Dirty fork oil syndrome

[dirtbird]

The fix for the broken free piston (the plastic bit) is to drill a 5 mm hole trough it before it happens. Hardly expensive.

I've read about the fix. I also read that still free pistons were broken. As I wrote, I don't care at the time. I do have a good set of KYB sss cartridges (meaning that they 're not broken). They would look good inside a WP fork...

WP forks don't fit as they are bigger at the lower triple clamp and need machining down.

My forks are still new (around 30 hours)
.....Lower triple needs some work as WP is 60mm dia and Sachs 59mm......

So there's more.......

[dirtbird]

So.... no subtitling this time as some of you get distracted. You will again....
Hint: machinist did some comments about the lower triple..... I'll let you guess but I should remind you that I don't do any triples.....





vs

[Marty Moose]

So.... no subtitling this time as some of you get distracted. You will again....
Hint: machinist did some comments about the lower triple..... I'll let you guess but I should remind you that I don't do any triples.....





vs

Come on spill the beans on the triple ideas ....... Baited breath waiting for an answer. Hell I'm going to compare them to my yamaha ones this has come up in another thread in recent times.

MM

[BDM]

So what are you suggesting these photos show?

The area shown is where the lower fork bushing is located. No way for there to be contact wear to the aluminum slider from the steel stanchion near a bushing (unless the bushing is way out of spec).
Something else is going on other than poor anodizing, as many fork sliders are not even anodized.

I accept that perhaps the slider and/or stanchion are deflecting and coming into contact with each other between the bushings, but not within an inch of the bushing.

Bruce

[dirtbird]

Bruce

The wear area is where the upper bushing (the one that is located on the stanchion tube and moves with it) rests at full extension.
Bike and fork has around 30-35 hours and has seen more than three oil changes. Teflon coating on all four bushes looks like new but I will replace them.
On left fork wear is on the front side, on right fork on the outer side. Agree that is not due to poor anodising (which it may be).

Marty

Lower triple holes were not true vertically and this was noticed on the lathe's table as the triple's bottom was not sitting in full contact. Much like having a warped triple. Except that is almost new. Also they were not perfect cicrcle. The machinist inserted special plates in the bolts area (they have an English name which I forgot) in order to hold them at 59mm and measured with a clock. Not perfectly round.
After enlarging the bore to 60mm, when not in tension (no bolts) 'new' upper slides down itself, before I had to open them with a flat screwdriver.
Never overtorqued them and for this purpose I use a FACOM 5-25Nm tool and greased bolts.
I do have a brand new one which I am going to check as well.
It should be also mentioned that triple clamps are not CNC but cnc'd after manufacturing (probably high pressure injection molding).

Normally I should check the upper clamp as well but I think I am going to ride this weekend and do it next week.

[twowheels]

I wouldn't expect the lower (or upper) triples to be round after squeezing them with the bolts, simply because of their geometry. The goal is to create sufficient friction between the outer tube without crushing or distorting the aluminum fork leg - apparently harder to do than it seems it should be.

Maybe instead of straight bolts the triple should close like a high-end exhaust clamp ... the hard part would be keeping it from experiencing the same distortion as the stock clamps. It seems like the Xtrig ROCS clamps are the current best, but I'm still waiting on KYB Technical Touch (the US importer) to tell me when they will be available for Betas.

Barring that, maybe we need to increase upper tube thickness, but that comes at the expense of front end feel. So we'll keep searching for answers ...

[JoeMaico]

Beta USA contacted my local dealer and I will bring in my forks to them this week. Beta will cover the work under warranty (even though I am out of the warranty period). Beta believes the Chocolate Malt I experienced when I changed the fluid was due to contaminated springs, more so than anodizing wearing off. They (Beta USA will perform the work at their shop if the local dealer is not prepared for the effort) will perform a thorough cleaning and inspection. If they find no issues, they will assemble it back up with new oil and seals and return them. If, however, they do find something more problematic, then they will address it. Not sure how they will address it – but it will be addressed under warranty.

Although I am not happy that I have to be without my bike for an extended period, I am glad that Beta stands behind their product and they are willing to make it right. I will post when I know more about what they found and what the resolution was. If it just a thorough cleaning and reassemble, then I will not know if it resolved the issue until after I change the fluid again. So – it will be awhile before that happens. If it required replacement of the tubes, and possibly bushings – then I will know much sooner.

I still find it interesting that more riders have not reported issues with their forks. Again, if it is a systemic problem – I would expect the various message boards to be full of rider complaints. Because I started this thread when I noticed the issue, and a few have reported that they have seen and experienced the same – I know at least some of us are impacted. Maybe it is only a few of us who will ever see a problem. Oh well – just an observation.

joe

[mistico]

I still find it interesting that more riders have not reported issues with their forks. Again, if it is a systemic problem – I would expect the various message boards to be full of rider complaints. Because I started this thread when I noticed the issue, and a few have reported that they have seen and experienced the same – I know at least some of us are impacted. Maybe it is only a few of us who will ever see a problem. Oh well – just an observation.

joe

Thanks for the update, Joe.

I think it's a small percentage of riders that service their own suspension and they don't do it as often as we've been doing these either. Heck, I've never changed fork fluid at 10hrs before! I'm extending my next change to 15 hours to see if it worsens.

[BDM]

Joe,
Thanks for reporting back. I think it is exceptional that Beta is will to do this, most manufacturers/distributors wouldn't.

Bruce

[Marty Moose]

Good outcome. My forks are still fine at 140 ish hours. I run the lower pinch bolts a little looser and the top ones a little tighter maybe this is the key if its and issue.

MM