Showing posts with label Rebound. Show all posts
Showing posts with label Rebound. Show all posts

Friday, October 11, 2013

Traxxion Dynamics' Linear Rate Springs - GSXR1000

Curing the K6 thou's bumpy bits.
Previous posts dealt with the suspension upgrades on the trusty '06 Gixer. The shock was re-shimmed, serviced and fitted with a linear rate spring. No problems there (with my limited ability at least). The 43mm Kayabas were re-shimmed and filled with fresh oil but, due to funding, came back with the standard 0.95kg progressive springs.
As the months progressed, they started to leak oil and preload adjusters were screwed right in to try and prevent bottoming out. The front was getting very harsh to say the least. Put up against modern bikes and she was beginning to show her age. Smooth roads were fine, but the bumpy stuff was iffy, sometimes scary.

SO...
A couple of emails to Traxxion Dynamics and they sorted me out with their straight-rate springs with an overall rating of 0.975kg. I just had to choose the fitting method for the type of spring - either cut the spacer, or alter the top-out springs within the cartridge. I decided to leave the cartridges alone and just cut the spacer.



Forks were stripped as per, leaving cartridges in place, then the old seals were taken out and plenty of brake cleaner inside the outer fork tubes to remove the dirty residue. Photos are limited unfortunately - I got carried away with the job and forgot to take enough of them!



Spring compressed ready for the fork top to be removed from the damper rod assembly.


New springs, note the extra length.


Traxxion provide all the instructions on how to measure the amount to be cut away, but they'd already given me the nod that 40mm was the way forward for the Gixer. The picture below shows the 40mm cut off the spacer (left), and new holes drilled in what's left for the spring compressor.


With new oil seals fitted, it was time to refill with oil and put them both back together. I'm running with the Suzuki standard air gap of 101mm. 
(Both forks were leaking, and when I stripped them they had an air gap of 140mm - no wonder they were getting harsh!)
I slipped the forks back into the clamps and refitted the mudguard, wheel and calipers. I only tighten the lower triple clamp bolts once the wheel is in and the suspension bounced up and down a few times. This relieves any tension/twist when fitting the wheel etc. 

Road test time.
I think we're onto something here. I basically just set my compression damping at ten clicks out, rebound at seven clicks and the preload to the first line on the adjusters. 



A blast along some of my favourite roads and I've still got an inch of travel in reserve! What a difference. It feels so much more stable in the bends now which could be as much do with oil level as well as the different geometry. I'll experiment with less compression damping to see if I can get a softer/more plush ride next.


Overall, I'm happy as. No leaks (for now), and the bike's actually easier to ride. A highly recommended mod. If you're not using a zip tie on your stanchions, go get one now. That little plastic tie is a mine of information!

Friday, March 23, 2012

Suspension Upgrades: Does A Six-Year Old Bike Still Cut It?

Can your bike's suspension be upgraded to match the latest technology?


This isn't about using professional racers to test on a short circuit track because that would mean nothing to the average road rider - like me. I want to hear in layman's terms if spending $500 - $1000 on your standard bike's suspension is a waste of money, or the best thing you could've done to improve it. We're the ones out there buying and riding the bikes, and most of us on the public roads only; so, can a basic upgrade to your favourite toy make it a match for the latest kit?


Let's find out.
  • The bike: 2006 GSXR1000K6 
  • The roads: A mix of fast, bumpy sweepers and the tightest of hairpins.
  • The question: Can the oldie hold its own against a newbie?
2006 GSXR1000 K6

Pointless?
Not for the majority of riders who have to battle on with their existing bikes because a new bike is out of their price range. And maybe the riders who think that the suspension must be effective just because it's fitted with Up Side Down forks and a monoshock.
I wanted to know for sure if what I'd heard is true. That spending money on suspension is the best use of readies that a person can throw at their bike. 
Or should you just get a race can? At least it'll sound fast when everyone's on your ass trying to overtake you!

150BHP? That's about 100 more than you need for the road!
That's what I was told by Peter Clements of ProMechA. And I know he's right, strictly speaking, but when did that ever matter?
But to be fair, this guy is very switched on and tells it like it is. When you can get hold of him on the phone, you're in for a great conversation. I had an idea on what the GSXR needed - I just needed to relay it to Peter. It's simple, I wanted the bike to be plush on bumpy roads (after all, it's quite stiff as standard), but have the ability to handle high speeds too but, on top of all that, be capable of destroying anyone else on a track day (should I partake in one)!
Should be easy, just a bit of spring manipulation - or so I thought.


