drum.
As for how it works on the E21 you have to remove the drum assembly, and then there is a special bracket that mounts the vw MK4 calipers onto the e21 323i trailing arms...

[Boosted20th2886]

ahh, i see. So is there any way to do it with the 320 trailing arms?

[semperjim]

you would need to build a bracket to bolt the caliper carrier to, then machine down the outside of the 320i hub to fit inside the vw rotor, that rotor should come from a mk1 vw with solid front rotors, then make an adapter for the parking brake cable from the 320i drum, or find a similar length replacement cable with the correct end

[Boosted20th2886]

Thanks for your help SemperJim.

I have a good buddy who has a lot of machine equipment in his garage and even more at work. I'm going to pick up some rabbit front rotors, a spare set of rear 320i hubs and see what we can come up with.

I love old VW parts, brembo replacement rotors for a Rabbit are only $26 each. haha

[JakeB]

I make this bracket to adapt the VW brakes to a 2002....I would guess it is the same thing for the e21. I have sold maybe 25 sets to 2002 guys and looking into putting together another run.

[Boosted20th2886]

I would be interested in that for sure. How much would you be selling them for?

[JakeB]

They are $80 a set shipped in the US. I might be able to bring them down if I do a larger run of them. They are water jet cut from 3/8" mild steel. On the 2002 you need to shim the caliper 2mm off the bracket to under it on the rotor. You also have to grind just a little bit below where the shock mounts. This may or may not need to be done on an e21....I would have to have someone test it.

I am in the process of find a good (cheaper) source for new calipers and carriers so I can offer an entire kit. If you were to send me you hubs I can have those machined down as well.

[semperjim]

Jake, where does this mount the caliper? I know I've seen pictures of the 2002 swaps and as far as i can remember the calipers have been mounted below the arm. Is there a way to work up a kit which mounts the caliper at the 2-3 o'clock position? I have all the pieces for the kit now (-brackets) spare control arms and already machined hubs (from the po's corvette caliper swap.) If i send you bolt hole dimensions and they match yours do you have a set of brackets I could buy off you?

[JakeB]

My bracket puts the caliper at the 3 o'clock ish position

If you send me some dimensions I can check them out. I don't have any brackets available right now but can get some cut over the next week or two.

[semperjim]

ok, give me a few days and i'll get some dimensions together

[bruno504]

Would be nice to continue this post, because I could try do something too, but no knowledge about other car parts that can be used on e21!

[JakeB]

My brackets work with the VW brakes on an e21

[captain awesome]

My brackets work with the VW brakes on an e21

What rotor are the people using with your bracket and does it require any machining? Rabbit MK1 front rotors like mentioned above?