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mbw479

Aer 48 holding down

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Just noticed my husky sitting low in the front, it is sitting 100mm too low. When I remove the bleeders I can pull it back up, but it drops straight down again. I have seen this is a common issue, does anyone know the fix?

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Yes ,there are some fixes ,it involves pumping them up to a high pressure and pulling them up

Try 175psi

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Yes ,there are some fixes ,it involves pumping them up to a high pressure and pulling them up

Try 175psi

Tried that one at 180psi, I have since read up too 250psi....seems risky. Going to disassemble then reassemble and see if I can find a problem. If not clean and reassemble and see what happens 🤷‍♂️

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you need to remove the base bolt adapter on the bottom of the cartridge in order to purge the negative chamber - which means a fair bit of dissassembly.  

You likely need a new (or updated) piston seal in the cartridge anyway - which is why it was stuck down in the first place.

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I have the same issue on my 2017 TC 125, AER 48 forks are new to me, is the negative chamber on both sides or just left side ?

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you need to remove the base bolt adapter on the bottom of the cartridge in order to purge the negative chamber - which means a fair bit of dissassembly.  
You likely need a new (or updated) piston seal in the cartridge anyway - which is why it was stuck down in the first place.

Yeah you’re onto it, I got it sorted. Not a cheap part. IMG_0967.JPG

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Why is it like that ?

To unscrew the nut above the plastic you have to melt the excessive amount of locktite used on the tread, repair was completed by ktm dealer. Apparently this is normal.

Replacing the fork seals on these is simple, but opening that inner chamber is not.

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14 hours ago, mbw479 said:


To unscrew the nut above the plastic you have to melt the excessive amount of locktite used on the tread, repair was completed by ktm dealer. Apparently this is normal.

Replacing the fork seals on these is simple, but opening that inner chamber is not.

Nonsense, you just have a ham fisted mechanic who used WAAAAAY too much heat.  Done properly you will neither melt the seals, nor the plastic top out spring guide.  There are a few other parts to update in the old style cartridge (the melted part is one of them) but you should be looking at ~$100, NOT the whole cartridge rod assembly.  

BTW, I have over 230 hours on my OEM '18 aer forks, and the cartridge has been apart 3 or 4 times.  Original seals, seal head, etc....

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Nonsense, you just have a ham fisted mechanic who used WAAAAAY too much heat.  Done properly you will neither melt the seals, nor the plastic top out spring guide.  There are a few other parts to update in the old style cartridge (the melted part is one of them) but you should be looking at ~$100, NOT the whole cartridge rod assembly.  
BTW, I have over 230 hours on my OEM '18 aer forks, and the cartridge has been apart 3 or 4 times.  Original seals, seal head, etc....

Interesting, do you use locktite when you put it back together? How do you hold the inner tube when undoing the nut from it?

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21 hours ago, bikedude987 said:

Nonsense, you just have a ham fisted mechanic who used WAAAAAY too much heat.  Done properly you will neither melt the seals, nor the plastic top out spring guide.  There are a few other parts to update in the old style cartridge (the melted part is one of them) but you should be looking at ~$100, NOT the whole cartridge rod assembly.  

BTW, I have over 230 hours on my OEM '18 aer forks, and the cartridge has been apart 3 or 4 times.  Original seals, seal head, etc....

question, what level and type of ridding ? 

The reason I ask is I had my 2018 AER modded and one of the things I was told was that the piston seals in the stock fork dont last long for expert/pros in MX use. 

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They do 50 hours , at pro use maybe 20 but that's top-level mx riding

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Ok yea part of the work done on my forks was to put a better seal in there.

BTW Mog I read in one of your posts somewhere that fork outer seals life span is usefully increased IF you clean and oil lower tube after each wash/ride.

I have tried this and I was surprised to see that how much dried concrete like hidden dirt specks and hard water spots are there.

So far I have about 40  hrs on stock seals with no leaks. I usually get half that. Will be interesting to see how far it goes...

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To be fair it was Dave j who came up with this theory,only one i have agreed with lol

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Posted (edited)
On 8/16/2019 at 6:43 AM, lowmass said:

question, what level and type of ridding ? 

The reason I ask is I had my 2018 AER modded and one of the things I was told was that the piston seals in the stock fork dont last long for expert/pros in MX use. 

purely rocky offroad, around a low A pace - which means very fast shaft speed, but relatively seldom fully bottomed.  Bottoming should have a minor effect on the seal anyway, other than a pressure increase.  Shaft speed, on the other hand, should have a larger effect on seal life.  The 18's came with the updated seals, it was only the pre-18 that had the less capable x ring seal.

Edited by bikedude987

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Hmm now I wonder if im confused.

It may have been the damping piston seal band/bushing that the suspension tuner was talking about. I know he said the stock shock seal band wasn't great and he replaced with something similar to Jap shock band, but I thought he said fork as well

Do the stock 18" AER fork damping piston bands have issues?

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No , but you should not bottom the aer, it can damage the air side seal head

The air side seal head was updated in 18


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Hmm  interesting I bottom mine. Not a lot but I do bottom. In fact a couple times in last month I have done a solid metal to metal clack but that only when over jump 

Cannot run more air with present setup ether. just 2 more lbs and the chassis is unbalanced. And a few clicks more damp and the great action through washboard at turn entrance isnt quite as good.

Maybe I need a little more oil? A bit more ramp up at end of stroke? But honestly I wonder a bit about AER bottoming system ( no idea haven't seen it) 

How does AER bottoming system compare to jap forks?

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The aer doesn't really have a bottoming system ,that's the issue ,the seal head hits something when it bottoms , yes add just 5 or 10cc of oil , it helps and sometimes you get a plusher feel

Other forks don't seem to suffer if you clang them hard when you bottom out

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