Dual disk

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Actionabe

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This post may be a little rambling so I apologize. So for some background, I saw the concept 701 when it was released and fell in love, however I could not justify paying the premium price when the production model came out. Fast forward to now and I picked up a 2020 701 Vit and love it. My long term goal is to get another 2018-2019 vitpilen as well.

Now the thing that really annoys me with the production Vitpilen is the single front brake. I know the braking is fine with the single disk but it just screams beginner/budget bike, I would be willing to bet something as silly as that is part of the reason for low sales.

Now looking at the pictures of the mag wheels it looks like the hub is made to accept a disk on the right side so the main issue is the lower right fork tube not having the mount for the caliper. Looking at the concept bike i doubt they made a custom lower right fork leg just for the concept and the forks look suspiciously like the Duke 790 forks with caliper spacers for the larger disks. So my plan right now is to research and use my 2020 701 as kind of a test bed to figure this out. I know it will take awhile and the changes will mainly be cosmetic but I think it is doeable. First step is to compare axle measurements and fork length.. the 790 leg has the mount for the abs sensor so hopefully that would work as well, other main issues would be actual abs system limitations and master cylinder size. So I guess my main question is has anyone else looked into this? I haven’t found anything about it.
 
Great topic!(y)

I've seen some guy replacing the whole front end with that of a supersport 600, but you could be on to something.

That said, 2 rotors weigh more than one. Unsprung/rotating mass.... I still aim for better braking with one rotor. Braketech cast iron?
 
Max Kool said:
Great topic!(y)

I've seen some guy replacing the whole front end with that of a supersport 600, but you could be on to something.

That said, 2 rotors weigh more than one. Unsprung/rotating mass.... I still aim for better braking with one rotor. Braketech cast iron?
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Honestly in my case it is almost totally about matching the look of the concept bike, the increased braking is a nice side affect but not primarily what I am going for.. it will probably be a long term project but kind of wanted to throw it out there to see if anyone else had looked into this.. biggest issue will be if the 790 axle is very different, I want to keep the stock vitpilen mag wheels.
 
Max Kool said:
Think KTM RC8 front end. That at least came with a 5 spoke wheel. Probably the same wheel actually (not sure).
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Good point, I was looking at that but besides the scarcity I would have to replace the triple tree because of the fork diameter. The 790 caught my eye because it looks almost identical to the concept and is 43mm, I need to measure the length on my vitpilen later since the 790 forks are 32”
 
So I looked more into the RC8, the wheel does look very similar, so it may be an option because I incorrectly assumed that they used the super duke forks on the rc8 but the rc8 actually has 43mm forks as well. I guess the main thing to look at is the axle dimensions to see if either set up could run the stock wheel which would be preferable. The rc8 fork lowers do look different than the concept 701 where the 790s look very close.. the abs sensor hole on the 790s is a big plus for that option to avoid any electronics issues.
 
Yeah, the fork lowers are actually pretty unique on the Vit. Just look where the holes are for the front fender... The RC8 forks are defo different than the Vit forks (still have rebound (?) adjusters on both fork lowers).

You just need a decent KTM wreck yard, and lego till it fits.
 
Max Kool said:
Yeah, the fork lowers are actually pretty unique on the Vit. Just look where the holes are for the front fender... The RC8 forks are defo different than the Vit forks (still have rebound (?) adjusters on both fork lowers).

You just need a decent KTM wreck yard, and lego till it fits.
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Yeah the fender mount would be an issue, I want it to look factory so would take some work, that’s another point for the 790 front end because on the concept bike you can see the mount bolts for the front fender drilled into the side of the fender braces where the 790 mount bracket is.. true about needing to wonder a junkyard with a tape measure and calipers..
 
I've had a couple bikes with a single front disk. Frankly, it really benefits the steering making it lighter. Also reduces unsprung weight.
Unless you are actually disappointed with the braking... I'd really hesitate to add a second disk.
I'd change the pads and then make try an aftermarket disk first. If you can do stoppies fine, you are all set. ;-)

And if you add a disk, be aware how it will likely slow down the steering and make the bike feel less nimble.
 
Vintage Veloce said:
I've had a couple bikes with a single front disk. Frankly, it really benefits the steering making it lighter. Also reduces unsprung weight.
Unless you are actually disappointed with the braking... I'd really hesitate to add a second disk.
I'd change the pads and then make try an aftermarket disk first. If you can do stoppies fine, you are all set. ;-)

And if you add a disk, be aware how it will likely slow down the steering and make the bike feel less nimble.
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All very good and valid points, I haven’t had any complaints about the braking, I just enjoy a challenge and the single brake rotor just annoys something in the back of my mind, not so much with the spoke wheels but the mags with the single disk just do not seem right, all just personal preference. I swapped a CBR front end and rear onto my Triumph Thruxton and find it hard to not tinker with things.. I’m sure the money would be better spent on fork cartridges for the stock set up...
 
