In a message dated 5/8/03 9:31:32 PM, htmills@bright.net writes:

Anyone ever have to change the bearings on their trailer? Mine are holding up (knock on wood) but I've never done a trailer axle before and am thinking it would be nice to know what

to expect. I have bearing buddies in the ends of the hub. What would be the R/R procedure? I'm guessing there would be a nut inside there somewhere holding the hub on the spindle but don't know for a fact...It's a Trailrite trailer. I've heard of people taking a complete hub assembly with them for a spare, so when I was in the local

Tractor Supply I browsed the trailer parts but didn't see anything quite like my hubs (which use lug BOLTS rather

than studs/nuts).

Webmaster Doug, your latest additions to the web page are superb as usual! Thanks to you and Keith for facilitating the free flow of knowledge!

Thanks,

Tod

Tod, I have done the hubs on my M15 Trail-Rite several times (first time full bearing/race/seal replacement, periodic subsequent inspections/repacks). Disclaimer: I am posting this for the sole purpose of describing my process of inspecting, removing, and/or replacing wheel bearings and associated components on my specific trailer. My description does not constitute a recommendation that anyone attempt the work as described, nor do I make any claims that the procedures described are similar or sufficient for any other trailer, regardless of manufacture. Anyone attempting this type of work should verify the configuration, equipment, specifications, and procedures specific to his or her trailer, and should be qualified to perform such procedures. Failure to do so could result in injury or death. Phew! Now that I made that clear, here is what I do: 1) I loosen lug nuts (or bolts) partially, jack up and safely support trailer so that wheel is off ground (I use jack stand(s) --I don't rely on jack only). I remove lug nuts/bolts and wheel. 2) I then remove the 'Bearing Buddy.' It can be easily removed by tapping lig htly on each side of the outer edge with a rubber mallet. I alternate tapping a little on each side so that it 'walks off.' 3) Once the 'Bearing Buddy' is removed, I see little other than a pile of grease. I Wipe this away/out, and I can then see the threaded end of the axle shaft spindle with a cotter pin through a small transverse hole (a little in from the end). Before I remove this cotter pin or loosen anything else, I check for play in the bearings (this is actually easier to do when wheel is on trailer is jacked-up--I grab left and right side of tire and push left/pull right and vice versa). I also spin wheel while jacked up and listen to bearings, and note how long it takes for wheel to stop. I make a mental note of play/freespinning. 4) I carefully remove the cotter pin. I have a star shaped retainer that is cupped over a large nut just inboard. The cotter pin goes through one of the many slots of this retainer and comes out another on the other side of the threaded axle (some axles have either a castle nut, or a split nut with a tightening bolt/allen bolt in lieu of the retainer/cotter pin). 5) I remove the retainer and the nut. There is be a heavy thrust washer behind the nut (it sometimes sticks to/comes off with the nut, or sometimes sticks to the bearing. 6) At this point, I find the outer bearing (just behind the washer/nut). It might fall out on its own, or I might have to grab the top and bottom of the hub and wiggle a little. I am careful not to let the bearing fall on the ground/in the dirt. I usually keep a zip lock bag at the ready. I write 'Left-Outside' or 'Right-Outside' on the bag (I want to reinstall any bearings I remove in the same races). 7) I can now pull the hub assembly off of the axle spindle. The inner bearing will not fall out, as it is kept captive by the inner grease seal. 8) I wipe the axle shaft/spindle clean and inspect the following: a) The two areas on the spindle where the inner and outer bearings ride. I look for galling, pitting, corrosion, and discoloration. b) The surface where the grease seal rides (usually a stepped-up portion of the axle shaft). 9) I note the position of and remove the inner grease seal from the hub (back/inner side of hub--it is a metal ring with an integrated seal). I do this very carefully, and without prying against or scratching the inner bearing or race residing just behind it. (Virtually all automotive shops sell an inexpensive tool for just this purpose--it uses the outer surface of the hub rather than the bearing, as might be tempting if you try and use a screwdriver, etc.). Removing this seal almost always destroys it, so I always have replacements on hand to reassemble. 10) After removing the inner seal, the inner bearing will either fall out, or I can stick my finger through the hole and pull it out. Again, I keep this bearing in a labeled bag for reinstallation in same location. 11) Now I have a hub with only the bearing races remaining (the races are the bright, slightly cone-shaped rings that are pressed into the hub--one for the outer bearing, and one for the inner). I wipe out all of the remaining grease from the entire hub. I follow with aerosol brake cleaner to remove any residual grease/contaminants (the brake cleaner cuts the grease, and evaporates-off without causing corrosion, etc.). 