This is a big write up!  Two things to remember.....

#  the authors first language is not English and so writing this 'technical' document in English was, lets say, a challenge!

#  neither the author or myself are especially technical guys

So whilst I've done my best to check and amend Knaapie's write up where necessary there are still one or two parts that may need clarifying.....I'll update this doc asap.

SV1000(S) Suspension write-up - by Knaapie Aug 2005

Earlier this year I had a technical day at Hyperpro Racing Suspension with the Dutch SV club. A perfect chance to figure out some funky details on the SV1000’s suspension and of course, how to replace your fork and shock springs.

What can you expect from my write up? Well, first of all I’ll try to describe what the weak points of the SV1000’s front fork/ shock are and how suspension in general works. Than I will describe how you can replace the fork springs and finally a description of a shock spring swap.

First some suspension basics.
The adjustment of the bike’s suspension (forks and rear shock) consists of three main things:

Preload
Compression damping
and
Rebound damping

I’ll use the rear shock as an example. The Preload adjuster is located on top of the shock (the two threaded rings). The upper ring locks the lower ring with which you actually set the Preload. With the Preload you can set the ride height of your bike. If you turn the lower Preload ring completely down (all thread above the spring is visible) you have maximum Preload. This results in a bike that enters corners very quick, perhaps too quickly because most of the weight of the bike has been transferred to the front wheel by lifting the rear of the bike. See pic 2.
On the other hand, minimum Preload (with no thread visible above the spring) gives a bike that runs wide in every corner you take as the front of the bike is much than the rear. See pic 3.
Neither of these extremes gives a good ride.
To improve or check your suspension, always start with the Preload!!! Based on the sag of the bike you can set-up the preload of your suspension to suit your weight and riding style.

Adjustment:
First the rear. Take a fixed point on the rear of your bike the distance of which can easily be measured from the axle e.g. the passenger grab rail or put a little piece of masking tape on the rear fairing. Measure the distance from that point to the rear wheel axle in a completely unsuspended position of the rear wheel (i.e. rear wheel off the ground - like on an Abba stand). Put the bike down and holding the bike upright (not on the sidestand!!!) without anyone or anything on it, measure again to the same spot. The sag (difference between the two measurements) should be about 10-20 mm. Now sit on your bike (with full riding gear on) and let someone else measure again. The sag should now be about 25-40 mm. If the static sag and/or ride height is more than the given dimensions you’ll have to increase the preload until you get it right. If the sag is less, decrease preload. If you (frequently) ride with a passenger or luggage the preload also needs some adjustments. i.e. more preload (and increase the rear tyre pressure).

At the front end it’s a little bit easier although it is necessary to get the front fork unsuspended (front wheel off the ground) which may not be easy for you. A paddock stand that uses the holes in the bottom of the front fork does not work for this measurement. In the unsuspended position you measure the length from the lower triple tree to the top of the oil seal on the fork leg. Having taken the unsuspended measurement put the bike back on its wheels again (not on the sidestand!!!) and measure the same distance again. This is the static sag of your forks and should be somewhere between 15 and 30 mm. Now sit on the bike (preferably with all your gear on) and have someone else measure the distance between the lower triple tree and oil seal again. The difference between the two measurements is the ride height which should be between 35 and 50 mm. If you get larger dimensions in one of the two cases (30+mm static sag and/or 50+ mm ride height), increase the preload.

Now you can start looking at the compression and rebound damping settings. These keep the shock/ fork under control by adjusting the sped at which the suspension compresses and uncompresses (rebound). If a bike didn’t have compression or rebound it would be a complete pogo stick of a ride! The compression is set to work when you hit a bump and the shock/fork is being compressed, the compression damping slows the rate of compression down. After you hit the bump, the shock/ fork has to return to it’s normal position and rebound damping controls the rate (speed if you like/ amount of time taken) at which this happens.

