Perennial problem dismantling forks for oil seal change

[stinkwheel]

I keep having a problem with dismantling forks to change the oil seals.

I take the bottom bolt out, remove the damper rod, dust seals out, circlip out. I heat round the seal area with a heat gun then slide-hammer the uppers and lowers apart.

About half the time, they come apart second or third knock. The other half of the time, I spend the next three hours sweating, swearing, heating, clamping in a vice, hammering then eventually destructively removing the seal and going back online to order a new set of bushes because the inner and outer have overridden one another. Usually damaging the fork lower in the process.

What am I doing wrong? Or does everyone else have this problem too?

https://lh3.googleusercontent.com/7X2VC3_XJnV1r_OCuk6h-N-QfOSzIM1at24TNQsZojBM_k-ot5tw-KCsrxapUIMk_F7GU-AtiC6SKzgW46a4mV2PmmvpL4cx9YjDb6qW76ukPNckckymdgUX0IYiDsXmiV8l_uS7sQ=w1164-h873-no
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Riejufixing]

I am having difficulty imagining how/where you position a slide hammer.

[Kawasaki Jimbo]

Vigorously sliding the inner and outer tubes apart to drive the seal out and separate the two.
Are you missing a washer between the seal and the upper bush?

[Riejufixing]

[Robby]

If it is happening on the same set of forks, then I would be looking at the area where the top bush seats. Something is stopping it from sliding out with moderate force. May be that you need to give the bush seat a rub with some fine emery paper.

Or you could just be hammering it too hard. You're meant to be gently tapping a soft bush using another soft bush. Hit it too hard and they will just jam together.

I have had a similar problem in the past, dismantling forks that have been together for 20 years. Usually it's a problem where the old seal is welded in place by a combination of rust, alloy corrosion, and very hard old rubber. Penetrating oil, tea, and patience help.

Fork seals are one of those jobs that can be a pain in the arse, no matter how experienced you are. So many little things can just be difficult for no good reason.

[stinkwheel]

[MarJay]

Having done four or five sets of forks in my time, I think it's just a PITA to be honest.
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Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[Islander]

This is why I prefer to change the bushes at the same time as the seals. I'd suggest trying a progressive increase in force rather than getting stuck straight in - it'll at least let you know whether there's going to be a problem with the bushes. Then you can remove the seal with a suitable puller and visually inspect before you get them really stuck.

[Meatybeaty]

I've used one of these with varying degrees of success.
https://www.ebay.co.uk/itm/O-RING-SEAL-PULLER-OIL-GREASE-SEAL-HOOK-REMOVER-REMOVAL-TOOL-282610-SILVERLINE/391840051842?epid=19017007796&hash=item5b3b7cb282:g:pDkAAOSwOWdcF~Au:rk:13:pf:0

[bikenut]

post a link off your exact bike to cmsnl so we can see the exploded views.....
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[stinkwheel]

[Meatybeaty]

[DrSnoosnoo]

Just to add another bit of personal experience.

Only done it once, on a ZZR600 at about 40k miles IIRC, my mate grabbed the lower, I grabbed the upper, we pulled, leg came apart.
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[G]

I've never heated them and never had that problem.

Whether there's any connection is another matter.

[Riejufixing]

Could it be something to do with the angle?

Do you always do them standing up, or do you lie them down first?

[Pigeon]

[Kentol750]

Might have missed it earlier, but why is it a regular problem? 2nd time would've seen me get new forks. Pitted or warped forks? Or just lots of bikes you hit potholes on?
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Some bikes.

[Riejufixing]

[bikenut]

Hi stinkwheel, thanks for posting the exploded view......

If the drain plug part number 20 ( yes it also has an other function as well ) was removed whilst the fork stanchion was still in the bike, and the circlip part number 12 and its associated upper "seal" removed then the lower fork leg could be removed via its own effective "slide hammer" and weight, once the mudguard etc is off ??

The other parts could then be removed for bench working?
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[chris-red]

I've never had an issue, I actually quite like doing forks, only problems I find is the mess and until I got an electric impact driver getting the lower bolt out.
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[sickpup]

Its a normal problem and one exacerbated by not changing the bushes with the seals and cleaning out the fork leg when seals are changed.

Wear on the bushes means the bottom bush will ride up inside the upper bush expanding it and jamming it into place.

Theres a surprising amount of wear that goes on inside a fork leg. When you have less than 500ml of oil in a closed system any particulate matter will cause excess wear.

[stinkwheel]

[stinkwheel]

[sickpup]

[stinkwheel]

Well, in this case, the fluid that came out was clear and colourless. So it was either changed just before it was parked up 13 years ago or it's in hell of a good nick. I'm sure nobody has had the fork tops off recently.

Anyway, as predicted, the second one came out with minimal fuss . So my 50:50 record is intact. I did heat them in the end, they didn't look like they were going to move cold, took three bashes after warming up. Although perhaps soaking them in ATF/Acetone mix loosened things up (it certainly loosened the paint I got a drip on!).

Got the new bushes and seals ready to fit and a bottle of multigrade fork oil but I'm going to give the sliders a coat of polyurethane laquer before I refit them to prevent stone chips.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.