Does this TX750 hub need milling do you think?

[JayR]

Hey everyone, hope you had a good weekend. I'd be grateful for you opinions on whether or not this hub needs machining on a lathe or just a good passover with sandpaper o glass beading?

As background, there was a pronounced 3-4mm wide lip that was about 1mm high at the edge of the hub. The "lip" is in the pics with my high quality calipers and the small screwdriver pointing to "lip" area.

I originally thought this lip was due to worn brake pads grinding down the iron of the inner hub, leaving the 3-4mm of metal on the edge.

But I scrubbed the insides down with steel wool a little and the lip scrubbed off, so cool. I think it was just 40 years of brake dust build up.

I don't have any experience with brake rotors, but I DID read 5Twins excellent posting on refurbishing rear hubs, and I will do this.

But I didn't find a lot on when you should machine a hub.

The brake shoes are shot, and I'll be getting new ones. What would you do with this hub? Do brake shops machine motorcycle hubs? I'll call around but wanted to float it by you all first. I believe that if I machine it on a latheI should wait until after the hub is laced up with the rim.

 

[gggGary]

That iron liner is very thin and cast in place. I tend to just clean it up by working around it a few times with sand paper and try not to disturb the sleeping ogre. Bad/worn out liner = throw out the hub. New shoes will quickly conform to to minor ridges and such. One of the reasons I don't use the drum rear brake much.

 

[fredintoon]

Hi JayR,
um, that ain't a micrometer, nor a Vernier neither, it's a caliper.
And the machine tool to re-surface that brake drum ain't a mill, it's a lathe.
OK. Rant over. There's things a machinist can't stand to see in print. Sorry.
That said, I'm with Gary; that cast-in brake surface is scarily thin to be re-machined.
Get the surface rust off it with an emery flapper wheel in a power drill or a die-grinder,
you'll be amazed at how well the surface will clean up.

 

[5twins]

Yes, that 3 to 4mm strip is outside the area rubbed by the shoes so it's normal for it to get crusty. Just cleaning it up as you did should be fine. Luckily, Yamaha continued to use these brake shoes on many other models up through the early '90s so replacements shouldn't be too hard to come by .....

http://www.boats.net/parts/detail/yamaha/Y-5A8-W2536-00-00.html

My originals were like new, not even fully seated in, but I still acquired a new set for future use. I got them from 650Central.

 

[JayR]

That iron liner is very thin and cast in place. I tend to just clean it up by working around it a few times with sand paper and try not to disturb the sleeping ogre. Bad/worn out liner = throw out the hub. New shoes will quickly conform to to minor ridges and such. One of the reasons I don't use the drum rear brake much.

Thanks gggGary, that's great advice, I wasn't sure what I had on my hands but it seems like it's actually in OK shape now that you experts have weighed in. I'll proceed accordingly

Hi JayR,\
um, that ain't a micrometer, nor a Vernier neither, it's a caliper.\
And the machine tool to re-surface that brake drum ain't a mill, it's a lathe.\
OK. Rant over. There's things a machinist can't stand to see in print. Sorry.\
That said, I'm with Gary; that cast-in brake surface is scarily thin to be re-machined.\
Get the surface rust off it with an emery flapper wheel in a power drill or a die-grinder,\
you'll be amazed at how well the surface will clean up.

Yes - I'll take my well deserved lumps on those points. Edits made for terminology Flapper sounds good, better than milling jk

Yes, that 3 to 4mm strip is outside the area rubbed by the shoes so it's normal for it to get crusty. Just cleaning it up as you did should be fine. Luckily, Yamaha continued to use these brake shoes on many other models up through the early '90s so replacements shouldn't be too hard to come by...

Thanks 5 Twins for the link - amazing that the bearings are still available too

 

[5twins]

The bearings on all these Yamaha wheels are just common metric bearings. The 650 and 750 rear wheels use the same bearings and internal spacers. Be aware that this includes that often lost (thrown away with the old bearing) "collar" internal spacer, #19 in this drawing .....

http://www.boats.net/parts/search/Yamaha/Motorcycle/1973/TX750/REAR WHEEL/parts.html

This spacer must be "reclaimed" (removed) from your old bearing and installed in the new one. Besides adding a heavy 1/8" or so to the internal spacing between the bearings in the hub, it also sleeves down the I.D. of that left bearing to 20mm so it fits on the axle.

