Shaun Moulds
Active member
- Dec 29, 2024
- 70
- 102
I've been asked a few times recently about front fork servicing on the gen 2 GSD. I thought I would immortalise my process here.
Just to clarify I am only a home mechanic so take what I say with a pinch of salt.
First off the advised service interval from suntour is 50h for a lower service and 100h for a full service. This is of course impracticable in real world use especially if you do high miles like I do, personally I do the lowers every 3 months and nothing more, if you keep onto of it you won't need new seals or bushes potentially ever and a lower service only takes 30min and a little grease. If you're a lower milage rider once a year should be the minimum in my opinion.
If like most people (as did I a while back) you are looking this up because you already have a problem with your fork, you will likely need new seals and potentially bushes too. Basically I'd advise doing the full service first time round.
First things first, you can either place the bike vertical or throw something under the centre stand and weigh down the back of the bike to lift the front end up. You only need enough room to get the front wheel out comfortably.
Once the front end is lifted you will need to remove the front wheel followed by the brake caliper, don't forget to remove the little clip that holds the brake line to the fork leg.
There is no need to remove the fork from the bike, no need to take of the mudguards or cafe lock off.
Now it's time to remove the fork lowers.
Loosen the nut and Allen bolt at the very bottom of each fork, now replace the nut and bolt a few threads, as you will need to tap these with a hammer to get the lower to separate front the upper.
Below you can see the nut loose but not fully removed.
Now for the trickiest part. With one hand apply a slight tugging force on the lower fork leg while gently tapping the head of the nut (and Allen bolt on the right side) with a hammer. When you feel the nut and bolt start to move freely you can remove them fully. Now with a bit of force you should be able to remove the lower legs fully.
Be careful to note what is hanging off the bottom of each fork as there are sometimes plastic spacers that you will need to remember to put back in the same order you removed them, take pictures as this will help later down the road.
Now, if you are just doing a 50h service (there are currently no issues with your fork) clean everything up with a rag or kitchen roll, don't forget to clean all the old grease out of the lower forks. Then reapply liberal amounts of fork grease (I use SRAM butter) to the seals and bushes which are inside the fork lowers. You'll see what the bushes look like later in this report. Put it all back together in reverse order and your good for a few more months.
Now if you're having issues and need to do the full service it's time to remove the old seals with a large flat blade screwdriver. You'll also need to remove the plastic bushes from the lowers by flicking the tab up with a thin screwdriver. This should make more sense when you're holding the parts. If you can't afford bushes or they're not available then don't worry too much, just do the seals and grease.
Here's what they look like when removed.
Now time to clean up all the old grease and dirt. It's not unusual to get a lot of water in the left hand leg, in my experience this comes through the preload adjuster, I'll come back to how to stop that later.
Now fit the new plastic bushes into the fork making sure the locking tab fits into the recess correctly.
Replace the seals using the correct seal tool found here
And looks like this.
You can butcher it in using a bottle lid but I'd advise just getting the tool.
Now one last thing to do for a full service is to remove the spring, there is only one and it's located on the left side (the other side is the lock out cartridge) you need a special tool for this but it's cheap and easily available.
Here's a link
And here's what it looks like removing the preload adjuster/spring cap on the left side of the fork.
Once the preloader is out, the fork spring pulls straight up and out.
Again it's now a case of cleaning everything up, apply plenty of grease to the spring and replace. Now for me the most important thing, plack the preload adjuster/ spring cap with grease as much as you can. In my experience this stops all the pater ingress into that left leg.
Now rebuild as you removed it and your all good. If you've never set up a brake caliper before it's not too difficult and I would advise YouTube for this.
From now on if you keep on top of the lower servicing you will hopefully never need another seal or bush set.
Good luck and don't hesitate to message me here or on Facebook if you have any questions.
Oh and don't forget to put that brake pipe retaining clip back on!
Just to clarify I am only a home mechanic so take what I say with a pinch of salt.
First off the advised service interval from suntour is 50h for a lower service and 100h for a full service. This is of course impracticable in real world use especially if you do high miles like I do, personally I do the lowers every 3 months and nothing more, if you keep onto of it you won't need new seals or bushes potentially ever and a lower service only takes 30min and a little grease. If you're a lower milage rider once a year should be the minimum in my opinion.
If like most people (as did I a while back) you are looking this up because you already have a problem with your fork, you will likely need new seals and potentially bushes too. Basically I'd advise doing the full service first time round.
First things first, you can either place the bike vertical or throw something under the centre stand and weigh down the back of the bike to lift the front end up. You only need enough room to get the front wheel out comfortably.
Once the front end is lifted you will need to remove the front wheel followed by the brake caliper, don't forget to remove the little clip that holds the brake line to the fork leg.
There is no need to remove the fork from the bike, no need to take of the mudguards or cafe lock off.
Now it's time to remove the fork lowers.
Loosen the nut and Allen bolt at the very bottom of each fork, now replace the nut and bolt a few threads, as you will need to tap these with a hammer to get the lower to separate front the upper.
Below you can see the nut loose but not fully removed.
Now for the trickiest part. With one hand apply a slight tugging force on the lower fork leg while gently tapping the head of the nut (and Allen bolt on the right side) with a hammer. When you feel the nut and bolt start to move freely you can remove them fully. Now with a bit of force you should be able to remove the lower legs fully.
Be careful to note what is hanging off the bottom of each fork as there are sometimes plastic spacers that you will need to remember to put back in the same order you removed them, take pictures as this will help later down the road.
Now, if you are just doing a 50h service (there are currently no issues with your fork) clean everything up with a rag or kitchen roll, don't forget to clean all the old grease out of the lower forks. Then reapply liberal amounts of fork grease (I use SRAM butter) to the seals and bushes which are inside the fork lowers. You'll see what the bushes look like later in this report. Put it all back together in reverse order and your good for a few more months.
Now if you're having issues and need to do the full service it's time to remove the old seals with a large flat blade screwdriver. You'll also need to remove the plastic bushes from the lowers by flicking the tab up with a thin screwdriver. This should make more sense when you're holding the parts. If you can't afford bushes or they're not available then don't worry too much, just do the seals and grease.
Here's what they look like when removed.
Now time to clean up all the old grease and dirt. It's not unusual to get a lot of water in the left hand leg, in my experience this comes through the preload adjuster, I'll come back to how to stop that later.
Now fit the new plastic bushes into the fork making sure the locking tab fits into the recess correctly.
Replace the seals using the correct seal tool found here
And looks like this.
You can butcher it in using a bottle lid but I'd advise just getting the tool.
Now one last thing to do for a full service is to remove the spring, there is only one and it's located on the left side (the other side is the lock out cartridge) you need a special tool for this but it's cheap and easily available.
Here's a link
And here's what it looks like removing the preload adjuster/spring cap on the left side of the fork.
Once the preloader is out, the fork spring pulls straight up and out.
Again it's now a case of cleaning everything up, apply plenty of grease to the spring and replace. Now for me the most important thing, plack the preload adjuster/ spring cap with grease as much as you can. In my experience this stops all the pater ingress into that left leg.
Now rebuild as you removed it and your all good. If you've never set up a brake caliper before it's not too difficult and I would advise YouTube for this.
From now on if you keep on top of the lower servicing you will hopefully never need another seal or bush set.
Good luck and don't hesitate to message me here or on Facebook if you have any questions.
Oh and don't forget to put that brake pipe retaining clip back on!
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