How to repair a broken joint

 Multi section wheels are joined by two of four pairs of pins and sockets. Older wheels used pin diameters of about 16mm, and over time these pins have a tendancy to fracture.

Newer wheels have pins of 20mm diameter with a bigger radius at the root of the pin and these are unlikely to fracture unless maltreated.

The pins and sockets are welded to the rims and great care must be taken to ensure absolute accuracy when the pins are replaced, or the wheel will suffer from a permanent and incurable wobble.

Do not try to replace a joint yourself unless you have a good workshop and the requisite skills. You will need welding, cutting and grinding equipment and the skills and experience to do an accurate job. You may also need a lathe.

Stages in the replacement of a joint with a new 'Standard Joint'

You can get new joints ready made from the normal Rhoenrad suppliers.

The following instructions are for a standard joint, but if you are replacing a joint in an old wheel, try and get long joints as these make the job much easier, then follow my instructions for long joints

Peel back about 25 Cm of the PVC either side of the broken joint
Measure and mark very carefully the exact position of the joint. The picture shows the new socket laid on the wheel so that the cutting point can be marked. The same must be done with the pin end. You may find it easiest to assemble the wheel before marking these positions.

Cut out the old joint. This can be done with a hack saw, but the steel is hard and it will take some time. The old joint will be solid so you will be cutting into solid steel, not a tube

If you leave the rim a bit too long you can grind it off. If you cut it too short you will have problems. Take care!

Grind the cut ends of the rim to ensure that they are the right length and absolutely square. The problem now is to make the new pin register centrally on the rim. I did this by marking the centre of the end of the rim, pop marking it and drilling a 13mm hole in the centre.

This is probably the most difficult bit of the operation, but it is crucial to doing a good job. The end of the rim should be blued and the position of the hole marked with several lines to ensure that the hole is central.

 

Try not to let the swarf get inside the rim or it will rattle as you roll!

The new pin looks like this, it is designed to fit into the end of a tube, but as the end of our tube is the solid end of the old pin, it is necessary to turn down the pin base to fit our 13mm hole

Here you can see the base of the new pin turned down to 13mm so that it will fit the hole drilled in the end of the rim

The pin can now be pushed onto the end of the rim. The pin must be turned so that the dimples for the clamp bolts are lined up with the inside of the rim. This pin can now be welded into place

The socket end of the rim must be similarly ground to length and square to the rim. Again you cannot locate the new socked inside the tube, so you must turn off the end of the new socket which was designed to go inside the tube.

Now you should assemble the wheel with the new socket bolted in place over the new pin, all being well the rim end of the new socket should align pretty well with the end of the rim. Using clamps or whatever you have to hand, centre the socket to the rim and clamp it tight while you weld the joint.

Finally grind down any roughness or protruding weld before glueing back the PVC covering

 

Use of Long Joints

The use of long joints will make your job much easier and quicker as you can saw through the rim tube and not the solid steel of the old joint

If you have obtained some long joints then follow these instructions.

Peel back about 25 Cm of the PVC either side of the broken joint. I then assemble the wheel and make two pip marks with a punch, either side of the joint and an exact distance apart. This helps accurate assembly later.
Measure and mark very carefully the exact position of the joint. The picture shows the new long socket laid on the wheel so that the cutting point can be marked. The same must be done with the pin end. You may find it easiest to assemble the wheel before marking these positions.

Cut out the old joint. This can be done with a hack saw.

If you leave the rim a bit too long you can grind it off. If you cut it too short you will have problems. Take care!

Grind the cut ends of the rim to ensure that they are the right length and absolutely square.

The new 'long joint' pin looks like this and will fit into the end of a tube. As the tube is likely to be slightly flattened, you may have to do some careful work with hammers and a file to ensure a good fit.

The pin can now be pushed onto the end of the rim. The pin must be turned so that the dimples for the clamp bolts are lined up with the inside of the rim. This pin can now be welded into place

The socket end of the rim must be similarly ground to length and square to the rim. you can locate the new socked inside the tube, again you may need to hammer the tube and file the socket to get a good fit into a slightly flattened tube

Now you should assemble the wheel with the new socket bolted in place over the new pin and align the wheel sections using the pip marks punched earlier and weld both the pin and socket ends to the rim.

Finally grind down any roughness or protruding weld before glueing back the PVC covering

 

Please email me with any comments or suggestions and I will include them on this site