Heat Shrink Boots
Raychem heat shrink boots and HellermannTyton moulded boots for professional wire harness boots applications — straight, 90°, T-shape, and Y-shape transitions in fluid resistant modified elastomer. Used across motorsport, aerospace, and automotive harness builds where environmental sealing, strain relief, and long-term high-temperature performance are required.
What Is a Heat Shrink Boot?
A heat shrink boot is a moulded part made from recoverable elastomer that is placed over a wiring harness transition point — typically at a connector backshell or at a cable split — before recovery with a heat gun. Unlike plain heat shrink tubing, a moulded boot is shaped to match the geometry of the transition: a single cable exit for straight and 90° boots, two or more exits for T-shape and Y-shape transitions.
After recovery the boot forms a tight environmental seal, provides mechanical strain relief, and protects cables against abrasion, vibration, and fluid ingress at the most vulnerable point in the harness.
Key characteristics:
– Material: Fluid Resistant Modified Elastomer — withstands fuel, oil, hydraulic fluid, and cleaning agents
– Operating temperature: -75 °C to +150 °C continuous
– Shrink temperature: minimum +135 °C (use a calibrated heat gun, not open flame)
– Adhesive: not adhesive-lined as standard — requires a two-part harness epoxy for a fully sealed system: HellermannTyton V9500 or its in-stock equivalent ResinTech RT125
Boot Shape Guide
| Shape | Branches | Typical use |
|---|---|---|
| Straight | 1 in / 1 out | Connector backshell — harness exits inline with connector axis |
| 90° (Right Angle) | 1 in / 1 out at 90° | Connector backshell — harness exits perpendicular to connector axis; tight chassis clearance |
| T-Shape | 1 in / 2 out | Main harness trunk splits into two branches |
| Y-Shape | 1 in / 2–3 out | Angled branch split from main trunk; more compact than T-shape |
Straight boots are the most common choice. Use a 90° boot when the cable must bend sharply immediately behind the connector — a straight boot would cause the cable to strain against the boot wall. T and Y shapes are used at harness branch points rather than at connectors; they are sealed with V9500 epoxy because the multi-branch geometry requires adhesive to fill any gaps at recovery.
Understanding Dimensions — H, J, P
Every Raychem and HellermannTyton boot datasheet lists three core dimensions. XTRA Motorsport lists all dimensions as as-supplied (unshrunk) → after recovery (shrunk).
| Dimension | Name | Meaning |
|---|---|---|
| H | Big End diameter | The large opening — fits over the connector backshell or harness bundle |
| J | Small End (port) diameter | The cable exit port — must be matched to the cable outer diameter after recovery |
| P | Total length | Overall length of the boot after full recovery |
| R | Entry length | Straight entry length before the boot shoulder (straight boots only) |
How to Select the Correct Moulded Boot Size
These are heat shrink moulded boots for wiring harness protection — not footwear. The sizing process is based on connector backshell diameter and cable outer diameter:
- Measure the connector backshell outer diameter → this must be ≤ H as-supplied
- Measure the cable outer diameter at the exit point → this must be ≥ J after recovery
- Confirm P (total length) gives adequate coverage over the strain relief zone
Example: Raychem 202A111-25-G07 — H: 17 → 7.9 mm / J: 17 → 2.2 mm / P: 25 mm. The 2.2 mm recovered J port suits a single 22–24 AWG wire. For a larger cable bundle, choose the 204W series with a larger recovered J.
Lipped vs Non-Lipped Boots
A lipped boot has a moulded retention lip on the large end (H port). The lip locks mechanically against the connector backshell groove or locking ring, preventing the boot from sliding back along the harness under vibration or strain. All Souriau 8STA and Deutsch AS connector boots stocked by XTRA Motorsport are lipped.
A non-lipped boot has a plain, open large end. These are used where the connector does not have a backshell groove, or where the harness transitions mid-run rather than at a connector.
