KTM SXF WP Trax shock

Notice the same thing on my 2015 Trax
My CV Fork is out for Service so ask the Suspension Tuner to replace the Top Bearing on the Trax

This sound is normal for a TRAX shock as it`s the Trax mechanism that you hear there. Depending on how many Trax springs are installed inside the effect and also "sound" is more or less. I wouldn`t worry about it too much.

There should be no knocking in a properly working Trax shock.
Have the trax system checked, the springs inside might be broken, it happens.

Turbojez wrote:

There should be no knocking in a properly working Trax shock.
Have the trax system checked, the springs inside might be broken, it happens.

The shock only has 6hrs on it from the last service by the previous owner. I have heard that is was possible for the springs to break. do you know if there is a way to check this yourself without pulling the whole shock apart, can just the Trax part of the shock be undone and inspected?

Would like to avoid the cost of sending the shock to the mainland be serviced again if possible after such few hours.

Is it maybe other parts if your linkage that has some play?

Imo the trax springs aren`t broken as I´ve heard that kind of noise on some TRAX shocks now... nevertheless checking all bearings (linkage, swingarm, etc...) is a good idea anyway.

CarlinoJoeVideo wrote:

Is it maybe other parts if your linkage that has some play?

I will look at the other bearings tonight again, but they were all fine with no knocking with the standard shock, like I said the bike is relatively new with only 18hrs.

Heres a video i took last night of the knocking albeit not a good one, difficult when your by yourself aha https://www.dropbox.com/s/dkkf6kvrp634r92/IMG_0593.MOV?dl=0

Generally when you hear sounds like that you've more than likely got a broken spring or 2 in the dropout part of the shock. It's happened to me twice and both times I had multiple broken springs in the trax.

Does anyone have a service manual on how to replace the springs? or give me a bit of a step by step guide?

aaron63 wrote:

Hi,

I just bought a second hand trax shock. I've installed it and it seems to have a slight knock when lifting the bike up from the back, as if the bushings are gone. But when looking at the bushing there is no play in them. is this just the trax feature and is pretty normal? or should I be looking at getting the shock serviced, although it was done 6hrs ago according to the previous owner which he gave me his receipt for proof.

The bike is a 2018 sxf350 with only 18hrs on it so linkage bearings are all fine.

So...I'm not sure what "internal springs" some of the users here are talking about.

There are some coil-compression springs in this shock, but nearly all shocks use them. And compression springs don't normally break.

But...perhaps there is something about this shock where "the springs: were a problem.

With that....I'll add this.

Often bushings look and feel perfectly fine but still end up making noise when the forces applied via the swing arm are there. So...this could be a bushing or bearing thing.

Secondly, WP often uses what is called a "top-out" spring in their shocks, and they are beefy. This is a short but large spring that sits on top of the seal head that cushions the blow when the shock goes to full extension. Some shocks use a spring, other shocks use a hydraulic top out. Now...what matters here is that the top out spring counters the effect of the main spring when the shock goes to full extension, meaning the shock is not as tight at full extension as other shocks. That can me the movement coming off of full compression is soft.

You could measure for this by putting a zip tie on the shaft, with the bike on the stand, and then seeing how far you can compress the shock by pulling up on the tire with your hands.

NOW...that said, if this is not a bushing or bearing problem, what I really think it might be is free piston top out. I say this because I often open up a lot of recently serviced WP shocks where the free piston is knocking against the top of the reservoir when the shock goes to full extension. This means at full extension, the pressure in the shock is zero, giving the top out spring even more effect, (F=PA against the area of the rod).

This is because the service person did not properly set-back the free piston before filling and charging the shock, made all the more likely when service dudes use shock pumps to purge trapped air. And...free piston top out is way more noticeable on a WP shock because of their big top out springs.

Is that making any sense?

You only get this problem with free pistons, and not with bladders (but I do prefer free pistons over bladders). So does Ohlins.

Bottom line, I would not ride the bike until you fix this because if it is this, then the free piston is hammering against the shock body each time the shock goes to full extension.

Thanks to Slavens for the image.

That large but short spring on top of the seal head is the top out spring. This wants to compress the shock when it's at full extension and with shock that have softer springs or little pre-load, it can produce some slack. But again, I have never seen this cause a knocking noise but would exacerbate the free piston top out matter.

aaron63 wrote:

Hi,

I just bought a second hand trax shock. I've installed it and it seems to have a slight knock when lifting the bike up from the back, as if the bushings are gone. But when looking at the bushing there is no play in them. is this just the trax feature and is pretty normal? or should I be looking at getting the shock serviced, although it was done 6hrs ago according to the previous owner which he gave me his receipt for proof.

