2010 KTM 530 EXC Suspension Rebuild

So on my last real ride on the 530, we were running dirt roads through the Davy Crockett NF. The roads were nothing real bad, just your typical dirt roads, but they were beating me to death. My 530 had lost that Cadillac ride I had come to love. I mentioned it to Roger "Rsquared" and he said he was about to do a rebuild of the suspension on his 450 EXC and he'd be willing to help me do mine. So a month or three goes by and I finally get all the parts and a free day. I pulled the forks and shock and headed down to Roger's.

Roger is my special tool hero. I have a few here and there, he has a collection. You just have to love those special tools because they just make things sooooo much easier. It did not take long before I realized that I would have been in a world of pain and aggravation if I had tried to do this myself. When I arrived, Roger was ready to rock and we got right down to business with the forks. I didn't get many pics of the process because Roger is fast! He was explaining as he went though, which was nice because he has really researched this stuff way more than I have!

Special tool for removing fork caps.


Fork oil gets dumped in oil pan, pretty black...


Shim stack for rebound damping?


Cleaning all the internals


Oil gets shoved through holes in the body of this piece and has to push past the shims which restrict the flow. Thicker or thinner shims make it harder or easier for oil to flow. Adjusting once assembled allows oil to bypass the "valve" so oil flows easier. More flow means fast rebound, less flow means slower rebound. Rebound is the extension of the fork after a compression stroke.


Compression valves? It got sprayed but not disassembled. Work on the same principle as the rebound valves by controlling the flow rate of the oil. More flow means softer feeling hit at the bars (longer stroke) and better bump absorption. Less flow means harder feeling hit (shorter stroke) and less bump absorption.


Special care must be taken when freeing the seals so that you don't accidentally nick or scrape the slider. That would be BAD as it would lead to premature wear of the new seal!


Bushings and seals on slider


Unless you really know what you are doing, it is a good idea to REALLY pay close attention to the order in which these parts come off the slider. This is where a little point and shoot digital camera comes in handy for those of us with poor memory skills...


New bits waiting for installatoin


Another special tool to prevent tearing of seals as they are pushed over the end of the slider.


Special tool for seating the seals


Fork reassembled, new oil is added and the fork is repeatedly compressed and extended to bleed it before checking for proper oil level.


Special tool for setting proper oil level. When I did this on my KLR 650 years ago, I was dipping a wooden dowel into the fork and trying to measure how deep it was from the top of the fork. It was a total pain. This tool is awesome. Simply set the desired depth level on the gauge etched on the tube, set the cap on the top of the fork, suck until you get air. Easy peasy!!


Roger knocked out the forks pretty quick. I think it was maybe an hour or so at most. Had I not been asking questions and getting in the way taking pictures I am pretty sure he could do a set of forks in under an hour without much trouble. I would likely have wasted at least an entire day because of my lack of special tools

With the forks done, our attention turned to the rear shock. This is a bit more work. The rear shock has NO AIR in it like the forks have. When the shock is compressed, the oil pushes into the reservoir on the side of the shock and pushes against a free floating piston with 150 psi of Nitrogen on the other side of the piston. When it extends, the Nitrogen pushes the oil back into the shock body. Like the forks, there are some valves that allow for tuning the oil flow rate.

First step, release the preload on the spring after measuring so we can get it back to the right spot after reassembly. This requires a spanner wrench.




With the compression load off the shock, the restraining clip is removed.


The normal KTM procedure does not involve releasing the Nitrogen. However, we will be doing that and checking the condition of the reservoir and the piston. Here the Nitrogen is CAREFULLY released.


Time to remove the slider from the shock body


This is one of Roger's LITTLE drift pins... Seriously


He works his way around the cover, popping it off a little at a time at each point until the whole piece comes off.


The screw at the top of the reservoir here is where the oil is drained.


Another cool special tool! A ratchet on two gimbals. Used to remove the plug screw.


Draining the oil. Doesn't look horrible, but definitely not new.


The orangish brown rubber piece at his right hand gets replaced. It is a bumper to protect the pieces in case the shock gets totally compressed.


