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Author Topic: Lessons learned from dual disc setup  (Read 3794 times)

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Offline 70CB750

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Lessons learned from dual disc setup
« on: July 17, 2012, 07:47:17 pm »
- drilled discs create some nasty sharp shavings
- cobalt drill bit from Lowes/HD is good enough to drill the disc but it helps to sharpen them every 40 holes or so.
- after converting the speedo drive, the axle needs spacers to center the wheel.
- after converting the speedo dtive, the screw has to be shortened.
- there is a correlation between the thickness of spacers under  the right brake bracket and the thickness of the passive brake pad.  New thick brake pad kept locking up while half used pad works fine
- locked up disc brake burns pads and creates smokes
- bleeding brakes is not a science, just stick to basics and have enough brake fluid and beer at hand
- the hoses from slingshot cycles are of excellent quality
- in dual disc setup the brackets and calipers block access to mounting bolts. The only way is to take the whole brake bracket with caliper off

and yes, it is worth it, I like the resulting increase in stopping power.
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Offline grasscutter

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Re: Lessons learned from dual disc setup
« Reply #1 on: July 17, 2012, 08:00:23 pm »
Pics!
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Online scottly

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Re: Lessons learned from dual disc setup
« Reply #2 on: July 17, 2012, 08:27:35 pm »
Quote from: 70CB750 on July 17, 2012, 07:47:17 pm

and yes, it is worth it, I like the resulting increase in stopping power.
1+  ;D
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Offline DJ_AX

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Re: Lessons learned from dual disc setup
« Reply #3 on: July 17, 2012, 09:21:44 pm »
...and would you need to upgrade the front suspension too? Progressive springs maybe?
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Offline 70CB750

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Lessons learned from dual disc setup
« Reply #4 on: July 18, 2012, 04:58:20 am »
One more:

- from the switch to the caliper you can run hose with straight banjo for the switch and 90 degrees banjo for the caliper. Fits well.
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Offline 70CB750

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Re: Lessons learned from dual disc setup
« Reply #5 on: July 20, 2012, 09:27:56 am »
Seems like I will be coming up with additional points for a while. 

Anyway, this one is about bleeders and brake lines.  The both holes on the caliper are the same with M10x1.25 thread (that would be fine M10).  The only difference is, that the bleeder hole has a pressed in steel seat for the bleeder to seal against.  Since I wanted to run the brake hose to the closer hole on both sides of the fork, I had to press the seat out.

To press the seat out:

- file a nail to fit in the caliper hole but bigger than the hole in the seat
- cut the nail short enough to fit in the piston cavity
- push the nail through the seat and secure it in a vice
- with rubber mallet tap on the caliper several times
- the seat should come out without much effort

An alternative would be to make a puller from thin bolt and nut, but this worked well enough for me.

Now you need to run a correct tap M10x1.25 carefully through both threads to clear out the accumulated gunk and you are ready to install brake lines in whichever hole suits you  better.  From my experience, the bleeder seals fine without the seat, but I also used silikon tape on threads of the bleeder.
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Offline MCRider

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Re: Lessons learned from dual disc setup
« Reply #6 on: July 20, 2012, 10:13:42 am »
Your method works well, I've done one like that. I had another that just wouldn't budge, so i went at it with a drill. Went up one bit size at a time. Withiin a few the seat came lose and pulled out with the drill bit. easy peezy.
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Offline 70CB750

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Re: Lessons learned from dual disc setup
« Reply #7 on: July 20, 2012, 10:22:13 am »
Makes sense, thanks for the additional tip.
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Offline 70CB750

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Re: Lessons learned from dual disc setup
« Reply #8 on: July 21, 2012, 05:19:01 am »


Thousand words, eh? :)
« Last Edit: July 21, 2012, 05:29:48 am by 70CB750 »
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Offline 754

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Re: Lessons learned from dual disc setup
« Reply #9 on: July 21, 2012, 09:08:54 am »
 I stay away from banjos if I casn...use adaptor to -3 line..
 First time I pulled the wheel with dual disc, I tokk the adjusters and springs off 4ever...
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Offline Rookster

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Re: Lessons learned from dual disc setup
« Reply #10 on: July 21, 2012, 12:06:05 pm »
+1 on removing the springs and screws.  You don't need them.  The piston sets its own level based on the thickness of the disk and the thickness of the stationary pad.

Scott
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Offline 70CB750

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Re: Lessons learned from dual disc setup
« Reply #11 on: July 21, 2012, 03:54:14 pm »
Banjo never failed me - unlike steel of SS lines and associated adapters. And due to the size of banjo bolt you are always able to take it out - unlike old fittings.

I run the brakes without springs for testing but couldnt find any reference about taking them out completely - I use them now.
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Offline MCRider

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Re: Lessons learned from dual disc setup
« Reply #12 on: July 21, 2012, 04:07:31 pm »
I hear the idea of leaving the adjusters off. First hand experience as to why not.

I'd left mine unadjusted, with a lot of play, maybe 1/4" or more. Like leaving it off. After an extended period of not using the brake I went for a handful and it wasn't there. Instinct had me pump it a couple of times and I got it back.

What happened was the A pad, unimpeded by the adjuster had moved into the caliper a fair bit/ From being joslted on the road bouncing and such. THen when I went to use it, I had to pump it to get the A pad back to where it belongs.

Go without it at your own peril.
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Offline Pecantree

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Re: Lessons learned from dual disc setup
« Reply #13 on: July 21, 2012, 05:22:31 pm »
754..
Curious why you don't use banjo, did you have one fail?

Steve
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Offline 754

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Re: Lessons learned from dual disc setup
« Reply #14 on: July 21, 2012, 10:44:20 pm »
 Dont like the looks of a 90  degree or angled turn, not that clean looking, and more parts.. wish I had a closeup shot of my old line I made in79 or so.. straight out the master, thru the steering stem to a T.. 2 45degree fittings off the tee, then gracefully arcing lines straight into the finned caliper, via the caliper to line adapter.
 I must say this does not work as well with a 550 or late 750 smooth caliper, as the outlet is angled..
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Offline 70CB750

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Re: Lessons learned from dual disc setup
« Reply #15 on: July 23, 2012, 05:34:46 am »
In my book if it works and is reliable it makes it pretty.
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Offline SKTP

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Re: Lessons learned from dual disc setup
« Reply #16 on: July 23, 2012, 10:59:33 am »
What master are you running?
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Offline 70CB750

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Re: Lessons learned from dual disc setup
« Reply #17 on: July 23, 2012, 11:09:16 am »
The original.  Correctly installed and bled calipers dont need big volume of fluid moved to work properly.
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