Suspension gurus check this out !!!

[AdamW21]

I have a 12 rmz 450 ( 48 mm Showa forks) so the brake side fork keeps leaking on the lower tube. It has had 3 sets of seals put in by a Certified mechanic that has done mine in the past with no issues it has also had new bushings put in it aswell. Used all balls wipers and seals twice and then most recently oem Honda seals and wipers ( I know it's a suzuki but my local delear does not sale suzuki, but these showas are the same ones that was on some Honda models) I have taken a cotton ball and rubbed it over the lower tube to look for sharp pieces of metal that could possibly cut the seal and have found nothing. Any of you other guys have any ideas what could be the issue ? The seal will leak just enough to attract dust if all the jumps and cleared and etc but if you case or come up short or any hard landing then the fork will leak quite bad. Even with the bike on the ground and being rocked back and forth the fork will leak. I'm stumped on what could be the problem

[Woodsweapon350]

I have a 12 rmz 450 ( 48 mm Showa forks) so the brake side fork keeps leaking on the lower tube. It has had 3 sets of seals put in by a Certified mechanic that has done mine in the past with no issues it has also had new bushings put in it aswell. Used all balls wipers and seals twice and then most recently oem Honda seals and wipers ( I know it's a suzuki but my local delear does not sale suzuki, but these showas are the same ones that was on some Honda models) I have taken a cotton ball and rubbed it over the lower tube to look for sharp pieces of metal that could possibly cut the seal and have found nothing. Any of you other guys have any ideas what could be the issue ? The seal will leak just enough to attract dust if all the jumps and cleared and etc but if you case or come up short or any hard landing then the fork will leak quite bad. Even with the bike on the ground and being rocked back and forth the fork will leak. I'm stumped on what could be the problem

First you should be using skf seals and nothing but. Besides that, take a straight edge and a flash light to see if you can find even the ding or dent in the fork tube.

[indy rider]

  It could be caused by a scratch in the lower fork tube. It will allow a little oil out every time the seal goes over the scratch.

[AdamW21]

  It could be caused by a scratch in the lower fork tube. It will allow a little oil out every time the seal goes over the scratch.

I took a bright flash light to the tube and looked at it you can see some scratches but they are so small you can't even feel then with a finger nail. Is there a do it at home way of removing these ? I wouldn't think that something that small would cause it to leak. I would think it would have to be deep enough to feel it with a finger nail

[indy rider]

3 minutes ago, AdamW21 said:

 

I took a bright flash light to the tube and looked at it you can see some scratches but they are so small you can't even feel then with a finger nail. Is there a do it at home way of removing these ? I wouldn't think that something that small would cause it to leak. I would think it would have to be deep enough to feel it with a finger nail

Man, I don't really know what to try. The one time I had the issue, the scratch was easily identified and deep enough that I just replaced the lower tube.

[AdamW21]

Man, I don't really know what to try. The one time I had the issue, the scratch was easily identified and deep enough that I just replaced the lower tube.

Got cha. Mine are not deep at all it looks more as a scuff then anything no cotton ball finger nail or anything snags on it

[rjg]

Give it the old sand paper job.......

 

How many hours do you think are on the life of the forks?

[Hans Schmid]

Positive the certified mechanic isn't putting the seals upside down? 

[AdamW21]

Positive the certified mechanic isn't putting the seals upside down? 

We have asked ourselves that several times. I believe the lip goes down ?

Give it the old sand paper job.......
 
How many hours do you think are on the life of the forks?

What grit ? And maybe 60-70 hours

[rjg]

I am a hack at suspension, I was being slightly sarcastic although it is possible to accomplish via DIY. If you try a Google search there are many guides. Research the idea a bit before trying it.

 

In regards to the hours, I was asking to find out if maybe these forks had hundreds of hours on them and maybe there was the possibility that tolerances are exceeded causing lateral motion thus the seal leaks

[EnglertRacing]

What's your fork alignment procedure consist of?