Cover on far right, then retaining ring, sealing o-ring, then the valves with slider bushings around the outside of them.


You can see the different diameter and thickness of the shims here. The combined stack acts like a circular cantilevered beam that is fat at the wall and tapers to a point out at the edges. It flexes easier and quicker and then gets progressively stiffer and more flow resistant as more oil tries to push through. We don't mess with the shims and valves other than to spray clean them. They aren't really wear items like the seals and bushings.


Roger removes the adjustment valve between the main shock body and the reservoir. Adjusting this fine tunes the flow of oil between the body and reservoir.


The cover


The valve. Adjusting it simply lets oil bypass the valve for more flow.




I did not get a picture of a previous step, but before draining the oil, Roger had the shock fully extended after the Nitrogen was released and he measured the location of the piston from the open end of the reservoir. This is so that when we reassemble the shock, we can make sure to get the piston back to that same position before recharging the Nitrogen.

VERY important step. Roger is pushing the piston to the FAR side of the reservoir. Removal of the reservoir requires heating it around the threaded end to get it to release. We DON'T want to burn the o-ring on the outside of the piston!!


SOME of Roger's special tools...


Shock body in bench vise prior to heating the reservoir


Heating gun, another tool I do not have...


It doesn't take much, so you have to be careful. You don't want to get it too hot. I think Roger had the gun on low and only heated it for maybe 10-15 seconds as he was going around the circumference of the body.


There's a special tool here, but it is black and you might not spot it


It is the piece between the socket and the reservoir body


Here it is. It fits onto the end of the reservoir body so you can torque it to break the threads loose. Without this, you'd be forced to use some kind of clamp or BIG wrench on the body itself which would risk deformation of the body and impede the free movement of the piston. A bad thing!


Now we turn our attention to the slider, valves, bushings and seals


Not a great shot, but I was trying to show the shims


There are a lot of parts when this all comes off the slider. Slipping it all over the end of this pick keeps everything in the proper order for reassembly.


New and old bumpers. You can see a bit of deterioration on the old bumper. But otherwise it is still in pretty good shape.


This is the end cap. It has an o-ring around the outside that seals against the inside diameter of the shock body and the brown bushing shown here where the slider goes through.


Special tool: slide hammer for pulling out that interior bushing shown in the above picture.


A couple of whacks and the bushing pops right out


Yet another special tool for getting the new bushing in place


No, not the socket...


The hydraulic press. I am sure you could use a rubber mallet and a little block to tap the bushing into place, but this worked really well and allowed Roger to watch every step of the way to make sure the bushing was not getting tweaked to one side or the other.




This tool is like the larger one used on the forks. It allows everything to slide easily back onto the slider without risking the tearing of new seals and bushings.


Then it is simply a matter of slipping everything off the pick back onto the slider.


Roger lifts one of the shims so I can show how thin they are


Here is a better pic showing the different diameters of the shims.


Locking everything back in place


With the shock internals back together, he turns his attention back to the reservoir and piston, giving both a good cleaning.


Never seen this before. Roger loves it and has been using it forever. It works great so it must destroy the planet... I can't believe it is still legal


Now we come to a no turning back decision. Without the special KTM tool for recharging the Nitrogen, we have to install a schrader valve so we can put a new Nitrogen charge in the reservoir. This means drilling and tapping the bottom of the reservoir so the schrader valve can be installed. Once he starts drilling, there's no going back. Well, he's already done two on his own bikes, so what the heck! You can see the two holes here where that special tool fit for removing the reservoir from the shock body.


Maybe a drill press might be better for absolute straight drilling, but Roger gets the job done nicely by hand.






Oh yeah, that will be getting a GOOD cleaning before reassembly!!


Now comes the tapping


I don't have a decent set of taps




Beautiful!


Shiny new schrader valve installed after everything is cleaned. It got a wrap of Teflon tape around the threads before being screwed in place.


Piston goes back into reservoir. Pay attention to orientation!


Special tool used again to reinstall reservoir. No torque value given. If I remember right, blue Loc-Tite is used and it is snugged firmly.