I thought dual disks where so you could slow down from over 150mph.

Otherwise, I would say am pretty pleased with my motomaster brakes' performance, and was pleasently surprised what that loss of a few hundred grams really feels like.
 
I think that it has more to do with over engineering the brakes and having two to avoid brake fade, especially on the track.. the single disk has more than enough power but will tend to overheat quicker..
I don’t personally ride the track so honestly it’s more about looks, the only bikes with a single front disk in the US are beginner bikes like the gs500, cb250 or smaller cruisers. I think that as silly as it sounds the single front brake really hurt sales because the 701 is definitely not a beginner bike and especially at its original price point.

Looking closely at the concept I think it is using 48mm super duke forks and brakes and a rc8 wheel, it’s the only thing that looks exact. The closest thing to the super duke forks in 43mm are the duke 790 so I think I’ll get an axle from one and do some measurements. The forks are only 3/4 “ longer so that can easily protrude out of the top of the triple tree so the biggest thing will be fitting the stock wheel to the axle and getting the spacers right... it will be a slow process, especially since this is predicated on either getting second earlier bike to put it on once I figure it out or having a second set of mag wheels for my 2020 since I want to keep it original if I choose.
 
Actionabe said:
I don’t personally ride the track so honestly it’s more about looks, the only bikes with a single front disk in the US are beginner bikes like the gs500, cb250 or smaller cruisers. I think that as silly as it sounds the single front brake really hurt sales because the 701 is definitely not a beginner bike and especially at its original price point.
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I'd replace the word "beginner" with "lighter". ;-)
Think RC390, TZ250...

Joking aside, I suspect it's a combination of bike weight and cost considerations for the manufacturer. I suspect they really don't think; "Hey, those beginners don't need good brakes! Lets just give them one disk.)

But I think you are right about brake fade and dual disks. Heavier bikes ridden more aggressively will be more prone to fade.

I have a 1992 Ducati 750SS with a single front disk. The bike is nearly identical to the 900SS, except for the engine size and the larger bike has a dual disk. But there is a remarkable difference in handling that many attribute to the smaller bikes single disk.
 
Vintage Veloce said:
I'd replace the word "beginner" with "lighter". ;-)
Think RC390, TZ250...

Joking aside, I suspect it's a combination of bike weight and cost considerations for the manufacturer. I suspect they really don't think; "Hey, those beginners don't need good brakes! Lets just give them one disk.)

But I think you are right about brake fade and dual disks. Heavier bikes ridden more aggressively will be more prone to fade.

I have a 1992 Ducati 750SS with a single front disk. The bike is nearly identical to the 900SS, except for the engine size and the larger bike has a dual disk. But there is a remarkable difference in handling that many attribute to the smaller bikes single disk.
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True about the weight part, I would be willing to bet a large portion of the bikes out there don’t need dual disc set ups but have them purely to appeal to riders. Hard to sell a bike for 12k with a single disk when even the mt-07 has a dual set up for nearly half the price.

I feel like Husqvarna planned on using a dual disk setup but somewhere along the way the accountants denied it to keep the margins larger or to keep the cost down on an already expensive bike, why else would the wheels be drilled and machined to accept two disks. Kind of like the cheap instrument display. I wish they would have kept the dual disk and skimped on the calipers to meet costs because that is a lot easier to remedy...

The electronics on this bike are already so finicky another concern is the abs, the 790 forks should be able to mount the sensor and I feel like if I didn’t do this it would causes a bunch of errors and gremlins in the system, hence not being able to use the rc8 front end. I could care less if the abs is functional or not, if it has issues with the extra volume of fluid I may bypass the control unit entirely if it doesn’t throw any codes or cause other electronic issues.
 
Actionabe said:
I feel like Husqvarna planned on using a dual disk setup but somewhere along the way the accountants denied it to keep the margins larger or to keep the cost down on an already expensive bike, why else would the wheels be drilled and machined to accept two disks.
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I bet there’s a KTM that has the same wheel with two rotors…

I personally prefer a single disk that’s good enough than two disks on this bike. Still wondering how well a cast iron rotor would work, especially with an upgraded caliper.
 
There are a couple videos on how to do this to KTM 390...
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Vintage Veloce said:
There are a couple videos on how to do this to KTM 390...
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I’ll have to watch those and see if it gives any good pointers, thanks!
 
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