I recently decided to perform a removal and inspection of the cool hubs and bearings on my 1998 Ranger Trail boat trailer (1998 Ranger Trail D4600). I’ve documented the entire process of Cool Hub Removal and Inspection here, I hope it helps walk you through this basic maintenance procedure. I have all the original paperwork from when the boat was new, and the UFP (Unique Functional Products) parts list with part numbers and parts diagram helped a lot with obtaining the correct or replacement parts.
Cool Hub Removal and Inspection Tools/Materials needed:
Tire removal tools
1 – 32oz bottle of gear lube
13mm or 1/2″ wrench
21mm or 13/16″ Wrench or Socket & Ratchet Combo
8″ long piece of 2×4
Channel Lock pliers
Pair of side cutters (Dykes)
Large straight screwdriver
4 hub seals
To get started, using a jack, raise the axle until the wheels are off the ground. Remove the center cap and wheel(s) and set them aside. Place a jack stand under the axle for stability and safety.
Remove the brake caliper, caliper bracket, and brake pads.
It is now time to drain the cool hubs and remove the wheel bearing protector/inspection window assembly. To do this rotate the hub until the 3/16 Allen plug is on the top, remove the plug and rotate the hole back to the bottom and drain the hub into a drain pan.
The protective cap assembly, which is also the oil inspection window, is an interference fit. Meaning it is pressed into the hub. Once the hub is drained, use a 2×4 block and a rubber mallet to remove the cap. The correct procedure from UFP is to lay the wood against the side of the cap and strike the block of wood with the mallet. Then place the wood on the opposite side and hit it again. Continue this procedure to slowly “walk” the cap out of the hub. They actually say to use a hammer but I prefer to use a rubber mallet. I also only walk the protective cap assembly out enough to get behind the lip and gently tap it out with a straight screwdriver. Do not use a small or sharp screwdriver with my method: they can poke a hole in the metal cap assembly. As with any of my suggestions, if there is any doubt I recommend sticking to the factory procedure.
Once the cap is off, the inside of the cap should look like this.
Back to the hub, a cotter key holds the hub adjusting nut secure, bend it straight and remove it with the side cutters (dykes).
Remove the retaining cover over the adjusting nut and remove the nut.
Once the cotter key and retaining cover for the nut are removed, it’s likely the adjusting nut is only finger tight. However, channel lock pliers may be necessary to remove it. Remove the nut and flat washer. Then wiggle the rotor assembly and the outer bearing should easily pop out of its race. Catch it; do not let it hit the floor as this can damage the bearing.
Now with the outer bearing out, it’s time to remove the inner bearing and seal assembly. I use an “old school” way of removing the inner bearing and hub seal at the same time. With the outer bearing removed, reinstall the adjusting nut to the spindle threads about three or four turns.
Grab the rotor at the 3 & 9 o’clock positions and slowly slide it towards you until the rotor drops down onto the spindle. As the rotor is pulled forward, feel for the inner bearing to contact against the adjusting nut which was reinstalled.
Now, slide the rotor back about an inch and quickly pull the rotor towards the adjusting nut. This will pop the seal and inner bearing out of the hub assembly leaving them sitting on the spindle.
Again, this is my way of removing the inner bearing and seal. The manufacture’s procedure is to slide the rotor off the spindle with inner bearing and seal intact, then use a seal puller to remove the seal and lift the bearing out. Or once the rotor is removed, drive the bearing and seal out from the front of the hub using a brass drift placed on the inner bearing race. Tap the bearing race until the seal and bearing fall out. No matter which procedure used, the hub seals will have to be replaced.
At this time, I like to lay everything out in the order it came off and clean and inspect each piece.
I use brake cleaning solvent to clean the bearings. Rotate each bearing while spraying it. Once it is clean, rotate it slowly and inspect each bearing roller for pits, flat spots or wear marks. A good rule of thumb is if any possible damage can be felt with a fingernail, replace it. Also, inspect and clean the bearing races inside the hub.
If there is wear or damage, bearings and races should be replaced as a set. They are usually sold as a set. Even if everything looks good for reinstalling, take the time to write down the part numbers of the bearings and seals for future reference. This allows parts to be purchased before any future work starts. Once the bearings and seals are clean, part numbers are easily identified.
On Timken brand bearing, and most bearings, the part number is stamped on the edge.