The main problem with the SV1000 rear shock is that it has too much low speed damping and not enough high speed damping (and only adjustment for overall damping). This problem doesn’t really occur for the forks which have a pretty good damping characteristic according to Hyperpro. Not enough high speed damping means that you get lifted off the seat (and your balls hit the tank...:-) when you hit even a relatively small bump at speed. The suspension just isn’t capable of absorbing the bump. Also the SV rear shock has a pretty stiff spring which makes the problem even worse! A different shock spring improves handling and comfort of the SV1000 shock, but it doesn’t change anything in the damping characteristics of course. And this is where one of the problems is. The SV shock (and Suzuki shocks in general) have too little high speed damping and way too much low speed damping. This also goes for the GSX-R shocks which SV1000 owners often use as a replacement shock. The reason that SV riders consider this as an improvement is mainly because of the different (softer) spring that is mounted and it’s also possible that the GSX-R does have a slightly better overall damping characteristic. But the damping problem remains!

There’s no need to buy an aftermarket rear shock to get the best out of your bike as the stock suspension elements can be reshimmed/revalved (edit=AndyW: I’m not sure this is right for the OE shock. Will check and update asap). I’ve taken a Hyperpro racing shock as an example because I found one dissembled whilst I was at HyperPro. As you can see in the photo the shock has several parts.

The damping characteristics however are determined by the shim stacks. These are several very thin rings with different diameters and thickness, placed on each other. See photo 2.

The shim stacks (red arrow) are located on both sides of the piston. Hyperpro uses a special machine to test the characteristics of the shock and to compare it with the ideal damping curve. The shim stacks are changed (more/less shims, thicker shims and/or wider shims) until the ideal damping curve is reached.

Now finally something about how the shock absorber and shim stacks work. The compression damping consists of two parts: a needle valve located in the piston rod and the piston rod itself. When the shock is compressed, the fluid in the shock is pushed down. If this happens at a low flow rate the needle valve controls the compression damping. If the compression is at a high flow rate (rapid compression) the shims underneath the piston open up to allow a greater rate of flow. The fluid enters the piston through the holes highlighted in photo 2 by the green arrow and is squeezed out from underneath the shim stacks. The opposite happens with rebound damping: the fluid in the shock is pushed upwards by the pressure of the gas. If the velocity is high during the rebound the shims on top of the piston open up to allow a greater flow.

If you find it hard to understand what I’ve been trying to explain, take a look at this file from Ohlins: http://www.ohlins.com/pdf/07241-02.pdf. It also has some very good images in it, which I unfortunately can’t use because of the copyright.

The SV1000’s front end suspension isn’t that bad as I already mentioned but the springs are weak. As you can see in the photo, the Hyperpro springs differ a lot from the stock springs. The stock springs are a two-step linear spring and can be best described as two different springs moulded together. The Hyperpro spring is progressive and becomes stiffer when the spring is compressed more and more. *photo 3*

Replacing front fork springs
You can replace your springs and fork oil in one of two ways:
- by removing the fork legs from the bike or
- by just opening up the fork, remove the springs and suck out the old oil with a siphon. This write-up is based on the first option (preferred/best method)

Removing the fork legs.

1) Make sure your bike is supported in a solid and safe way. Use an Abba stand or paddock stands for this. The main issue is to get the front end off the ground including the front wheel and then the fork legs can be removed.

2) You start by loosening the axle pinch bolts on the right fork leg. After that, loosen the front axle with a special 24mm Hexagon tool. This tool is available on eBay for a decent price.

3) Loosen the bolts holding the brake callipers and remove both of them. You could use some straps, rope or tie-wraps to tie the callipers to the lower yoke. That way the brake hoses won’t be under undue strain and the callipers are out of the way.

4) Now remove the front fender, which is mounted with two bolts on the outside and two on the inside of the fender.

5) It’s recommended to loosen the fork caps slightly now (do NOT remove them yet!) because the fork leg is still firmly mounted in the yokes.

6) Now loosen the clip-ons, slid them down the fork leg and carefully rest them on the fairing.