12) I inspect both races for any scratches, pitting, galling, corrosion, discoloration (usually pretty shades of blue). If I see any of these, I replace both that race and its mating bearing. I also check for any ridges or rounding of the surface. If smooth and blemish free, the races might be OK. 13) Now I clean each bearing/cage (the cage is the outer ring that holds the individual rollers in place, and is not removable). First, I wipe as much grease as possible out of the bearing (I wipe while spinning bearing). Then I go at them with the brake cleaner until totally free of old grease (I usually do this over an oil drain pan--the brake cleaner will evaporate-off and leave a greasy residue that I can wipe out and dispose of properly). 14) I then Inspect the bearings (rollers) for scratches, pitting, galling, corrosion, discoloration. I also check for excessive rounding of the edges, and for excessively loose fit in the cage (this takes some experience--I find it best to compare to a new bearing). 15) Finally, I take the clean (no dirt/debris) bearing and fit in clean race. The bearing rollers should ride in the center portion of the race if they are not overly worn (I can usually see a polished area on the race where the bearing has been riding). 16) If everything checks out OK, I then repack and reinstall my existing bearings. If either the bearing or race is questionable, I replace both together. In any event, I protect the hubs and bearings (I keep in bags and spray with WD-40 or comparable if I am not going to repack right away). Assuming everything is OK: 1) I make sure hub and races are clean (I spray clean with brake cleaner again if I used WD-40 to protect). 2) I Make sure I have the proper replacement inner grease seal (I check both the hub inside diameter and the axle shaft diameter where the seal rides for fit) before proceeding. 3) I repack bearings using an appropriate grease (non-soluable high-temperature boat trailer wheel bearing grease). A note: In spite of appearances to the contrary, one CANNOT properly repack the bearings using the 'Bearing Buddy' caps. The grease pumped into these caps is meant to replace lost grease in the hubs AND to keep positive grease pressure (and therefore waterproofing) intact when one plunges a hot trailer hub into cold water (otherwise the cooling tends to form an immediate vacuum which pulls water past the seals). Repacking is best done with a repacking cone/tool that hooks up to a grease gun (pressure loads ALL sides of the bearing and cage), and this is the method I normally use. I can, however do a satisfactory job with a heavy duty clear plastic bag (like Zip-Lok freezer bag): a) I put a good size dollop of grease in a clean, new bag (again, I mind the location it came from). I check the bearing for any dust/dirt, and reclean with brake cleaner/dry if necessary. b) I drop the clean bearing into the bag with grease and close. c) Using my fingers on the outside of the bag, I force grease between the rollers and cage from all angles. I Rotate outer cage on bearing and repeat until entire bearing/cage is completely full of grease (no voids). I Leave in sealed bag until ready to reinstall. 4) Starting with the inner, I apply a thick layer of grease in the inner race. I also pack the center cavity of the hub (between the two races). Note: Packing the center cavity is for Bearing Buddy systems only. I normally wouldn't want entire hub full of grease due to increased heat retention, but BB system requires a fully packed hub to remain waterproof). I take the packed inner bearing from its bag (with a healthy coating of grease on the rollers), and install into the inner race (I mind the orientation--taper into cone). 5) I wipe all grease from just inside of inner hub (hub, not race) where the new grease seal is to be installed. Hardly anybody does this next step, but I find it can help keep water out: 6) I take a little RTV sealant (any automotive store has), and spread a thin layer on the outside rim of the new grease seal. 7) I carefully line up seal and press/tap (rubber mallet and block of wood) into the inside hub opening (the flat part out/cupped part in). Most seals install flush with the inside of the hub. I don't over tap, as it might not line-up/seal against the axle shaft, or worse, might interfere with the inner bearing. I wipe away any excess RTV sealant from the face of the seal/hub. 8) I check/clean axle shaft including grease seal riding surface, and cover with thin layer of grease. 9) I gently slide hub over end of axle shaft (might have to wiggle a little to get inner bearing to slide back all the way). A blob of grease is pushed out of center of hub by axle shaft--I push as much as possible back into center cavity around shaft and inboard of outer bearing race. 10) I apply thick layer of grease to outer race. I take the packed outer bearing from its bag (with a healthy coating of grease on the rollers), and install into the outer race (I mind the orientation--taper into cone). I am careful not to torque the hub assembly, as the loose outer bearing will pop out. 11) I take the thrust washer (cleaned) and install it against the bearing (it might have flat spot in hole to be lined up with flat spot on shaft--I can't remember). 