Judy XC damper rebuild/modify?

ishaw said:

You'll want seals at the bottom between the shaft and hole and an equivalent at the top.

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Was thinking if I can match the bore diameter I’d just use the seals that the original uses.

Twiui it’s not that the seal is insufficient rather the retention of the seal in the cartridge. I’m picturing the oil leaking around the seal not through it if that makes sense?

I've always wondered about making something. Alloy tube threaded at both ends. Caps with seals screw in each end around the damper shaft with the internal gubbins needed to actually produce the damping.

Could produce one the opposite way round for compression damping in the other leg instead of the dummy shaft as per the old Judy DH.

It still galls me today that the postal service lost me a set of NOS Judy DH dampers.

I had this with a plastic cartridge and identified the top and bottom shaft seals as the source of leakage. I did this work two years ago and the cartridge was returned to fully working, non-leaking order. This was a very old (gold) Judy XC fork which had been lying around in the workshop for 20 odd years. Basically the seals had gone hard, and then worn fast as a result. The damper shaft was a bit glossy but not badly worn. This guy had replacement parts at the time and still does....


These '4' seals are the ones you likely need. Two needed, one at top, one at bottom.
They are held in place with internal-fitting circlips - devil to get out without circlip pliers - easy with. Make sure shaft is smooth and has no built up crud which can wear the seals. I don't think that rider weight should affect things at all. Use the RS website for the amount of oil and its weight rating (viscosity). This is a non-stressed part, unlike the springs.

So I have no circlips in my cartridge, at the top that no4 seal just sits up against the top of the cartridge casing molding and at the bottom I presume its just meant to be a press fit.

The cartridge is retained inside the stanchion by a circlip but it has no circlips of it's own.

I believe the metal cartridges have a circlip to retain the seal and then the circlip to hold it all in the stanchion is that not right?

ishaw said:

I've always wondered about making something. Alloy tube threaded at both ends. Caps with seals screw in each end around the damper shaft with the internal gubbins needed to actually produce the damping.

Could produce one the opposite way round for compression damping in the other leg instead of the dummy shaft as per the old Judy DH.

It still galls me today that the postal service lost me a set of NOS Judy DH dampers.

Click to expand...

I figure using the seals that fit the original cartridges would be the easiest way to keep the oil where it's meant to be and then it's just a case of keeping those seals in place.

I'm saying I'd braze a cap on to replicate the way the plastic one is molded but probably would actually be easier to make it a circlip at each end, perhaps with a delrin washer or something to spread the load?

While you can service the plastic ones (it is quite easy) as mentioned they will go again, the plastic just isn't up to the job and you'll be doing it again in a year or so if lucky.
Heat build up etc.

Anyway an alternative is to fit a hydrocoil setup. It's a bit more faff though...
See the wiki and or a post somewhere in the depths of retrobike.

Development of the hardbody kit is done and production will start shortly. We will do another drop shipment to the UK when they are done. (photo is of the protoype, production parts will be anodized and etched)

We are also playing around damper valve upgrades but that is a long term project.

kokies said:

Development of the hardbody kit is done and production will start shortly. We will do another drop shipment to the UK when they are done. (photo is of the protoype, production parts will be anodized and etched)

We are also playing around damper valve upgrades but that is a long term project.

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Interesting, do you have a ball park price?

klunkrider said:

Interesting, do you have a ball park price?

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We are trying to hit $60 for the complete kit. Tube, snap ring, support plate, 2 X oil seals, oil and tube of grease. You need to re-use the complete functioning shaft/valve from your current plastic body damper.

We can also do the kit without the oil and grease for $55.

We will offer the tubes in 2 lengths (107mm and 120mm) to accommodate all 3 travel lengths.

kokies said:

We are trying to hit $60 for the complete kit. Tube, snap ring, support plate, 2 X oil seals, oil and tube of grease. You need to re-use the complete functioning shaft/valve from your current plastic body damper.

We can also do the kit without the oil and grease for $55.

We will offer the tubes in 2 lengths (107mm and 120mm) to accommodate all 3 travel lengths.

Click to expand...

would these be available to use on 100mm judy xl?