very significant brake upgrade!

[emeglasson]

Figured you all might get a kick out of this, and have a few opinions to share about the concept as well. My buddy and I both picked up our 390's two weeks ago. We did a track day the first weekend we owned them. We both agreed, the bikes are awesome, but the brakes needed some work.

I went the more traditional route; I upgraded everything as one would; I got the 320 wave rotor from Galfer, some Galfer race pads, and a new 16mm radial master cylinder from Braking. Those items are all installed, and there is certainly a big improvement. Though, they are still certainly not the most powerful brakes I have experienced. I also have new stainless brake lines that will bypass the ABS system on order from the guys at Commonwealth Motorcycles in KY. (helpful guys, I found them here on the forum).

I haven't had a chance to really get a feel for my set up yet; been busy with work and the weather hasn't been great.

My friend Matt, on the other hand, decided to go a whole different direction. He opted for the dual disc upgrade. This evening he is finishing bolting on a GSXR 600 fork, calipers, radial master cylinder and wheel. (!) See photo. He replaced the steer tube in the gixxer's triple clamp with the one from the 390 using a press. The tube fit right in. Everything is on and fits, he just needs to make sure the body work clears now. I am extremely interested to compare the two bikes side by side. I am anticipating his will have stupendous brakes compared to mine, even after all of my upgrades.

Yes, he will have to deal with getting new springs, and adjusting the fork oil and dampening. But if it fits, he'll get it all dialed in and we'll report back. BTW, not a bad way to end up with adjustable damping on the fork either...

 

[DCMoney]

Wow nice work!

 

[emeglasson]

So here it is re-assembled. There are some clearance issues with the fork legs to the plastics. We are going to take the two bikes for a spin tomorrow to try his and my brakes back to back. And, the now black front wheel highlights another issue; you end up with a wider front wheel. Not sure how that will feel. I suppose you could mount a 110 on it, but the profile would be a bit off.

He obviously had some cosmetic fun with a black re-spray and new graphics as well.

 

[rc_Guy]

That color scheme and black front wheel looks pretty good!

 

[Treachery]

Gotta be the first front-end transplant onto an RC390. Kudos!

 

[ray]

I just logged into to ask if a simple front brake reservoir upgrade would help the braking and then I see this.

I am logging off because holy shit! :O

 

[guzz46]

Wow, twin discs originally from a bike with a top speed of 157mph on a light weight bike with a top speed of only 110mph, that's taking a leaf from Home Improvements Tim the Toolman Taylor the back end bike fish-tails around and skips off the ground easy enough on my bike with just one disc.

I wonder if it will effect the handling with the heavier unsprung weight? I also wonder if the fork length is the same?

 

[mr-fabricator]

Fantastic work there fellas ,
Was thinking of something similar myself with rc8 forks. . U beat me to it


Regards lee ..

 

[Chris The Welder]

Love it. Might take a minute to dial it in. Worth the effort I think. Can't have too much front brake imo.

 

[ryandalling]

Wow. I can get the rear off the ground with the stock brakes and abs on when braking hard. That setup would be insane. Hello stopies.

 

[emeglasson]

Yeah, I agree; even with the stock set up I could also lift the back tire when I squeeze the lever hard. But that was squeezing about has hard as I can with two or three fingers. I have owned 600's that will do the same with one finger, without working hard, at all. That is the power I am after. I like easy to pull with one finger, easy to modulate brakes, that feel like they have some 'bite'. Headed over to Matt's now to ride the bikes side by side. He has noted significant clearance problems. I'll snap more photos and post some notes on all of the items to be aware of when considering this conversion.

 

[guzz46]

Hmmm, mine doesn't require much pressure at all, out of curiosity, did he weigh the GSXR front end?

 

[emeglasson]

Okay, we tested the bikes back to back, analyzed the benefits & drawbacks, and have decided to pull the gixxer fork back off. Here's why; single biggest reason relates to geometry. Something just feels very different, somewhat 'wrong'. The new fork triple clamps have 1/2" less forward offset, but they do have the same angle. That shortens the wheelbase a half inch. That doesn't sound like a lot to me, but it seems to make a big difference. The light and nimbleness of the 390 changed to the point that you really had to push on the bar to maintain a turn. Interestingly, the first 15 -20 % of the turn initiation is lighter than stock, almost twitchy feeling. But once leaned in, you have to push much harder to maintain the line. I'm sure someone that understands bike geometry better than me could explain why this is.

Other issues; the fork legs sit further apart, so there is significant rubbing on the inside of the fairings. The shorter bars from the gixxer created a situation where both the brake lever and the clutch lever hit the fairing.

The new wheel was wider by about 1/2", but it still had a 110 tire mounted on it. The tire profile was obviously different than the stock one, so this may have contributed to the different feel.

Your hands are quite a bit lower, as the clip-ons sit under the top triple clamp. This was expected. But, we both liked the slightly more upright riding position of stock. This may not prove the best on faster tracks where a low tuck will be important, but it is one of the things we both love about the 390; it's so comfortable and easy to ride.

As mentioned in the earlier post, the springs and dampening were way off, as expected. But, I don't think it would take much to get that sorted, probably just a lighter spring.

Brakes: the whole point of this swap was to improve brake performance. While the new double disc definitely offered more bite, it wasn't a dramatic improvement over my master cylinder / disc / pads upgrade. Matt is going to take the gixxer fork off, and go back to the stock fork with the more standard upgrades.

So, good experiment, but it would take a LOT of tinkering and fiddling to make things work and fit. And you would still have a bike with non-factory geometry. And for me, there would always be a question of when you might get bucked by a bad speed wobble when least expecting it.

 

[emeglasson]

We did not weigh the gixxer front end.

 

[Chris The Welder]

Hat's off to you for trying it anyway.

 

[Manbeard]

Weight+the fatter front tire would be my guess in what felt wrong with this setup. I'm quite happy with the brake feel myself, but I'm no Valentino Rossi...