7) The next step is pretty important. Measure how far the fork legs stick through the top triple clamp so you have a reference when you’re remounting the fork legs. Remember that the left and right leg both have to stick through the clamp the same length!!!

8) Loosen the bolts on the top triple clamp that grip the fork legs. Don’t worry, they won’t fall out, because the legs are also mounted in the lower triple clamp.

9) Now CAREFULLY loosen the two bolts on the lower triple clamp. You don’t have to take the bolts out, just loosen them. While you are doing this, hold the fork leg with one hand so it can’t fall out and hit the ground. Also watch the clip-on which is still on the fork leg!!!

10) Ok, job well done! The fork leg should be in your hands now. Off course you can repeat step 8 and 9 for the other fork leg as well. *photo 4*

11) Now it’s time to open up the fork leg. If you followed my advice in step 5, taking the fork cap off should be easy. BE CAREFUL! There is pressure on the fork cap due to the partially compressed spring within. Carefully loosen the fork cap and keep pressure on it while you do that. The result should be this *photo 5*.

12) Now the trick is to get the fork cap off, so the stock spring can be removed. Use a tool to hold the fork cap and than use a spanner to loosen the inner rod lock nut (located behind the white spacer in the photo). Also see the SV1000 workshop manual part 6, page 21, the first picture.

13) The fork cap (# 1) can now be removed. Following this, you can remove the washer (# 2), the spacer (# 3), the adjuster rod (# 4) and the spring. *photo 6*

14) All of the old oil has to be drained out of the fork, so turn it upside down. Make sure you have something like a jar to put the old oil in. At Hyperpro they had a special tool that was screwed onto the inner rod/cartridge. With this tool (# 5 in photo 6) the cartridge could be moved up and down to pump the last drop of oil out of the fork. That is the most difficult part to do when you want to do it yourself and don’t have that tool. Perhaps you can borrow the tool at your local dealer.

15) When you finally got all the oil out, don’t remove the tool from the cartridge yet. It’s now time to reassembly the fork again, starting with putting new oil in it. Hyperpro uses 15W oil and a 170 mm air chamber for their springs. By ‘air chamber’ I mean the distance between the top of the inner fork leg and the fork oil level.

Although Hyperpro followed a different procedure I think the way that the workshop manual describes is easier to do if you’re doing it yourself.

Hyperpro way: Fill the fork with new oil, be careful not put too much oil in! Now start moving the cartridge up and down again, this time to pump the oil in the rest of the fork. Measure the oil level. Do this several times until the oil level is right and there are NO MORE AIR BUBBLES IN THE OIL!

Workshop manual: Compress the front fork fully. Now pour in the oil up to the top of the inner rod. Move the inner rod slowly more than ten times until no more air bubbles come out from the oil. Also move the inner tube up and down several times until no more air bubbles come out of the oil. Keep the fork vertical and leave it like that for 5-6 minutes. After this, keep the fork horizontally and suck out oil until the correct level has been reached.

16) Time to reassembly the fork again. Pull up the inner rod with the tool I mentioned earlier.

17) Now insert the new spring. The close pitch end of the fork spring should be at the top of the fork leg.

18) Reinstall the adjuster rod, the spacer and the washer.

19) The lock nut for the fork cap should still be at the correct position but check that the distance between the top of the inner rod and the top of the lock nut is 11 mm (0.43 inch).

20) Mount the fork cap to seat on the lock nut by hand tightening. Hold the fork cap with a tool and tighten the lock nut at 15 Nm (11,5 lb-ft).

21) Put a little fork oil on the O-ring of the fork cap before remounting it.

22) Compress the fork leg, so you can remount the fork cap again. Be careful not to damage the thread of the inner tube if you can’t get it remounted at once. When the fork cap is back on, do not tighten it to the specified torque settings yet!

23) Finally clean the entire fork leg before remounting it to the bike. It’s a hard spot to clean, so now is your chance!

