First, and most importantly the parts list.
Complete trailing arms, left and right.
Brake rotors (same as e36 M3 rear)
Brake calipers
MZ3 halfshafts (much larger/beefier then the e30 unit)
MZ3 diff output flanges (much larger bolt pattern then e30 units)
Complete trailing arms
MZ3 trailing arms are far superior to the e30 unit. The overall design is the same but they have added camber/tow bracing that makes them a much more solid design. A complete trailing arm should come with the arm itself, and the hub/wheel bearing still pressed in. Buying bare arms without the hub/bearing sucks. Alot of work for someone without the special tools to press them in.
You will have to use the e30 trailing arm brake hardline. The locating tab on the brake backing plate is missing on the MZ3 backing plate. I choose to cut it off a set of e30 backing plates and tack weld it onto the MZ3 backing plate.
While you have the arms off the car it would be smart to weld on the sway bar re-enforcement tabs. Turner, IE, etc sell them, or you can make them yourself.
Brake rotors
Brakes are a big upgrade with this conversion. The MZ3 rear disc brakes are 312x20mm vented units. The same rotor used by the e36 M3 in the rear. A e30 325i has puny 258x10mm solid rear discs! I'd suggest buying new, but the used ones I got from a 16k mi MZ3 were in very good shape.
Brake calipers
Calipers are standard issue single pistons, much the same as the stock e30 rear caliper in design. They are however much larger! I decided to disassemble, beam blast, paint, and rebuild mine. Rebuild kits are cheap, and not very difficult to do. Rebuilt units can be had for < $100. Got a pair from a 16k mi MZ3, but rebuilt them anyways.
M-Roadster / Coupe rear halfshafts
AFAIK these are unique to these cars. They are much larger in diameter then the e30 units. These list for ~$350 each new, and I had no luck finding rebuilt unit. Got good used ones from a 16k mi MZ3.
M-Rodster / Coupe diff output flanges
I think these are also unique to these cars, E28 output flanges can be used as well. That may be true but the E28 halfshafts are not! Different design. Get these used. The MZ3/E28 flanges will swap into a e30 diff. They just pull and push in.
The rear suspension swap is pretty straight forward. Unbolt and remove everything related to the stock suspension and remove it. MZ3 arms bolt directly in with no modification. You CAN reuse your stock brake line if your car originally had ABS and rear disc's. It just needs to be bent up slightly to run down the arm and up to the caliper (rather then around the backside etc) Be very careful not to kink the line while you are bending it.
As for the ABS sensor. You have 2 choices. Splice the e30 connector onto the MZ3 sensor, or install the e30 sensor with a spacer. Problem is the e30 sensor is much longer then the MZ3 and would bind on the pulse ring. To solve this problem I found a copper crush ring in the crush ring assortment that was the exact right internal diameter to fit snuggly on the sensor. I think it took 4 or maybe 5 of the crush rings stacked to make up the difference in the length. I installed them with a longer allen screw and my ABS works perfectly. I will double check the # of spacers and photograph it when I get a chance.
The e30 ebrake cable will route through the back of the MZ3 trailing arm and connect to its native ebrake hardware perfectly. The MZ3 ebrake hardware is very similar to the e30, but much larger and beefier. Let me tell you.. I had brand new ebrake shoes on my e30 suspension, and I could drive with it locked without a problem. The MZ3 shoes LOCK the rear wheels. If you try to go anywhere you are out of luck.
Complete trailing arms, left and right.
Brake rotors (same as e36 M3 rear)
Brake calipers
MZ3 halfshafts (much larger/beefier then the e30 unit)
MZ3 diff output flanges (much larger bolt pattern then e30 units)
Complete trailing arms
MZ3 trailing arms are far superior to the e30 unit. The overall design is the same but they have added camber/tow bracing that makes them a much more solid design. A complete trailing arm should come with the arm itself, and the hub/wheel bearing still pressed in. Buying bare arms without the hub/bearing sucks. Alot of work for someone without the special tools to press them in.
You will have to use the e30 trailing arm brake hardline. The locating tab on the brake backing plate is missing on the MZ3 backing plate. I choose to cut it off a set of e30 backing plates and tack weld it onto the MZ3 backing plate.
While you have the arms off the car it would be smart to weld on the sway bar re-enforcement tabs. Turner, IE, etc sell them, or you can make them yourself.
Brake rotors
Brakes are a big upgrade with this conversion. The MZ3 rear disc brakes are 312x20mm vented units. The same rotor used by the e36 M3 in the rear. A e30 325i has puny 258x10mm solid rear discs! I'd suggest buying new, but the used ones I got from a 16k mi MZ3 were in very good shape.
Brake calipers
Calipers are standard issue single pistons, much the same as the stock e30 rear caliper in design. They are however much larger! I decided to disassemble, beam blast, paint, and rebuild mine. Rebuild kits are cheap, and not very difficult to do. Rebuilt units can be had for < $100. Got a pair from a 16k mi MZ3, but rebuilt them anyways.
M-Roadster / Coupe rear halfshafts
AFAIK these are unique to these cars. They are much larger in diameter then the e30 units. These list for ~$350 each new, and I had no luck finding rebuilt unit. Got good used ones from a 16k mi MZ3.
M-Rodster / Coupe diff output flanges
I think these are also unique to these cars, E28 output flanges can be used as well. That may be true but the E28 halfshafts are not! Different design. Get these used. The MZ3/E28 flanges will swap into a e30 diff. They just pull and push in.
The rear suspension swap is pretty straight forward. Unbolt and remove everything related to the stock suspension and remove it. MZ3 arms bolt directly in with no modification. You CAN reuse your stock brake line if your car originally had ABS and rear disc's. It just needs to be bent up slightly to run down the arm and up to the caliper (rather then around the backside etc) Be very careful not to kink the line while you are bending it.
As for the ABS sensor. You have 2 choices. Splice the e30 connector onto the MZ3 sensor, or install the e30 sensor with a spacer. Problem is the e30 sensor is much longer then the MZ3 and would bind on the pulse ring. To solve this problem I found a copper crush ring in the crush ring assortment that was the exact right internal diameter to fit snuggly on the sensor. I think it took 4 or maybe 5 of the crush rings stacked to make up the difference in the length. I installed them with a longer allen screw and my ABS works perfectly. I will double check the # of spacers and photograph it when I get a chance.
The e30 ebrake cable will route through the back of the MZ3 trailing arm and connect to its native ebrake hardware perfectly. The MZ3 ebrake hardware is very similar to the e30, but much larger and beefier. Let me tell you.. I had brand new ebrake shoes on my e30 suspension, and I could drive with it locked without a problem. The MZ3 shoes LOCK the rear wheels. If you try to go anywhere you are out of luck.
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