New bushings installed on outside of valves


That gold part is a special tool for driving the end cap back into place without tearing up the outer seal.


Once we get the shock reassembled, the real fun starts. Remember how I said there is NO air in this shock? Well, the oil has to be put back in the shock and it has to be bled. Doing that on the forks is easy. Not so with the shock. The process is called degassing and there is a SPECIAL tool for that which runs into the thousands of dollars. Now Roger likes special tools, but he is also frugal and very much a hands on kind of guy. Somewhere on the internet he found references to people building their own systems. Using that incomplete information, he built his own.

Behold a work of art


What you are looking at there is a big water filter housing. The left side of the cap is for controlling the pressure inside the canister. It will alternate between 20 psi and a vacuum. The upper left valve goes to a vacuum pump. The lower left valve with the hose and fitting goes to a compressor. The hose coming off the bottom of the canister goes to a valve. The hose on the right that goes back up to the pressure gauge is a return line for oil that comes back out of the shock during bleeding and gets dumped right back into the canister. The two valves here control whether oil is being pushed into the shock or sucked out and back into the reservoir. Roger welded up the stand from some metal rod he was going to use to build a luggage rack that he abandoned before completion. The last, but VERY important part is a little screwed fitting that screws into the valve body at the fill hole. That is a real odd ball thread and Roger had to search high and low for a fitting that would match the thread.

Here it is for those that might be interested. They come in a pack of three. The corners of the hex had to be filed down a bit to avoid contact with a lip around the hole in the body so it would fit down into the threads.


Here's the vacuum pump. It sucks...


The pressure gauge on upper right. Note that is also shows vacuum.


Roger pushes the left over oil from his shock into the bottle using positive pressure from the compressor.


Now he uses the vacuum to suck my new oil into the canister. At this point, the valve going to the bottom of the canister is closed and the return line is open to the top of the canister.


The oil REALLY foams up. At first, I am thinking we'll be here a while waiting for all the foam to go away.


However, once the contents of the bottle have been transferred to the canister, Roger closes the return valve and subjects the canister to an increasing vacuum and the bubbles are quickly collapsed!


Getting to this point took maybe 15-20 seconds.


Ready for action. Clear hose on left goes to compressor under the work bench. The funky fitting for the shock body is in the end of the red hose under the canister.


Connected to the shock. Note that at this point, there is still no Nitrogen in the shock reservoir. We want the piston to move freely as oil goes in and out of the shock.


We set the shock down below the level of the work bench to stretch out the tube and to facilitate the rapid flow of bubbles up the line to the return valve.


A final check before starting.


The bleeding process is pretty simple. The only tricky bit is keeping track of which valves should be open or closed when alternating between the 20psi and the vacuum. During the process, the shock slider moves back and forth in the body. Roger shuts off the vacuum a little before the shock is fully collapsed to avoid sucking air in past the seals. Yes, the vacuum will actually get strong enough to do that!! After the shock is fully bled and we see no more bubbles escaping, we move it around and tap it to get any little trapped bubbles to float free. Once that is done, Roger screws the schrader valve into the bottom of the reservoir and pressures it up, after resetting the location of the piston.





Now, there was a whole mess of "Other steps" that I am gonna leave out here because we had a few of those "DOH!" moments... One occurred right at the LAST moment when Roger fortunately realized we messed up a VERY IMPORTANT step. We were lucky he realized it then and not after I got home and told him the bike was riding like crap!! Then there was that hose leaking right before it popped off and started spraying oil all over the place Sooo... we did it all again

Here he slides a long T handle Allen wrench into the reservoir to once again check its location with where we noted it before removing it.


See the bar along the side of the reservoir body? Just right.


Here are a few shots of his shop...



He races TORCS occasionally




And so does his son Mason


It went quicker the second time around and we were soon back to where he realized we had missed a step before. Here he's putting the drain/fill plug back in place before wiping everything down and taking a break.


Shop guard dog... SPOILED like you wouldn't believe, hehe.


Roger and Mason's rides


Okay, time to charge the Nitrogen for the reservoir. I won't reveal his sources for Nitrogen.