 

[fredintoon]

Hi JayR,
it's my turn to confess.
Looking at the photo more carefully shows that your el-cheapo measuring tool is indeed a Vernier caliper.
It lets you measure to within 1/128" or 0.05mm if your vision is still good enough to see the markings and you can still remember how to read a Vernier scale.
These days I rely on a digital caliper.
Nice big numbers and all I have to remember is to keep a spare battery on hand.

 

[JayR]

The bearings on all these Yamaha wheels are just common metric bearings. The 650 and 750 rear wheels use the same bearings and internal spacers. Be aware that this includes that often lost (thrown away with the old bearing) "collar" internal spacer, #19 in this picture...

This spacer must be "reclaimed" (removed) from your old bearing and installed in the new one. Besides adding a heavy 1/8" or so to the internal spacing between the bearings in the hub, it also sleeves down the I.D. of that left bearing to 20mm so it fits on the axle

5Twins - yeah that sounds like something I would do thanks for the heads up. Hey what about those oil seals parts # 10 and 20, prolly just get news one too I suppose.

 

[JayR]

Hi JayR,
it's my turn to confess.
Looking at the photo more carefully shows that your el-cheapo measuring tool is indeed a Vernier caliper.
It lets you measure to within 1/128" or 0.05mm if your vision is still good enough to see the markings and you can still remember how to read a Vernier scale.
These days I rely on a digital caliper.
Nice big numbers and all I have to remember is to keep a spare battery on hand.

Haha - I had a feeling that POS tool would start some sort of discussion. Since you brought up the subject of digital read outs, I saw this little device at Harbor Freight this weekend. I need to re torque my head this winter and was wondering if this is the way to go. Will measure a couple different ways, adaptable to different ratchets. It even has a voice feature that yells at you when you are close to the desired setting - like my wife!

 

[5twins]

Those "oil" seals are more correctly labeled as grease seals, but they're not a 100% seal like an oil seal. They're more of just a dust and water shield for the hub. The bearings have their own seals. If you're careful removing them and they aren't damaged or falling apart due to age deterioration, you can just re-use them.

If you're careful, a small pry bar like so can be used to pop the seals out .....

Better yet, leave them in place and let the old bearings push them out as you drive them out. Removing the bearings on these wheels that have that #19 "collar" in the left one is easy. If you look at your 1st pic in your 1st post, that sleeve visible through the hole in the grease seal is that #19 collar, pressed into the bearing's I.D. Find a socket that just fits through the hole in the seal and rests on the sleeve. Drive the sleeve down into the hub. It will push the center tube spacer, right side bearing and its seal out the right side. Then it's a simple matter to drive the left bearing and seal out from the right side with a long drift pin, length of pipe, whatever.

 

[retiredgentleman]

Haha - I had a feeling that POS tool would start some sort of discussion. Since you brought up the subject of digital read outs, I saw this little device at Harbor Freight this weekend. I need to re torque my head this winter and was wondering if this is the way to go. Will measure a couple different ways, adaptable to different ratchets. It even has a voice feature that yells at you when you are close to the desired setting - like my wife!

That device is the wrong range for these bikes. It starts at 29.5 ft-lbs, which is too high for 80% of the bolts on these bikes.

Buy yourself a good quality torque wrench with a range of about 5 ft-lbs to 80 ft-lbs. I'd say places such as NAPA , sell high quality tools.

If your Harbor Freight store is anything like our Princess Auto here in Canada, you do not want to but a torque wrench from them. No quality, with cheap tools they sell.

Actually when you need to torque the small 6 mm threads, you really need a torque wrench thats calibrated in inch-lbs.

 

[JayR]

The bearings on all these Yamaha wheels are just common metric bearings. The 650 and 750 rear wheels use the same bearings...

