Desperately in need of help with a brake conversion

[maxim8]

I have a 1985 318i sedan that has been swapped with an inline-6 2.0L that is currently in the process of a rear drum-to-disc conversion. I have swapped the rear lower control arms (due to rust issues) and I have no clue what model or year car they came from and its really screwing me over with this disc conversion. I have the emergency brake shoes fully setup on the backing plates and I have been interrupted with a caliper mounting issue. I have calipers from a 325i and they don't seem to fit on the mounting hole on said control arms. I'm left with either finding some sort of bracket that supports the calipers, fabricating some sort of bracket, or giving up and slapping on some drums. I have no idea of what the best solution is as I have no solid grasp on the options that are available to me. I also don't understand how to add photos to this post.

[dworthy]

So all the E-30's, expect the M3 use the same caliper carrier bracket. I wonder if you have a E-36ti or Z-3 rear arms, for the will use a different ones.

[maxim8]

How would I identify or confirm that? The arms are a 4 bolt pattern

[dworthy]

There will be part numbers on the arms, should be 7 digits with a BMW roundel next to it.

[nick325xit 5spd]

show pictures of all the parts that you have. I'm wondering if you have the wrong calipers.

[mbonder]

They can't be e36 trailing arms, those would be 5 lug hubs.

As mentioned earlier, all e30s except for the m3 use the same calipers, so if the caliper bracket mounts to the trailing arm but the caliper doesn't mount to the bracket, you have the wrong calipers.

[dworthy]

Not if they didn't come with the hubs, for I have seen them installed in E-30 and they used the E-30 hubs.

[mbonder]

The assumption I'm making here is that these were purchased second hand from a salvage yard or from a private seller, in either case, you'd figure they would have mentioned if the arms didn't come with the original hubs.

Either way, get some pictures up and we can further assess what is needed.

[maxim8]

[82eye]

you need trailing arms from any 325i e30 to be certain. 320i and 318i could be either drum or disc depending on year and market. if you stick with a 325i trailing arm you'll be sure to get the correct set up.


edit : i should add if you're only running an m20b20 you won't need more than the drums for stopping power. if you are modding for more power then it may be worth your time to look in to it.

[maxim8]

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[nick325xit 5spd]

Hmm. Something looks very wrong with the hub / rotor/ ebrake / backing plate interface. I'm pretty sure that those calipers are correct. Can you mount the calipers without the rotor in place?

[nick325xit 5spd]

are those 325iX rear hubs? if you've put a 325i rotor on a 325iX hub, it wouldn't get close to the backing plate the way that it should be.

- - - Updated - - -

ix hub:
https://www.turnermotorsport.com/p-6...uine-bmw-part/

rwd hub:
https://www.turnermotorsport.com/p-1...325ees-325iis/

[nick325xit 5spd]

this is what a 325iX rear rotor looks like, for reference:
https://www.fcpeuro.com/products/bmw...163145#fitment

iXes get a whole bunch of extra rear track.

[82eye]

it looks like it has the drum brakes installed. something's really off here.

[maxim8]

I'm fairly certain that those brake shoes are just for the parking brake

[dworthy]

So two things I can see, doesn't look like the hub is fully seated, and your axle nut is missing. As that being said, I bet the rotor isn't sitting flush to the backing plate, and the caliper carrier isn't fitting either.

[82eye]

I'm fairly certain that those brake shoes are just for the parking brake

it just looks bigger in the photo than what it really is on the car.
there's no way he could get the hats on if it was an actual drum brake.

[dworthy]

^^+1

Beside drum brake shoes will not fit on those backing plates anyway, way too big.

[nick325xit 5spd]

So two things I can see, doesn't look like the hub is fully seated, and your axle nut is missing. As that being said, I bet the rotor isn't sitting flush to the backing plate, and the caliper carrier isn't fitting either.

The iX hub sticks way the hell out vs. the RWD hub. Put a RWD rotor on an iX hub and you get that symptom.

[maxim8]

FM9Ccu6.jpg So I’m assuming that I need to get some IX rotors now right? I’m just worried about if my calipers are going to fit on them cause the original problem was that they were only able to get about 1/2 of the pads covering the RWD rotors, so would anybody know what the full diameter of the IX rotor would be?

[nick325xit 5spd]

The iX uses the same caliper and brake pads as a RWD E30. So if the problem is that you have iX hubs (which is what it seems like), then an iX rotor will solve the problems.

It would be helpful if you posted more and better pictures of the actual parts, though.

[mbonder]

Doesn't look like the hub is seated properly if it is an I/IS hub. If it is an IX hub than it makes sense. The rotor is definitely sitting too far away from the backing plate.

[dworthy]

+1

Same caliper set-up for all of the E-30's, except the M3 of course.

So the IX rotor is 75mm deep while the stock rotor is 60mm, so that about 1,5cm difference.