The FIR Timing Chain Camchain Breaker/Rivet Tool

When working on motorcycle camchains one thing that quickly becomes evident is that there is usually a need to break and rejoin the camchain. This will arise either because the new chain is too long or because a continuous new chain just cant be fitted short of a bottom end rebuild. Many new camchains are actually supplied with a joining link to overcome these problems. However, this is a rivet link. It is most certainly not the reusable type of  chain master or clip link found say on drive chains, and although such links are available in size 25, they are for use in external drive chains in small monkey-bikes and the like. All sources agree that this type of link should never be used in a camchain and the rivet type is essential. 

However, although they can break smaller chains, most motorcycle chain tools cannot rivet anything smaller than a 35. My moped uses a 25H chain but thesezare expensive precut to the correct length (70 link)and so I bought an 80 link Chain for shortening and joining. This was DID item 741.16.89. It comes with a rivet type master link. I bought this FIR tool specifically because it stated that it can both break and rivet a 25 size chain. If you have come here hoping to find out how to use this tool then you may be disappointed- exactly as I have been. I will say here and now that although it can split a 25H camchain, and press on a chain side plate, I can't find any way that it could rivet or flare the master link on  a chain that size. In fact its design would seem to make that function impossible.

Clearly what is needed is a comprehensive set of instructions akin to those provided with other rivetter/breakers like the Sealey VS779 which I have often used. However my tool arrived with no instructions and not even a parts or assembly  diagram. Naturally I wrote to ask for then and was astounded to find that the makers DO NOT PRODUCE ANY INSTRUCTION LEAFLET AT ALL!!! They could also offer no guidance whatever apart from taking pains to inform me that correct use of the tool is essential... however the manner of its correct usage appears to be a company secret.

TOOL AS RECEIVED

UNPACKED

What follows is my description of the tool and the results I got attempting to use it.

The tool consists of 5 components, none of which are marked.

The central part is an "H" shaped aluminium casting with a threaded hole in each arm. Im calling this the manifold. The holes in two of the arms are lined with steel threaded nuts, and 2 are threaded directly into the aluminium. The steel nuts are again internally threaded. They look identical and both protrude into the void of the H, but one of them has a narrower protrusion than the other and is marked with a groove. I think they are not intended to be removed.

There are 4 black threaded inserts; 2 large size, which thread directly into the threaded holes in the aluminium arms (in either position), and 2 smaller ones that thread into the steel inserts. These would also thread into either position. One of them however is marked with a groove and is presumably intended to be fitted into the silver nut that is also marked this way. Those threading into the aluminium have a knurled thumbscrew on one end whilst those fitting into the steel liners have hex bolt heads. The tool also came with a spanner that fits the hex heads. Taken together this suggests that the thumbscrews are for hand tightening to position the chain, whilst the spanner, hex head and steel threaded mounts suggest that these two are intended to exert force in the riveting and breaking procedures.

Although they have the same thread, the 2 smaller fittings are not the same; one ends in a 2.0mm probe, whilst the other ends in a shorter but fatter (2.3mm) probe. When screwed into the silver nuts the thinner probe projects right through whereas the thicker does not emerge from the silver nut.

I'm calling the shorter and wider fitting (on right here) the Anvil probe (guess?), the thinner and longer probe (left) I'm calling the breaker probe. Note that the anvil will screw into either of the steel fittings but the end will not protrude from either.

The larger screws have interchangeable threads. One has a hollow end, I'm calling this the roller pin receiver and the other has a spring-loaded projection. I'm calling this the alignment guide.

Pin receiver stud on left, alignment pin on right

pin receiver is hollow (top) and alignment pin projects (lower).

OK so how is this used? There is only one, poor quality photo available and literally this is all. It doesn't help much.

The picture shows the tool in use for both breaking and rivetting. The important details are of course which of the 4 threaded plugs is positioned where? Secondly, which way round is the chain link? By that I mean the master link... this consists of a plate with 2 pins prefitted, and a second plate to be pressed onto the other side of the chain.

The question is then which side goes against the spring loaded alignment pin and which against the anvil... see on.

Firstly although the 2 silver nut inserts look the same, their width on the inside of the H does differ. This is just visible in the photograph, and the side with the narrower projection into the gap of the H is the breaking side. On closer inspection it would seem that both the silver nut on the presumed breaking side abd the breaking pin are marked with a groove.

... presumably to indicate that they go together? 

Grooves on chain breaking side

Close examination shows that the black knurled plug fitted on the break side in the photograph supplied has no projection. It is therefore the roller pin receiver as anticipated. The hex plug added above it does project through and the probe end is visible so this must be the pin breaking plug with its longer probe. Operation would then see to be;

Fit the Breaker pin into the tool above the pin receiver. Withdraw the breaker pin into the silver holder by screwing it up inside. Place the chain between the 2 studs aligning the target pin inside the hollow of the pin receiver and tightening the knurled receiver to hold the chain. For breaking it doesn't matter which way round you have the chain.

Screw the breaker pin down until it contacts the other side of the target pin.

