Problems with front forks and finger pain (rmz-250)

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12/10/2018 7:31 AM
Edited Date/Time: 12/10/2018 9:24 AM

Hi guys,

I have a question regarding my front forks on my Suzuki RMZ-250 2013. Earlier this year I had a crash which resulted in a skewed front wheel. The front forks had gone out of alignment, so I followed the usual procedure and loosened the clamps in order to get the forks and front wheel aligned again. However, when I was about to take off the front wheel in order to change a flat (which also occured during the crash), I was unable to get the axel rod out. It was completely stuck, and I had to use considerable force before it finally came off. I noticed that the culprit of the stuck rod was one fork being slightly shorter than the other. I did some research and found out, however, that this was normal and that sometimes one fork can be shorter or longer than the other. In order to mount the front wheel again, I actually had to loosen the clamps on the shorter fork just to be able to get the axel rod back in and mount the wheel. Once the wheel was mounted, I applied pressure to the handle bars and tightened the clamps when both forks were on the same point. I figured this was normal and continued using the bike without further consideration.
After a few days on the track, I noticed that the front wheel did not spin freely any more as it did after I mounted it as well as before the crash. So I went ahead and took the wheel off again (same procedure as last time, had to loosen the clamps on one fork just to get the axel rod out), and I lubed the bearings as I thought this might be the culprit. This helped a bit, but after a few laps on the track the wheel once again stopped spinning freely. Additionally, I noticed some harsh pain in my fingers after riding a few times. I had never experienced this pain before. I googled it and found out that this might be related to my front forks not being adjusted correctly. This leads me to believe that I have an issue with my front forks/front wheel or something along those lines.

So my question is, do you think there is a problem with my front forks? Is it normal than one fork is longer than the other? I find it kinda weird that I have to loosen my clamps every time I want to take my wheel off just to get the axel rod out, considering that this has never been the case with my previous bikes. Also, do you think the finger pain I’m experiencing is related to all this?

I’m thinking about removing the forks and handing them into a shop so they can take a look at them. What do you guys think?

Thanks in advance

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12/10/2018 8:03 AM

Having 1 fork longer sounds goofy to me. Are they in the top clamp at the same height? Are you torquing your axle nut or giving it a good pull with a cheater bar? Overtightening it can cause issues.

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12/10/2018 8:13 AM
Edited Date/Time: 12/10/2018 8:14 AM

kb228 wrote:

Having 1 fork longer sounds goofy to me. Are they in the top clamp at the same height? Are you torquing your axle nut or giving it a good pull with a cheater bar? Overtightening it can cause issues.

Yes they are at the same height in the top clamp. After loosening the clamp on the longer fork, I mount the wheel and then apply pressure to the handle bars to get the longer fork at the exact same point as the other one before tightened it. I always use a torque wrench and torque in accordance to specs from manual.

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12/10/2018 9:01 AM

I havent heard of setting fork height the way you described. The way i do it is measure the distance between the fork cap and the top clamp with the depth gauge on my calipers and then tighten the forks. Maybe the way youre doing it is causing an issue? Not sure just worth checking

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12/10/2018 9:22 AM

kb228 wrote:

I havent heard of setting fork height the way you described. The way i do it is measure the distance between the fork cap and the top clamp with the depth gauge on my calipers and then tighten the forks. Maybe the way youre doing it is causing an issue? Not sure just worth checking

Yes, I know, that is the correct way of doing it. I also do it like that usually. The problem here is that I am not able to mount my front wheel with both forks tightened at the same height, simply because one fork is slightly shorther than the other. My axel rod will not be able to go through both forks since they are not aligned (because one is shorther than the other). Therefore, in order to be able to mount my wheel in the first place, I need to loosen the clamps on the shorther fork to make it fall down in line with the other, then mount the wheel, and then tighten the fork clamps so that it is at the same height as the other fork. Because one fork will be at a lower point when the wheel is mounted (the fork I loosened), I have to apply pressure to the handle bars after mounting the wheel to get the shorter fork at the same point as the other, and then tight it. I realize that this method is far from optimal, but it's really the only way I'am able to mount my front wheel and tighten the the forks at the same height.