[turbo dan]

Sounds like there is excessive play between the upper and lower tubes.  If the bushings are new and the play is still there it is possible that something very bad has happened to these forks at some point and the tubes themselves are bent or deformed.

[PaydayGabe]

Sounds like there is excessive play between the upper and lower tubes.  If the bushings are new and the play is still there it is possible that something very bad has happened to these bbc.co themselves are bent or deformed.

I agree with this theory.
The fork is obviously a USD type which are harder to damage the lower tubes(bend), but I'd guess not impossible.
I would suggest you have your mechanic check the lowers for any bending. Naturally they would need to be completely disassembled and then checked on a super flat surface.
At this point you've had the forks apart a few times, and that gets $$$pricey. So if you do go for another teardown it may be cost effective to just replace those lower tubes? That's your call. Good luck, let us know what you find.
G.[emoji106][emoji41]

[turbo dan]

I would guess the uppers if anything.  In any case though, a set of used forks would probably be the easiest way to definitively solve the problem.

[EnglertRacing]

so whats the fork alignment procedure consist of?

[Marcus Robertson]

5 hours ago, EnglertRacing said:

so whats the fork alignment procedure consist of?

Making sure your lower forks in proper parallel or centered lined with uppers.. If they are not, you will get premature fork seal wear. Expect about 4 hours then leak.

Motion Pro sells a tool to check your forks with that is very useful.

Some leave axle pinch bolts loose on your adjustment side, take bike off the stand, compress forks a few times, then carefully tighten pinch bolts. Put back on stand and torque to spec. I prefer the Motion Pro tool.

[turbo dan]

The only foolproof way to get them aligned is to collapse them with everything put together and the bars off, then tighten the axle in the correct order, then run them through the stroke to check your work.  On the few bikes I've worked on I set up the floating side flush with the fork lug, tighten the pinch bolts on the floating side, tighten the axle nut to spec and then tighten the nut side pinch bolts.  I have confirmed this method by pulling the bars and fully compressing the forks with everything tightened down.  No binding and I get years out of bushings and seals with regular oil changes.

The manufacturer knows the center to center distance between the forks and makes the axle and wheel spacers to suit.  You just have to put it together right.  Once you get it worked out you don't need to recheck it again unless you take the triple clamps off or something.

[EnglertRacing]

5 hours ago, Marcus Robertson said:

Making sure your lower forks in proper parallel or centered lined with uppers.. If they are not, you will get premature fork seal wear. Expect about 4 hours then leak.

Motion Pro sells a tool to check your forks with that is very useful.

Some leave axle pinch bolts loose on your adjustment side, take bike off the stand, compress forks a few times, then carefully tighten pinch bolts. Put back on stand and torque to spec. I prefer the Motion Pro tool.

Yes I know all about it but I wanted to hear the OP's procedure.

Personally I prefer removing the fork springs to the motion pro tool.. but what a pain in the ass....

[tsouth556]

Not as common with Showa as it is with kyb but I have seen it. Check to make sure the lower tube isn't coming loose from the fork foot.

[numroe]

On 8/14/2017 at 11:38 AM, Monk said:

Positive the certified mechanic isn't putting the seals upside down? 

That's my first guess too. Big hits and the oil pisses out.

OP, look at the seals and when you consider that the internal pressure should increase the sealing pressure of the seal, it's usually easy to work out which way around the seal goes. I always remember the tension spring being on the inside.

If the seals are in the right way, then check the bushing free play with bike on a stand and front wheel off. Maybe those new bushes are junk.  Any seal can only cope with so much play. A few mm at the lower end when extended is normal.

When the lower tubes are removed, I'd check how straight they are. Easy with a quality metal ruler.  And cross hatch sand them with some 400 paper. Just to be sure.

If for tube alignment is an issue then I think you'd feel a lot of compression harshness on rough ground riding before the seal would fail.