Radius Arm Rebuild
To overhaul the Mini rear suspension trailing radius arms, I used a 13/16" hand reamer for reaming out the bronze bush. It cost me little more than the price of one radius arm repair kit.
The reamer I used has a helical flute with a tapered cutting edge, which is essential when you are reaming by hand. The tapered cutting edge enables the reamer to self centralise when it starts to cut the bronze bush. The other end of the reamer is guided by the needle roller bearing, this keeps things concentric. The reamer needs to be at least 9" long with a cutting edge of around 2" or more in length.
The other main tools to do the job is a length of threaded rod at least 14" long, and preferably 3/4" diameter with two suitable nuts, and two steel washers with a thickness of 1/8". The threaded rod is used to press the bush and bearing in.
Also used was a solid steel bar approximately 15" in length x 1/2" thickness, this was used to drift out the bush and bearing.
So, first I clamped the radius arm in a large vice. Then removed the pivot pin. Then using the solid steel bar (1/2" thick by approximately 15" long), I inserted it through the bush end, and located it on the edge of the bearing at the other end. Then I started tapping the bar around the edge of the bearing until it started to come out.
Once the bearing was removed, I inserted a hacksaw blade through the inside of the radius arm and then attached the hacksaw to the blade.
Next I made three cuts through the bronze bush, taking care not to cut into the body of the radius arm.
Once the cuts were made, the bush was bent in where the cuts were made. Then the bush was tapped out the same way the bearing was removed.
Now the grease guide sleeve can be removed. Some sleeves are plastic, like the one you will receive in the new kits available, the early ones are steel and require a bit more patience to remove.
This is what was removed from the radius arm. Plastic grease guide sleeve, needle roller bearing, and the bronze bush.
Two new radius arm repair kits to overhaul both sides.
After cleaning out the radius arm of all the old grease, I inserted the threaded rod, and fitted the nut and washer at the bush end. At the other end of the threaded rod the bronze bush was put in place before adding the washer and nut. Before the bush was pressed in, I smeared a bit of fresh grease around the outside of it before attempting to fit, this will stop the bush from sticking while being pressed into the radius arm.
With the bronze bush fitted, I then fitted the plastic grease guide sleeve. Note the sleeve is tapered, so the narrow end goes in first through the needle roller bearing end.
This is how the sleeve should look when fully seated in position.
Next I smeared some grease around the outside of the needle roller bearing, and pressed it in until flush with the radius arm, same proceedure as fitting the bush.
Now the reamer was carefully inserted through the bearing end at a vertical position.
Once the reamer gently made contact with the bronze bush, I started to rotate the reamer clockwise using a suitable spanner, and at the same time applying a small amount of pressure. IMPORTANT do not be tempted to turn the reamer the other way at any time, as this can damage the cutting edge.
Once the reamer appeared from the bush, care was taking to stop it dropping out and possibly damaging the cutting edge.
Next I washed out the inside of the radius arm with paraffin. Once the inside was clean, I smeared some fresh grease on the pivot pin and fitted it, making sure the hole in the pin for the grease nipple, was at the bush end.
At the bearing end the larger thrust washer was smeared with grease and fitted, making sure the grooved off set circle was facing inward towards the radius arm.
Next I fitted the spring washer and nut, though the nut and spring washer will need to come back off before fitting back to the subframe, but in the meantime it will prevent the pivot pin from sliding out.
Next I greased and fitted the smaller thrust washer to the bush end, again with the off set grooved circle facing towards the radius arm.
Next I fitted the grease nipple, taking care not to over tighten.
The grease seals were then fitted to both ends by stretching them over the thrust washers, and covering the stepped part of the radius arm.
The radius arm is now ready to fit back to the subframe, and pump it with grease until it is seen coming from the rubber seals.
Making The Brake Regulator Adjustable
The weight bias is all on the front of the car when braking, causing the rear wheels to lock up before the front. This mod will allow fine brake proportioning, and balance the brake pressure between front and rear.
Once removed from the car the regulator needed a good clean.
Underseal and muck removed
Next I stripped the regulator
Next I used the drain hole as a pilot for drilling a 10mm hole.
Below a 10mm hole has been drilled.
Then I tapped a 12mm thread into the drilled hole, and then cleaned out the regulator with paraffin.
Next with the regulator fully assembled, I inserted a suitable bolt until resistance was felt.
Then I measured 1" between the bolt head and the regulator. Then I removed the bolt and cut it to this length. Then I welded a piece of 6mm bar to the end to allow adjustment by hand. This way there will be no need for any spanners to adjust the brakes. However, to prevent the adjuster from moving from vibration, a locking nut can be fitted, and should be if the car is used on public roads, if so, it should also be mounted outside the passenger area. Mounting it in the engine compartment would be the most suitable position for a road car.
Then just to finish things off, I gave it a lick of paint.
Modifying The Battery Box
As the car is intended for competition use, I thought I would remove the bottom 3" of the battery box to gain ground clearance. This way I get to remove weight and not gain weight with a skid guard plate.
Steering Column Drop Bracket
I decided to make my own instead of fitting one of these
Metal cut and bent to shape.
Then welded together. See the difference in length to the standard bracket on the left.
Holes drilled to remove some weight, and then painted.
Before fitting a drop bracket, be sure to slacken off the steering rack "U" bolts before moving the column down to its new lower level.
To be continued