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Big-Serts®
Big-Sert® thread repair kits are designed to restore damaged or oversized threads that standard thread inserts can no longer repair. These heavy wall solid inserts provide a durable, permanent repair for applications requiring maximum thread strength and reliability.
Unlike traditional wire inserts, Big-Sert solid thread inserts feature a locking design that expands during installation to prevent backing out under vibration or repeated service. They are ideal for repairing holes that have previously failed or have been repaired with other thread insert systems.
ThreadKits offers Big-Sert repair kits in both inch and metric sizes, including spark plug repair kits and universal head bolt repair kits for automotive, industrial, and maintenance applications.
Big-Sert Inch Kits
| Kits | Insert Length | Carbon Steel Part No. |
||
|---|---|---|---|---|
| Thread Sizes | Part No. | in | mm | |
| 1/4-20 | TS5420 | .380 | 9.4 | TS54201 |
| .500 | 12.7 | TS54203 | ||
| 1/4-28 | TS5448 | .380 | 9.4 | TS54481 |
| .500 | 12.7 | TS54483 | ||
| 5/16-18 | TS5561 | .450 | 11.4 | TS55611 |
| .620 | 15.7 | TS55613 | ||
| 5/16-24 | TS5562 | .450 | 11.4 | TS55621 |
| .620 | 15.7 | TS55623 | ||
| 3/8-16 | TS5381 | .400 | 10.1 | TS53810 |
| .520 | 13.2 | TS53811 | ||
| .750 | 19.0 | TS53813 | ||
| 1.000 | 25.4 | TS53815 | ||
| 1.250 | 31.7 | TS53817 | ||
| 3/8-24 | TS5382 | .520 | 13.2 | TS53821 |
| .750 | 19.0 | TS53823 | ||
| 7/16-14 | TS5761 | .600 | 15.2 | TS57611 |
| .870 | 22.0 | TS57613 | ||
| 1.000 | 25.4 | TS57615 | ||
| 1.250 | 31.7 | TS57617 | ||
| 7/16-20 | TS5762 | .600 | 15.2 | TS57621 |
| .870 | 22.0 | TS57623 | ||
| 1/2-13 | TS5121 | .480 | 12.2 | TS51210 |
| .650 | 16.5 | TS51211 | ||
| 1.00 | 25.4 | TS51213 | ||
| 1/2-20 | TS5122 | .650 | 16.5 | TS51221 |
| 1.000 | 25.4 | TS51223 | ||
- Recommend using sealer 6020 on external thread of insert for added strength.
- Bold text are insert lengths supplied in kits.
Big-Sert Metric Kits
| Kits | Insert Length | Carbon Steel Part No. |
||
|---|---|---|---|---|
| Thread Sizes | Part No. | in | mm | |
| M5X0.8 | TS5508 | 0.300 | 7.6 | TS55081 |
| 0.394 | 10.0 | TS55083 | ||
| M6X1.0 | TS5610 | 0.370 | 9.4 | TS56101 |
| 0.470 | 12.0 | TS56103 | ||
| M7X1.0 | TS5710 | 0.394 | 10.0 | TS57101 |
| 0.800 | 20.0 | TS57107 | ||
| M8x1.0 | TS5810 | 0.460 | 11.7 | TS58101 |
| M8X1.25 | TS5812 | 0.460 | 11.7 | TS58121 |
| 0.640 | 16.2 | TS58123 | ||
| 0.708 | 18.0 | TS58125 | ||
| M10X1.0 | TS5011 | 0.360 | 9.0 | TS50111 |
| 0.600 | 15.0 | TS50113 | ||
| M10X1.25 | TS5012 | 0.550 | 14.0 | TS50121 |
| 0.800 | 20.0 | TS50123 | ||
| 0.960 | 24.5 | TS50125 | ||
| M10X1.5 | TS5015 | 0.550 | 14.0 | TS50151 |
| 0.800 | 20.0 | TS50153 | ||
| 0.960 | 24.5 | TS50155 | ||
| M11X1.251 | TS5112D | 1.180 | 30.0 | TS51125 |
| M12X1.25 | TS5212 | 0.360 | 9.0 | TS52120 |
| 0.600 | 15.0 | TS52121 | ||
| 0.689 | 17.5 | TS52122 | ||