The bike is a 2018 sxf350 with only 18hrs on it so linkage bearings are all fine.

DaveJ wrote:

So...I'm not sure what "internal springs" some of the users here are talking about.

There are some coil-compression springs in this shock, but nearly all shocks use them. And compression springs don't normally break.

But...perhaps there is something about this shock where "the springs: were a problem.

With that....I'll add this.

Often bushings look and feel perfectly fine but still end up making noise when the forces applied via the swing arm are there. So...this could be a bushing or bearing thing.

Secondly, WP often uses what is called a "top-out" spring in their shocks, and they are beefy. This is a short but large spring that sits on top of the seal head that cushions the blow when the shock goes to full extension. Some shocks use a spring, other shocks use a hydraulic top out. Now...what matters here is that the top out spring counters the effect of the main spring when the shock goes to full extension, meaning the shock is not as tight at full extension as other shocks. That can me the movement coming off of full compression is soft.

You could measure for this by putting a zip tie on the shaft, with the bike on the stand, and then seeing how far you can compress the shock by pulling up on the tire with your hands.

NOW...that said, if this is not a bushing or bearing problem, what I really think it might be is free piston top out. I say this because I often open up a lot of recently serviced WP shocks where the free piston is knocking against the top of the reservoir when the shock goes to full extension. This means at full extension, the pressure in the shock is zero, giving the top out spring even more effect, (F=PA against the area of the rod).

This is because the service person did not properly set-back the free piston before filling and charging the shock, made all the more likely when service dudes use shock pumps to purge trapped air. And...free piston top out is way more noticeable on a WP shock because of their big top out springs.

Is that making any sense?

You only get this problem with free pistons, and not with bladders (but I do prefer free pistons over bladders). So does Ohlins.

Bottom line, I would not ride the bike until you fix this because if it is this, then the free piston is hammering against the shock body each time the shock goes to full extension.

Hi Dave,

the internal springs we are talking about are the ones inside the trax mechanism on the shock.
I wouldn't expect the top out spring to be broken internally. The shock has been ridden with this knock happening and still performs better than the oem one which came on the bike, so therefore that rules out that anything internally to do with the top out is broken.

I've spoken to the suspension tuner that last serviced the shock, and he said that it was normal for these shocks to knock like this with the trax feature when being lifted up. I've also looked at the were the movement is coming from and it is definitely from the the trax mechanism, and he has ensured me that on the last service these trax springs would of been checked and replaced if needed. Also said that it is unlikely for the newer model traxs shocks to have the broken springs because of the tighter tolerances and strong springs.

aaron63 wrote:

Hi,

I just bought a second hand trax shock. I've installed it and it seems to have a slight knock when lifting the bike up from the back, as if the bushings are gone. But when looking at the bushing there is no play in them. is this just the trax feature and is pretty normal? or should I be looking at getting the shock serviced, although it was done 6hrs ago according to the previous owner which he gave me his receipt for proof.

The bike is a 2018 sxf350 with only 18hrs on it so linkage bearings are all fine.

DaveJ wrote:

So...I'm not sure what "internal springs" some of the users here are talking about.

There are some coil-compression springs in this shock, but nearly all shocks use them. And compression springs don't normally break.

But...perhaps there is something about this shock where "the springs: were a problem.

With that....I'll add this.

Often bushings look and feel perfectly fine but still end up making noise when the forces applied via the swing arm are there. So...this could be a bushing or bearing thing.

Secondly, WP often uses what is called a "top-out" spring in their shocks, and they are beefy. This is a short but large spring that sits on top of the seal head that cushions the blow when the shock goes to full extension. Some shocks use a spring, other shocks use a hydraulic top out. Now...what matters here is that the top out spring counters the effect of the main spring when the shock goes to full extension, meaning the shock is not as tight at full extension as other shocks. That can me the movement coming off of full compression is soft.

You could measure for this by putting a zip tie on the shaft, with the bike on the stand, and then seeing how far you can compress the shock by pulling up on the tire with your hands.

NOW...that said, if this is not a bushing or bearing problem, what I really think it might be is free piston top out. I say this because I often open up a lot of recently serviced WP shocks where the free piston is knocking against the top of the reservoir when the shock goes to full extension. This means at full extension, the pressure in the shock is zero, giving the top out spring even more effect, (F=PA against the area of the rod).

This is because the service person did not properly set-back the free piston before filling and charging the shock, made all the more likely when service dudes use shock pumps to purge trapped air. And...free piston top out is way more noticeable on a WP shock because of their big top out springs.

