[busa1300]

I have a set of H-spoke wheels for a RZ350, that I'm trying to make useful again.

Problem #1.....Having a SERIOUSLY difficult time getting bearings out. Being magnesium, I cant use too much heat on wheel to race area...or the whole garage might burn down from wheel catching fire. Slide hammer is not working, and the center spacer will not allow me to use a punch from the inside.... ::hairpull:
Problem #2 the sprocket.... It has a 325 stamped on it.....I have never see a chain that size on a bike under 50cc's. And I can not find anyone who has a sprocket available with this type of hole pattern...

Have tried contacting Dymag several times, and they will not respond in any way... even with replacement spacer questions

Any old school guys that have used these back in the day, or vintage racers that can help out here?

 

[a_morti]

Get a large expanding rawbolt and open it up in the centre of the bearing, this will give you something decent to strike against.

I believe Dymag has been through a change of ownership or two in the intervening years, you may have trouble getting info on old products?

http://www.talon-eng.co.uk/product_category/sprockets/road-road-race/
These guys make a lot of custom sprockets and ISTR they made original sprockets for Dymag wheels although I could be mixed up. They may know what you need, and if you supply measurements will make you some up even if it's not on their database.

Spacers are almost certainly going to have to be custom made, but at least that way you can get them in stainless or aluminium.

Cool wheels

Have you tried just ordering a sprocket and see how they react?
http://www.dymagsdirect.com/sprocket/

You wheel should have the part/type number on it somewhere.

Remember for those bikes people often used TZR125 wheels, so could be you have wheel for one of those fitted. Also widen your search with RD350LC, the European model designation.

 

[busa1300]

Guys at dymag just contacted me, and said they have no info on a wheel this old. So I should ship it to them so they can take measurements to make the right spacer....problem is, I'm in the USA, they are in the UK....

I've tried the expanding puller, and it will not stay in bearing...

The web site they have does not list the sprocket design I need...


Just got a great idea from guy who definitely knows his vintage racing....
Weld something to the bearing center... Then beat it out the other way with a long punch...
Going to try that tomorrow...

 

[busa1300]

I've tried every method of pulling, or hammering on these bearings...
I managed to get the rear ones out....still trying to figure out my next approach to the front wheel..as the welding method just breaks off the bearing where the weld penetration stops.

Can not push the spacer over in any way, as you can see by its design. And if I beat on the spacer,i t will be destroyed, and DYMAG said this wheel is so old of a design, they have no records...

 

[robtharalson]

Original Dymags? I'm jealous.

Regardless of the metal, when removing bearings heat is your friend. Having machined, welded (TiG and oxyacetylene), and cast magnesium you could say I have a pretty good understanding of it.

Having said that it must be pointed out that you don't need to get anywhere near melting temperature to remove bearings. A paint stripper heat gun held 6 to 10 inches away from the hub face and continuously moved to prevent hot spots for 3 to 5 minutes will usually expand the mag enough to have the bearing fall out of it's own accord. Repeat on the other side and Bob's your uncle.

An alternative is to place the wheel on a trash can to catch runoff and pour a couple gallons of near boiling water over the hub area. It's an old flat tracker trick that works quite well. Be careful to avoid splashing on your clothing causing scalding.

The new bearings can be installed by the same method, just remember to freeze the bearing for at least 1/2 hour before installation. In this case dry heat is preferred.

As to sprockets, Go Cart Galaxy http://www.gokartgalaxy.com/sprocket_blanks.htm carries aluminum sprocket blanks in most of the usual chain pitches and tooth counts with a 1" hole bored in the center. Boring out the center to fit the register of the wheel is a simple job for a machine shop. Once that's done make a transfer punch by getting a bolt with the right diameter and thread pitch to thread into the wheel, cutting the threaded end off of to about 3/4" length and file or grind one end of it to a point that is as concentric as you can get it. File two diametrically opposed flats on each side of the point so you can thread it in and out of the wheel with needle nose pliers. Once that is done thread it in to any of the sprocket bolt holes until the point is only ~0.05" above the surface of the hub, put the sprocket on the wheel and give it a light tap with a dead blow hammer to make a mark on it. Remove the sprocket, repunch the mark if necessary, and drill a hole just slightly larger than the diameter of the bolt. Put the sprocket back on the wheel with the hole opposed to the location of the transfer punch, run a bolt through the sprocket and into the wheel but don't tighten it down, lift the sprocket away from the punch and rotate it back and forth until it is as centrerd on the bolt as possible and tap on it to make a second mark. Drill that hole and repeat the process until all necessary hole are drilled. Do not try to mark all the holes after drilling the first one: it's tempting, but can cause "stacking tolerances" and an inaccurate bolt circle requiring enlarging the holes to compensate.

That's about it. Good luck.

Rob

 

[Cookie2000ad]

Cut it. Dremel and mini diamond discs + steady hand and patience. I had to do this last month.



I cut it as far as i could without cutting into the side / bottom of the bearing seat, maybe 3/4 though from the top then put a large flat head screw driver into the slot and hit it, splitting the last part, you can see the cut then the cracked off section best on the left of this photo. ^

That lets you get the center out, then the spacer. Then you can hammer out the far one using a socket, then the remains of this one with a bigger socket.

 

[87flatside]

Here's a link To Steve Turner he worked for Dymag for 20+ yrs he has his own shop now
He was a big help w/ my 2pc Dymags
http://tpcs-magnesium-refurbs.co.uk/

 

[busa1300]

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All figured out....
welded a steel bar the size of axle to inner bearing race and into the roller bearing area solid. turned wheel over and beat bar and bearing out as one piece... No amount of heat or cold helped at all.

New bearings in, spacers saved, brakes rebuilt, new chain, and sprocket numbers all figured out...
Also got speedo drive figured out, so I can tell how slow I'm going.........

 

[busa1300]

Just hooked myself up with another set of Dymags...
2.75x18 and 4.0x18....Originally for a first generation GSXR1100
Problem is the drive pin holes in rear wheel are busted up a bit.... And need to be reworked...

Any experience out there with welding on these...not sure if ends are aluminum or magnesium. The wheels are built up from 3 major parts, two ends and the wheel with spokes and open center circle.

 

[RatFighter]

I'm no help, but I hate (love??) you for the DYMAG wheel porn. :fu:











:doh:

 

[busa1300]

Real porn...heres a centerfold look under the skirt....