| 0.950 | 24.0 | TS52123 | ||
| 1.180 | 30.0 | TS52125 | ||
| M12X1.5 | TS5215 | 0.360 | 9.2 | TS52150 |
| 0.640 | 16.2 | TS52151 | ||
| 0.950 | 24.0 | TS52153 | ||
| 1.180 | 30.0 | TS52155 | ||
| M12X1.75 | TS5217 | 0.472 | 12.0 | TS52170 |
| 0.640 | 16.2 | TS52171 | ||
| 0.950 | 24.0 | TS52173 | ||
| 1.180 | 30.0 | TS52175 | ||
- Not for Deep Holes
Spark Plug Inserts & Kits
| Spark Plug Kits | |
|---|---|
| Part No. | Desc. |
| TS5141S | M14X1.25 Spark Plug Repair Kits. Repair Oversized holes as large as .660 inches or 16.8 mm. “DO NOT” include inserts. |
| TS5141E | M14X1.25 Spark Plug Repair Kits. Repair Oversized holes as large as .660 inches or 16.8 mm. “DO NOT” include inserts. |
| TS5553 | Spark Plug Repair Kit for Ford Triton Kit Include (5) inserts. |
| TS5600 | (not recommended for virgin holes use TS5553 Kit) Ford Triple Oversized Spark Plug Kit M14X1.25 Repair holes from 17mm to 18.5mm or (.670 in) to (.730 in) |
| TS5588 | “Add On Kit” Ford Triple Oversized Reducer to M14X1.25. This is a special kit that is used in conjunction with (TS5553 or TS5141E). You must have 1 of these kits above to use this addon repair. The kit will repair holes as large as .730 inches by installing a special oversized insert that will accept our 3/4 reach M14X1.25 BIG-SERT inserts TS51459, TS51407 or TS51457 |
Universal Head Bolt Kits
Universal head bolt kits can be used in any application of bolt size listed right. A simple tool setup is all that is required.
| Universal Head Bolt | ||||
|---|---|---|---|---|
| Thread Size | Kit Part No. | Insert Part No. | Insert Qty. | Insert Length |
| M10X1.25 | TS6250BS | TS50125 | 10 | 25mm |
| M10X1.5 | TS7580BS | TS50155 | 10 | 24.5mm |
| M11X1.25 | TS11125BS | TS51125 | 10 | 28mm |
| M11X1.5 | TS2200BS | TSJ-42385-507BS | 10 | 30mm |
| M11X2.0 | TS3700BS | TS37004 | 10 | 30mm |
| M12X1.25 | TS4700BS | TS52125 | 10 | 30mm |
| M12X1.5 | TS4800BS | TS52155 | 10 | 30mm |
| M12X1.75 | TS4900BS | TS52175 | 10 | 30mm |
Tap Guides
Tap guides insure that the threads are square to the surface of hole.
Frequently Asked Questions (FAQs)
Big-Sert is a heavy wall solid thread repair system designed to restore oversized or previously repaired threads. It provides a stronger repair than standard wire thread inserts and locks securely into the parent material.
Yes. ThreadKits offers Big-Sert kits and inserts in a wide selection of SAE and metric thread sizes, including specialized spark plug and head bolt repair kits.
Yes. Big-Sert spark plug repair kits are designed for damaged or oversized spark plug holes, including applications where previous repairs have failed.
Big-Sert is commonly used when the original threads have been excessively damaged or when a previous thread insert repair has failed. Its larger outside diameter allows it to restore oversized holes while creating a strong, permanent repair.
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