It also seems goofy to me that one fork is longer than the other. I have not had to do things this way on any of my previous bikes, because the forks have been equally long. Because of this, I suspect that the problem of the wheel not spinning freely as well as the pain I'm experiencing in my fingers is related to this. So I'm thinking about handing the forks into a shop so that they can take a look at them.

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12/10/2018 11:19 AM

Id let a shop look at them. I have a feeling something is broken in your shorter fork. Since youre compressing the one fork to match the other, youre riding in the harsh part of the stroke. I could see that causing issues in your hands.

Maybe slipdog or pawpaw might reply with a good answer. Hard to tell without taking them apart.

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12/10/2018 2:39 PM

Make sure you have let the air pressure out of the short fork. Negative pressure can certainly cause a fork to compress slightly.

Your forks are engineered to pretty tight tolerances and they should absolutely be the same length. How different in length are you measuring?

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Braaapin' aint easy.

12/10/2018 6:37 PM

Being that they are not air forks I'd have to lean towards something is coming apart inside one of the forks allowing it to extend further than normal. It's somewhat common, for example, for the KYB cartridges on the Yamaha to come apart from lack of loctite being used at the factory. When one cartridge unscrews the fork leg will drop an inch or two further than the other when you remove the front wheel.

Without having them to take apart I'll guess you could maybe have the rod coming loose from the rebound/base bolt. As stated, it's not right for them to be different lengths so it would be best to have them looked at by a professional or you could be looking at major damage to your forks or worse yourself if they shit the bed while you are riding.

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12/10/2018 7:08 PM

slipdog wrote:

Being that they are not air forks I'd have to lean towards something is coming apart inside one of the forks allowing it to extend further than normal. It's somewhat common, for example, for the KYB cartridges on the Yamaha to come apart from lack of loctite being used at the factory. When one cartridge unscrews the fork leg will drop an inch or two further than the other when you remove the front wheel.

Without having them to take apart I'll guess you could maybe have the rod coming loose from the rebound/base bolt. As stated, it's not right for them to be different lengths so it would be best to have them looked at by a professional or you could be looking at major damage to your forks or worse yourself if they shit the bed while you are riding.

I understand.

Will hand them in to my local shop as soon I get the chance. Thanks for the help guys.

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1/8/2019 1:29 AM

Hi again,

So I just received a call from the shop after handing them in a week ago, and apparently the forks seemed fine in all aspects. I was told that the reason one was longer than the other was due to a really stiff spring, and they therefore suggested to either replace it with a shorter spring or just leave it be. Any suggestions?

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1/8/2019 6:41 AM

so there is a different spring in one fork?
i would just buy a new set of springs for your weight.

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1/8/2019 9:23 AM
Edited Date/Time: 1/8/2019 9:26 AM

Antoni-Berg wrote:

Hi again,

So I just received a call from the shop after handing them in a week ago, and apparently the forks seemed fine in all aspects. I was told that the reason one was longer than the other was due to a really stiff spring, and they therefore suggested to either replace it with a shorter spring or just leave it be. Any suggestions?

yeah, both springs need to be the same. so if the shop is correct about the springs, then they are not a matched set and at least one of them has been changed.

if you did not have trouble removing the front wheel before the crash, check your axle to see if it is bent. if you always had trouble removing it and it is not bent, the problem may be from the tubes not being the same length.

fit the axle to the forks without the front wheel then fit it to the wheel by itself to see if it binds.

.

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1/8/2019 9:26 AM

brody wrote:

so there is a different spring in one fork?
i would just buy a new set of springs for your weight.

There is only spring on one side on those forks.

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1/8/2019 11:54 AM

brody wrote:

so there is a different spring in one fork?
i would just buy a new set of springs for your weight.

Antoni-Berg wrote:

There is only spring on one side on those forks.

Correct, they are Showa SFF's. Spring in only the right side sitting on the bike.

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2018 KX450F
2005 KX250
2003 KDX 220
1984 KX 80
1982 RM 80
1980 RM 80
1977 XR 75
1969 Honda Mini 50

1/9/2019 10:23 AM

Antoni-Berg wrote:

Hi again,

So I just received a call from the shop after handing them in a week ago, and apparently the forks seemed fine in all aspects. I was told that the reason one was longer than the other was due to a really stiff spring, and they therefore suggested to either replace it with a shorter spring or just leave it be. Any suggestions?

