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Discussion Starter · #1 ·
Hi, last year i buy a brand new ohlins shocks for my 02' m900.
Orered in april it arrived in july and start leaking oil in december:
985982


I got it rebuilded with new bushing and seals and also softer shimming by an andreani/ohlins autorized shop.

Now, after only 500km, i can see oil on the shaft:
985983


In the last pic i cleaned the shaft and only done 3 or 4 km..:mad:

Any advice? Don't know what to do...
 

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Yes thats not normal return to whoever rebuilt it last time is sensitive so do not wait too long. Also if you have a damaged shaft it will tear seals. 1 rock thrown from the rear wheel can damage a shaft in a second. That's no ones fault and would not be warranty. IF that is the case be sure to run a rear hugger to protect that shock.
 

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Discussion Starter · #4 ·
Thanks belter & ducvet.
The first hugger was modified by p.o.
986009

After shock rebuild i put an oem hugger
986010

It is good enough?
I haven't found any stone chips.

The end joints were quite sticky:
986011

They require more than shock weight to turn. It's common?

At the shop the tell me that is common and also that the shaft was good (they polished it), but anyway they haven't found the cause of the leak..
 

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I have plenty of ohlins shocks myself, tons of customers with them. Chronic leaking like you are seeing is not common.

Penske shocks will tell you in the owners manual that the shock will "weep" and a thin film of fluid on the shaft is both expected and normal. Well they also want shims changed yearly or something silly. I run both on street and track and in hot and cold weather and I so far have never had a shock seal leak on my ohlins shocks.

I would consider sending the shock to Ohlins service center and make sure they are aware of the issue you are having so they take a long careful look. The fenders you are running so no issues there . I assume the bike is sprung properly and you are not 400lbs and like to do double jumps with the bike. .

I would be disappointed if that was mine so I understand the frustration. It might also be worth asking the question of Ohlins in Sweden as I would expect that does not seem right to them either.
 

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Discussion Starter · #6 ·
Yes, I'm quite disappointed.
I weight 60kg, with 90N/mm spring i have more than 10mm of unused shaft travel before touching the bump stop, so no abuse of the shock.
Tomorrow i will take some more pics and contact the shop that rebild it.
If they say they want more money to repair it i will try contacting the dealer or the italian distributor (Andreani) or Ohlins sweden...
 

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Discussion Starter · #7 · (Edited)
Update: the service center that rebiult it says that this shocks (with no external reservoir) cavitate a lot and under cavitation the seal get misaligned and start leaking.
They says that it is a cheap shock with cheap seal and can't work any better.
The only solution is to rework the sealing head to use some good showa or kayaba seal.

:mad:

Now I'm waiting for seller response...
 

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Discussion Starter · #8 ·
Update: i've sent the shock to the seller and he send it to Andreani, the italian ohlins distributor.
They bench tested it and said that it is good and did not leak.
They also said that it's not their problem, not anymore, because i serviced it by another company.
( the "other company" is the approved local andreani/ohlins service center)

Here is the last time I use it, after cleaning the shaft and doing 10km:
995303


Any idea?
 

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Yes something is not right I would be inclined to reach out to Ohlins directly and give them this whole story. This does not sound right at all and the story about the non-reservoir shocks sounds totally crazy. I have sold a number of them with no issues and have 2 more due in for customers. I would not sell anything that leaked that bad regardless of who made it, thats poor service. I wonder if there is some friction between Adriani and their re-seller. It happens I knew of a few Ducati dealerships that Ducati would not allow to do engine rebuilds under warranty because Ducati had no faith in their mechanics.

I would bet that seal head(and seals) are the exact same parts as on their other shocks. Ohlins is not one to have different seals unless you received one from the race department with no stiction because it does not seal. I am kidding but who knows , a street seal should not weep and if yours does and is within warranty I would hope Ohlins can make this right.
Which model is this ? It should be stamped at the top DU**** what numbers do you see?
 

