More Brake Caliper Questions

[Celtic67]

Sorry for the length of this post, I'm getting more confused with all the searching, rather than understanding these things better.

I've dismantled my caliper & been able to remove the piston, but still have some questions. I've done a fair bit of searching and am struggling to get to the point where I'm sure what to do.

Firstly, there's a shim that I'm missing. On the CMSNL website, it's part number 12. Sorry I couldn't link to a decent diagram, I've not been able to find one.

My system is missing that shim & it seems to be impossible to buy anywhere. I did read the last comment in this previous thread, which said it wasn't essential, but others said it was. Can I manage without it?

While searching for a manual with better pictures, I found this one. On page 92 of the PDF, it shows a diagram with the pads but no shim. The text, though, them says to grease the shim.

On the next page, it mentions bridge bolts and that they need to be replaced every time the caliper is removed. I can't find any diagram to tell me what they mean by a bridge bolt, though.

Next is the state of my parts. The dust seal & clip were missing completely, along with the shim.

As mentioned in my previous thread, I had to use an impact driver to remove the screw that holds one of the pads in place and I'd like to replace it. The bottom 5mm or so has no thread, as shown here:

I did try a normal M5 screw, but it wouldn't go all the way in, so I assume other end of this hole (below) is narrower than the screw thread.

The Yambits shim set for the XS650 (can't find one for XS400) shows a screw with a thread all the way along. Do I need to clean it up or re-tap it, or is it supposed to be like this?

Next, the bits from the same kit that are marked as "4. Retainer" on p92 of the manual I linked to. I've cleaned mine up, but when I put the pads back, they're quite tight and don't move freely on those retainers. Is that normal? See these 2 photos, where the pads don't slide down under their weight, but stay where they are:

The rubberboot for the bush & the bush seems fine. When putting them back, can I just push it through to a rough point, then bolt the bracket back to the caliper and it'll align itself? Or does it need to be a specific distance through?

Last question hopefully. There are a couple of photos of the piston below. There was a bit of corrosion that I've tried to clean up. Do you think it needs to be replaced, or is it OK?

 

[levdir]

I'd replace that. I rebuilt my front caliper when I first got my XS because it was seized, and my piston had less pitting than that. I thought it'd be fine but once everything was back together I had a persistent leak. Replaced the piston and it was good.

 

[Sesty]

when i bought new pads it came with shims and a new screw

 

[Celtic67]

All the pad sets I've looked at have no shim or screw. Some descriptions make it clear that these are no longer included. After reading the Haynes manual, I'm thinking the later bikes maybe didn't have the shim.

I've found a refurbished caliper for not much more than the parts will cost if I include the piston. That has the advantage that I know the screw will fit and looks better than mine. It still doesn't have that shim, though. On the other hand, the piston might be no better than mine.

It's that screw being dodgy and the pads not moving smoothly on the retainers that concerns me most about rebuilding the one I have. If I buy the shim kit, it may fix that. Anyone know if the pads are supposed to move smoothly?

I just realised that I didn't check the thread on the 5mm screw to see if it's the same pitch. Could be that the one I tried has a different pitch, rather than the hole being narrower than the thread. I suspect not as it screwed in fine to that point, but I'll double-check.

As the parts manuals linked to on this site don't seem to work any more, is there anywhere else I can get them, including part numbers? It might help if I could confirm whether the XS650 and SR500 caliper are the same.

 

[Sesty]

basically that Shim kit came in the box with the pads i got from Parts and more.. the screw was all the same diameter... i didnt even know the pads were coming with shims.

i didnt replace the OEM backing shim on there since it was in decent shape... (I did step on it which bent some of the tabs, but its a flimsy thing and straightened back out.)

i dont know how necessary the backing shim really is. I think it helps eliminate brake squeal and help insulate the piston from heat

 

[Celtic67]

Haynes do describe it as being anti-chatter, I think.

I figured out how to get at the parts diagrams on CMSNL and that the bike is a D, not an E (checked the VIN). The diagram for the D shows no shim:

I'll be heading out to the garage again soon to measure the thread on the screw and see if the hole that it goes through is clogged at the end.

I'm used to drum brakes on old Brit bikes, so this is all fairly new to me. I'm also finding it surprising how difficult it is to get proper parts lists for the Yamaha when it's so easy for the older bikes. Of course, BSA seemed to changed part numbers every week, depending on how they felt.

 

[Sesty]

i always use my local yamaha's online catalog for diagrams and parts lists./
http://www.stumpys.com/fiche_select.asp there are better sites out there that offer cross referencing for part numbers to see what other years and models used the same part.

 

[Celtic67]

I'll give that a try, thanks. I can see bits that look like they'll be the same, but I can't be sure. If I find somewhere that I can cross-reference, that'll be a big help.

After a bit more brake cleaner and scrubbing, the hole for the pad screw is now clear and I can screw in a normal M5 screw. The strange bit, though, is that the threaded bit won't go through the hole on the brake pad. The old screw, with its slightly narrower end, goes through fine.

So, although the pads have plenty of wear left, I'll probably need to replace them.

The bleed nipple seems to be blocked as well.

So I'm now thinking I'll get the refurb caliper to get the bike on the road and use that to compare how bits should be, such as whether the pads should slide easily along the retainers. I can keep the old one as a spare & get the bits needed later.

 

[Celtic67]

I'm starting to learn something now. I'll post this in case it's of use to anyone that finds this.

Comparing the XS400D and XS650D/E/F, part numbers for the bits are all the same, except for the caliper itself. I can only guess that it mounts differently, probably a bigger disc?

The SR500E, on the other hand, is a left-hand caliper, with a similar part number, presumably right & left versions of the same thing. Both begin with 1L9. All parts are the same, except the SR has the shim, so it corresponds to the XS400E.

The bridge bolt mentioned in 1 of the manuals is, I think, the bolt that holds the caliper to the bracket. I found a description that reads:

This bolt should always be renewed when removing and replacing the calliper to ensure the correct torque can be applied to a new thread that has not already been 'stretched'.