First of all, the fork assemblies should be the same length. The only time I see them being different, and acceptable, are the SFF-Air forks, where one fork is charged and the other is not, making the air side longer, (crappy design).

For your forks they should be the same.

Now...if someone put a stiffer or longer spring in one leg and not the other, then one fork would be longer due to the added force applied to the top out spring.

This is...sort of okay. It sort of depends. There is nothing wrong with running different lengths and different rates as long as it's done correctly. But having two leg assemblies that are a different length is a pain in the butt when it come to taking the wheel off and one. The axle will bind and that may make it harder to get a proper parallel alignment.

And a fork spring with excessive pre-load (usually more than 5mm) might make the front a little stiff when there is less of a load on it (going up hills, etc).

Try to get some more details from the shop. They should also check the spring rate as well.

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1/11/2019 5:20 AM

I just spoke to the mechanic and im really confused now. As I mentioned, the spring is way too stiff (only spring on one side). And that is causing one foot to be longer than the other one. He believes that the previous owner may have modified the forks and intentionally put in a stiffer spring, but he is not sure. He told me that there is a shell/sleeve at the bottom of the spring foot that puts a 5-6 cm gap between the bottom of the foot and the spring, making the spring even more compressed. He told me that in most other forks the spring goes all the way to the bottom of the fork and he wasn’t sure whether this was a modification or just standard in the showa forks. Does anyone know the build of these forks? Is my mechanic incompetent? Need to know how to proceed from here. Thanks.

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1/11/2019 12:09 PM
Edited Date/Time: 1/11/2019 1:01 PM

First off, having a heavy spring in the right fork doesn't make it longer then the left fork. My guess is they are the same length you just haven't laid them down beside each other and measured them against each other (oh, and you need to ensure the left leg is fully extended, do this by pulling the upper and lower with your hands to ensure it is fully extended as this is only a damping fork and doesn't have a spring pushing to extend it). You haven't stated in any of your posts what the forks measure and how much of a difference exists.

If indeed they happen to be different lengths then I go with what slipdog said, a rebound bolt (left fork) or base bolt (right fork) has come loose, allowing one to extend further and could be dangerous if ridden in that configuration. You could verify this by seeing if either of them spin freely.

As for the right fork and the stiff spring, no there isn't a sleeve at the base of the spring, only sleeve is the plastic one at the top that has to two holes that allow you to compress the spring with a fork tool and an aluminum one on top of the plastic.

You should probably watch the below videos just so you have a better understanding of what is inside your forks so you don't sound incompetent when talking to your mechanic.




Both videos are from RMATVMC and will show you what is inside each fork.
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2018 KX450F
2005 KX250
2003 KDX 220
1984 KX 80
1982 RM 80
1980 RM 80
1977 XR 75
1969 Honda Mini 50

1/11/2019 2:34 PM
Edited Date/Time: 1/11/2019 2:41 PM

dkurtd wrote:

First off, having a heavy spring in the right fork doesn't make it longer then the left fork. My guess is they are the same length you just haven't laid them down beside each other and measured them against each other (oh, and you need to ensure the left leg is fully extended, do this by pulling the upper and lower with your hands to ensure it is fully extended as this is only a damping fork and doesn't have a spring pushing to extend it). You haven't stated in any of your posts what the forks measure and how much of a difference exists.

If indeed they happen to be different lengths then I go with what slipdog said, a rebound bolt (left fork) or base bolt (right fork) has come loose, allowing one to extend further and could be dangerous if ridden in that configuration. You could verify this by seeing if either of them spin freely.

As for the right fork and the stiff spring, no there isn't a sleeve at the base of the spring, only sleeve is the plastic one at the top that has to two holes that allow you to compress the spring with a fork tool and an aluminum one on top of the plastic.

You should probably watch the below videos just so you have a better understanding of what is inside your forks so you don't sound incompetent when talking to your mechanic.