24) Step 11 to 23 should be repeated for the other fork leg.

25) When both fork legs are rebuilt it’s time to mount them on the bike again. Make sure you use the correct fork leg on the correct side of the bike!!!

26) Slowly stick the fork leg through the lower triple clamp and slide the clip-on onto it. Then slide the fork carefully through the upper triple clamp and temporarily tighten the bolts of the lower triple clamp. Do not completely tighten the fork leg in position yet because you still have to make sure both fork legs stick through the upper clamp at the same height. Repeat this step for the other fork leg as well.

27) Now make sure both fork legs stick 6,3 mm (0.26 inch) through the upper triple clamp or use the dimension you measured in step 7.

28) Mount the fork caps to the specified torque of 23 Nm (16,5 lb-ft).

29) Tighten the bolts of the upper and lower fork clamps to 23 Nm (16,5 lb-ft).

30) Finally tighten the handlebar clamp bolts at 23 Nm (16,5 lb-ft).

31) Remount the front fender.

32) Install the front wheel and tighten the axle temporarily. Make sure the arrow on the wheel/tyre point out the correct direction of wheel rotation!!!

33) Remount the front brake callipers and tighten the bolts the specified torque of 26 Nm (19.0 lb-ft).

34) Tighten the front wheel axle to the specified torque with the special tool I mentioned in step 2. Specified torque is 100 Nm (72.5 lb-ft).

35) Before tightening the two axle pinch bolts on the right front fork leg, bounce the forks up and down four or five times without applying the front brake. Of course you have to take the bike of the paddock or Abba stand to do this.

36) Tighten the two axle pinch bolts to the specified torque of 23 Nm (16.5 lb-ft).

37) Done!!! Check again if you tightened all the bolts. Time to do the fork set-up!

The fork set-up is personal to individual riders of course. The settings Hyperpro used are the following:

- Preload: 3 or 4 rings visible which should give a static sag of about 24 mm. If not, give the fork more preload (3 or less rings visible) until the sag is correct. Again, the preload is very personal, so take your time to measure it in you personal situation!
- Compression: This is the adjuster at the bottom of the fork. First turn the adjuster fully clockwise. The compression is now at it’s stiffest position. Than turn out the adjuster 2,5 turns.
- Rebound: This is the adjuster on top of the fork. First turn the adjuster fully clockwise. The compression is now at it’s stiffest position. Than turn out the adjuster 2 turns.

MAKE SURE YOU APPLY THE SAME SETTINGS TO BOTH FORK LEGS!!!

If you compare these settings to the stock settings (1 turn out from stiffest position for both compression and rebound), you notice that the fork with Hyperpro springs gives you much more room to adjust the suspension! That’s the biggest advantage of different fork springs. This is due to the different spring rate of the Hyperpro springs which is much higher than the spring rate of the stock springs. This should also apply to other brands of springs of course.
Some extra details and tips:

- The front fork springs of the 2005 SV1000 model are not the same as the ones from the 2003/2004 model!!! Probably Suzuki has done some internal changes to the 2005 model but did not mention it. So the mechanics of Hyperpro were very surprised when it turned out that the springs they had didn’t work! The correct springs should be made by now and the problem was temporarily solved by putting a extra spacer in the front fork.

- The GSX-R 1000 2005 model front fork is crap. The springs are pretty good but the damping is really bad. One of the mechanics of Hyperpro races in the Dutch Superbike class with this bike and he had to do a complete reshimming of the fork before the damping was correct. So let this be a warning for the people who are thinking of a fork swap. Just because forks are from a GSXR does not automatically mean that the suspension will be better!



Replacing the rear shock spring
I’m not gonna tell you how to remove the shock because this can be found in the other write-ups on the website. The only part that will be discussed here is replacing the spring and the setting up of the shock.

