View Full Version : Piston Pin Retainer Problem

06-24-2007, 08:56 PM
This is a continuing story of re-using my current pistons, in a 65 FLH. These pistons have the snap-ring style "C" clip, that use a pair of snap-ring pliers to install/remove. On advice from a former harley dealer, I went to harley to get replacement rings. The p/n is 22588-78. They look identical to my original rings, but my originals had to have the ends overlapped to install or remove them. These new harley rings do not require any overlapping, and, and this is the big AND, after installing, I can rotate them with my finger; the original ones were very tight. This seems like a formula for failure.

Any ideas would be greatly appreciated!


06-24-2007, 09:14 PM
I forgot to mention one thing. The grooves in the pistons for the retaining clips have square edges, so it looks like that would not be a problem. Are there other styles of clips that would actually work, and be better to use in these pistons, or is it time for new pistons, pins, and clips?


Tom Lovejoy
06-24-2007, 10:39 PM
No engine builder by any means, but I have been in a couple, just assisting. A builder told me last time about keepers that you kind of thread in, he said they were a bit of a pain to put in but he had never had one come out. Same thing when taking them out, you have to get in there and kind of unscrew them. I have used the standard clips and mine would rotate with finger pressure, that worried me. I was told if their fully in the grove dont worry. Its been several thousand miles no problems - but it is a bit worrying. Expecially after you've seen a bunch of cylinders with damage from the clips coming out. I have been told the button idea is a good way to go also, like I believe Tommo suggested and I was told always use new also, good luck.

06-25-2007, 09:53 AM
Thanks Tom. I guess I had expected the new harley clips to be the same as the original ones.

06-25-2007, 02:10 PM
Try some clips from amother source. You'll waste more time than money, but I wouldn't run clips that you can turn with your finger, if they can move freely there would be a potential for wear. Dont forget to install flat side out.

06-25-2007, 11:39 PM
Thanks. I was planning on contacting Wiseco to see if they have clips that would fit stock pistons, and my machinist, to see what suggestions he might have.

06-26-2007, 12:06 PM
What about these?

06-26-2007, 03:19 PM
I think it should be said here that the condition of the circlip groove is just as important as the circlip itself and if attempts have been made to remove the circlip with anything other than the correct tools for the job the chances are that the groove has been damaged and compromised.
The main reason I have to fully float the gudgeon pins and use buttons like Kojack has indicated is because people have damaged the circlip grooves trying to get the circlips out using improper tools for the job.
You must always use the correct style circlip for the groove and not put a wire style circlip into a groove designed for a flat style one or visa versa. I have seen this done many times and when it fails the person wonders why.
Don't be tempted into putting a slightly larger dia circlip into yours in an attempt to tighten the circlip in the groove, any circlip used should pass nicely up the gudgeon pin bore when compressed with a set of circlip pliers and if they don't something is wrong.
If you don't know exactly what style of circlip your piston should have then take them to someone who can tell you exactly what they should be and don't be surprised if one piston has a different style to the other especially if one cylinder has been bored a different size to the other.
Never take anything for granted. Always check, recheck and check again as mistakes on this old stuff is not as easy to fix as it is on moderns where you just go to the agent and order new parts.
Hope this helps.


06-26-2007, 11:53 PM
Originally posted by Kojack
What about these?

I have something similar to this in a Ironhead Sportster that has a 4.5" stroker kit. The pistons and retainers were made by S&S.

06-27-2007, 11:21 PM
Thanks everyone. I have three possible scenerios:
1) I find the proper circlips.
2) I use the button retainers(I know nothing about these) and have my machinist modify the pistons for these.
3) I purchase a new piston, ring, wrist-pin, retainer kit, and have my cylinders bored 0.030 over.

06-28-2007, 07:14 AM
Do any builders here have good experiences with wristpin buttons? I've never been brave enough to use them. I've only seen them used in race applications, and those wore down very quickly. Of course, race conditions are not the same. But, I want life out of what I use. I'll just need a bit more convincing than I've had, from reading on other forums.


06-28-2007, 12:52 PM
I've never tried them but I've never heard any complaints about them either. I bought a used stroker kit that has them so I'll get a chance to try them one of these days. By the way, you don't modify the piston to use them, they just slide in. I would think that you'd have some kind of serious problem to put enough force on them to wear them out, that teflon is just about indestructable. I made a primary chain shoe out of teflon for my shovelhead after I melted a couple of plastic shoes and I've never had a problem with it since.