Is that making any sense?

You only get this problem with free pistons, and not with bladders (but I do prefer free pistons over bladders). So does Ohlins.

Bottom line, I would not ride the bike until you fix this because if it is this, then the free piston is hammering against the shock body each time the shock goes to full extension.

aaron63 wrote:

Hi Dave,

the internal springs we are talking about are the ones inside the trax mechanism on the shock.
I wouldn't expect the top out spring to be broken internally. The shock has been ridden with this knock happening and still performs better than the oem one which came on the bike, so therefore that rules out that anything internally to do with the top out is broken.

I've spoken to the suspension tuner that last serviced the shock, and he said that it was normal for these shocks to knock like this with the trax feature when being lifted up. I've also looked at the were the movement is coming from and it is definitely from the the trax mechanism, and he has ensured me that on the last service these trax springs would of been checked and replaced if needed. Also said that it is unlikely for the newer model traxs shocks to have the broken springs because of the tighter tolerances and strong springs.

I just can't see any coil compression spring breaking in a design as such. Doesn't add up.

Coil compression springs can break, but...it's very very rare. They are simple and super tough. You can get millions of cycles out of them.


And the noise in the video is...well, unacceptable. I can't think of a noise like that ever being normal based on how I see any shock designed. Something is not right.

The bushing/bearing thing is a possibility, but I'm still hot on the likelihood of the free piston topping out. More so because of how often I see this, even after a WP shock has been serviced from a reputable tuner.

Okay...so if you want to test my theory on the free piston topping out, take the shock out, remove the main spring, and see how soft the initial compression is. It's also likely that the shock is not even fully extending during this test so test to see if you can pull the shaft out further.

If the free piston is NOT topping out then the shaft should easily and firmly glide to full extension, with a sharp stop.

You could also depressurize the shock, remove the hex screw from the top and measure the distance down where the free piston is. It should down at least 30mm.

Yes the shop is full of shit if they say that is normal for a Trax. Never felt or heard a special Trax sound on my 2018 Trax on a sxf 450. Neither on other bikes with Trax I helped set sag on

I've re contacted the shop and ive also emailed WP to see what they say with this new video.

https://www.dropbox.com/s/45xa557gbloc0f1/IMG_0600.MOV?dl=0

This video you can see the trax mechanism extending.

Call Mx Tech , they know all about WP suspension

aaron63 wrote:

I've re contacted the shop and ive also emailed WP to see what they say with this new video.

https://www.dropbox.com/s/45xa557gbloc0f1/IMG_0600.MOV?dl=0

This video you can see the trax mechanism extending.

Okay...so the noise in that video, (I assume that is yours) is ONLY because of one of two things.

1. Someone removed the top out spring from the seal head.

2. The free piston was never properly set and is topping out at full extension, (assuming you have not lost oil).

Now...the only other consideration is that the shock was shortened. Shortening a shock means putting a top out spacer inside, and these can defeat a top out spring or end or stroke hydraulic lock.

IMO, this is not WP's responsibility. They don't owe you an explanation. If you get one, great. If you don't, don't be upset.

The shock is not behaving as designed, and as I noted earlier, it's very common for shops to not properly set the free piston.

I had a trax shock that did what you described. I was certain it had broke 1 of the 5 small trax springs . Billy at PB serviced it for me & found internal threads in the trax mechanism had come loose. It made an audible click & if you grabbed the clevis it rocked a few degrees on the shaft... get it looked at . Not worth the chance of shock damage or a possible malfunction & what can result from that.

This rod is inside the trax unit that sets on the lower clevis. Those springs can break or in my case the threaded parts can unscrew.

mxracer515 wrote:

I had a trax shock that did what you described. I was certain it had broke 1 of the 5 small trax springs . Billy at PB serviced it for me & found internal threads in the trax mechanism had come loose. It made an audible click & if you grabbed the clevis it rocked a few degrees on the shaft... get it looked at . Not worth the chance of shock damage or a possible malfunction & what can result from that.

Very interesting!!

I just had a customer bring his new 450 by to set sag after a revalve and I thought of this thread. His Trax definitely did not make that noise pulling up or pushing down.

I've decided to send it in for a full service, so will let you know what the noise was when we know next week sometime!

aaron63 wrote:

I've decided to send it in for a full service, so will let you know what the noise was when we know next week sometime!

Aaron, what was the verdict?

Natester551v wrote:

Aaron, what was the verdict?

If I remember correctly, it was one or two stretched springs in the trax system, and we just replaced the top bearing on the shock anyways as a piece of mind