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Discussion Starter · #11 · (Edited)
It's a DU321
995308


Edit: i can't find any ohlins direct contact email address.. the site always redirect me on local distributor..
 

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Yeah that's what I thought. Your sealhead (seal) is the same one used on monsters,supersports,749/999 and desmocedici...etc so the idea your shock is a low spec part shock is foolish.

your shock also has a internal gas piston separating gas from oil. If the ohlins dealer tells you otherwise something is not right.

"The STX46 Street Performance Line is based on our popular STX46 DR1 shock absorber and developed for naked sports bikes and street performance bikes. It features a large 46mm main piston and an internal gas reservoir within the main body of the shock. "

To be fair and to cover all bases I would clean the shaft dry and put say 100km on the shock wiping it down each time to verify you are not just seeing the oil remains from a rebuild. It is hard to get the seal area clean and dry after refreshing one so it takes time and persistence on the part of the person doing it to get it dry before handing the shock back to the customer. If you clean it does it come back worse?
The same?
or less?
 

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Discussion Starter · #13 ·
Yes, persistence.
After the repair I've checked the shaft about after each ride, from march to september, and wiped it about 1 time each week.

Initially the things seems to improve but in agoust/sept it start to became worst, and also it start to make some different noise.
I had also to close the extension a few clicks to keep the rear stable (from std 14clicks).
995319


The noise:


Don't know if is common....
 

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Hello,
as I have no direct experience with this shock, I did not feel I could contribute anything that has not already been said, it seems to be a very strange problem. However, there are a few things that sort of stand out to me, after all.

As stated above, the seal head components are exactly the same as on the "ordinary" Öhlins shocks (i.e., with external reservoir & compression / rebound adjusters). i.e., no budget parts, and on the market in the millions, probably. That should be OK.

On my track bike, I had the bottom of the swing arm (or wherever, can´t remeber exactly) get oily a few years back. I was worried it might be the output shaft seal on my newly assembled motor, but after keeping track of that for a while it turned out to be the shock shaft seal , the shaft looked pretty much like in some of these pictures.

I then serviced the shock, and went to the next track day a few days later. When I arrived and went about to take the bike out from the trailer, there was a pool of oil under the bike. During the trip in the trailer the shock had started to leak oil, without any other movement than what happens strapped down in the trailer. I did a sloppy job on replacing the seal, and I´m happy I got that reminder on my own bike.
The bottom line of this is that I find it very hard to believe that the seal could be leaking oil onto the shaft without oil being pushed out due to the gas pressure inside the shock, proveded there is a gas pressure inside, of course.
It´s easy to check an Ohlins for gas pressure; if you have clicks on the rebound knob, you have gas pressure.

If you have the shock off the bike, and the spring off, you could knock the end cap off the body and have a look at the top of the seal head to see if there´s any oil / grease in there, that could give you a clue. Presumably, if the shock seal is leaking, there should be a good deal of oil in there.

Some suspension greases are pretty oily / thin and can look like oil on a freshly rebuilt unit. There is some space between the scraper (#24 above) and the top of the seal head, and maybe if that´s packed full with grease it might leave oily traces.

Well, no solution, just my thoughts after all the infos posted so far.

Kind regards,
Torbjörn.
 

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Discussion Starter · #15 · (Edited)
Hi,
Some non expert ramblings:
With 20bar and 16mm shaft the force to start moving it (no spring) is 40kg, plus the seal sticktion (5/10kg on mine)
I've tested it on a weight scale and it's about correct..

Anyway i think that before to loose a measurable amount of gas pressure a lot of oil has to leak.
And possibly the separator has to sit on its end of stroke ring in the main body (there is one?) or start hitting the piston near the end of the stroke.