Personally I think swapping the spring on a shock absorber is something you shouldn’t try at home because it requires a tool with which the spring can be safely removed. At Hyperpro they have some kind of device which compresses the spring while the shock is being held steady. That way a ring at the bottom of the shock is revealed. This ring isn’t really mounted, it’s just held in place through the pressure of the spring. This ring can be loosened with a small screw driver (if it’s stuck because of dirt for example) and than removed from the shock. ***photo 7***

The hole (slot) in the ring serves for two purposes. First, without the hole in the ring it wouldn’t be possible to remove it from the shock. Second, the hole in the ring also makes sure that water and dirt can leave the shock. The shock is “attacked” by road dirt every time you ride, especially when the road is wet. As the shock is always mounted in a forward leaned position (assuming the hole in the ring is mounted to the front of the bike), water and dirt that end up in the bottom of the shock can also exit the shock. If the hole is in the wrong position water and sand can’t escape and can cause serious corrosion and damage to seals on the shock. See the two drawings below. Don’t pay any attention to my drawing skills please... :o)

Next thing is to clean the shock and the component you just removed. This is a very hard part to clean while it’s on the bike, so take the chance!!! When you’ve cleaned the shock it’s time to mount the new spring. As you can see in the ***photo 8*** there are some differences between the stock spring and the Hyperpro spring.

Besides the colour, which you will either love or hate, you can also see the progressive part of the spring. Just like you could with the front fork springs. The idea behind the progressive shock spring is that the windings close to each other (top of the spring in the photo) provide more comfort in small bumps, something the stock spring lacks. When the shock is compressed more the Hyperpro spring gets stiffer thus providing more feedback and the stiff spring you want at that point. For example when you are riding on a track where high corner speeds are really making the shock work.

The spring is mounted as shown in ***photo 9*** with the close windings upwards. Then the spring can be compressed again and the mounting ring can be remounted.

Make sure you put the hole on the correct side of the shock like I mentioned before. Finally the spring can be decompressed and the spring swap is finished! This is a very easy thing to do (takes about 15-20 minutes), but you do need the correct equipment for it. The shock can now be remounted on the bike.

The settings that Hyperpro advices for the SV1000 shock with their springs is the following. Please remember that these settings are also very personally and depend on the weight of the rider, just like the fork set-up.

- Preload: Hyperpro uses a preload setting of 20 mm. To be honest I don’t know how they measure this. It could be the distance between the bottom of the thread and the lower preload ring. But it also could be the difference between the length of the spring fully uncompressed and the length of the spring compressed with only the weight of the bike on it. So if the spring length is 190 mm, the length of the spring mounted and with the weight of the bike on it should be 170 mm.

As with the front fork, take your time to figure out the preload settings!!!

- Compression: This is the adjuster at the top of the shock. First turn the adjuster fully clockwise. The compression is now at it’s stiffest position. Than turn out the adjuster 2.5 turns.
- Rebound: This is the adjuster on bottom of the shock. First turn the adjuster fully clockwise. The compression is now at it’s stiffest position. Than turn out the adjuster 2 turns.


Hopefully this write-up has cleared some of the fog around the subject of suspension. It is a very hard topic and every suspension manufacturer (WP, Hyperpro, Wilbers, Race Tech, Maxton etc) has it’s own vision on suspension. The key thing is that most bikes benefit from a different set of fork springs (and shock spring) regardless of the brand. And as suspension is the link between the tires and the bike itself I’d say good suspension is an investment well made.

Finally an impression of a Dutch SV1000 rider after riding with his newly suspended (different fork and shock springs) SV1000 for a couple of days:

“Very satisfied, I’ve got a completely new bike!

Huge stability, like it’s glued to the road! The front end suffers from less dive so corners can be entered much quicker and faster. The bike absorbs all kind of bumps and gives lots and lots of confidence and feedback plus the bike is also stable at 200+ (km/h...) speeds.”


Disclaimer: I cannot be held responsible for any damage that is suffered by following this instructions. I am not a mechanic and this write-up is merely a guide for the technical riders among you who may want to do this themselves.

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