Nice digital gauge!


He sets it for 150 psi.


Charging the reservoir


Getting ready to remount the spring


A few minutes later everything is completely reassembled, correctly It is late afternoon and I'm hungry. Roger gets in touch with his wife to see if she'd like to join us for a late lunch/early supper. She agrees and we head to a nearby Rudy's BBQ so I can treat them to dinner. It does not disappoint. Afterward we head back to his place so I can load up my stuff and head North.

Roger's wife, Lisa, a VERY understanding woman


The lovely couple, sweet hearts from a young age.


I get everything in the truck and start the hour plus drive back up to Huntsville. I stick everything in the garage and head inside. I'm in no hurry to get it all back together and it can wait a day or so. In fact, I get it back together Sunday afternoon and take it for a spin. The bike feels MUCH better on the harsh bumpy stuff, but it still needs a little fine tuning of the adjustments to get it back to that Cadillac feel I've been missing.

A HUGE thanks to Roger. I would not have been able to do this without his help and I would have had to spend a large fortune on special tools and equipment. Also, a big thanks to Lisa for allowing me to steal her hub away for a day, and for all those trips I've dragged him away on over the years. Like I said, understanding...

Nice. Good pictures. I just finished all of this on my KTM 950, except I actually re-valved the stacks as well. I thought about taking pictures and posting, but it was too distracting trying to do it all myself.

Near the first pictures you posted, the base valve that is being held up with the hand in the blue glove is a compression valve.

A few pictures later is a picture showing the damping rod with the valve attached at the end. This actually does two things. There is a shim stack on both sides of the valve (you can see in your pic). The stack nearest the nut holding the valve onto the rod is the rebound stack. On the top side of the valve is the mid valve stack. The mid valve affects compression.

As the rod/valve assembly moves through the cartridge, on the way down the mid valve shims are the ones that move, and as the suspension rebounds and the valve goes back up, then the shims on the bottom deflect and come into play.

Nice write up. I am getting ready to do mine and was trying to decide how I was going to charge the nitrogen. I think the Schrader valve makes the most sense. I also need to build the vacuum bleeder that I have most of the parts for but never finished.

I find this subject fascinating to the point that I bought (and read) the Racetech suspension bible. Interesting that the aeration of shock oil is covered extensively in the book & so well illustrated in your pictures. I can't pretend that I understand more than about 25% of this but I think given a life to live again, being a suspension engineer for race team would be a great way to make a living.

I think this thread illustrates perfectly why the real thing is so expensive. Like the best microphones we use, precision engineering is difficult and lacks much in the way of economies of scale.

Thanks for sharing.

Johnf3 said:

Nice. Good pictures. I just finished all of this on my KTM 950, except I actually re-valved the stacks as well. I thought about taking pictures and posting, but it was too distracting trying to do it all myself.

Near the first pictures you posted, the base valve that is being held up with the hand in the blue glove is a compression valve.

A few pictures later is a picture showing the damping rod with the valve attached at the end. This actually does two things. There is a shim stack on both sides of the valve (you can see in your pic). The stack nearest the nut holding the valve onto the rod is the rebound stack. On the top side of the valve is the mid valve stack. The mid valve affects compression.

As the rod/valve assembly moves through the cartridge, on the way down the mid valve shims are the ones that move, and as the suspension rebounds and the valve goes back up, then the shims on the bottom deflect and come into play.

Click to expand...

I thought I might be messing that up. So let me try to get it straight...

The set of valves that come out of the BOTTOM of the fork near the axle clamp, THAT is the compression valve?

The set attached to the rod is the rebound valve AND compression?

So there is one valve for rebound but TWO for compression? Is it like a high speed and low speed compression system?

Tourmeister said:

I thought I might be messing that up. So let me try to get it straight...

The set of valves that come out of the BOTTOM of the fork near the axle clamp, THAT is the compression valve?

The set attached to the rod is the rebound valve AND compression?

So there is one valve for rebound but TWO for compression? Is it like a high speed and low speed compression system?

Click to expand...