06-28-2007, 02:24 PM
I've heard that drilling three holes in the buttons is a good idea to relieve air pressure. So as to avoid having them pop out. If you you were to go that route of course.

Tommo summed this senerio up beatifully.

I would very much like to make a teflon chain tension shoe for my Indian. Quite it down a bit.

06-28-2007, 05:51 PM
There's more to it than just popping in buttons and away you go.
The pin must be full floating which means it must be what I call a light press fit in both the piston and the rod. You must be able to push the pin in and out with finger pressure only.
Ideally the internal bore of the pin should be parallel so that the button ends up looking like a top hat and when fitted you should have about 40 to 50 thou clearance. That is the assembled pin and buttons should measure about 40 to 50 thou less than the finished bore size.
One or more small holes in the button is essential to allow the trapped air to expand and contract.
The right material must be used and I'm not going to mention types here as we may call it a totally different name to what you call it over there. Anyone building drag racing engines will be able to put you right.
I dropped the 305 out of my Chev Malibu coupe and put in a pretty warm 327 about 40,000 miles ago and it has button retained gudgeon pins that have given no trouble what-so-ever in that time.
Like anything done right this type of pin retention will give you no trouble at all.
Almost forgot! The clearances given are greater than used in liquid cooled applications and if you are getting this done by an engine reconditioner be sure he knows and understands it is for an air cooled engine.
Gary, Don't let this discussion put you off using the pistons you have and please remember you only have parent metal once and if you bore the cylinders you have lost that parent metal forever.
When I do J motors over here the first thing I do is hone the bore until I have an acceptible finish and then finish the pistons to that bore size. I end up with some very strange bore sizes that very rarely match front to back but as has been said elsewhere this doesn't affect vee twins and the person riding the bike would never know unless he was told. I use piston blanks from an Australian company and get the rings made by a company here in NZ.
What am I saying. Don't remove any parent metal unless you really have to and at this stage if I read you right you don't have to.
Is this any help? Tommo

06-28-2007, 10:45 PM
Maybe the set of buttons that Jack saw worn out were caused by tight pins. Tight pins working their way out of a piston could maintain enough pressure on a button to wear it out. I've seen the top hat style of button. The S&S buttons are just plugs and evidently work OK also. They don't have holes in them either, probably because they're not that tight of a fit, but having holes certainly couldn't hurt anything.
AdminGuy, I'm getting off the subject here but, oddly enough, the teflon shoe whines more. This worried me for a while and I kept checking it. Usually the chain plates wore groves in the plastic shoes down to the level of the rollers fairly quickly. The teflon shoe shows only very slight grooving from the plates. It hasn't seemed to hurt anything but is definately noisier. BTW, I was experimenting with a sealed primary and ATF when I melted the plastic shoes. The teflon shoe held up fine but I couldn't seem to keep the ATF inside the primary. I got tired of chasing leaks and went back to the oil system.

T. Cotten
06-29-2007, 08:43 AM
I agree with just about everything that has been posted here, but I gotta add some perspective and a question.

No means of retaining the wristpin (gudgeon) will cure sidethrust from misaligned rods. Buttons just lengthen the fuse a little, as they cannot be kicked out or broken like metal retainers.
If the rods are really straight, the pin should never exert much force on any style of retainer.

Buttons were innovated for racing, but as Tommo points out, they are great for saving exotic or expensive pistons. Racers can occasionally manage to melt them, and sometimes particles of metal can embed to then carve into the cylinder wall, but most vintage machines will not be treated so harshly.

I am considering button retainers for a project where I wish to increase the reciprocating mass considerably. And I have a lot of scrap PEEK on hand, with superior temperature resistance and tensile strength than teflon.

So my questions are...

Shall I cut the buttons with press-fit tangs to hold them within the pin, and thus seal it? (Did that on my Knuck in the '80s, but haven't torn it down for inspection yet!)

How do I cut the radius of the outside of the button without a Holdridge?

Thanks in advance,


06-29-2007, 10:31 AM
Right Cotton, straight rods are important and should be checked anytime the cylinder is removed. It only takes a little effort and is easy enough for anyone to do. I bet that a lot of clip problems are caused by bent rods.

