1974 TX500 Rear drum hub plate... Interchangeability?

[Norman1950]

I was able to get a good wheel for my hardtail project. But the thing is it doesn't come with the rear brake hub plate. Does anyone know of any other drum plates that would work with the tx500? I believe the axle size is 17mm.

(I have seen a couple on Ebay, also what is the "cable" coming out of the plate for?)

Thanks.

 

[5twins]

I think the 500 brake plate is unique to that model. The wheel should take a 20mm axle, just like the 650. The wire coming off the plate is an electric brake shoe wear sensor. Some of the 650s of that era had it as well. Brake shoes are still readily available because Yamaha used them in other models like the Radian and Virago.

http://www.boats.net/parts/detail/yamaha/Y-4H7-W2536-00-00.html

 

[Norman1950]

Thank you very much. So on the wire/cable part, I could just plug that off with no worries?

I will grab one of those hub plates off ebay or find out if anyone has one they are getting rid of.

Thanks again for the info.

 

[Scrambled]

Are there many parts on a TX 500 that fit an XS 650 and vice versa ? There is a local guy that is trying to restore a TX 500 , just curious if any of my spare bits would help him out . Thanks .

 

[5twins]

Yes, you can just remove the wire. It connects to a plunger type switch in the hub below the brake arm. I had no luck finding a bolt plug for that because it has a rather large fine metric thread. I just left the switch in place. This is from a TX750 but the brake switch set-up is the same .....

You can also cut the casting off the hub that the wire went through. Here's an "after" shot of the above brake plate .....

To use the TX/XS500 rear wheel, you're going to have to do some spacer fabbing. It's not too difficult and all the spacers can be made from an old 500 or 650 sprocket. The 500 hub is narrower than the 650 one and also mounts its sprocket closer to the rim. If you just mount the wheel so the sprocket aligns with the front one, the rim won't align with the front rim. You need to space the wheel over to the right more to align rims, then space the sprocket back to the left for it to align. As I said, all the needed spacers can be cut out of an old sprocket .....

 

[Norman1950]

Awesome, thanks again for the info!

 

[5twins]

In response to Scrambled, no, not a whole lot swaps between the models. Nothing really motor related, a few carb parts maybe but not the complete sets. Some running gear parts like the front wheel and brakes will, rear wheels no. The 500 rear can be made to work on the 650 as we're discussing here but I don't think the switch would work the other way. The 500 has a narrower rear hub and swingarm. Even if you could squeeze the 650 wheel in there, there would be rim alignment issues with the front.

Turn signals and switch gear are very similar, if not the same. And of course, all the metric fasteners. The 500, although maybe a good bike in its day, never really caught on or was that popular. I've had two given to me over the years for free. Honestly, I think they're ugly and so obscure that I didn't even consider fixing them up. I stripped them of anything I thought might be useful and took the "hulk" to my dealer's boneyard. I will say that the can of metric fasteners I got has come in very handy over the years, as have some of the brake parts. Oh, the coils were the same as stock 650 points coils too.

 

[Docwits]

5Twins, great info. I have a set of 75 xs500 wheels with the six bolt sprocket. For a neewbie bike builder like myself, can you elaborate on where the spacers you cut from the sprocket go?

Thanks in advance for your help.

 

[5twins]

I most certainly can and I'm glad you asked. When I first presented this swap a year or so ago, there was absolutely no interest (silly boys). There is a very good reason for going through the little bit of trouble involved here - you gain a rubber mounted, "cush drive" sprocket. The 650 never came with that and those springs on the back of the clutch hub that were used instead are prone to breaking. Anything we can do to reduce the load on them is a good thing - like this rear wheel with a cushioned sprocket.

To start, yes, only the spoke TX/XS500 wheels with the 6 bolt sprocket mount are what we're going to address. The mags had a 4 bolt sprocket and probably could be adapted but mags are not my thing. Figure it out on your own if they are.

So, as I said, the 500 hub is narrower and the sprocket mounts closer to the rim. I have all the numbers written down somewhere but the simple explanation is you need to space the wheel more towards center to align the wheels front and rear but then space the sprocket back to the left so it aligns. Luckily, this all works out to about 8 or 9mm spacers which is the thickness of a sprocket.

