17 300 Sachs Shock Falls Apart

[Jebster]

I’m about 1/2 way through a harescramble and notice an unusual noise coming from the bike. If my suspension performance was suffering at that time I didn’t notice it. After another 2 laps I came around a corner after one of the few fast sections the track after which I got crossrutted. All of a sudden the bike felt strange then shot off the track into a tree.

I ended up with a loose tooth somehow, a headache and a banged up arm & knee. The tooth was the worse so I’ll be alright.

But here’s what happened to the shock.



How? The shock has not been serviced other than a spring change. I’ve heard of shock seals blowing out and leaking oil and the bladders rupturing but never this.

Hopefully I can get this thing serviced in a hurry and back on the bike, another harescramble next Saturday. Suggestions?

[dirtbird]

Broken shaft at the clevis joint?

This isn't an easy nor cheap repair. Requires complete disassembly and thorough inspection before ordering parts.

While Sachs' shaft is not amongst the hardest ones, I suspect that overtorqued lower bolt may introduced some extra stress...

[Jebster]

The shaft is not broken, it became unscrewed as best I can tell. Note the threads at the end of the shaft. I will have the thing off the bike later today and will provide more pictures.

It’s weird that the shaft would spin as it’s in use and eventually come undone.

I’m also certain that it was not over torqued, I torque about everything in the bike except the plastic mounting bolts.

[hawaiidirtrider]

That’s a weird one. Ive not seen any Beta or any bike have the head come off and be unscrewed. After you wash off the much you might see what happened better. It doesn’t look broken from just that pic but Im sure you can tell better later. . Just a guess part of it is the shock bolt got loose and came off first.. then maybe the head. .. just guessing
Nope the head is still connected.. I don’t know. Thats a weird one. Never saw on any bike. Must be with each bounce the shaft somehow is easier to unscrew? .. can’t tell unless you look closely after clean.

[Jebster]

It looks like the shaft unscrewed from the shock clevis over time. Meaning a very, very poor shock assembly. Reading the Sachs manual, you're supposed to have to heat the clevis to be able to remove it. You have to wonder if it was even tightened at all.

I think the assembly from the shaft on up is fine. The shaft spins easily within the shock body which it should. Using a fair amount of force I can compress the shaft and movement feels smooth, and upon release the shaft moves back out smoothly, uniformly and completely as I believe it should. The rebound adjustment rod is still in the shock rod. It's a miracle but the shaft end thread is not damaged.

The clevis will definitely have to be replaced as the threads are damaged. The shaft only screws in about 4 revolutions before it comes to a stop, but the first half of the threads are flattened and the threads don't engage until the shaft is in about half way through the threaded portion.

The rebound regulation pin is fine. Found it in the clevis when I took it apart.

Unfortunately it's going to cost me a few dental implants as well!

Such a shame that this happened, I consider this an egregious error, a flat-out f##k up by the assembly line.

[hawaiidirtrider]

Sounds like you can run a tap and clear the threads and put the Shock together. I’d contact your dealer and see what he says. You are over warranty but let him know to get feedback to Beta and see what happens. Nothing is broken though? It just unscrewed ?? What parts would you need to get back going? You are the only person that Ive heard this happened to.I don’t know.. It looks like clear the threads and put it back together and ride.

[aj_mariner]

Damn. It’s a bummer that you have another race so soon. Knowing that, you’re probably in rush mode to get it back together. Just don’t take any shortcuts in haste. The threads on the shaft don’t look so hot, but the grime might be adding to that. If those aren’t so good and they are steel, then the clevis threads are probably toast (aluminum). do you still have the adjustment rods?

[twowheels]

Unless it happened all at this one event, it's surprising that you didn't notice it getting harder to swing a leg over the seat. Just before the shaft seperated from the clevis the seat height increase is likely in the 2 to 2-1/4" range.

Mechanical systems can fail, and apparently it did in this instance. Surprised that the threads on the shaft are in as good of shape as they are. How are the clevis threads?

[Jebster]

The clevis threads are pretty much toast, particularly near the top portion where they have been flattened a bit.

So the clevis has to be replaced as well as black fiber washer that you can see has been broken. I should be able to reuse the rebound adjuster mechanism that resides in the clevis.

You can be sure that there will be Loctite on these threads when I’m finished!

Interestingly enough, I measure sag fairly often and was perplexed recently when the sag number was off. Now I know why. And yes, come to think of it I DID notice and thought it strange that The seat seemed a little higher. I thought it was age!

[Marty Moose]

Strange issue the loctite used is good. How many hours on the bike ? The rebound damping would have been toast as it came loose did you not feel this ?
MM