Owners of Dunbier Jet Ski trailers – which account for roughly half of all Jet Ski trailers sold in Australia – are being advised to read the owner’s manual and schedule routine maintenance as the company confirms it has not used wheel bearings with “triple lip” marine seals for at least 10 years.
Photos of stranded Dunbier Jet Ski trailers have appeared on social media in recent months, with a number of owners claiming the wheel bearings wore prematurely, overheated, or failed.
Representatives for Dunbier Jet Ski trailers told Watercraft Zone failures can occur if owners ignore the recommendations in the owner’s manual and neglect routine maintenance.
Dunbier – which has been building boat trailers for more than 50 years, since 1969 – manufactured Jet Ski trailers in Australia until early 2021, when it switched to importing galvanised frames from China and completing final assembly at its facility in Melbourne.
However, Dunbier representatives say wheel bearing failures are not related to its new Jet Ski trailer manufacturing process – or the standard installation of automotive wheel bearings with “single lip” seals.
Dunbier says the small number of wheel bearing failures on its Jet Ski trailers stem from customers not conducting routine checks, ignoring annual maintenance, and overlooking the owner’s manual which is taped to the frame in a plastic sleeve on delivery.
An updated version of the Dunbier owner’s manual – dated June 2022 – has been published on the company’s website. You can read it here.
Other leading manufacturers and suppliers of Jet Ski trailers in Australia – such as Tow Rex, Boeing, Sales Trailers and Trailer City – told Watercraft Zone they only use wheel bearings with “triple lip” marine seals.
Dunbier says the decision to equip its Jet Ski trailers with automotive wheel bearings with “single lip” seals – instead of wheel bearings with “triple lip” marine seals – was not a cost-saving measure.
The company says it made the switch more than a decade ago based on years of real-world experience and customer feedback.
Dunbier says it has been installing automotive wheel bearings with “single lip” seals on its Jet Ski trailers for at least 10 years.
Mackay trailers – bought by Dunbier in February 2015 – also now uses automotive wheel bearings with “single lip” seals on its Jet Ski trailers.
Dunbier assembles between 3000 and 4000 Jet Ski trailers each year, which amount to roughly half the 8000 or so personal watercraft sold in Australia annually.
The national sales manager of Dunbier, Andrew Murphy, told Watercraft Zone: “We use automotive bearings with a standard ‘single lip’ seal for one simple reason. The vast majority of buyers of our Jet Ski trailers fit Bearing Buddies (metal dust caps that allow bearing grease to be topped-up via a small nozzle).
“In our experience, when we sell a Jet Ski trailer to a dealer, the dealer fits Bearing Buddies, or it’s often the first thing the customer does.”
The Dunbier executive added: “We don’t recommend Bearing Buddies be fitted to trailers with ‘triple lip’ marine seals, because when you start pumping grease into the hub, it forces the seal out of the back of the hub. And the moment you put the trailer in the water, you’re going to get water into the bearing grease.”
Dunbier says, in its experience, Bearing Buddies work better on wheel bearings with “single lip” automotive seals.
“The more grease you pump into a wheel bearing with a ‘single lip’ seal, it forces the seal harder against the stub axle … and makes it work more effectively,” said Mr Murphy
“With a ‘triple lip’ marine seal, Bearing Buddies have the opposite effect. When you pump grease into it, it forces the seal open at the back, because the pressure is coming from the wrong direction.”
The Dunbier executive said when the company previously equipped its Jet Ski trailers with wheel bearings with “triple lip” marine seals “we saw a massive increase in premature bearing failures.”
“The common denominator with those failures: the trailers were equipped with Bearing Buddies,” said Mr Murphy.
“We believe we would see a greater rate of bearing failures if we equipped our Jet Ski trailers with wheel bearings with ‘triple lip’ marine seals.
“Our research shows the overwhelming majority of Jet Ski buyers put Bearing Buddies on their trailers.
“So we made the intentional decision to install automotive wheel bearings with ‘single lip’ seals on our Jet Ski trailers.
“We have just updated the owner’s manual with a lot more detail. It’s available online, and a printed copy comes in the plastic sleeve that’s attached to the trailer at the point of sale.
“We encourage all owners of Dunbier Jet Ski trailers to read the owner’s manual to make sure they know how to properly maintain their trailer.”
Included in the advice on the Dunbier website: customers should inspect the wheel bearings on their Jet Ski trailer in the first three, six and 12 months, before undertaking annual bearing maintenance and/or bearing replacement.
“Wheel bearing protectors (such as Bearing Buddies) do not replace the need for regular servicing,” says the Dunbier website.
“We recommend (Bearing Buddies) only be used with ‘single lip’ seals, as this prevents the positive pressure from forcing grease past ‘triple lip’ seal systems.”
Today, Dunbier fits wheel bearings with “single lip” automotive seals – and installs Bearing Buddies – across its range of boat trailers.
However, while Dunbier fits wheel bearings with “single lip” automotive seals to its Jet Ski trailers, it does not install Bearing Buddies as standard.
Instead, Dunbier relies on Jet Ski dealers – or Jet Ski buyers – to purchase and install Bearing Buddies (grease top-up devices that replace the standard dust caps, pictured below).
Watercraft Zone’s advice based on information from experts, and our own experience:
- On Jet Ski trailers equipped with wheel bearings with “triple lip” marine seals, retain the standard dust cap and do not use Bearing Buddies.
- On Jet Ski trailers equipped with wheel bearings with “single lip” automotive seals, consider fitting Bearing Buddies – or retain the standard dust cap and be vigilant with routine maintenance and/or annual wheel bearing replacement.
- Based on thousands of kilometres of towing various brands of Jet Ski trailers (with and without Bearing Buddies, and with and without ‘triple lip’ marine seals), Watercraft Zone recommends Japanese wheel bearings with ‘triple lip’ marine seals, a standard dust cap, and annual bearing replacement.
Whatever choice you make, trailer experts canvassed by Watercraft Zone strongly recommend replacing the bearings on Jet Ski trailers each year – perhaps using registration renewal as an annual reminder for this routine maintenance.