Custom Pivot Bolt

Hey guys,

I've been trying to source someone to make me a new pivot bolt for my zephyr swingarm swap on my 650. I need to go fro m a 16mm to a 17mm bolt. I haven't found anyone local that has a die larger than 10mm to turn the threads.

I've received a couple of online quotes for around $180usd.

Does that sound right on the price or should I be able to find someone cheaper?

I've also tried to source some metric tube to make a sleeve, but I haven't been able to find the right size.

Any suggestions?

Any good machine shop can use a lathe to turn threads on a shaft.

Or you can buy one of these for $16.12 plus shipping.
(Ignore the 1/2x20, the link takes you to a M17x1.5)




From MSC www1.mscdirect.com/CGI/NNSRIT?PMPXNO=12344053&PMT4NO=43009867

But you'll probably need a handle also for $6.16 plus shipping.



Also from MSC

www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1721812&PMT4NO=43010378


Or just take it to a machine shop, but that will probably cost more ($50 hour, 1 hour minimum).

And instead of a sleeve, you could just drill out the pivot bolt holes in the frame.

Thanks Steel!!

I think I'll go that route.

I think I found a place to buy the metric stainless bar, as long as they don't have a minimum order!

if you have a zephr swingarm bolt how about just boring it out on a lathe and ushing it as a bushing?

PLUMMEN wrote:

if you have a zephr swingarm bolt how about just boring it out on a lathe and ushing it as a bushing?

Easier said than done

17mm - 16 mm = 1mm
1mm = approx .040"
That's a wall thickness of .020"

ID is 16mm, that means the largest boring bar that's going to work is 1/2" (12.7mm), bolt is approximately 12" long, that means the boring bar is going to be hanging out of the holder by at least 12.5". That means that the boring bar is going to flexible as heck, no rigidity as all, chatter and squeal (think ear plugs) and very unlikely to make a round hole.
Beyond my capabilities, can Solmrus do it?

Now, why stainless? Less tensile strength than some of the other alloys, and a total bear to thread. Stock pivot bolts aren't stainless (on the KZ's anyway), 1018, 1045, or 4140 (overkill) would be better, in my opinion anyway. Stay away from 12L14 or drill rod, 12L14 rusts easy and drill rod lacks the tensile strength needed.
Whatever you use, buy some cutting fluid (like Tap Magic) to use when cutting the threads.

That's why we just enlarge the pivot bolt holes in the frame to 17mm

Cutting fluid, die and handle are on the way!

I was going to use stainless based on someone else's zephyr swap.
That was the only basis for my decision. I'm now trying to find someone to sell me some 1018 or 1045.

Steell, thanks again for all the info, it is much appreciated!

I think the easier thing to do is have new races made for the Zephyr bearings. That way you're not going to have to bore the frame and have the bolt and crush tube made. Sometimes you get lucky and the bearings are the same and you can just swap out the stock races between the two arms.

Later, Doug

StreetfighterKz, I don't understand what you are saying, am I missing something?

The bearings are needle bearings, roughly an inch or so long, and the actual bearings fit inside a race with a lip on each end to keep the bearings from sliding out. The race is hardened and ground to final tolerance with an ID grinder, and not something your average machine shop is going to be able to make.

This does give me another idea that I hadn't thought of though. How about removing the needle bearings and replacing with sleeve bearings? There are places that specialize in doing this for racers because at least some racers consider the sleeve bearings to have less flex than the needle bearings. And some (at least) of the earlier KZ's used sleeves bearings (bushings) instead of needle bearings (76-77 KZ750 twin for example).
The sleeve bearings (bushings) would be a whole lot easier to make than a full length sleeve, a new pivot bolt, or a bearing race.

I'm going to give that some more thought and take some measurements, have to do something about seals also.

The Zephyr arm is different from the stock 650 arm in that it doesn´t have the caps on each side but a flat end spacer (red box in the pic below) that fits inside the pivot tube and over the sleeve - the bearings are sunk into the pivot tube about 5 mm, the sleeve is exactly the same width as the pivot tube.

With the end spacers installed the Zephyr arm is exactly the same width as the stock 650 arm with the caps installed - if you add any width to the Zephyr arm whatsoever it won´t fit between the pivot studs on the inside of the 650 frame.

By far the easiest solution is to have a 17mm pivot bolt made (or find one that fits) and drill the frame - the way mine is made is simply a length of round bar threaded at each end with a dome nut on both sides.

Btw Phil, sorry if I gave you the impression that you needed stainless, that´s just what I chose for no other reason than that I´m passionate about rust - I hate it with a vengeance. I realize it has less tensile strength than other alloys but so far I have been running it for a couple of years with no problems.

I posted a write-up about the swap over at KZ650.info, here´s a link - you might need to be registered/logged in to see the pics.

It seems like there is no single solution for all the different swingarms, different things have to be done for each model of swingarm.

In my case (83-85 GPz750 swingarm, KZ750E frame) it's either two new sleeves (long one and short one) or drill the frame to 17mm and cut down the inside of the pivot bolt hole bosses on the inside.
The 83-85 GPz swingarm uses the needle bearings, but it also uses a roller bearing on one side, so that limits me to the above two options, unless I want to re-engineer the swingarm pivot anyway, and that would make things entirely to complicated for me.

Well, if it was easy it wouldn´t be any fun, would it?