We used to have one of our small lathes set up with a very simple system to cut large radii. The lathe had a punch mark on the headstock, under the chuck and between the ways. There was a matching punch mark on the cross slide of the carriage. We had a several pointed rods in various lengths and it was easy to make up any length needed. The length of the rod was the same as the radius that needed to be cut. The handwheel of the carriage was used to hold pressure against the rod and keep it between the punchmarks. Then the cross slide was used to cut across the face of the workpiece. The carriage would follow an arc that matched the rod length. (I hope you can visualize all this) This system was a bit cumbersome to set up and the tip of the cutting tool had to be in line with the punch mark at the center of the arc but the cost of the system was hard to beat. You should be able to make up a moveable parallel with a punch mark to fit between the ways if you needed to move the punch mark away from headstock for some reason like a shorter radius, and, although we didn't try it, you should also be able to do the same thing using the tailstock if you want to cut a concave face.

06-29-2007, 11:02 AM
Go with your scenerio #3

06-29-2007, 01:58 PM
I have a friend that makes these buttons in his spare time...he swears by them...he wants me to tear my motor back apart this winter and let him make some for it....as much trouble as I has getting different clips this winter I may let him....I finally went to an implement company and purchased some internal clips....bought 6 for under $2...so far so good...Skip

rick anderson
06-29-2007, 09:56 PM
I personally do not like snap ring type lock rings, I have seen alot of trashed cylinders from these rings coming out. Also I don't know for sure if it matters witch side of the ring goes against the pin, because if you look close, the outer edge of the lock ring has a chamfer on one side, and a sharp edge on the other side, but I also noticed that if you look at a side view, holding the ring in the position when it is installed, the sharp edge is not square to the face of the ring, at least not the ones Ive seen.


06-30-2007, 10:30 AM
One thing that I just noticed in my big twin service manual, it states that you should not use the 22588-78 retaining ring in early style pistons, it will fit too loose. You should only use it in pistons marked "7" or "77" on top. I'm not sure how this applies to '73-'77 pistons which originally used the spiro-lock retainers. Are the later snap rings considered interchangeable with those? The spiro-locks are hard to work with and I've replaced them with snap rings on a couple of Sportsters but now I'm wondering if this is bad practice.

Rick, the manual doesn't specify which way to install the snap rings but standard practice would be to have the sharp edge facing out.

rick anderson
07-01-2007, 11:52 AM
I agree, but as I stated, the clips I've seen that come with the after market pistons are not a square edge to the face of the clip and I also agree that there should not be any presure from the pin pushing on the clip unless there is a bent rod or a crooked bore.

07-01-2007, 12:29 PM
Thanks everyone, for all the info!

T. Cotten
07-01-2007, 07:17 PM
One last note on the bent rod thing:

Lots of straight rods have shucked a clip for no other reason than they were loose as a goose.


07-02-2007, 02:21 PM
Thanks everyone, for all the info!


08-02-2007, 07:14 PM
Jack, I scoffed at teflon buttons, many years ago........until I took apart a flathead 80, with a ton of miles on it, and found teflon buttons that were so virgin looking, you could see the machining ridges on the surface that rode on the cyl. bore. They were the only good pieces in the whole top end!

Well, now, I've been a believer for a long time, and use them in every motor I touch.

The coeffiecient of friction/wear on teflon covered with oil is like a theoretical zero. Providing there is no severe pressure. So make sure to float the pin sufficiently.

08-03-2007, 04:33 PM
I'm open to try anything good. What is your source for teflon buttons? Or, do you make them yourself? If so, what are the specs to look for in selecting the teflon?


08-03-2007, 09:10 PM
I keep teflon rod on the shelf, and make them as needed. Teflon of any type all has about a 600 degree melt temp. Just don't use glass filled teflon, it's abrasive. Peek would be good too.

I don't subscribe to drilling holes. Just use a slip fit , button to the pin.

Holes in buttons plus tight fit, is a recipe for gathering oil in the pin, (up to hole level) and affecting balance, as well as having the oil boil, possibly making them overheated, expand, and turn your pins blue. (seen that too). Remember, your pin is exposed to lots of oil. (and should be). I also recommend some extra oil grooves in the pistons' wristpin bores.

Having straight rods is a given.

You'll be taking a top end off, and back on in a couple minutes, without pulling your hair out.