Remove 900GTS rear brake shoe springs? HOW?

[colinpdx]

I am in the process of dismantling a 900GTS with drum brakes and I am flummoxed.

How do you remove the springs that pull the shoes away from the drum? They seem impossible to pull off and through the holes in the shoes. Do you just pry them off with a lot of force and hope they return to shape?

What's the trick?

Thanks
Colin

[machten]

I needed to bend the "hooks" open a bit to get them off the shoes of my Sport and 750 GT (which I think are the same brakes). It does take a bit of force. I figured there is a limited number of times you should do that to the same springs, and it was clear from marks on the springs that they had been opened and closed before at least once. I don't know how much of an issue that is, but I managed to find some new, unused ones (well they were new 30 years ago, anyway). The "new" springs had the hooks more openned and needed to be closed up in order to clear the hub webbing.

Kev

[colinpdx]

Kev

This is very helpful - thanks for the response. I'll try that.

I also think it might be possible to clip a little off the spring "hook" without harming their effectiveness.

Best
Colin

[machten]

Colin,

Here's what the springs look like "new" and unused...



They need to be bent to fit inside the webbings after fitting the brake shoes.

Kev

[tomb7949]

As a metallurgist, I can tell you that any time that you bend (plasticly deform) iron based alloys (spring steel, in this case) to the point of permanent change of shape, you are injecting microscopic damage in the form of increased density of dislocations in the crystal structure of the metal. This results in the phenomenon known as work hardening. Good up to a point, damaging past that point. Think of what happens when you bend a paper clip multiple times.

I suspect that these springs were intended to be safely bent to shape during installation only once. Every time that you force the spring hooks open and then bend them back again, you are putting in more internal damage increasing the likelyhood of failure. I would definitely recommend using new springs everytime that you rebuild the brakes unless you can figure a way to dismantle and reinstall the springs without bending them.

[DM860SS_90003*]

I seem to remember from last servicing bike drum brakes (about 30 years ago and not on a Ducati) that this was achieved by removing the shoes and springs from the posts/cams as one unit - allowing the springs to be fully at rest, loose in their holes and capable of being "naturally" stretched and unhooked.

I appreciate this may have been tried/may not be possible or relevant here/be "teaching granny to suck eggs"...

[colinpdx]

Thanks everyone. I ended up with a compromise solution - I used a Dremel to cut off a small amount of the spring end so that I reduced the amount of deformation required to get the springs off the shoes. There really is no way to stay this side of the limit if elasticity and still get the springs past the shoes. There is also not a lot of room to insert pliers beefy enough to easily bend the spring ends - or my personal strength is more degraded than I thought as I approach 60 (and I not mean mph) I hope these work when replaced but I'll try and find some new springs.
Thanks again
Colin

[Steve Foster]

If you reckon it's difficult disassembling, just wait 'til you try putting 'em back together again.

I seem to remember from last servicing bike drum brakes (about 30 years ago and not on a Ducati) that this was achieved by removing the shoes and springs from the posts/cams as one unit

This is the technique I used, and I tried the same in reverse to reassemble. I remember that the judicious application of brute force was required with an element of luck and a fair bit of verbal encouragement ...
I always wondered how they did it on the assembly line.
Steve

[machten]

You can definitely taken them off as a single unit, and that's what it I have done unless I was getting the shoes reshod. I've knocked in a few pieces of the right size flat soft pine wood between the shoe ends, and lifted the shoes and springs out under spring tension so they come out as a unit, maintain their position, and slide straight back on later. You can use the eccentric lever to help you do this at the variable end.

Of course if you need to re-shoe, that's kind of a moot issue as you still need to remove the springs.

Kev