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jackleberry wrote: You might also consider that you may be over torquing the bolts. Locktite acts as a lubricant and if the torque spec given was intended for dry bolts (usually for brake parts, it is), then you may be over torquing by a significant amount.

Perhaps, but I don't think so. They were already collapsed/distorted by 22 ft/lbs - far under the 25-33 spec'd in the FSM. They are definitely made from a softer, more ductile material than other tab washers I've come across in other, but similar applications.

I still have a second set of these 'Koyama's for the second disc. I'll try these tonight with 'dry bolts' and dabs of grease on the mating surfaces to see if this alters the outcome.

You could attempt to harden them yourself with oxy/acetylene but may discolour them

OK - so I tried again this evening using the second set of 'Koyama' tab washers supplied in the dual disc kit.

This time i used no Loctite, I greased both the contact areas on the fresh tab washers and the underside of the heads on the fresh, second set of bolts. The threads were definitely 'dry'.

Marginally better, but these were still only torqued, in steps, to the lower setting in the FSM of 25 lbs/ft. All three are distorting.




I'm done with 'Koyama' tab washers!

Tomorrow, the discs are going to be mounted using plain old flat/spring washers and Loctite.

If I change up to a trailer queen resto job down the road, then I'll hunt down new OEM tab washers when the time comes.

Thanks to all who answered this thread with tips and pointers - ultimately I think that the sub-standard nature of these 'Koyama' reproduction rotor tab washers was been shown beyond too much doubt.

I don't know how far along your build is, but you're much better off restoring/refinishing OEM parts. Aftermarket/repro stuff is hit or miss but they all have an "over restored" look IMO. I bought an aftermarket set of carb holder clamps and they seem to be made from the same cheap material as those lock washers. I just threw them out and found some decent used OEM ones.

At least you can use them as twist-ties for garbage bags.

Well that sucks.

Kidkawie wrote: I don't know how far along your build is, but you're much better off restoring/refinishing OEM parts. Aftermarket/repro stuff is hit or miss but they all have an "over restored" look IMO. I bought an aftermarket set of carb holder clamps and they seem to be made from the same cheap material as those lock washers. I just threw them out and found some decent used OEM ones.

Very true. The original tab washers were MIA from a PO rebuild. Wherever possible I'm using NOS/OEM parts. Unfortunately most people who've bought out stocks of original parts and sell these on Fleabay etc., would have you believe that they are all made from 'unobtainium' and want crazy-high prices, especially if they are tagged/bagged with the original Kawa packaging and carry a Z1 part number.

For most fasteners, I order from boltdepot.com. They have a decent range of metric fasteners in the correct zinc-plated finish and you can usually get them to correct lengths, give or take a mm or so. They also sell them in 'onesies and twosies' rather than having to order 50 at a time. As long as you plan ahead, the shipping won't eat your budget up either.

loudhvx wrote: At least you can use them as twist-ties for garbage bags.

Lesson learned.

jackleberry wrote: Well that sucks.

Indeed it does!

Hopefully others can learn from my experience.

I sent my original hardware out for replating, along with spare hardware. Nothing like waiting on some bolts to stall a project. Also, those bolts marked with 4's and 7's get pretty desirable.

Kidkawie wrote: I sent my original hardware out for replating, along with spare hardware. Nothing like waiting on some bolts to stall a project. Also, those bolts marked with 4's and 7's get pretty desirable.

Waiting on parts can be frustrating, especially if its something small that's holding up reassembly.

I've heard lots of good things about the Caswell hobby kits for zinc plating. I may look into getting one, as the Z1 is just the first of a few of my bikes that I'm planning to rebuild in the future. I already have a good-sized ultrasonic tank plus dry- and vapor-blasting cabinets, so if I can complete the fastener/hardware refinishing process from start to finish 'in house', that should help to keep things flowing.

As I said - the heck with those junk repro tab washers.

I've now got both rotors snugged down tight with regular flat/spring washers, Loctite blue and 30 ft/lbs of torque.

They aren't going anywhere.

I'll keep an eye out for some OEM replacements and change them out down the road.




Thanks again one and all.