Grip the chain between the silver pin guide and the black pin receiver by tightening the knurled black screw by hand. Make sure the roller fits into the hollow of the pin receiver

 Use the wrench to screw the hex head of  the breaker pin down allowing the pin to push the chain roller pin out and into the receiver. It's good practice to grind or file the flare on the pin breaker side so that it can pass easily through the chain and out. On these small chains (25H) this grinding is not absolutely necessary.

use the wrench to screw out the breaker pin so that it displaces the chain roller into the receiver stud.

Plate Pressing.

It seems that master links actually come in 3 types: the clip reusable type that has no place onside a crankcase, the rivetsble type used in larger chains like motorcycle drive chains and a third the Pave Lock type where the free plate on the master link is an interference fit and binds irreversibly onto the pins of the link as it's pressed on. No rivet or clip is necessarily required although sources differ as to whether the pins need peening after fitting. Small chains, it appears are often of this "Pave link" type.... although they may often be described as "rivet" links. This is the basis of much confusion.

The picture doesn't have an illustration entitled "plate pressing" although I suspect it would look the same as that marked "riveting".

For pressing a plate my best guess is that first you should measure the width of the chain between two external links.

Fit the master link into the chain and place it between the anvil pin and spring-load alignment pin. Orient it such that the plate with the 2  pre-mounted rollerpins is against the alignment pin and the free ends of the pre-mounted roller pins are towards the anvil.

Position the locking plate over the free heads of the master link where they protrude through the chain and holding everything in position, tighten the knurled handscrew until the chain and spare plate are gripped lightly in the tool.

Check the position of everything, the free end of the master link rollers should be positioned in line with the holes in the locking plate with one of them directly over the receiving area of the anvil. The pin of the alignment screw should be centred on the opposite side of that roller pin.

Tightening the knurled screw by hand, or gently with pliers, pushes the alignment pin into its housing against its spring, until its surround comes to bear on the side plate of the master link around the roller pin. Check alignment again and then continue tightening the knurled screw. This is now pressing on the plates together on both sides of the chain, and there is no more pressure on the roller pin. This squeezes the locking plate down the pin of the master link.  Press only a little,  noting that the roller pin enters the void above the anvil as it emerges from the locking plate. Stop and reposition to tool to press the second pin through the locking plate. 

It is possible that the recess depth of the anvil is a guide for the amount of "press" required since it acts as a "stop" for the emerging roller pin. I'm not sure about this though, so I check the chain width achieved with calipers so as not to over press. The plates should not bind on the side of the chain and there should be no stiffness at the joint. If there is you will need to press out the rollers to separate the chain and start again... preferably with a new master link.

Riveting

The picture doesn't help much with the assembly for riveting. Presumably it is using the same two fittings as for plate pressing above.

The trouble is that this arrangement does not seem suited to applying significant pressure to the roller pin itself to flare it. In fact it seems designed to press on the chain side plates and specifically not the roller pin!

For riveting or flaring to work, the chain roller pin of the masterlink needs to be squeezed by the riveter and whatever applies force to the pin has to do so at both ends of the pin itself, not the side plates. On one side the pin presumably should contact the anvil surface and on the other, it would contact the a rivet pin... as used in say the Sealey chain riveting kit. A rivet pin is solid and well suited to supplying force, however this tool has no such fitting. Thexalignment pin cannot act in this way since its heD simply recesses as pressure is applied until force is raken by the side plate. This defeats the process of riveting. On the other side of the link, the anvil pin does not and cannot project beyond the silver threaded mount and remains recessed even when screwed fully home. Consequently, although it does bear a hex nut for wrench tightening, it can't move any farther. This means that it is not capable of compressing anything either!

  

Anvil pin recessed below surface of the silver nut mount when screwed fully in.

It may be that this setup works better with larger chains, although Im not sure even about this, but it was advertised for camchains and I bought it specifically for the 25H. This it cannot rivet or flare. I have found that some master links are intended to be locked into place simply by pressing the second side plate into place; flaring is not necessary for these pave link fittings and this tool would be able to accomplish this. I dont know how to identify this type of fitting, but perhaps these are simply the norm for these very small chains. In any event I can see no way that this tool could achive the flaring or rivetting required in a true rivet link.

Of course I may misunderstand the use and purpose of this tool entirely. However, I'm going to attribute this to the complete lack of guidance or advice from the suppliers and manufacturer of the chain tool. One fuzzy, out of focus and unclear photograph is just not good enough, especially as the suppliers attach such importance to this tool's correct use. If anyone does know how this tool should be used on a 25 camchain I really would like to know, and I will happily amend this blog to include the instructions.

Well HAPPY DAYS!! I eventually heard back from DID themselves ... the chain I'd bought is a 25H camchain part number 741.16.89. DID confirmed that this is the Pave Link type requiring pressing but not riveting/flaring. This greatly simplifies matters and means that this tool is well up to the job. However to continue my moan above, it would be lovely if chain manufacturers like DID could actually state this somewhere on the box and not refer to these master links as "rivet type"!!!