Space the wheel over to the right with an additional ring spacer on the sprocket side .....

Then space the sprocket back to compensate for that with the big ring spacer you make from the old sprocket .....

Since the 500 hub is narrower, you will also need to add a ring spacer to the right side. I welded it to the original as you can see in the 2nd pic above. Longer sprocket bolts are now a good idea. I got them from McMaster-Carr, 5mm longer about $6 for a 10 pack.

 

[Docwits]

Thank you, perfect, all I needed. I picked up a set of near perfect 75 xs500 wheels on ebay auction for $50! I couldn't believe it, no one wanted up.

Thanks again!

 

[5twins]

Those do look very nice but still, I would suggest pulling the cush drive apart and lubing it. Mine was seized solid. It also appears you don't have the dust cover/spacer for the sprocket side. It is different from the 650 one and they don't swap ......

Here's an exploded parts diagram to help with the dis-assembly. You (like me) have the later type wheel that uses the parts 51 and 52 (shown in the inset at the upper right) instead of parts 29 and 30 .....

Knock the lock tabs down on part 51 and 52 will thread right off (with the help of a hammer and punch in the notches). Then the sprocket carrier #22 can be removed to reveal the rubber pucks. I needed to use a puller on mine because it was rusted to the steel sleeve insert in the hub .....

Once cleaned up, these parts got a thorough coating of anti-seize before going back together .....

Try to save and re-use the two large o-rings installed in the carrier if possible. Yamaha still lists them but they're like $8 or $9 each (ouch!).

 

[Docwits]

Man, can't express my gratitude. I had already found a drum for it on ebay, but now I am thinking it might make sense to keep looking for a complete wheel orbhub justvfor the parts, if you look at the pic I am pretty empty inside. I have also considered spoking the 650 hub to the 500 rim. I have never spoked a wheel before, not sure how hard it is or expensive for custom spokes. I can weld so would prefer your method

 

[5twins]

Spokes will not be a problem, they're the same as used on the 650 .....

http://www.boats.net/parts/detail/yamaha/Y-256-25304-00-00.html

Yes, you need a brake plate. I was lucky in that I pulled the whole wheel from a 500 sitting in my dealer's boneyard. I grabbed everything needed - all spacers, brake assembly, even the axle although it's too short. In fact, that was one of the 500s I put there about 10 years ago. Back then, I didn't have a 650 so felt no need to keep the wheels. 10 years outside did them no good, lol .....

Yes, besides the rust, that green is mold growing on the hub, lol. Nothing my bead blaster and buffing wheels couldn't fix though .....

I plan to lace this to a flanged alloy 650 rim, the original that came on my '78.

 

[Norman1950]

Thanks again for the explicit info. Thinking i might just have to go pick up the whole wheel at my local bone yard. Hopefully they don't want an arm and leg for it.

 

[Docwits]

One more quick set of questions for, then promise to stop bothering you! You've already been so helpful. I am assuming that is the cush drive in dotted line box on diagram? And what did you use to lubricate it?

Thanks again

 

[5twins]

The cush drive is the 6 slotted rubber pucks (part #21) that fit into the hub (last pic in post 11). The sprocket carrier has tabs on the back that fit down into the slots in the rubber pucks. The carrier is a slip fit on the steel tube insert on the hub. This is what you want to lube so the carrier can rotate on it, also to keep it from rusting. Like I said, mine was rusted together so there was no rotation or damping action happening. I coated the tube on the hub and the bore in the carrier with anti-seize but a good waterproof grease would probably work as well. Just don't assemble it dry. The two o-rings in the carrier bore are probably meant to keep the water out but probably aren't 100% effective.

 

[Docwits]

5twins, the day has finally here, got all my parts in, if all goes well I'll have a 500 wheel on my 650 by the end of it, again thanks for all your guidance!

 

[Docwits]

5twins, thank you again for all of your help. Put my build on hold for two years due to a family illness/death but today I finally mounted the 500 wheel on the bike. Your spacers worked great but I couldn't fit the brake side spacer in. Everything lines up great though. Gonna have tires mounted tomorrow, will get some picks.