I only partially agree with the budget shocks theory.
There is no "base valve", so no pressure buildup in the compression chamber during compression stroke.
The pressure is kept rather constant at 20 bar by the (internal) separator and nitrogen chamber

With 46mm piston and 16mm shaft the force corresponding to a pressure drop of 21bar across the piston is 300kg.
(20+1)(4,6×4,6-1,6×1,6)×3,14/4 = 300kg

In this condition the pressure on rebound chamber is zero. No more force is possible and cavitation bubble start to appear.

300kg on the shocks is something like 130kg on wheel. I think it can happen on harsh bumps. (More than 1 m/s ?, it depend on required compression damping/installed shim stacks.)

The part the tech says, and on that i have some dubt is the following:

When the pressure on rebound chamber goes below the ambient pressure the seal xring get misaligned and some air bubble enter in the shocks and some oil exit.
At least until the pressure recover to bigger than ambient and the xring can seat on its white backup ring.
This cause noise, spongy damping and oil seepage.
After some time in this condition the xring get damaged or permanently misaligned and a big oil leak occurs.

It's hard to believe that ohlins has failed the xring groove design. They also sell a zillion of this single clickers...
It is possible that are all leaking around?

Back to my expensive yellow doorstop:

Sure I will check the space under the cap.

Yesterday I found an ohlins email contact in the .eu website and sent an email.
It's something like a new product info contact, I start to dubt that someone will ever reply...

Catch-22 Reminder:

Ohlins extend the shocks warranty up to 5 years if you do the maintenance on approved service center.

Italian ohlins approoved service center are Andreani.

If you do the maintenance on Andreani approoved service center you loose the warranty from Andreani and Ohlins.
 

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Discussion Starter · #16 ·
Update: finally the shock came back with a dyno sheet that says that it's ok.
A part from this little error:
996124

I inspected under the cap and it is rather clean:
996125

996126


I've only find about 0.5mm out of center of shaft in the cap.
Tight side:
996127

Loose side
996128


In the meantime ohlins.eu replied to send it in germany for an inspection
 

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Discussion Starter · #17 ·
Update: the shock arrived from ohlins.
They initially replaced the seal head, than dynoed it but still leak.
Then they replaced the shaft and sent it back to me.
We are still in lockdown with a lot of ice in the morning so I've tryed it only for a couple of km, in the afternoon, at about 4°C
1000599

Can be assembly grease? How long can it take to seep out all the assemby grease?
 

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Discussion Starter · #18 ·
Ok, this is not assembly grease, it is oil.
1001015

1001016

1001017

1001018

Il is less viscous than oil.
In about 5km it leaked down to the bump stopper.
After driyng the shaft it leak an appreciable amount of oil on each single stroke.
 

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Just a fyi on testing suspension in cold temperatures.

I do not know what temperature range the ohlins seals are designed to run in, this may be some of your issue in cold as low as 4c. I see plenty of forks leak when the temperature is that cold as the seals stiffen in the cold and the steel shrinks. A seal not designed for that cold may lose its ability to hold back oil that is now thick due to the cold as well. it is common for showa and ohlins fork seals to do this .

If they changed both seal head and shaft there are no other parts to change or cause your issue . I would clean it up well and when you get to normal riding temperatures see if it leaks then. If it does or you find that your goal is to ride in cold weather I would suggest at this point to try another brand and move this one along as a fresh rebuild. do NOT consider Penske as they mention this in their literature that a slight oil film is NORMAL. you might look at Wilburs or over in your area bitubo .

Whichever you buy make sure they are rated for cold weather so the seals will work in those temperatures. I do not know if that is your problem but given the work done on your shock and the parts changed I do not see it as a good option for you as it would be hard to have confidence in something giving you this much grief. I see nothing Ohlins could do different as they have changed anything that would cause the issue. Could be your application does not line up with their product.

The shock cap is not really a precision part so having a gap be different will make no difference to function or reliability as long as you have clearance you are good to go. If the shaft is orbiting or loose in the cap that would be another story.
 
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