A Hondasaki final drive

I see from your pics that you've machined a spigot for alignment fit on the flange. I hope you plan on setting it up with a root gap so that when the weldment cools the tube and the flange have some allowance to shrink together. In my pipefitting/welding days I saw a lot of slip on flanges that a previous welder had put together and bottomed out the flange on the pipe and welded it up thinking that the machined surfaces would keep the flange square to the pipe (which it did) and then 2-3 months later we would have a leak and find a crack in the weld right down the middle of the fillet because there was too much stress on the weld induced from the fitment of the two pieces before welding.

I'm also not a big fan of mig welding especially on structural welds. The penetrating qualities of mig are poor so there's little to no blending of the parent metals and the filler metal which can induce stress between metals of different hardness. If I were doing the welding I would be stick welding or tig welding. 1/4" tack welds in 4 locations for checking alignment and then if all is good, reinforce the tacks one at a time in a crisscross pattern to minimise the distortion with tacks that are about 3/4" long, feather the stops and starts of your tacks with a grinder and then finish the welds 1/4 segment at a time, one side then the opposite side , then diagonally opposites. Once it's all welded up, wrapped it in a fireproof blanket or insulation and let it slowly cool to minimise embrittlement of the weld area.

Just my 2 cents as a ticketed pipe welder who welded pipe at a nuclear power plant for 20 years.

I love what you're doing here and want to se you succeed. My big worry would be if the weld broke while you're up riding on it and the rear wheel breaks free on you. I see a lot of stresses in play here on that particular weld between the torque induced during power up and power down (torque of the motor) plus the forces acting on it vertically and horizontally (weight and side loads).

I also like you thinking on putting a sleeve over the drive shaft weld to help reinforce that area. It's a bit of overkill but better to do this then end up on the side of the road with a broken driveshaft. I have seen funny cars with narrowed rear ends made up using similar approach and all they do for the drive shaft is vee down the two halves so that they can put in a full penetration weld between the two half shafts and then they punch 2000 horse power through the weld with no issues. The only trick is to ensure the welded area has the same hardness as the rest of the shaft which means heat treating the entire shaft back to original design specs.

Kawboy,

Some great observations there! One in particular is the use of a root-gap. With other than thin-walled tubing (or, stamped/formed tubing in this case) I would agree with the root-gap practice, but with thin-wall material the maximum strength you can achieve is determined by the thickness of the tube itself. No matter how you weld it or how much penetration you can get, the thickness of the tube right along the weld is the determining factor. Hence, it is very important to not get any undercut, and to limit the heat buildup (Mig!).

The pics of the parts set together are a bit misleading to someone with your eagle eye for weld fitting. The end of the swingarm tube is still rough cut in the pics. Once I have my jig set up I will be able to tell just how much more material needs to be removed for alignment I plan about 1/8" gap to be able to penetrate all the way to the root and be able to do a slow weave pattern to fill it in evenly to the tube's edge. Considering how the factory welded this joint, and I've never heard of one breaking here, I feel quite confident in matching what they did.

We'll just have to disagree on Mig's ability to penetrate! If your goal is to blend (flow) the two parent metals together rather than fill with a correct alloy filler, then you are quite right. Tig should be used with a tight fit-up! For such small, detailed work as this I would never use stick. Not enough start and stop control. Although most Migs don't have this, my 250 Lincoln has a variable start-up voltage to get things going, then it tapers down a bit for travel.

Using the spark-test to identify the metals used here, Kawasaki didn't go exotic. Just some good old 1018 (or close to it) for the stampings and the castings, so S-6 filler wire will work fine.

I would also like to point out that Kawasaki uses MUCH thicker-walled stampings to make their swingarms than Honda. Just thumping them tells you that.

can,t wait for the demo ride rpm!!!good luck with that!c

Just wanted to update the project here. I now have all of my alignment mandrels done and I did a trial fit today. Everything was close enough to tell me that I still need to trim about 1/4" off the edge of the swingarm tube to get the rear axle parallel with the swingarm pivot axis.

The next step is to make up a jig frame (probably out of 2" angle-iron) that will locate the two alignment shafts and also hold them parallel and in the same plane.

There is a LOT of setup time involve in this first one to assure everything is just right. After all the welding is done with all of the shafts, mandrels and frame, it will be an easy job to make up a final jig from the finished swingarm that will line me up for a perfect cut on the next swingarm tubes and then will locate and solidly hold the Honda's flange exactly where it needs to be for welding. Won't even need to align everything with shafts and mandrels anymore.

First pic is of the shafts and mandrels. Second pic is of the shaft with one of the mandrels and tension spring in the swingarm pivot bearing. The reason for the spring is that the pivot bearings are tapered roller bearings and have to be lightly preloaded toward each other to correctly center themselves. The third pic is of the inside of the ring gear of the final drive showing the two surfaces I chose to use to index off of (arrows). The fourth pic is of the mandrel that aligns the whole final drive assembly to the alignment shaft. Colored arrows correspond to the arrows in the previous pic. The fifth pic is of the whole works basically assembled. The last pic isn't really clear, but it does show the very slight misalignment of the shaft to the swingarm end. By cutting about 1/4" off the swingarm tube where the flange will be welded, this alignment should fall right in place.

I forgot to mention one other issue that has been addressed on this drive. On the '84 Gold Wing final drive, the pinion gear shaft, where it protrudes forward and is bolted to the internally-splined driveshaft coupling, is drilled all the way through so that the gear oil in the drive case can slowly migrate forward to lube the splines between the driveshaft and the splined coupling. This is how Honda typically lubes their splined couplings. Kawasaki just uses grease to lube these same splined couplings. Both methods seem to work equally well, but Honda relies on a seal to keep things from getting really messy inside the swingarm tube.

I won't get into the details of why I can't use that seal anymore on my driveshaft hybrid, but I had to seal off any possibiity of gear oil from running through that pinion shaft. It's only about a .200" diameter hole and about three inches deep, so I made up an aluminum plug about 1" long with a shouldered head. Looks a lot like a miniature golf tee. I cleaned out the hole with lacquer thinner, then red-Loctite'd the plug into the hole. I made sure that the head of the plug didn't interfere with the fit of the splined end of the driveshaft when fully inserted. It's really a simple fix.

Looking good there Mister. Looks like you've got all the bases covered.
Have you got a trammel to check the center to center distances of your pivot shaft to axle shaft? Just curious.