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#363753 - 03/19/11 3:15 am Dual disc conversion: worth it?  
Joined: Nov 2005
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JubeePrince Online content
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JubeePrince  Online Content

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So I have a couple of sources for the RH lower slider with the caliper boss for a dual-disc front end. I realize there are many other components needed for this conversion: brake lines, different MC, another disc (I have a spare caliper)pinch bolt, hose, line fittings, etc, etc....

I was considering just slowly gathering the bits over the next year or so, then install it when I have all the bits...

Some questions: Is the extra braking power worth it?

Is a well-sorted double disc THAT much better than a well-sorted single?

Is the extra weight worth it?

Am I right in thinking that all I need for the front wheel are four longer disc bolts or is it a straight bolt-on?

While my brakes currently work well, I wouldn't mind a little more stopping power (plus I kind of dig the way the dual-disc looks!). If I'm barking up the wrong tree, you can tell me that too!

Thanks in advance,

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
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#363771 - 03/19/11 6:05 am Re: Dual disc conversion: worth it? [Re: JubeePrince]  
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tridentt150v Offline
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Great Southern Land
More weight and you have to drop a caliper or remove one side of the mudgaurd/fender to get your front tyre out, harder to bleed, a PITA.

On the up side more progressive feel to the braking, better braking esp. in the wet. Brakes feel balanced, and look better [personal opinion] I have it on both bikes and recommend also going to the larger m/c ID.

You used to be able to get nyloc half nuts and use the same bolts, but I eventually went with new slightly longer bolts.

Last edited by tridentt150v; 03/19/11 6:06 am.
#363776 - 03/19/11 7:48 am Re: Dual disc conversion: worth it? [Re: JubeePrince]  
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Stuart Online content
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Stuart  Online Content
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Hi Steve,

Originally Posted By: JubeePrince
Is the extra braking power worth it?
Is a well-sorted double disc THAT much better than a well-sorted single?
Is the extra weight worth it?
all I need for the front wheel are four longer disc bolts

Definitely. Definitely. Definitely. Yes.

Also, you lose the twisting of the front wheel under braking by the single disc.

Originally Posted By: tridentt150v
you have to drop a caliper or remove one side of the mudgaurd/fender to get your front tyre out,

Shouldn't have to. Using a proper right-hand slider, which places the caliper behind the slider like the left-hand one (as opposed to using a second left-hand slider and turning it around so the caliper's ahead of the slider), the caliper mounting should be helicoiled 3/8"UNF for two bolts (the standard left-hand slider isn't helicoiled and is threaded 3/8"BSF).

On both my T160's, which both have twin front discs, I had the left-hand sliders' caliper mountings helicoiled to 3/8"UNF as well. Then, having braided hoses, when removing/replacing the front wheel, it's much simpler to unbolt both calipers, suspend 'em from a bunjee looped over the frame, do what you want on the front wheel, then refit the calipers over the discs once the wheel's refitted.

Originally Posted By: tridentt150v
harder to bleed,

One T160 has handed Lockheed alloy calipers, the other has two single-disc steel calipers, the right-hand one being normally upside-down. Again, because the hoses are braided, for bleeding, it's a simple matter to unbolt the upside-down caliper and suspend it right-way up.

Originally Posted By: tridentt150v
recommend also going to the larger m/c ID.

Agree.

Originally Posted By: tridentt150v
I eventually went with new slightly longer bolts.

Triumph dealers certainly used to have the longer bolts as standard spares, because that's what the Co-op used.

Originally Posted By: JubeePrince
other components needed for this conversion: brake lines,

If you haven't done so already, take a look at L.P. Williams's "Twin disc braided hose kit" (part no. LEG-0006). Even if you want to make up your own brake lines (I always use stainless reusable end fittings whereas I believe LPW supplies swaged plated fittings), certainly LPW used to be happy to supply just the crossover piece. This bit will also take a proper hydraulic brake light switch so, if your bike is pre-'79, you can either back up or get rid of that Heath Robinson arrangement in the right-hand switch cluster. bigt

Originally Posted By: JubeePrince
different MC,

LPW also do just the larger cylinder in stainless, so you don't have to buy a new lever, mounting, etc.

Hth.

Regards,

#363781 - 03/19/11 9:14 am Re: Dual disc conversion: worth it? [Re: JubeePrince]  
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RetroRod Offline
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You must be kidding Jubee!! These rattletrap old tarts that put out a whopping 40hp with dual discs? They'll be pointing the finger at you at the local watering hole bro.

You must have too much money and too much time on your hands mate. However, the cool factor might make it justifiable.

Beware! the first time you use them in anger you'll probably bend the front forks. RR

Last edited by RetroRod; 03/19/11 9:16 am.

'72 Bonneville
"He who praises you for what you lack wishes to take from you what you have." - Don Juan Manuel
#363784 - 03/19/11 11:15 am Re: Dual disc conversion: worth it? [Re: JubeePrince]  
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blue67 Offline
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Go Retro!
Ausie Ausie Ausie........You know the answer.......oiu!

#363797 - 03/19/11 1:08 pm Re: Dual disc conversion: worth it? [Re: JubeePrince]  
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JubeePrince Online content
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JubeePrince  Online Content

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Thanks to all who have responded.....suspicions confirmed! bigt

Stuart, I like that Heath Robinson switch in the right cluster and take GREAT pride in the fact that mine works! laughing

Retro - Ahem, that's *42.5*bph!!

Cheers,

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
#363869 - 03/19/11 5:38 pm Re: Dual disc conversion: worth it? [Re: JubeePrince]  
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DMadigan Online content
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DMadigan  Online Content
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ca, us
It is not the HP of the motor that matters but the weight of the bike (and rider). If you cannot lock the front wheel or pick up the rear tyre then your brakes are hardly adequate. The single disc can stop as well as the dual disc if you grind off the chrome, change to braided lines, use the proper brake pads and reduce the master cylinder bore. You just cannot do it repeatedly without getting fade since all the heat is going into one disc instead of two.

#364023 - 03/20/11 9:14 am Re: Dual disc conversion: worth it? [Re: JubeePrince]  
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tridentt150v Offline
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Great Southern Land
I should have explained better, you have to remove the bolts holding your caliper and let it hang [I also use an okie strap] OR remove the bolts holding your lower leg to the mudguard then spin the lower leg so that you swing the caliper put of the way.

The distance between the twin disc calipers is less than the tyre/wheel rim width.

And doesn't matter how you bleed your twin disc setup it is harder than doing a single because air seems to rermain in both sides for longer. I usually bleed one side, then the other side, then finish off by bleeding both together. Don't bleed both together from the start, you'll be an old man before you get it right!!!

#364049 - 03/20/11 1:14 pm Re: Dual disc conversion: worth it? [Re: tridentt150v]  
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JubeePrince Online content
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Back on the mainland!
Originally Posted By: tridentt150v
Don't bleed both together from the start, you'll be an old man before you get it right!!!


Thanks for the tip, trident bigt

While all this may sound like a PIA, it CAN'T be any worse than bleeding the back one! crazy

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
#364051 - 03/20/11 1:36 pm Re: Dual disc conversion: worth it? [Re: JubeePrince]  
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D.W.R. Online content
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Winston-Salem N.C.
I recently went with dual discs on my Rocket 3. Didn't do some of the recommended stuff (used the standard M/C, dual lines with a longer banjo bolt on the M/C end), and I couldn't be happier with the results! Feel is excellent (no, the lever travel is no more than before), and stopping power is very strong without a tendency to lock up. I did it strictly to compensate for the onset of arthritis in my right hand/wrist, problem solved!
Don R.


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