| Series | Lipped? | Notes |
|---|---|---|
| Raychem 202A-G07 | Yes | Most popular straight lipped micro boot at Xtra |
| Raychem 204W | Yes | Smaller H diameter than 202A; shell size 6 / 8STA |
| Raychem 202K | Yes | Straight lipped boot — shells 08–24 (8STA / Deutsch AS) |
| Raychem 222K | Yes | 90° lipped boot — shells 08–24 (8STA / Deutsch AS) |
| Raychem 224W | Yes | 90° lipped boot — shell 06 / ASL / ASU |
| Raychem 202A (no G suffix) | No | Non-lipped straight boot |
| HellermannTyton 1030-4-G | Yes | Straight lipped — equivalent to Raychem 204W221-25-0 |
| HellermannTyton 1037-4-G | Yes | Straight lipped — ASU shell 03 |
| HellermannTyton 1181-4-G | Yes | 90° lipped — equivalent to Raychem 224W221-25-0 |
| HellermannTyton 176-1-G / 177-1-G / 178-1-G | Yes | Straight lipped, large diameter |
| HellermannTyton 102-1-G / 104-1-G | No | Straight non-lipped, various sizes |
Raychem vs HellermannTyton
Both brands manufacture moulded boots from fluid resistant modified elastomer to the same performance standard. HellermannTyton boots are a direct alternative to Raychem (TE Connectivity) equivalents at lower unit cost. The key differences:
| Raychem (TE Connectivity) | HellermannTyton | |
|---|---|---|
| Part number format | 202A, 204W, 224W, 322A series | 102-1-G, 1030-4-G, 1209-1-G series |
| Shapes available | Straight, 90°, T, Y | Straight, 90°, T |
| Temperature range | -75 to +150 °C | -75 to +150 °C |
| Adhesive lined | No (standard) | No (standard) |
| Shrink ratio (H) | ~2:1 | ~2:1 |
| Cross-reference availability | Industry standard | Documented per product page |
Raychem part numbers are more widely quoted in connector datasheets and assembly drawings, making them the reference standard. HellermannTyton equivalents are listed on every applicable product page at XTRA Motorsport.
Connector Compatibility
This table shows the recommended boot for each connector type stocked by XTRA Motorsport. Straight = inline cable exit; 90° = right-angle exit.
| Connector | Straight — Raychem | Straight — HellermannTyton | 90° — Raychem | 90° — HellermannTyton |
|---|---|---|---|---|
| Deutsch ASL (shell 6) | 202A111-25-G07 / 204W221-25-0 | 1030-4-G | 224W221-25-0 | 1181-4-G |
| Deutsch ASU (shell 03) | 204W221-25-G03-0 | 1037-4-G | 224W221-25-G03-0 | 1182-4-G |
| Deutsch DTM (E007 backshell) | 202A111-25-G07 | 1030-4-G | 224W221-25-0 | 1181-4-G |
| Souriau 8STA shell 4–6 | 204W221-25-0 / 202A111-25-G07 | 1030-4-G | 224W221-25-0 | 1181-4-G |
| Bosch Kompakt 2/3-pole | 202A111-25-G07 | 1030-4-G | — | — |
| EV1 injector connector | 202A111-25-G07 | 1030-4-G | — | — |
For harness branch points (no connector): use T-shape (Raychem 322A / HellermannTyton 1209-1-G) or Y-shape (Raychem 382A / 462A) with V9500 epoxy.
FAQ
At what temperature do heat shrink boots recover?
Minimum shrink temperature is +135 °C. At XTRA Motorsport we set the heat gun to 250 °C. When recovering a boot on a connector, start at the large end (H port) over the connector backshell and move the air flow evenly toward the small end (J port). This ensures the boot seats correctly against the backshell lip first, then the J port closes tightly around the cable. Do not use open flame — uneven heat causes incomplete recovery and bubbling.
Do I need adhesive with these boots?
Standard Raychem and HellermannTyton moulded boots are not adhesive-lined. For a fully sealed system — particularly in motorsport where the harness is exposed to fuel, oil mist, or water ingress — apply HellermannTyton V9500 Epoxy or ResinTech RT125 inside the boot before fitting. This is mandatory for T-shape and Y-shape transitions. If you need adhesive pre-applied from the factory: Raychem boots with the -225 material code (e.g. 202A111-25-G07 / 202A111-225-0) are adhesive-lined versions; HellermannTyton boots with the -24 suffix have adhesive pre-applied. After recovery, if excess V9500 squeezes out from the J port, wipe it clean before it cures.
What is the difference between Raychem 202A and 204W?
Both are straight lipped boots. The 202A series covers a wider range of sizes including larger H diameters. The 204W series is designed for micro-connector applications — the H diameter is smaller (11 mm as-supplied vs 17 mm for 202A111) and the part is shorter (P = 19 mm vs 25 mm). For Deutsch ASL, ASU, and Souriau 8STA shell size 6, the 204W221-25-0 is the correct fit. The 202A111-25-G07 also fits shell size 6 but with a larger H opening, making it more tolerant of backshell diameter variation.
Can I use HellermannTyton boots instead of Raychem?
Yes — the material specification and shrink ratios are equivalent. Each HellermannTyton product page at XTRA Motorsport lists the Raychem part number it replaces. The cross-reference is verified against dimensional data, not just catalog claims.
What is the J dimension and why does it matter?
J is the small-end port diameter through which the cable exits the boot. After recovery, J shrinks to its recovered value (e.g. 2.2 mm on the 202A111-25-G07). This must be greater than or equal to your cable outer diameter — otherwise the boot will not seal properly around the cable. If your cable is 3.5 mm OD, you need a boot with a recovered J ≥ 3.5 mm. Check the Diameter J attribute on each product page for both the as-supplied and after-recovery values.
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