Universal U Bolts with Fitting Position Front Axle, Rear Axle for TOYOTA HIACE LH, RZH 100, 103, 113, 125

Nolathane universal U-bolts clamp the leaf spring pack to the axle on your LH, RZH 100, 103, 113, 125 HIACE, as well as trailers and caravans. Selected by inner width, length, thread size and top profile rather than make and model, they are a dependable choice for trailer U-bolts, leaf spring rebuilds, lowering block installations and axle work where the original bolts are corroded, stretched or the wrong size.

Each listing shows the inner diameter, length, thread size and top style, so you can match the U-bolts to your axle and spring plate before ordering.

The Role of U-Bolts in LH, RZH 100, 103, 113, 125 HIACE Leaf Spring Suspension

On a leaf-sprung axle, the spring pack sits on a perch or pad on the axle housing. A centre pin through the spring locates it on the perch, while U-bolts wrap around the axle and pass through a spring plate (also called a U-bolt plate or saddle) on the other side. When the nuts are tightened, the U-bolts clamp the spring, axle and plate into a single, solid assembly.

That clamping force does more than hold the parts together. It creates the friction that stops the axle shifting on the spring under braking, acceleration, cornering and load. The centre pin only locates the spring; it is not designed to carry those forces on its own. If U-bolts loosen or stretch, the axle can move, the centre pin can shear, and the vehicle or trailer can become unstable.

Types of U-Bolts

Round Top U-Bolts

Round top U-bolts have a curved bend that wraps closely around a round axle tube. They are common on trailers, caravans and many rear axles, where the U-bolt sits directly against the axle housing.

Square Top U-Bolts

Square top U-bolts have a flat top and square corners. They suit square axle sections and applications where the U-bolt clamps over a flat pad, block or spring seat. Choosing the correct top profile ensures the bolt sits fully against the axle or pad and clamps evenly.

Spring Plates

Spring plates sit beneath or above the spring, opposite the axle, and provide the holes the U-bolt legs pass through. They spread the clamping load across the spring and often include mounts for shock absorbers. A plate that is cracked, bent or heavily corroded should be replaced along with the U-bolts.

Choosing U-Bolts for Your LH, RZH 100, 103, 113, 125 HIACE and Trailer

Correct selection is essential for a secure axle. Measure and check:

• Inner diameter or width: The distance between the inside of the two legs. It must match the axle tube diameter for round top U-bolts, or the width of the axle or pad for square top U-bolts.
• Length: The inside length of the legs, measured from the inside of the bend. It must be long enough to pass through the axle, spring pack, any lowering block and the spring plate, with full nut engagement and a few threads showing.
• Thread size and pitch: The thread must match the nuts, and larger, heavier vehicles generally use larger diameter U-bolts.
• Strength and finish: High-tensile U-bolts suit heavy loads and towing. Corrosion-resistant finishes are valuable on boat trailers and vehicles used near salt water or on dirt roads.

If you are fitting lowering blocks or thicker spring packs, the U-bolts will need to be longer than the originals. Compare your measurements with the details in each listing.

Fitting U-Bolts Correctly on Your LH, RZH 100, 103, 113, 125 HIACE

Support the vehicle or trailer securely on stands under the chassis, and support the axle with a jack. Work on one side at a time so the axle stays located.

Remove the old nuts, U-bolts and plate, and clean the axle pad, spring and plate. Check the centre pin is intact and seated correctly in the perch. Fit the new U-bolts so they sit squarely against the axle, then fit the spring plate and new nuts.

Tighten the nuts gradually and evenly in a cross pattern, so the spring pack is clamped flat and the legs stay parallel. Finish by tightening to the vehicle or axle manufacturer?s torque specification. If the legs are trimmed after fitting, leave at least full nut engagement plus a few threads, and dress the cut ends to prevent thread damage.

Always fit new U-bolts and nuts rather than reusing old ones. U-bolts stretch slightly when they are tightened, and a used bolt may not hold its clamping force when re-torqued.

Trailer U-Bolt Maintenance

Trailer U-bolts work hard and are often neglected until something goes wrong. A simple maintenance routine helps keep the axle secure:

• Re-check torque after fitting: Check the nuts after the first short trip and again after the first loaded journey, as the spring pack and plate settle.
• Inspect before long trips: Look for loose nuts, rust, cracks, bent legs or damaged threads.
• Watch for axle movement: Shiny marks or gaps between the spring, axle pad and plate can indicate the axle has shifted.
• Wash after salt water use: Rinse boat trailers and vehicles used on beaches to slow corrosion.
• Replace when in doubt: Corroded, stretched or damaged U-bolts should be replaced, not re-tightened.

Carrying a spare set of correctly sized U-bolts and nuts on long trips is a practical precaution, especially for trailers and caravans travelling remote roads.

Signs Your LH, RZH 100, 103, 113, 125 HIACE U-Bolts Need Replacing

Worn or loose U-bolts can show up in several ways:

• A trailer or vehicle that tracks to one side or feels unstable when braking.
• A clunk from the rear axle when moving off or stopping.
• Visible movement between the axle and spring.
• A sheared or missing centre pin.
• Heavy rust, cracking or thread damage on the U-bolt legs or nuts.

If any of these appear, inspect the U-bolts, plates, centre pin and leaf spring bushes before using the vehicle or trailer again.

Limitations and Trade-Offs

New U-bolts restore clamping force, but they cannot fix a cracked spring plate, a damaged axle pad, a broken centre pin or worn leaf spring bushes. Inspect these parts at the same time. Over-tightening can crush the spring pack or damage the threads, while under-tightening allows the axle to move. Following the correct torque and re-check procedure is essential.

Universal U-bolts rely on accurate measurement. If you are unsure of the correct size, measure the original U-bolt and axle carefully before ordering.

Compliance

U-bolts are critical to axle location, so any replacement must keep the vehicle or trailer safe and within the standards that apply where it is registered. In Australia, requirements for trailers and vehicles vary between states and territories, particularly where lowering blocks or suspension changes are involved. In the UK and Europe, suspension condition is checked at the MOT or periodic roadworthiness inspection, and trailers may have separate inspection rules. Tell your insurer about any suspension modification.

Nolathane Suspension Experience

With more than 50 years of experience in replacement and upgrade suspension components, Nolathane develops parts for mechanics and DIY owners across Australia and beyond. That practical focus extends to essential leaf spring hardware such as U-bolts, alongside the signature red polyurethane leaf spring bushes that keep the spring eyes and shackles firmly located.

Warranty and Support

Nolathane universal U-bolts are backed by Nolathane?s warranty. Our fitment guarantee means the U-bolts you receive match the dimensions shown in the listing, and a 60-day returns window gives you time to confirm the fit. Our local support team can help with sizing and fitting advice, whether you are rebuilding a trailer, fitting lowering blocks or servicing a leaf-sprung axle.

Shop Universal U-Bolts for Your LH, RZH 100, 103, 113, 125 HIACE

U bolts sized by length and diameter are found in Nolathane's universal parts range.

Measure your axle, spring stack and existing U-bolts, compare them with each listing and choose the round top or square top U-bolts that suit your LH, RZH 100, 103, 113, 125 HIACE. Orders are sent with fast shipping, so you can secure your axle and get back on the road with confidence.