I hung up the main stand, but for some reason the front and rear tires are still on the ground. How did it happen? I found that the screw that tightens the footpeg bracket, which also serves as the mount for the main stand, to the crankcase was slack and about to fall out. In this case, a permanent thread repair is essential. This is where the “recoil” of thread regeneration comes in handy.
- Honda 4 mini tightened to the crankcase
- Recoil for permanent thread repair
- Drill the correct pre-hole size.
- Be careful of collapse when drilling and tapping.
- Air blow before recoil insertion
- This is safe! Stand up
- Perfectly stable even when standing on both legs on the footpeg.
Honda 4 mini tightened to the crankcase
I am building a custom off-road style machine based on a Honda Dax. The footpeg that is attached to the removed footpeg bracket was appropriated from the authentic and exaggerated off-road style footpeg for the Honda ATC185 three-wheeled baby carriage. This is a rugged footpeg, but the mounting conditions were not good, and the threads of the fastening bolts were raised (or damaged).
Recoil for permanent thread repair
The screw threads have been damaged, and the footpeg bracket cannot be fixed securely unless it is repaired properly. Recoil is a reliable ally in such situations. The tightening bolt size for the footpeg bracket is M8P1.25. Prepare a recoil that matches this screw size and pitch. For the length of the coil, I decided to use 1.5D, which is 1.5 times the length of the screw size.
Drill the correct pre-hole size.
When hammering in the recoil, some products come with a set of taps for the screw size and a drill for the preparation hole. Since the bolts are M10P1.25 size, I used an 8.3mm diameter drill as specified by the manufacturer. The motorcycle was laid on its side for the pre-drilling, and the pre-drilling was done while being careful not to collapse the drill against the slotted bolt hole.
Be careful of collapse when drilling and tapping.
Be careful not to fall through the crank case when drilling! Let’s proceed with the work without panic and haste. After checking the depth of the threads, it is also a good idea to wrap a piece of tape around the drill and use it as a guide for the machining depth. After machining the pre-drilled hole, the recoil tap is used to create the threads, but again, be careful not to let the tap fall backwards or forwards.
Air blow before recoil insertion
After finishing the tapping process, blow the inside of the threaded hole with air to thoroughly blow out the dust (chips), and slowly and carefully insert the recoil set in the insertion handle. Once it bites into the threads, turn it smoothly and lightly to insert it without pushing it.
This is safe! Stand up
The insertion process is completed when the end of the recoil dives about a half pitch to one pitch against the end face of the threaded seat. Place the push stick of the special tool on the 90-degree bent tongue part, and tap it lightly with a hammer to remove the tongue part. Let’s make sure we got the snapped off tongue part out of the bolt hole. Next, turn the tightening bolt with your finger to see if it goes in smoothly. Be sure to check it thoroughly. If it goes in smoothly it is fine, but if it is hard or reluctant, the insertion is considered to have failed.
Perfectly stable even when standing on both legs on the footpeg.
Excellent stability even when the motorcycle is standing on the main stand! Of course, the stability remains the same even when a large rider straddles the motorcycle and puts both legs on the footpeg. Dax of this era have a load distribution that is neutral or the front wheel floats lightly when the main stand is up.
- Point 1: There are various ways to regenerate the threads, but even in an engine, if the part is not directly related to the internal combustion engine, it can be repaired permanently by recoiling.
- Point 2: When drilling or tapping, be careful not to let the drill or tap fall over.
- Point 3: When inserting the recoil, concentrate only on turning the recoil, as pushing the recoil will cause failure.
There must be many Sunday mechanics who have faced such problems as bolts cannot be loosened during the process, bolts got broken, screw threads got stripped, and so on. 80% to 90% of broken bolts occur during the loosening process, and the number of problems where bolts break while being tightened should be extremely small. When I think back to events that happened in the past, I think the ratio is roughly like that.
It has often been said that rescuing (removal of the broken part) of a bolt that has been broken during tightening is easy. However, on the contrary, the fact is that it is extremely difficult to remove a bolt that has been broken in the process of loosening. The most common cause of this is when a bolt that has been torqued and loosened gets caught, and when the bolt tries to be loosened as it is, the threads and the bolt become frayed, causing the bolt to break off. The cause of the galling itself is thought to be dust contamination or rusting on the bolts. There is no way that a bolt that has been broken under a jammed screw state can be easily removed.
On the other hand, most of the bolts that have broken during tightening are thought to be caused by metal fatigue. If the end of the broken bolt is sticking out, you should be able to pick it up with a pair of pliers, and the broken threaded part should be able to be pulled out easily. It is also possible to screw in a bolt that is too long for the depth of the bolt hole, and break the bolt by continuing to turn it even though it is bottomed out. In any case, it’s very different from a bolt that seems to have crazed during extraction and broken as a result, and I think that problems during tightening can often be managed.
In the process of tightening bolts, when you try to apply the specified torque, you will find that the screw thread is not as tight as it should be. If the bottom of the threaded hole is deep enough to allow for additional threads to be tapped, emergency measures can be taken by replacing the bolt with a longer one. However, if the bolt has been completely nailed, a new thread must be made. When the counterpart is an aluminum part, such problems are more likely to occur, but the repair method using recoil can permanently repair and regenerate such thread problems. Some parts that require strength are not directly screwed into aluminum parts, but coils are inserted (hammered) from the beginning to ensure rigidity of the fastening part. For example, the OEM caliper brackets (made of aluminum) of Kawasaki Mach and Z2/Z1 models, which began to be equipped with disc brakes as STD, were designed with coils inserted in the fastening area to reduce damage to the threads.
Here, I have tried to practice repairing the threads of the footpeg mount at the bottom of the crankcase. Recoil is recommended for repairing threads in such places. A hand drill and tapping handle are essential for work progress. Blow the air after tapping, but you can also clean the inside with parts cleaner. The most important thing to keep in mind when practicing drilling and tapping is that the drill and tap should not fall from perpendicular to the mounting surface and progress at an angle.
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See Accessories for HONDA DAX70 (ST70)
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