Both videos are from RMATVMC and will show you what is inside each fork.

Actually, it does.

A longer (more pre-load) or higher rate spring in one fork, if the difference is great enough, puts added force against the top out spring, which would make that fork longer than the other one.

I don't mean to imply that the different lengths could only happen from different springs. There are many things that could cause this. But it does sound like the guy working on the suspension found different springs.

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1/11/2019 2:40 PM

Antoni-Berg wrote:

I just spoke to the mechanic and im really confused now. As I mentioned, the spring is way too stiff (only spring on one side). And that is causing one foot to be longer than the other one. He believes that the previous owner may have modified the forks and intentionally put in a stiffer spring, but he is not sure. He told me that there is a shell/sleeve at the bottom of the spring foot that puts a 5-6 cm gap between the bottom of the foot and the spring, making the spring even more compressed. He told me that in most other forks the spring goes all the way to the bottom of the fork and he wasn’t sure whether this was a modification or just standard in the showa forks. Does anyone know the build of these forks? Is my mechanic incompetent? Need to know how to proceed from here. Thanks.

I'm a little concerned that he seems to be giving you information with some level of uncertainly verses giving you facts.

He should know the spring rate, the spring length and any added parts.

This is a very traditional SHOWA close cartridge fork. It has a spring bearing at the bottom, but none of that can really be seen or removed. If there are any added spacers or devices in there, then it's not stock.

I'm under the impression that this is just a mechanic that sometimes works on suspensions, but not a dedicated suspension guy.



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1/11/2019 2:44 PM
Edited Date/Time: 1/11/2019 4:06 PM

dkurtd wrote:

First off, having a heavy spring in the right fork doesn't make it longer then the left fork. My guess is they are the same length you just haven't laid them down beside each other and measured them against each other (oh, and you need to ensure the left leg is fully extended, do this by pulling the upper and lower with your hands to ensure it is fully extended as this is only a damping fork and doesn't have a spring pushing to extend it). You haven't stated in any of your posts what the forks measure and how much of a difference exists.

If indeed they happen to be different lengths then I go with what slipdog said, a rebound bolt (left fork) or base bolt (right fork) has come loose, allowing one to extend further and could be dangerous if ridden in that configuration. You could verify this by seeing if either of them spin freely.

As for the right fork and the stiff spring, no there isn't a sleeve at the base of the spring, only sleeve is the plastic one at the top that has to two holes that allow you to compress the spring with a fork tool and an aluminum one on top of the plastic.

You should probably watch the below videos just so you have a better understanding of what is inside your forks so you don't sound incompetent when talking to your mechanic.




Both videos are from RMATVMC and will show you what is inside each fork.

DaveJ wrote:

Actually, it does.

A longer (more pre-load) or higher rate spring in one fork, if the difference is great enough, puts added force against the top out spring, which would make that fork longer than the other one.

I don't mean to imply that the different lengths could only happen from different springs. There are many things that could cause this. But it does sound like the guy working on the suspension found different springs.

You do realize we are talking about SFF's. And I didn't read anywhere this guy wrote that the guy working on them found different springs.

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2018 KX450F
2005 KX250
2003 KDX 220
1984 KX 80
1982 RM 80
1980 RM 80
1977 XR 75
1969 Honda Mini 50

1/11/2019 4:30 PM

dkurtd wrote:

First off, having a heavy spring in the right fork doesn't make it longer then the left fork. My guess is they are the same length you just haven't laid them down beside each other and measured them against each other (oh, and you need to ensure the left leg is fully extended, do this by pulling the upper and lower with your hands to ensure it is fully extended as this is only a damping fork and doesn't have a spring pushing to extend it). You haven't stated in any of your posts what the forks measure and how much of a difference exists.

If indeed they happen to be different lengths then I go with what slipdog said, a rebound bolt (left fork) or base bolt (right fork) has come loose, allowing one to extend further and could be dangerous if ridden in that configuration. You could verify this by seeing if either of them spin freely.

As for the right fork and the stiff spring, no there isn't a sleeve at the base of the spring, only sleeve is the plastic one at the top that has to two holes that allow you to compress the spring with a fork tool and an aluminum one on top of the plastic.