"You can't have it all," says Peter. "What are you going to be using it for? Track days, or the road?"


"Hmm, road work I guess."


"OK, well I can't give you a sports-tourer and a race bike all in one. You need to choose what sort of bike you want." 


And that's when it hit home. There is no best of both worlds, no adaptive suspension that works for every road or track. And that's the first thing you need to understand. 
I've watched videos, read everything i can find on the internet and bought books on the subject of tuning suspension, but until you realise there isn't a perfect fix for every road surface or track, you're bollocksed. 


20km/h? You can do better than that!


And don't forget, your suspension needs to be serviced too. 
Oil deteriorates with use, gets contaminated with metal (from the springs/sliding surfaces) and needs to be flushed out and renewed at regular intervals. 
If, like my GSXR, your bike is well overdue for fresh oil, have the shock and forks serviced before adjusting any of the preloads or clickers. Any adjustments made before this will just not be as effective and will probably put you off the learning process.
It may be daunting to start playing around with the settings initially, but once you get into the spirit of adjusting things, it starts to become clearer and, the more you play, the more you learn. Just remember to write down your original settings so you can always go back to your start point if need be.


OK, forks and shock serviced, correct weight springs fitted. What now?
Peter has a stack of information on his website covering a good variety of bikes. For me he advised a complete service and re-valve (compression/rebound pistons and shims), a linear rate spring and an anti-squat valve for the shock, and a service and re-valve on the forks retaining original springs (standard being near enough for my weight).

Although you can strip the forks yourself at home, would you know how much porting or changes in shim arrangement are required? A suspension pro will have a fair idea on what works for the chosen conditions which is going to save you time and money in the long run. These are the guys that have put in the hard hours already.


Anyway, let's get on with it. First run out, and I had a play with the rear shock. Leaving the forks at Peter's recommended starting point, I adjusted the sag on the rear and then played with the compression and rebound adjusters. This also involved a quick run with them fully unscrewed, which was against Peter's advice I might add, just to feel the difference.


This caused the Gixer to tie itself in knots coming out of bends hard! 

It wallowed and weaved its way all over the shop so probably not the best testing method, but then it's good to feel the difference:) I'm now at a base/standard setting and it's working quite well.

With only a few weeks on it, the "ripping" effect I had on the rear tyre is starting to clear up with the shock working correctly, but there is evidence of a rebound issue (uneven tread wear pattern). Hopefully fine tuning will cure this, but my idea of fast road work probably isn't the same as a genuine fast rider's - which is what it's valved for. Oops.
The forks are still harsh on most of the low-speed local roads, but then it always was. However, the faster you're prepared to push, the better it gets - is this a good thing? Probably. If the bike is safer and more capable at speed, when there's more chance of mistakes, less time to react and the unknown is lurking around every bend, this can only be a good thing.


Smooth roads, happy days.


This is a learning curve.
What I thought I wanted, and asked for, probably isn't what I actually needed. Having ridden a mate's 2006 CBR600RR, I knew how plush a sportbike's suspension could be on slow, bumpy roads. But until I actually tried pushing down on the front end of the CBR at standstill, I'd never have realised how soft they were as standard! It's like a trail bike, due to its progressive springs, where the GSXR is rock solid all the way through. 
No wonder you meet the nicest people on a Honda.
I wanted something to soak up the slow, bumpy roads and then perform well at high speed, but it's impossible - you have to decide where your trade-off is. 


Forget the bragging rights, ask yourself this question:
How often do you exploit the top speed of your bike? 
Honestly? Not very often.
As a quick comparison, I took the DRZ out for a quick spin in some notoriously tight, uneven bends. The supermoto flies round bumpy, 60-80km/h corners without a flinch whereas the Gixer, although holding its own while you bounce out of the seat, makes you work harder for it. 


Conclusion
I can see why the softer, streetfighter-styled factory bikes are so popular nowadays. Easily as fast in the real world, but with the added comfort to protect you from all the jarring and hits you take from the average, poor road surface.


I guess I ended up with a fast road bike that spends most of its life at slow speeds. In respect of whether this bike can hold its own against a new one, no problem at all, but is that due to the rider, the components, or the fact that superbikes haven't really moved that far forward in the last six years? 
A smidgen of all those I guess, but I will say this for the GSXR, now when you crack it open to make rapid progress, the world underneath it just smoothes right on out. 


ProMechA
If you're looking to upgrade the bouncy bits on your bike, give Peter a call on 03 9574 1164 and let him explain what does what, and why. He'll tell you exactly what's needed to turn your bike into the bike you actually want - and that's far more important than turning it into something you don't need!