Cheap rear shock absorber cure

[Redryder]

Here is how I fixed the lousy, bumpy ride from the standard back shock absorber on my 99 SV650S curvy - without spending a cent.
In a nutshell, I reduced the rear spring preload by 4mm on the softest setting, by modifying the preload adjuster ring.
Now it rides a hell of a lot smother, corners better and just feels great, whereas before it was the bikes glaring weakpoint (after sorting the front forks out).

First up, I weigh 85kg and most of my riding is commuting on rough rural ashphalt roads with spirited ride up and down the local twisties once a week, also rough asphalt with patches, holes, bumps and even blacktop washboards on corners. Speeds here are 80-100kmh. I am not racing or cornering at 160kmh regularly. If you are, this mod might not be for you.
But if you have tried the softest setting on the stock shock absorber and it is still pounding you off the seat over bumps, here is how to fix it.

Step 1.
Remove shock abosorber from bike, as per the manual. I made a centrestand out of 4X2 timber and a couple of angle brackets that bolt onto the lug on the bottom of the engine.
Tip: The shock bolts and dogbone bolts are tight. Use the ring end of a combination wrench and belt the other end with a big rubber mallet to shock the loose.
Beware: the top shock mounting bolt has an undersized 14mm across-the-flats nut that rounds easily. Take the tank off for good access. Us a six-point impact socket on it if a normal wrench slips.

Step 2.
Pull spring off shock absorber.
I did this by using two ratchet tiedown straps to compress the spring, notch by notch. Then grab the spring retaining collet with a pair of vice grips and pull it out. Keep fingers of of the way in this process, and wear safety glasses. The sping has tremedous power and if those ratchets slip a bit, the result can be nasty.

Step 3
You want a total of 4mm reduction in preload.
So first, file down the two little tabs on the shock body that engage with the preload ring, by 1.5mm. Use a 10-inch ******* file with the teeth ground off one edge so it does not file the shocker body as you file down the tabs. Measure the tab with a vernier, micrometer or maybe a ruler before starting and file down to the same, minus 1.5mm. Then refile the radius on the tab so adjuster ring will move smoothly over it. Black spray paint the tabs to stop rust. Dont file more than 1.5mm off the tabs as it may get too close to the retaining rivets.

Step 4.
This consists of filing down the notches on the preload adjuster ring by 2.5mm. You want the new notches to follow the profile of the old one so it can move from notch to notch smoothly for adjustment.
I painted the area to be filed with a black marker pen, to make my mark-up easier to see. Then I took a pair of engineer's dividers - a sort of double ended compass for scribing circles on steel - and set the two points 2.5mm apart. By running one point along the old notch profile and the other along the adjacent metal, a line is scribed parallel to the old profile, but 2.5mm lower. Do this on both sides.
I then clamped the aduster ring to the bench and used a 10-inch round file, half round file and square file to file the notches down to the new, lower profile.
Smooth it all off with a bit of emery paper and hit with some silver spray can paint to stop rust.
PUt a bit of copper grease on the ring and notches.

Step 5.
Reassemble spring onto shocker, with tie down straps compressing it still. Use rubber mallet to pop spring retainer back into place.
Make sure spriing adjuster ring is in softest position so it is easier to get spring on.
Put shocker back into bike as per manual.

Step 6.
Test ride. Set shock spring preload to desired softness by using the c spanner from toolkit.
Remember: You have taken a total of 4mm preload off. (1.5mm on the tabs plus 2.5mm on the notches in the ring).
This means that notch number 5 ( fifth from softest) now gives the same preload as the stock notch number one notch (softest).
So, notches four to one are progressively 1mm softer than the stock softest setting.


And the best thing is that it cost me absolutely nothing to do this.
Yes, a GSX shock or 636 shock might give a better result if you are racing or riding really hard on the road, but I would try this fix before forking out the money for regular road use./

Enjoy
Redryder

[jambo]

Given the lowest setting of preload on the rear shock was allowing me to bottom the SV out, and I weigh a significant amount less than you I see this helping fairly few people.

It's a possible way to reduce the preload, I'd imagine, but people need to be sure that they have measured the sag correctly using a set of steps such as this:

http://www.gostar-racing.com/club/motorcycle_suspension_set-up.htm

You are clearly happy with the result, but it's important that people are very clear about what has been changed. If your weight is unable to compress the spring enough, even with the preload ring on the first setting, it's quite possible the spring rate is wrong for you.

Jambo


Edit: From your description the roads round where you are are massivly rough which may be why the standard settings were not suiting you, but I would be intrested to know what the static and rider sag are now?

[Blue_SV650S]

85kg is ~13.5stone ... which is a fairly average mansize* i.e. it is not like you are a 7st lightweight … therefore - like jambo, I am surprised you need to go BELOW the lowest adjustment!! :shock:

Have you checked the linkage bearings are all well lubed/good condition??? I'd say you might be experiencing resistance elsewhere ...

*I am about 80-85kg (depending on pies)

[Redryder]

Surprising feedback.
Definitely no binding in the linkages or other resistance.
With the stock arrangement, static sag was 25mm, rider sag was 25mm. And you could barely move the rear end down at all from bouncing on the seat.
Rider sag is now about 30mm and movement by bouncing on the saddle feels about the same as my Honda VFR800, which has perfect suspension for our roads. (Purely a seat of the pants measurment!)

Maybe the previous owner of my SV650 put a stiffer spring on the back if the usual problem is that it is too soft?
They had 30wt oil in the front forks, along with 14mm preload spacers, so perhaps they were just into masochism?? I now have 12mm front preload and 15wt fork oil, which is much improved but plan to go for Racetech linear springs and cartridge emulators to get that little bit better ride on the rough.

And yes, the roads around here are a lot rougher than you find in the UK or US for the most part.

Cheers
RR

[Blue_SV650S]

Maybe the previous owner of my SV650 put a stiffer spring on the back if the usual problem is that it is too soft?


Id say that is quite probable as my curvy SVs rear end is well compliant with the stock shock!! :(

Is there any writing on the spring? What colour is it?

At the end of the day if it works for you that is excellent and suspension setup is a personal thing, but I am surprised there wasn't enough adjustment on the stock shock!! :shock:

[Redryder]

Id say that is quite probable as my curvy SVs rear end is well compliant with the stock shock!! :(

Is there any writing on the spring? What colour is it?

At the end of the day if it works for you that is excellent and suspension setup is a personal thing, but I am surprised there wasn't enough adjustment on the stock shock!! :shock:

The spring is yellow, as is the bike. I didnt see any writing on the spring , but wasnt looking for any. It was definitely way harsh though, even with SWMBO on the back, the back end just sat up solid. I have found, somewhere on a net forum, one other bloke from Australia who has done a similar thing, filed 1.5 mm off the preload notches to give a smoother ride. Perhaps the Australian models had harder springs than other markets?
But as you say, the end result is that it now suits me just fine and the how-to advice is on file for anyone else who finds themself with the same problem.;)

[Blue_SV650S]

But as you say, the end result is that it now suits me just fine and the how-to advice is on file for anyone else who finds themself with the same problem.;)

Quite :)

[Robw#70]

Dont you just love the internet:smt046

[zadar]

there is nothing wrong with what you did but(except spring compressing tool) I dont think that is stock spring.
you should have measured free length of spring while you had it off.