Project GSX-Reborn: Episode 3
By Bruce Dunn
Welcome Back to BeMoto Project GSX-Reborn. The story so far...
Episode 3: What The Fork
So far I have brought our derelict Suzuki GSX-R600K3 back to life by replacing all the fuel system components, including the tank, complete injector rail and fuel pump. Getting rid of all the skanky petrol is not going to be the last of the dirty jobs though, as my next task is to get the forks out and pull them apart - if the insides are anything like the state of the outside then it's going to be messy!
Replace or Restore?
I know what you're thinking, wouldn't it be easier to just buy a second-hand set and lob them in? Yes, it probably would, but I feel a bit of a duty to make the most of the existing parts (or maybe I'm just a glutton for punishment) so here it goes...
Take a long look at the pictures here; the rusty spots on the upper parts of the chrome stanchions do look bad enough to warrant a date with the skip, but I'm hopefully that a bit of OCD-spec scrubbing with a Scotchbrite pad will prove them to be recoverable. The lower fork legs are really scabby, and the underlying alloy has started to corrode where the coating has started to lift, oxidising to a white powder. When I get the stanchions stripped out I will try and rub them down and get them back to a standard satin finish.
The internals of the forks are mostly serviceable - the dust seals, oils seals, bushes and washers are all going to be replaced courtesy of an aftermarket service kit put together by the amusingly named All Balls Racing.
One thing I hadn't really noticed on the bike was the state of the radiator, but once I got the front wheel out I could see how rotten it was, with loads of flattened cooling fins and white alloy corrosion everywhere. But that will be a job for another day...
Once the forks are removed it's clear that the right-hand-side stanchion isn't too bad, but the left is looking pretty crap, with loads of surface rust on the chromed area of travel. To be honest, it's going to be touch and go as to whether it will clean up. Added to all this, the top of the dust seal has split and begun to rot from the inside out. Deep joy.
As for the fork lowers, the painted finish has been blasted away by 40,000 miles of road dirt and debris, and where the alloy has been exposed more corrosion has got a foothold. As the icing on a very corroded cake, there are also a couple of mudguard mounting bolts that have sheared off, but these will have to be dealt with at a later stage.
Upside-Down Forks?
As a side note, one thing that occurred to me while doing all this was the fact that this generation of Suzuki GSX-R600s (K1, K2 and K3) never had upside-down forks. It just seems odd now especially when you look back at the demand for 600s in this period, and the fact that the GSX-R750 had been decked out with upside-down forks since the 'L' model, which was released in 1990. The other bikes in the class like Honda's CBR600, Kawasaki ZX-636 and Yamaha R6 all held off with uprating the forks, and it was in fact Kawasaki that went first with upside-downers on their 2003, and after that the K4 GSX-R600 followed suit along with the rest.
The Trusty Haynes Workshop Manual
Taking the forks out and stripping them down is fairly straightforward and using a Haynes workshop manual as a reference makes it a lot easier. There is a specific sequence and order in which they need to be stripped down, and there is not really a need for any specialist tools which makes it do-able for anyone that's up for it.
The very first thing to do when you are planning to take forks out and strip them down is loosen the fork caps before you remove the forks, this is because there isn't really an easy way to undo them once they are out. Unless you're daft enough to put them in a vice, which runs the high risk of distorting and damaging the fork tube. So once you have cracked the caps, then the callipers, front wheel mudguard etc can be removed and put to one side. The forks simply drop out once the yoke and handlebar clamps have been loosened.
Good Preparation and Planning is Key
A good tip for anyone taking forks apart is to prepare an area to lay the bits out as they come out in sequence. You also need to make provision for the internals to be covered in oil, so laying them on an absorbent cloth or an old towel is ideal. As well as the sequence, also make a note of the orientation of the bits, for example: the spring is progressive and fits in one way, tapered side facing downwards.
Rebuilding the forks starts with removing the old bushes, and then giving all the parts a proper good clean with de-greaser if necessary and a nylon brush on the outside of the bottom fork leg. Then give all the internals a good blast of brake cleaner and blow with an airline to make sure all the old deposits of oil and debris are clear. When it came to cleaning the outside of the fork legs, they still looked like scrap even when de-greased, so I shot over to my pal Roland at Hardcore Motocross in Ramsey, Cambridgeshire. One of the many services he offers is vapour blasting – just check out the difference in the pictures, he got them looking like new in no time.
Rebuilding the forks is a case of diligently following the directions and detail in the manual, including all the precise measurements of oil capacities and air gaps etc. Fitting the bushes is easy and re-assembling the fork is straightforward, just make sure to fit new O-rings and washers that are provided in the kit. When it comes to filling the fork tube with oil, the GSX-R needs 528cc, but pour it in gradually, and gently move the rebound damper rod up and down to bleed the air out. The air gap needs to be measured with the fork compressed without the spring. If you don't have a measuring tool, use a ruler or tape measure.
Time to Torque: Yoke Bolts
When it comes to installing the forks it's really important to torque the fork yoke bolts up to exactly the correct value; a lot of people just whack them up tight which in most cases will be far too much and potentially disrupt the smooth action of the forks - 23Nm is the spec for the fork/yoke pinch bolts.
Shocking Linkage
Next up is the rear shock and linkage, once again the brilliant ABBA Superbike stand does the job of supporting the bike from the swingarm spindle. As mentioned before the GSX-R600 lends itself to being stripped down and worked on quite well, and the shock and linkage are another example of this. There is good access and plenty of room to get the spanners in. I've taken the rear wheel out to make life a bit easier, as it takes the weight out of the swingarm when rebuilding the linkage.
The outside of the linkage looks rank and the linkage bolts are so tight that I have to use an impact gun to shift them. The hammer action of the gun causes a worrying amount of corroded alloy white powder to fall from the linkage and onto the work bench. Once the shock is out I can see that it looks in fairly good condition, and when I first got the bike I gave the back end a bit of a bounce and felt there was a satisfactory amount of damping. So we will stick with the rear shock for the moment.
The linkage however is a different story, the needle bearings need replacing - just check out the picture. The one that mounts to the shock is so knackered it fell apart as I withdrew the pin. I got the bearings from a trade stockist, but the pins had to be bought from Suzuki as there were no pattern parts available. Getting the old bearings out was easy enough, I yet again nipped down to my pal Roland at Hardcore Racing and popped the old bearings out on his press. And at the same time he insisted that we aqua blasted the linkage, and just like the fork leg lowers they came up mint!
Re-fitting the linkage and shock was straightforward, and that concludes the re-furbing of all the suspension components. There is a ton of other stuff still to do and the list is still growing. I think next time round I will be sorting out the radiator, probably going down the route of buying a pattern one, and at the same time I'll replace the coolant hoses. Then I've just sorted some new brake lines and a radial calliper conversion kit from Hel Performance. There is a chain and sprocket kit to fit at some point, plus the wheels need re-painting or powder coating and brand new Pirelli Supercorsa V3 tyres to fit. It's all go!
Special thanks to:
GSX-R600 K3 Spend So Far... £1,959.42
These are the bits we bought this month.
- 2 x litres of 10w fork oil £18.05
- Fork rebuild kit, including, bushes, dust & oil seals, O rings, washers £168.99
- Vapour blasting fork lowers & rear linkage £30.00
- Rear linkage needle bearings and pins £74.38
- New Radiator £155.00
- Manual £29.00
Total £475.42
Tally: £1,959.42 (including the bike)
Target: £3,000 (including the bike)
Look out for Episode 4 where we look at the radiator, coolant hoses and fitting a radial calliper conversion kit.
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