Removing rear knuckle cups

[innochadi]

Any suggestions on the best way to remove the rear knuckle cups?

I removed the front knuckle cups with pliers and a flathead screwdriver, but had the front arms out at the time, which made the task a bit easier. The same method isn't working as well on the rear cups with the arms installed. (it is working, but taking far more time and effort) Any advice from the pros to speed up the process? I'll have another go at it tonight after work.

[James T]

?? What is a knuckle cup ?? is it the cup that the end of the trumpet sits in, on the suspension arm?

[innochadi]

Yes, we're talking about the same thing. Maybe my lingo is wrong. It's the plastic/nylon cup that the knuckle ball joint sits in on the suspension arm:

[timc]

Yes, we're talking about the same thing. Maybe my lingo is wrong. It's the plastic/nylon cup that the knuckle ball joint sits in on the suspension arm:

those are a real bugger. I remember the front ones came out ok, but the rears were really tough to remove in comparison... basically a little at a time and a lot of paitience is what got mine out. I used a heat gun to soften it up a little and pull bits of it out at a time with pliers and a screw driver. haha. Maybe there was a better way, but it came out in about 10 pieces or so!

[innochadi]

Thanks Tim. So far that's my approach, too. Did the heat gun help?

[timc]

Thanks Tim. So far that's my approach, too. Did the heat gun help?

well, sort of..made it soft enough to make a hole through it and then able to use something to leverage it out from the hole... so either way they are a bugger whatever way you want to attempt it. I don't think you want to booger up the metal underneathe so be careful when prying it out.

[mascher]

I use a propane torch. It shrinks the nylon and only rarely sets it on fire. Once it cools you can pull out the cup easily with a pair of pliers.

Kelley

[innochadi]

Victory! After more fiddling with the screwdriver, we figured out how to pop out what was left of the cups in one turn of the wrist.

I'll definitely have to try the propane torch next time, Kelley. Thanks for the suggestion.

I assume the old knuckles are reusable with new cups?

[mascher]

As long as the old cups haven't worn through badly and there is no wear on the knuckle joints, new cups are all you should need.

Kelley

[Ozie]

I use a modified (old beater) screw driver sharpened for cutting on one edge and then dull and hooked on the other edge. It allows you to cut down the side of the cup relasing the tension going out ward or you can cut a section out then use the hook on the oppisite side to pull it out.

Oz

[innochadi]

Can you post a photo of your tool, Oz?

[Cheleker]

Second the torch idea. That's the way I do it.

[Ozie]

Several trys for this picture I hope this one works.
cuphooktool smaller.jpg
This has worked well for me, used 4 times.

OZ

[72 Norty]

Propane Torch

I Third the torch idea, I spent 30 minutes messing with a screw driver and a pair of vice grips before I thought of Propane torching. You just have to be accurate as to not singe anything else rubber or plastic. The second cup came out all by it's self in fear of being incinerated!!