Same for a NGK brand seal
Most auto parts suppliers, along with trailer repair shops carry my bearings, races, and seals. They can even be ordered online if time permits. These are the parts UFP and Wood manufacturing used on my trailer when it was built. If told these parts must be purchased from Ranger directly, it’s simply not true. I’m not suggesting not to order from Ranger Parts department, if there is time call Sherrie at the Ranger Parts Department 1-800-724-7273. She will look up the year and model and send exactly what’s needed. However, if broke down on the side of the road 300 miles from home, these numbers and an auto parts store may just save a lot of aggravation, money and time!
Also, since my trailer is a 1998, my exact seal part number is no longer available. I had to have the part number cross referenced to an available replacement seal.
Once all components are clean, flip the hub/rotor assembly over so the back side is facing up. Lubricate the bearing while slowly rotating it to evenly distribute the oil. Also, coat the bearing race with oil. Use the same oil used to refill your hub after reassembly is complete. Install the correct bearing into the hub; rotate the bearing once it is installed to further distribute the oil. Set the new hub seal in place and gently tap it into place.
I used a Crank Seal Installer off of a Subaru, which just so happened to fit perfectly and fully seated the seal into the hub using my Rubber mallet.
A large socket, a flat square block of wood or even a drift punch can also be used to gently and slowly tap around the edge of the seal until it is fully seated. Typically the seal will be slightly recessed. You will feel a definite change when tapping the seal; it will become very solid when it bottoms out.
Using a finger lubricate the inside lip of the seal at this time.
Clean the trailer spindle shaft and inspect the bearing and race mounting areas for any burrs, rust or paint. I cleaned my spindles with 1000 grit Emory cloth to make sure everything is smooth and clean. Wipe off any dust with brake clean on a rag.
Lubricate the spindle shaft with axle lube and gently install the rotor/hub assembly onto the spindle shaft. Ease it back into place, be sure to keep the weight of the hub/rotor off the spindle while centering the shaft. Once the rotor/hub fully seats by hand, install the lubricated front bearing over the spindle and into the hub.
Install the flat washer and hand tighten the adjusting nut until there is no play in the assembly while turning the rotor/hub by hand.
Using channel lock pliers tighten the adjusting nut firmly to seat the inner seal onto the spindle surface. The nut does not have to be overly tight during this process. However it should be more than finger tight, yet the rotor/hub assembly should be able to spin at this point. UFP and Ranger say tighten it 18-24 inch lbs which is slightly more than “Finger” tight.
Back the adjusting nut off completely and spin the hub. Next tighten the adjusting nut just enough to take out the free play (in and out movement) of the hub/rotor. “UFP and Ranger say tighten nut to 18-24 inch lbs.”
Install the nut retaining lock ring (this may take several position attempts, pulling it off and rotating it a notch to get the teeth lined up properly on the cotter key hole).
Once the teeth of the retaining nut and the cotter keyhole line up, slide the cotter key through the hole and bend the ends over.
Place a small amount of sealant around the hub inspection cover and gently tap it into the hub with the mallet or a block of wood. The sealant I use is GM engine sealant part #88864346, however any high quality sealant will work fine.
Once fully seated, wipe the excess sealant off the outside and fill the hub with the correct oil.
Oil fill procedures can be found in this article Cool Hub Maintenance
Now the job is done I want to add a couple things in closing. According to the manufacturer of my trailer, wheel bearing adjustment should be checked once a year. To do this, jack up on side of the trailer (make sure you use jack stands and chock the trailer wheels to keep the trailer from moving). Grip the edge of the tire and see if it will rock or move. If the outer edge of the tire moves more than 1/8”, the bearings may need to be re-adjusted.
If you decide to take on this job, plan for about an hour per hub. I stripped all mine down, painted them, resurfaced the rotors and reinstalled them and it took much longer. For a basic disassembly, inspection, and reassembly one could expect about an hour with hand tools. Please take into account this is after the hub has been drained (which can take a long time depending on temperature).
There are no specific guidelines on how often bearings should be removed for inspection. If the annual adjustment inspection is good, keep checking the inspection window oil level before every trip and periodically inspect the back of the seals for evidence of excessive leakage. Some seepage is normal and necessary to lubricate the wiper lip of the seal and sealing contaminates out. If it’s determined the seals need replaced, completely tear down the hub and inspect the bearings.
A final note: The owner’s manual I received with my boat trailer states, “If your trailer is equipped with COOL hubs, the system should be serviced once a year or every 20,000 miles whichever comes first”.