240sx Rear Disc Swap (In Progress)

[PandaSmash]

Hello,

I'm taking a stab at doing a 240sx rear brake conversion on my 67 1600. This is still a work in progress. I haven't got all the details figured out yet, but I'll share what I find as I go along here.

I started by modeling up the rear axle stub and referencing the original 240sx geometry as my starting point. I went with a design that uses three of the four mounting holes with a spacer between the bracket and the axle that acts as a strap to bridge the fourth hole.

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I'm still playing with the angle of mounting the caliper so it clears the springs and frame through suspension travel so I haven't finalized the brackets yet. The 240sx has them mounted on the front of the rotor 10° up from center, that ended up putting the e-brake mount pretty close to the springs. I also tried 15° like the 200sx rear swap, but that still looked pretty close, so I bumped it up to 20°.

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Then I turned my attention to the axle studs. The stock 7/16 x 20 studs would allow to much slop in the rotor mounting, so they got changed to m12 x 1.5s. I went with ARP part number 100-7709 which have a .485 knurl. The stock stud hole is about .455, so I wanted to stay as close as possible to that size considering there isn't much material there to play with.

Following ARP's guidelines for hole size I went .005 under with a .480 reamer.

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That just left me with cleaning up the axles and milling a flat on the studs to match the originals.

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That's all I've got for right now. My next step will be mounting the axle back in the car to check clearances and then getting the brackets cut out of the proper material. After that will be line routing and e-brake setup as well as figuring out a debris shield setup that works off the retaining plate.

Let me know what you think.

-EM

[fj20spl311]

IIRC, Some people have converted to cable e-brake to the roadster rod mechanism.
That would be COOL.

[PandaSmash]

IIRC, Some people have converted to cable e-brake to the roadster rod mechanism.
That would be COOL.

Unfortunately, I've already removed the brackets from the axle tube as I plan on doing a cable setup. For the stock 240 setup you'd have to flip the motion of the stock rod system to a pull instead of a push, but it would be pretty interesting to see.

I think I've got the backing plates sorted, I picked up a pair of plates from a 91-96 Infinity G20. Part numbers 44151-61J01 and 44161-61J01. I'm going to cut out the center section of the original plate and spot weld an adapter plate to them. I only modeled the adapter plate, but the G20 has the same 258mm rear rotors so everything should fit up.

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-EM

[240z666]

Hey

I did this conversion over the winter. It was pretty easy. I don't know if the performance is any better, but it look great.
I used the 240sx cables and the roadster E-brake hardware. I made a bracket to hold the 240 cables onto the axle and they were the perfect length to attach to the roadster
e-brake assembly.
Just a suggestion...bled the 240sx calliper with them Upside-down. The bleeder bolts should be facing up. It took me a while to figure that out.
If you want pics, let me know.

[PandaSmash]

So after playing around with some different setups on the car, it looks like my previous assumption that I needed more of an upward angle to avoid the springs was incorrect. With the 20° plate the caliper would definitely hit the frame rails before stopping on the bump stop. I ended up lowering it down to 5°, which puts it pretty close to the spring. I don't think the distance between the caliper and spring should change much over the spring travel, but what have other people who have done the swap experience been?

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Here is a rough placement on the dust shield.

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[240z666]

Email sent

[PandaSmash]

Progress has been pretty slow on this, but I finally had all the parts cut out and powder coated.

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Now it's time to turn my attention to the hose and parking brake cable routing. Those of you that have done this swap, are you eliminating the last body mounted parking brake linkage and attaching it there? I don't really see any good way of using the original mount on the axle tube.

Any feedback is appreciated.

-EM

[bobd]

http://www.311s.org/Pics/200sxBrakes/ebrakebrack.jpg

I recently sorted out my 200SX rear discs using the above bracket (from the wiki) but was not able to bolt it in place as described.

I wound up welding a mount next to the parking brake boss on the rear end and bolting the bracket on to that.

Here is a picture of the brake set up before the parking brake was done.

[spl310]

Very nice. I need to source a set of the mounting brackets as I have calipers.

[bobd]

The parking brake bracket installed

[Jdflyer]

If someone has the CAD/CAM files, I have access to a waterjet and would be happy to cut them out for people.