You should probably watch the below videos just so you have a better understanding of what is inside your forks so you don't sound incompetent when talking to your mechanic.




Both videos are from RMATVMC and will show you what is inside each fork.

DaveJ wrote:

Actually, it does.

A longer (more pre-load) or higher rate spring in one fork, if the difference is great enough, puts added force against the top out spring, which would make that fork longer than the other one.

I don't mean to imply that the different lengths could only happen from different springs. There are many things that could cause this. But it does sound like the guy working on the suspension found different springs.

dkurtd wrote:

You do realize we are talking about SFF's. And I didn't read anywhere this guy wrote that the guy working on them found different springs.

On a 13 250?

I'm almost positive it's a parallel design.

I deserve a whipping if I'm wrong.

And I thought I read that the guy working on them reported that each fork leg had a different spring. Could not tell if that was a length or rate issue.

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1/11/2019 4:34 PM

DaveJ wrote:

Actually, it does.

A longer (more pre-load) or higher rate spring in one fork, if the difference is great enough, puts added force against the top out spring, which would make that fork longer than the other one.

I don't mean to imply that the different lengths could only happen from different springs. There are many things that could cause this. But it does sound like the guy working on the suspension found different springs.

dkurtd wrote:

You do realize we are talking about SFF's. And I didn't read anywhere this guy wrote that the guy working on them found different springs.

DaveJ wrote:

On a 13 250?

I'm almost positive it's a parallel design.

I deserve a whipping if I'm wrong.

And I thought I read that the guy working on them reported that each fork leg had a different spring. Could not tell if that was a length or rate issue.

You're wrong, you deserve a whipping. Reading comprehension bro, never said different spring.

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2018 KX450F
2005 KX250
2003 KDX 220
1984 KX 80
1982 RM 80
1980 RM 80
1977 XR 75
1969 Honda Mini 50

1/11/2019 5:30 PM

dkurtd wrote:

You do realize we are talking about SFF's. And I didn't read anywhere this guy wrote that the guy working on them found different springs.

DaveJ wrote:

On a 13 250?

I'm almost positive it's a parallel design.

I deserve a whipping if I'm wrong.

And I thought I read that the guy working on them reported that each fork leg had a different spring. Could not tell if that was a length or rate issue.

dkurtd wrote:

You're wrong, you deserve a whipping. Reading comprehension bro, never said different spring.

The fiche shows the 13 250 with a parallel design and the 13 450 with a SFF.

Then both with the SFF in 14.

Fiche is wrong, and therefore, so am I.

So with the mention of a spring not being right and forks at two different lengths, I jumped to a conclusion that the springs were not the same.

Now...that said, on with life and the SFF.

There are two SFF springs. One is about 660mm in length and the other is about 739mm.

The RMZ SFF should be the 660mm, so...I wonder if someone, somehow, stuffed a 739mm spring into this fork.

If they did stuff a 739mm spring in there, it could change the length because that would most likely compress the top out spring.

Thanks for the correction, by the way.

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1/11/2019 5:38 PM
Edited Date/Time: 1/11/2019 5:43 PM

There is no top out spring in the right fork leg. Only a single spring that is preloaded by design, the reason you need a fork compression tool to change springs. Then another preload adjuster on top of the cap.

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2018 KX450F
2005 KX250
2003 KDX 220
1984 KX 80
1982 RM 80
1980 RM 80
1977 XR 75
1969 Honda Mini 50

1/11/2019 5:46 PM

dkurtd wrote:

There is no top out spring in the right fork leg. Only a single spring that is preloaded by design, the reason you need a fork compression tool to change springs. Then another preload adjuster on top of the cap.

There would absolutely have to be a top out spring. Fork would be crazy noisy going to full extension without one.

Let me see what I can find.

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1/11/2019 5:48 PM

dkurtd wrote:

There is no top out spring in the right fork leg. Only a single spring that is preloaded by design, the reason you need a fork compression tool to change springs. Then another preload adjuster on top of the cap.

DaveJ wrote:

There would absolutely have to be a top out spring. Fork would be crazy noisy going to full extension without one.

Let me see what I can find.

