What is this brake 'part'?

[armyofda12mnkeys]

So redoing the front end with my friend, and I see my MikeXS #29-3522 brake pads that i bought years ago match the ones in my 1978 XS400E. yay... but i realized while taking off the old brake pads, I lost one of the thin metal things that goes along with the pads (think there was one on the back of each of the pads, still have the other 1 left).
I took a picture of remaining one i have left.
Its on the right side of the pic here:

Can I buy that thin metal part somewhere (Dont see something that looks like it in the MikeXS DuPont Kevlar Brake pad kit I bought)?
Is it critical lol?

Thanks!,
Ari

 

[DARKMIDKNIGHTWARRIOR]

It's a pad shim. I think you can get them from Mike's. I don't know if they are 100% needed though. Hopefully others will chime in.

 

[xschris]

You need the shims to keep the pads where they should be. Most brake kits don't have them. You may need to go to yamaha to find one.

 

[armyofda12mnkeys]

Cool, Thanks guys, Looked it up on ebay and found a few XS400 brake shims that look like they will work out.
Next time will be careful where I store the brake-pads, probably fell on the floor somewhere and lost it.

 

[Scorpio1963]

Yeah I know its a bit late but yeah its a brake shim without them there would be too much play inbetween the pads and the rotor.

 

[XSLeo]

The shims are not for pad the rotor clearance. The piston seal does that.
They where used to counteract the tendency of the calipers to flex. As the rotor turns while using the brake the pads tend to rock, Tighter at the in side rear of caliper and wider at the out side, front of caliper. This is caused by flexing in the caliper. The shims are fitted to the rear of the pad so they are slightly tighter at the rear or in side of the caliper. Now as you use the brakes any flex is compensated for by the shim.
After a few years of use they found the flex they worried about wasn't a big problem, so they quit using them. You won't find much any difference with or without.
Leo