5Twins thanks for the big bearing drawing. I removed the big and small bearings last night using your method http://www.xs650.com/forum/showthread.php?t=7201. So easy the way you outlined it, thanks. A 17mm high impact socket for the top hat, and a 32mm impact socket with extension fit perfectly as a chase for removing the brake side bearing.

Can you confirm the small bearing dimensions if you have them? My calipers are s**t and I'm not confident they are accurate, but I believe the small bearing is 52mm OD, 20mm ID (it has to be), and 15mm wide? If so then it looks like this would be the small bearing from McMaster-Carr: http://www.mcmaster.com/#6304-ball-bearings/=v4whkf

Also, is the standard double sealed ABEC-1 bearing which is rated at 9,500 max rpm durable enough do you think? They also offer the "Precision-Plus Steel Ball Bearings—ABEC-1" version which is rated at 15,000 rmp. It costs about $10 more per bearing. It is about the same price as the OEM bearings on boats.net - so I am guessing that boats.net is selling the 15,000 rpm rated version, but that's a guess.

 

[JayR]

Buy yourself a good quality torque wrench with a range of about 5 ft-lbs to 80 ft-lbs. I'd say places such as NAPA , sell high quality tools.

Actually when you need to torque the small 6 mm threads, you really need a torque wrench thats calibrated in inch-lbs.

Is it best to have a higher range ft-lbs TW for jobs like torquing the head, and a lower range inch lbs for the smaller jobs like sump filter bolts? I looked around some but can't seem to find one that is well suited for both. It probably has to do with ratchet head size, 3/8" , 1/2", etc.

 

[5twins]

Yes, the 6304 bearing is correct for the right side. The standard version should be fine. You may have found a steel shielded type in there, maybe even one with open sides. Go with the 2RS (two rubber seals) type. Yamaha switched to the rubber seal type on later models plus you can pop the seals out and add grease in the future. In fact, I inspect new ones before installing to insure they have been greased enough from the factory. Sometimes you'll find one with little if any grease in it. If you ever do grease one, don't fill it completely, only about half way at most. Filling completely is over-kill and the excess will just ooze out when they warm up, making a mess.

Yes, a couple different torque wrenches are needed, the small inch/pound one for the little fasteners and a medium sized one for the rest. The inch/pound ones usually go up to about 250 in/lb, or about 20ft/lbs. A medium sized one will usually cover from about 10 to 80 ft/lbs.

 

[fredintoon]

Also, is the standard double sealed ABEC-1 bearing which is rated at 9,500 max rpm durable enough do you think? They also offer the "Precision-Plus Steel Ball Bearings—ABEC-1" version which is rated at 15,000 rmp. It costs about $10 more per bearing. It is about the same price as the OEM bearings on boats.net - so I am guessing that boats.net is selling the 15,000 rpm rated version, but that's a guess.

Hi JayR,
at 9,500 RPM at the rear axle your bike will be approaching Mach 1 so no, you don't need a high speed bearing, and high precision bearings are for machine tools, not vehicles.
Wheel bearings need good load ratings and adequate grease seals, is all.
Torque wrenches now; alas, you need two of the bastards.
A 1/2" sq drive Ft/lb one for the big nuts and a 1/4" sq drive inch/lb one for the little ones.
Typically, the 3/8" sq drive compromise that most folks use can't do both except at the very highest and lowest of it's settings where it ain't particularly accurate.

 

[JayR]

Hi JayR,
at 9,500 RPM at the rear axle your bike will be approaching Mach 1 so no, you don't need a high speed bearing, and high precision bearings are for machine tools, not vehicles.
Wheel bearings need good load ratings and adequate grease seals, is all.

LoL. 50 HP won't do Mach1? I'll be hard pressed to do 80mph.

All balls has the complete kit with grease seals for $24 US so I'll pick up a set of these http://www.allballsracing.com/25-1357.html

Thank you all for your advice and input - I appreciate it. Maybe a torque wrench for Xmas.

 

[XSLeo]

I like those cheapy plastic calipers. Not as accurate as a digital or electronic calipers but plenty for measuring things like nuts, bolts, other small stuff along those lines. And you can just chuck in the tool box, if it breaks, another couple bucks for a new one.
Leo