Yes, the valve at the bottom is compression. It is called the base valve. It controls compression at all suspension speed movements, but comes into play a bit more on low speed (suspension speed not MPH speed) hits. It really depends how you have your mid valve set up to how much the base valve influences your total fork damping.

Yes, the valve attached to the cartridge rod has both compression and rebound. Look at your (great) picture and think about it. As the rod/valve goes down, the shims on the bottom of the valve are going to be forced shut against the ports they cover and the uncovered ports will flow through the valve and cause the shim stack on top to deflect. This is the compression action that the mid valve provides. It is useful to tune this for mid speed and high speed (again suspension movement speed not MPH). It has to work in harmony with the base valve, so the settings have to work seamlessly together.

So, then as the fork rebounds, the midvalve (top) shim stack is forced close and oil flows through the open ports on the top side causing the rebound shims to deflect.

As far as looking at one as low speed, one as high speed, that is too simplified. It all depends how you have the shims set up. The variables are endless, but the above explanation is a general overview of how it all works.

Without hijacking this thread - I need some advice/assistance to get my F800GS set up properly for 2-up riding.

philipbarrett said:

Without hijacking this thread - I need some advice/assistance to get my F800GS set up properly for 2-up riding.

Click to expand...

On that particular bike, BMW basically made the forks one way and one way only. They crimped the cartridge inside so nothing can be changed. I don't think it has any external adjustment either. You could get springs installed, both front and rear that are more suited to two up riding. Other than that, the options are $$ in a hurry. Replacing all the fork internals with a serviceable cartridge would be the first step. High dollar.

I don't know why BMW did that, but it really limits your options, and makes upgrades really expensive.

Really good photos Scott. The new camera does a very good job on small detail, although something needs tweaking on the subject setting. I can't be that old and fat...

I've been doing my own forks for a long time and have always wanted to set up to do the shocks, so I broke down and got everything needed for that as well. Between my son's bikes and my bike's, not to mention his buddy's bikes, I figure it'll see plenty of use. I've been sending my shocks out to a guy in Oklahoma, and with the cost of shipping and labor, it won't take long to recoup the cost.

I recently replaced the valving in my 250 SX front and rear, with the Race Tech Gold valves. That was a good learning experience for me as to the relationship between the compression valve, the mid-valve and the float. I naturally started out with Race Tech's recommended shim stacks, but ended up disassembling my forks 5 different times for tweaking the adjustments. Once to re-shim the mid valve, three time to add a 1/10 mm to my float and once to re-shim the compression valve. It's amazing to me that you can feel the difference in 1/10 mm adjustment in the float. I also find it amazing how noticeable the difference is, just from servicing the suspension. I guess you really don't notice it degrading slowly over time, compared with one's that have been freshly serviced.

My next project will be to see if I can't make the suspension on my 690 a lot more plush.

Anyway, I know there's a lot of talented folks on this forum, and I really like to learn tips and tricks, so let's hear it...


.

Scott,

Some racers used to replace the KTM piston in the rear shock with a Race Tech bladder. Saying its was easier to repair and find parts for back then and also the piston would get hot over time and fade off where a bladder will not.

Rsquared said:

Really good photos Scott. The new camera does a very good job on small detail, although something needs tweaking on the subject setting. I can't be that old and fat...

I've been doing my own forks for a long time and have always wanted to set up to do the shocks, so I broke down and got everything needed for that as well. Between my son's bikes and my bike's, not to mention his buddy's bikes, I figure it'll see plenty of use. I've been sending my shocks out to a guy in Oklahoma, and with the cost of shipping and labor, it won't take long to recoup the cost.

I recently replaced the valving in my 250 SX front and rear, with the Race Tech Gold valves. That was a good learning experience for me as to the relationship between the compression valve, the mid-valve and the float. I naturally started out with Race Tech's recommended shim stacks, but ended up disassembling my forks 5 different times for tweaking the adjustments. Once to re-shim the mid valve, three time to add a 1/10 mm to my float and once to re-shim the compression valve. It's amazing to me that you can feel the difference in 1/10 mm adjustment in the float. I also find it amazing how noticeable the difference is, just from servicing the suspension. I guess you really don't notice it degrading slowly over time, compared with one's that have been freshly serviced.

