Technical & Reference Section > Tech and Restoration

***ACS rotor twin cable mod***

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oldschoolace:
As some of you will know i have been playing with the idea of running twin cables on my next build. I had discussed a few options with Terry and as i dont like the messy look of a gyro a modified rotor seemed the obvious choice  :)

As far as i know earlier ACS rotors have a circlip holding them together while the later ones, which are more common on the bay have a lock nut and split pin. The mod works with either but these pics show the lock nut model.

First using a small panel pin/nail tap out the split pin FROM THE INSIDE OUT. It is slightly tapered and much easier to get out this way.




Once removed hold the lower half of the rotor tightly (a vice is best) and undo the lock nut. It can take some effort to undo as the hole for the split pin can leave a burr on the thread.




Lift out the steel washer, stepped nylon washer and the bottom half of the rotor.




Remove the cable (it will probably have a little nylon ball grommet at the pear end) and mark the other side of the ring for drilling. It should be central on the rings width.




You can replace the stepped nylon washer and flick out the little black acs plug from the top section then put the two together to check your mark is exactly opposite the existing hole.



Drill a 4-4.5mm hole right through then flip it over and countersink the hole with a 6-7mm hole. Make sure the countersinks are on the same ring face. You only need to drill deep enough for the brake cable pear to sit just below the surface.






Next mark and drill a 5mm hole into the side of the top section where the plastic ASC lug was removed from. Tap for an M6 thread and turn in a mild steel bolt until it stops. Carefull file a flat spot on the thread as close to the rotor as you can and drill a hole large enough for a cable to run through. Cut to length for a washer and nylon lock nut.




Rebuild your rotor remembering to insert the cables and it should look something like this.










The only tricky bit is drilling a cable hole through the M6 bolt. A pillar drill is needed really although i'm sure trapping the cable between two washers under a ntt would work just as well.  :daumenhoch:

Will get some pics up of the instalation method tonight  :)

pickle:
how are you going to stop the upper cables?  i always thought the ACS rotor works well as it is with the single cable. 

i admire your work there but that's going to be fiddly as fook to set up.

best of luck and show us piccies once it's done  :daumenhoch:

oldschoolace:
I have always thought that main problem with Acs rotors is that the single cable wants to pull the rotor out of square so it binds on the stem post. Twin cables should keep it square. I'm running mine with a compatable stem and using the non compatable stem plate to run the other cable  :)

You could in theory use two of these if you didn't have the right stem

Gnarlyscoots:
Looks good that Clint. Can't you just use 2 x stem bolt tabs for the upper cables? Keeps it looking old school too  :daumenhoch:

oldschoolace:
Thats the plan Terry. Stem bolt tabs sounds better than a non compatable stem plate  :LolLolLolLol:

Going to run my ACS stem or a tioga rs-2 stem like this with a tab for the second cable  :)

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