How To Repair Stripped Out Aluminum Threads

Repair Stripped Threads In Aluminum

(Article and Pictures by Marker Trotta)

I of the bolt pigsty threads had stripped out on this 1965 Ironhead Sportster motor, which prompted engine disassembly and repair.

This article is a step-by-step on how to install thread inserts in aluminum. But outset, a quick mention on two other methods of repairing stripped threads.

Weld Hole And Re-Tap

If you happen to exist expert at aluminum welding, or willing to pay someone that is, damaged threads can be repaired by filling upwards the hole, and then drilling and re-tapping. This is the nigh permanent way to repair a stripped thread, only likewise the hardest and most time-consuming.

Enlarge Hole And Re-Tap

Another option for stripped thread repair is to drill a slightly larger hole and so tap new threads into it. Often times, this method may not be an option because of space constraints. It also takes a bit of originality away from the wheel, and having one different size bolt is often bad-mannered.

Thread Insert Kits

The most common way to repair stripped threads in aluminum is by installing a thread insert. Thread repair tools are commonly sold in kits, which include the inserts, a special tap for the inserts, and an installation tool. Some kits include the required drill fleck.

In that location are many styles and brands out at that place, 1 of the near well-known beingness HeliCoil.

The HeliCoil installation tool is a blackness plastic rod with a hook on the threaded end, and a square drive on the other.

I have several older HeliCoil kits with the diamond-mode handle. These besides work well, just the newer version makes it easier to install an insert deeper into a hole.

Stainless Steel Thread Inserts

The inserts that come up with the kit are made of stainless steel. When installed properly into aluminum, they give the bolt more than grip than the just threads in bare aluminum. And since the insert makes a stronger grip, if there are space constraints, the insert doesn't need to be the aforementioned verbal depth as the original thread.

Proper-Size Drill Flake

The first pace is to drill out the stripped hole with the recommended drill bit size. Some of the thread repair kits crave an odd-size drill chip. The 3/eight-16 HeliCoil kit I was using required a 25/64" drill bit.

Metal Chips Kill Motors

The small aluminum chips that the drilling action makes are mortiferous to an engine's oil excursion and bearings. Because of this business organization, most of the Sportster motor was disassembled to brand sure none of the metal chips would remain in the motor when washed.

After drilling the required size hole, chuck the foursquare bulldoze of the tap into a tap wrench. You can also use a crescent wrench or vise grip.

If you take a steady hand and adhered to the correct drill scrap size, the tapping volition go smoothly. Since I was tapping the new threads slowly by hand, I saw no demand for cutting fluid.

Next, install an insert on the lesser stop of the installation tool and a tap wrench on the top. Slowly plow it clockwise.

HeliCoil does not suggest calculation Loctite to the thread insert, although I suppose there's no harm in calculation a drib or two. I have never used any and have never had one come loose.

Blind Hole vs Through Pigsty

The majority of stripped thread repairs are for blind-holes, meaning the bolt does not come out the other side. When a commodities goes completely through (through-hole) the "tang" needs to be removed. It is not necessary to remove the tang unless it'south in the mode.

If a thread insert is besides long, you can cut it or grind it down to the length you lot demand. Conversely, if y'all need more thread, you can combine ii or more.

Here are links to the three nigh common coarse-thread, non-metric kits:

Shop: 1/4-20 Thread Repair Kit

Shop: 5/xvi-xviii Thread Repair Kit

Shop: 3/8-16 Thread Repair Kit

Helicoil Principal Thread Repair Kit (Coarse Thread)

This thread repair kit includes the 3 sizes above, plus seven/16-14 and one/2-thirteen, and then you get five installation tools, five drill bits, and 48 stainless steel inserts. It all comes neatly packaged in a plastic molded example.

Store: Helicoil Thread Repair Master Kit

Misc Notes

Disassembling the motor was a lot of extra piece of work, but the anaerobic gasket sealer I had initally sealed the engine cases with proved to be an easy clean-up.

Conclusion

When faced with repairing stripped threads in aluminum, always do what's all-time for the bike, even if it ways disassembling one-half the motor to practise it.

Read: Motorcycle Engine Build

Source: http://www.classic-motorcycle-build.com/repair-stripped-threads-in-aluminum.html

Posted by: manncamle1962.blogspot.com

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