My next project will be to see if I can't make the suspension on my 690 a lot more plush.

Anyway, I know there's a lot of talented folks on this forum, and I really like to learn tips and tricks, so let's hear it...


.

Click to expand...

I am not an expert and don't claim to be. I am behind you when it comes to moto specific stuff, but I have been servicing and tuning shocks on dirt cars. They are basically the same. The only advice I can give is to keep good notes. Like what oil you used, not just the weight, all manufactures oil is not the same by weight. Then you get into different oil by the same manufacture, i.e. Maxima has fork oil and fork fluid. Then you get to the shim stacks and the clickers, so for me I want to know where the clickers are set before and after a shim change. I believe that the clickers are most effective in the middle of the range, so if I am at one end or the other I need to make a shim change to get it back closer to the middle. I want to be able to note what I liked or disliked both before and after a change. The guy who's car I help with has all of this info in a spreadsheet and we can quickly see what has worked or not for different track conditions. I guess what I am trying to say is the Devil is in the details, so the more detailed you are the easier it will be to wrap you head around the black hole of suspension.

Let us know what you discover on your 690, so we can all learn.

ekms377 said:

Scott,

Some racers used to replace the KTM piston in the rear shock with a Race Tech bladder. Saying its was easier to repair and find parts for back then and also the piston would get hot over time and fade off where a bladder will not.

Click to expand...

I've been curios how much noticeable difference there would be using the bladder. It seems to me it could be more plush initially on square edge hits. And it makes sense that there could be some level of hysteresis in the N2 piston's action due to expansion from the heat, that wouldn't be seen with the bladder. I may have to give one a try...

bwdmax said:

I am not an expert and don't claim to be. I am behind you when it comes to moto specific stuff, but I have been servicing and tuning shocks on dirt cars. They are basically the same. The only advice I can give is to keep good notes. Like what oil you used, not just the weight, all manufactures oil is not the same by weight. Then you get into different oil by the same manufacture, i.e. Maxima has fork oil and fork fluid. Then you get to the shim stacks and the clickers, so for me I want to know where the clickers are set before and after a shim change. I believe that the clickers are most effective in the middle of the range, so if I am at one end or the other I need to make a shim change to get it back closer to the middle. I want to be able to note what I liked or disliked both before and after a change. The guy who's car I help with has all of this info in a spreadsheet and we can quickly see what has worked or not for different track conditions. I guess what I am trying to say is the Devil is in the details, so the more detailed you are the easier it will be to wrap you head around the black hole of suspension.

Click to expand...

That's a good point. I've jotted down all of the shim stacks on mine and my son's bike, but I need to do a better job of taking notes as to how each adjustment to the shim stack, float, or oil level has effected the feel.

bwdmax said:

Let us know what you discover on your 690, so we can all learn.

Click to expand...

Will do. This will be my first 4CS fork.

Rsquared said:

Really good photos Scott. The new camera does a very good job on small detail, although something needs tweaking on the subject setting. I can't be that old and fat...

Click to expand...

I noticed the same problem with your GoPro on the North Carolina trip a few years ago. It also made everyone slow and look like they had huge bald spots...

Rsquared said:

Will do. This will be my first 4CS fork.

Click to expand...

I would be interested in what you do to the 690. I have adjusted the sag on my stock one to close to what it should be. Is the 4CS fork the one that is a pain to just change the oil?

Roger is a man of talent! Riding the bike, working on it, whatever is needed. And always willing to help. Wish he would move a little closer to me. Great thread, thanks.

mcrider said:

I would be interested in what you do to the 690. I have adjusted the sag on my stock one to close to what it should be. Is the 4CS fork the one that is a pain to just change the oil?

Click to expand...

I'm not sure. I'll post up what I run into.

Irishcoffee said:

Roger is a man of talent! Riding the bike, working on it, whatever is needed. And always willing to help. Wish he would move a little closer to me. Great thread, thanks.

Click to expand...

You're being way too kind, George. Thanks. You need to come ride with us.