ODDUWON
5+ Year Contributor
- 31
- 8
- Sep 29, 2018
-
NORWALK,
California
Anyone have some tips for installing a Big-sert in a previously repaired hole?
I was taking the exhaust studs out of a 1G head I bought on Ebay, first stud I turned broke. The rest came out after I heated and WD40'd em. Found 2 that were already heli-coiled, one was loose and wiggled side to side.
To get the broken stud out, +1 on the sharp center punch BogusSVO recommended here.
How to Remove a Broken Bolt
Also Cobalt steel drill bits cut very nice (made a spiral of the waste). Spent ~3 min centering before I struck the punch. Was half the point width off center, but being sharp, I was able to shift and re-punch closer to center. I used a 5/64" left-hand drill bit to pilot for a 5/32" left-hand bit for the #3 extractor (all from McMaster-Carr - USA made!), hoping it would back out without the extractor. When the large bit hit the end of the stud, it hung up and spun in the already tight chuck (keyed). Thank goodness I went with the cobalt, or I would probably have had a broken oxide bit to remove. Sped up the drill and feathered taped it the last bit.
I heated up the stump with a propane torch and sprayed WD-40 before each step. I tried to use the solder effect, where the heat pulls the solder in to the joint. kinda worked.
So I ordered a heli-coil kit 5546-8 (M8x1.25) to try and replace the coil in the loose repaired hole, but when I pulled the old coil out, I found a hole with shallow threads, bald spots, and what appears to be the end of a stud still in there. Other holes are 20mm deep (~26mm on the center one with the open oil return). The heli-coiled holes are 18mm and the one pictured is only 12 mm deep (still something left over in there from the last "repair").
M8x1.25 Heli-Coil kit tap takes a 21/64" drill bit. Tap OD measures ~25/64" to ~3/8"
Oversize to 10MM stud with a M10x1.25 tap takes a 11/32 size Drill bit (8.7mm) (~22/64")
ID of this repaired hole with is 23/64" right now with the coil removed.
Big-Sert for an 8mm stud uses a 13/32" drill bit (~26/64")
Anyone ever used this Big-Sert kit #5812 ? Do I need to get the Tap Guide for it? I think the bit in the kit will follow the hole, but should I eyeball it straight or use a drill guide?
Also, if there is still some stud/drill/tap??? in this hole, should I get a Cobalt bit to drill through it? The one in the kit is probably not a cobalt.
I was going to try BogusSVO's set screw repair solution, but the cost of the taps, drill bits, and set screws was close to $60+shipping, so I'm leaning toward the Big-sert solution since the price difference is minimal. BogusSVO's solution linked below.
Broken Exhaust stud repair
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I was taking the exhaust studs out of a 1G head I bought on Ebay, first stud I turned broke. The rest came out after I heated and WD40'd em. Found 2 that were already heli-coiled, one was loose and wiggled side to side.
To get the broken stud out, +1 on the sharp center punch BogusSVO recommended here.
How to Remove a Broken Bolt
Also Cobalt steel drill bits cut very nice (made a spiral of the waste). Spent ~3 min centering before I struck the punch. Was half the point width off center, but being sharp, I was able to shift and re-punch closer to center. I used a 5/64" left-hand drill bit to pilot for a 5/32" left-hand bit for the #3 extractor (all from McMaster-Carr - USA made!), hoping it would back out without the extractor. When the large bit hit the end of the stud, it hung up and spun in the already tight chuck (keyed). Thank goodness I went with the cobalt, or I would probably have had a broken oxide bit to remove. Sped up the drill and feathered taped it the last bit.
I heated up the stump with a propane torch and sprayed WD-40 before each step. I tried to use the solder effect, where the heat pulls the solder in to the joint. kinda worked.
You must be logged in to view this image or video.
You must be logged in to view this image or video.
So I ordered a heli-coil kit 5546-8 (M8x1.25) to try and replace the coil in the loose repaired hole, but when I pulled the old coil out, I found a hole with shallow threads, bald spots, and what appears to be the end of a stud still in there. Other holes are 20mm deep (~26mm on the center one with the open oil return). The heli-coiled holes are 18mm and the one pictured is only 12 mm deep (still something left over in there from the last "repair").
You must be logged in to view this image or video.
M8x1.25 Heli-Coil kit tap takes a 21/64" drill bit. Tap OD measures ~25/64" to ~3/8"
Oversize to 10MM stud with a M10x1.25 tap takes a 11/32 size Drill bit (8.7mm) (~22/64")
ID of this repaired hole with is 23/64" right now with the coil removed.
Big-Sert for an 8mm stud uses a 13/32" drill bit (~26/64")
Anyone ever used this Big-Sert kit #5812 ? Do I need to get the Tap Guide for it? I think the bit in the kit will follow the hole, but should I eyeball it straight or use a drill guide?
Also, if there is still some stud/drill/tap??? in this hole, should I get a Cobalt bit to drill through it? The one in the kit is probably not a cobalt.
You must be logged in to view this image or video.
You must be logged in to view this image or video.
You must be logged in to view this image or video.
I was going to try BogusSVO's set screw repair solution, but the cost of the taps, drill bits, and set screws was close to $60+shipping, so I'm leaning toward the Big-sert solution since the price difference is minimal. BogusSVO's solution linked below.
Broken Exhaust stud repair
