Revitalise Your Bonneville's Rear Brake

Triumph Bonneville Rear Brake Caliper Rebuild: A Cost-Effective Solution

It's a common scenario for motorcycle owners: a beloved bike starts showing its age, and a seemingly minor component failure leads to a hefty repair bill. For owners of the 2008 Triumph Bonneville, a seized piston in the rear Nissin brake caliper can present just such a challenge. The original equipment manufacturer (OEM) replacement caliper, part number T2020239, can come with a price tag exceeding £400, a figure that often makes riders balk. Fortunately, there are more economical alternatives available, and one such option comes from a UK-based company, Powerhouse Automotive UK, offering a comprehensive rear brake caliper rebuild kit through eBay.

This article will delve into the experience of using such a kit, detailing its contents, the ease of installation, and the results achieved. We'll also touch upon the intricacies of Triumph's older drum brake systems to provide a broader understanding of rear brake maintenance for this iconic motorcycle.

The Powerhouse Automotive UK Rebuild Kit: What's Inside?

The kit in question, designed for Triumph Bonneville rear brake calipers from 2001-2010, offers a complete solution for addressing seized pistons and worn seals. The price point is remarkably attractive, with the user reporting a cost of just $36.31 (approximately £29.50 at the time of writing) including shipping from the UK. This is a significant saving compared to the cost of a new caliper.

The kit typically includes:

The inclusion of essential items like new seals, a bleed nipple, and crucially, the correct type of grease for the seals, makes this a truly comprehensive package. The inclusion of Hel copper banjo washers is also a nice touch, ensuring a leak-free connection at the brake line.

Installation: No Special Tools Required

One of the most significant advantages of this rebuild kit is that it requires no specialized tools, making it an accessible DIY project for most Triumph Bonneville owners. The seller, Paul from Powerhouse Automotive UK, provided excellent pre-purchase advice, confirming the absence of special tool requirements. This is a crucial piece of information for anyone considering a similar repair.

The process itself is straightforward:

• Piston Removal: The pistons can often be coaxed out evenly by pumping them gently while the caliper is still mounted on the bike. For stubborn pistons, once the caliper is removed, compressed air can be used to assist. It is vital to avoid using pliers or grips directly on the pistons, as this can cause damage.
• Cleaning the Caliper: Once the pistons are out, the seal grooves need to be meticulously cleaned. Small pick tools, or even a bent electrical screwdriver, can be used to scrape away any oxidisation or corrosion. A can of brake cleaner and an old toothbrush are ideal for cleaning the caliper body itself.
• Piston Preparation: The pistons should be cleaned with brake cleaner and a Scotch-Brite pad. It's important to inspect them for any pitting or scratches. While the kit doesn't typically include replacement pistons, you should replace them if they are damaged. Powerhouse Automotive UK does mention offering stainless steel replacements, which would be a worthwhile upgrade.
• Seal Lubrication and Installation: The provided red rubber grease should be lightly smeared onto the new seals and pistons to aid their installation. For the slide boots, automotive white grease is recommended.
• Reassembly: The process is then reversed, with the new seals and pistons being carefully installed. The caliper is reattached to the bike, and the brake system is bled.

The user's experience confirms that this method is effective, with the installation and subsequent brake bleeding going smoothly. The result? A rear brake that feels as good as new, with both pistons now functioning correctly, leading to a noticeably improved braking performance. This is a testament to the quality of the components and the straightforward nature of the repair.

Triumph Drum Brakes: A Look Back

While the focus of this article is on the disc brake caliper rebuild, it's worth noting Triumph's history with rear drum brakes, particularly on models from 1945-1974. These systems, typically featuring a 7-inch diameter cast iron drum, remained largely unchanged for three decades. However, there were some key variations:

• Sprocket Options: The brake drums came with either a machined-on 47-tooth sprocket or a bolt-on sprocket. The bolt-on versions used either CEI or UNF bolts.
• Brake Shoe Evolution: The brake shoes themselves underwent a change in 1963. Prior to this, shoes (part number W93) had a half-moon relief to rest on the stationary pin. After 1963, directional shoes (37-1406 and 37-1407) were introduced, offering greatly increased braking efficiency and being fully interchangeable with the later style. The older W93 shoes are no longer readily available.

Key points for drum brake maintenance:

• Spring Removal: When removing brake shoes, avoid prying the springs off, as this can lead to broken parts and injury. Instead, lift the shoe and carefully release the spring tension.
• Brake Cam Lubrication: The brake cam often has a small drilling for lubrication that can become blocked. It's essential to clean this out during maintenance and apply a small amount of high-temperature grease.
• Correct Shoe Orientation: When reassembling, ensure the wide gap on the brake shoe faces the direction of wheel rotation. The steel end of the shoe should rest on the stationary pin, and the flat aluminum side on the rotating brake cam.
• Spring Replacement: It's good practice to replace the brake springs (part number 37-0135) whenever you replace the shoes.
• Backing Plate Alignment: When refitting the backing plate to the drum, apply the brake lever while tightening the axle nut to correctly centralise the backing plate.
• Bedding-in: New brake shoes will require a bedding-in period. Be cautious with your braking for the first few miles until the shoes have properly seated into the drum.

Conclusion: A Smart Investment

For Triumph Bonneville owners facing a failing rear brake caliper, the rebuild kit from Powerhouse Automotive UK presents an exceptionally cost-effective and practical solution. It allows you to restore your bike's braking performance, potentially extend the life of your existing caliper, and save a significant amount of money compared to buying a new one. The availability of such kits, coupled with the fact that no special tools are required, empowers riders to undertake their own maintenance and keep their classic machines on the road.

If your Triumph Bonneville's rear brake is giving you trouble, investigating a quality rebuild kit like this is a highly recommended course of action. It's a clear example of how smart maintenance can keep your motorcycle running smoothly and safely without breaking the bank. Remember to always consult your motorcycle's service manual for specific torque settings and procedures.

Frequently Asked Questions

Q1: Can I use regular grease on the brake caliper seals?

A1: No, it's crucial to use the correct type of grease. Red rubber grease is specifically designed for brake caliper seals and pistons as it is compatible with rubber components. Regular automotive grease can degrade the seals over time.

Q2: What if my brake pistons are pitted or corroded?

A2: If the pistons are significantly pitted or corroded, they should be replaced. Damaged pistons can cause leaks and premature wear of the new seals. Stainless steel replacements are a good upgrade option.

Q3: How do I bleed the rear brake after rebuilding the caliper?

A3: You'll need a clear bleed tube and a container to catch the old fluid. With the reservoir cap off, attach the tube to the bleed nipple, open the nipple slightly, and operate the brake pedal or lever. Close the nipple before releasing the lever. Top up the reservoir as you go, ensuring it never runs dry. Continue until clean fluid flows with no air bubbles.

Q4: How often should I check my rear brake caliper?

A4: It's good practice to inspect your brake caliper and pads at every service interval, or at least every 6,000 miles. Look for leaks, uneven pad wear, and ensure the pistons move freely.

Q5: Are there any other companies that offer similar rebuild kits?

A5: While Powerhouse Automotive UK was mentioned, other specialist motorcycle parts suppliers may also offer caliper rebuild kits for various Triumph models. Searching online marketplaces and dedicated Triumph parts websites is recommended.

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