Nope, only one spring in the right fork. Watch the video I posted a link to.

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2018 KX450F
2005 KX250
2003 KDX 220
1984 KX 80
1982 RM 80
1980 RM 80
1977 XR 75
1969 Honda Mini 50

1/11/2019 5:59 PM
Edited Date/Time: 1/11/2019 6:04 PM

dkurtd wrote:

There is no top out spring in the right fork leg. Only a single spring that is preloaded by design, the reason you need a fork compression tool to change springs. Then another preload adjuster on top of the cap.

Okay...don't have one of the forks on hand but I found a cutaway type drawing from SHOWA.

This shows a top out spring in the left and right fork.

Keep in mind that these top out springs are small and seldom, if ever, come out during regular service and tuning. You usually have to remove a seal head assembly to see or get to them. Your videos would not show these.

By the way, thanks for your feedback and for correcting me on which forks these were.

Photo



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1/11/2019 6:00 PM
Edited Date/Time: 1/11/2019 6:02 PM

dkurtd wrote:

There is no top out spring in the right fork leg. Only a single spring that is preloaded by design, the reason you need a fork compression tool to change springs. Then another preload adjuster on top of the cap.

DaveJ wrote:

There would absolutely have to be a top out spring. Fork would be crazy noisy going to full extension without one.

Let me see what I can find.

dkurtd wrote:

Nope, only one spring in the right fork. Watch the video I posted a link to.

There would be four springs total in the design. Main spring, IC spring, left top out, right top out.

Actually, there would be six springs, four metal compression springs and two air springs.

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1/11/2019 6:15 PM

Antoni-Berg wrote:

I just spoke to the mechanic and im really confused now. As I mentioned, the spring is way too stiff (only spring on one side). And that is causing one foot to be longer than the other one. He believes that the previous owner may have modified the forks and intentionally put in a stiffer spring, but he is not sure. He told me that there is a shell/sleeve at the bottom of the spring foot that puts a 5-6 cm gap between the bottom of the foot and the spring, making the spring even more compressed. He told me that in most other forks the spring goes all the way to the bottom of the fork and he wasn’t sure whether this was a modification or just standard in the showa forks. Does anyone know the build of these forks? Is my mechanic incompetent? Need to know how to proceed from here. Thanks.

So...back to this.

Now that dkurtd has corrected me on what forks you have, we should get back to what might be the problem.

As noted earlier, the SFF metal spring forks used two different springs....one length in the earlier designs (KX250F) and then a different length in the later design. 660mm vs. 739mm.

The "spring cavity" on your SHOWA SFF would be suited to the 660mm. So...it might be worth it to have your mechanic measure the length of the spring that he/she took out.

A spring that is too long could be the problem.

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1/12/2019 4:29 AM

Antoni-Berg wrote:

I just spoke to the mechanic and im really confused now. As I mentioned, the spring is way too stiff (only spring on one side). And that is causing one foot to be longer than the other one. He believes that the previous owner may have modified the forks and intentionally put in a stiffer spring, but he is not sure. He told me that there is a shell/sleeve at the bottom of the spring foot that puts a 5-6 cm gap between the bottom of the foot and the spring, making the spring even more compressed. He told me that in most other forks the spring goes all the way to the bottom of the fork and he wasn’t sure whether this was a modification or just standard in the showa forks. Does anyone know the build of these forks? Is my mechanic incompetent? Need to know how to proceed from here. Thanks.

DaveJ wrote:

So...back to this.

Now that dkurtd has corrected me on what forks you have, we should get back to what might be the problem.

As noted earlier, the SFF metal spring forks used two different springs....one length in the earlier designs (KX250F) and then a different length in the later design. 660mm vs. 739mm.

The "spring cavity" on your SHOWA SFF would be suited to the 660mm. So...it might be worth it to have your mechanic measure the length of the spring that he/she took out.

A spring that is too long could be the problem.

Ok, thanks. Will ask him to measure the length of the spring. I am also concerned with the fact that he’s giving me information with uncertainly and not facts. And you are probably right, this is just a mechanic that sometimes works on suspensions and not a dedicated suspension guy. Unfortunately there are not any dedicated suspension guys around here.

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