12) I take the cleaned nut and thread on to the axle shaft until meets the thrust washer. I finger tighten while turning hub. 13) I adjust the bearing pressure (via tightening of nut): This is the trickiest part of the whole job. Too tight, and I will burn up the bearings. Too loose, and I will wear the bearings prematurely. I have done enough bearings that I know by feel. I can (and do) use a really accurate dial-type inch-pound torque wrench, but for field adjustments, I determine proper torque using more pedestrian means. Properly torqued bearings will actually have a minuscule amount of play. I put the wheel back on (still off the ground) and tighten the lug nuts/bolts (enough so that there will be no play between wheel and hub when I start yanking on the wheel). I put one hand on the left side of the tire, and the other on the right. I try to rock the wheel back and forth (push with left/pull with right--and vice versa). I listen closely at the hub for a small clunking sound. If I don't hear it, I loosen the nut a little bit. I should also feel a tiny amount of movement in the wheel while rocking. I then tighten the nut (by hand) until I don't hear the clunk any more (or feel the movement of the wheel). Then I tighten it a bit more using a wrench, but I go very, very easy--not too tight. I just want to push some of that grease out of the way, and seat the bearings in their races a *little* bit. I spin the wheel while I tighten. I keep spinning the wheel backward and forward for a few minutes (if it won't spin fairly easily, I know that I overtightened the nut). Then, I back the nut off very slowly while doing the rocking thing again. I stop when I can just hear the very faintest of clunks. (I can usually feel a very, very small amount of play--but I mean really small). This will usually occur when the nut is just finger tight, and no more. If I am having to tighten the nut with a wrench to get rid of the clunk/play, then I probably have worn bearings/races that need to be replaced. 14) When I get the adjustment where I like it, I take the clean star-shaped retainer and slide the cupped side over the nut (being careful not to turn that nut). Now I check and see if the resulting little slot in the retainer lines up with the hole in the axle shaft (the one that the cotter pin goes through). If it doesn't, I try sliding the retainer off, turn it (the retainer) a few degrees one way or the other, and slide back on. I repeat until I find a slot that is centered over the hole. When I finally get it, I double check the wheel play. If Still good, I put a NEW cotter pin in and bend the ends carefully (if not careful, it is easy to bend the little slot prongs off of the retainer). 15) I then take apart, clean, and test the Bearing Buddies. I verify that, when clean, I can push the plunger inward and have it return via spring without sticking, there is not rust, and the grease fitting still works. 16) I then replace the O'ring on the mating flange, and reinstall the bearing buddy by tapping it on gently with a rubber mallet. 17) I fill the Bearing Buddy until the spring loaded plunger is all the way out, and the grease overflow hole starts to flow. I spin the wheels, and repeat as necessary. 18) I then lower the trailer, torque the wheel lug nuts/bolts, check the air in the tires, and road test. I check after a short distance to see if hub is getting warm. I recheck after freeway speeds--both temperature and rocking/clunking (sometimes a new bearing will seat-in and require readjustment). 19) After road testing, I let the hubs cool overnight. The hubs suck grease inward to fill voids when they cool, so I check and refill the Bearing Buddies until they won't take any more grease. I am satisfied when wheel play and hub temperature are balanced (hub luke warm to the touch after sustained freeway driving, and wheel play no more than subtle clunk/very slight play. If wheel bearings/races need replacement: 1) I remove races using press and hardened socket (my hubs do not have the typical 'slots' in the hub's race seating flange that allows them to be easily driven out. In an emergency, I could drive them out using a punch. 2) I clean hub area where race is installed, and verify that no damage was done during removal. 3) Using a bearing race tool, I press bearing in using hydraulic press. In a pinch, I have used an appropriate sized socket and a plastic head hammer (gentle taps in circle to 'walk' race into hub). I always verify that race is properly bottomed out/square against the hub's internal stop/flange. 4) I make sure that I did not scratch, or otherwise damage the race during installation. 5) I always install new bearing with race. I always carry two extra complete packed hubs, ready to go. The races on my Trail-Rite were especially difficult to remove even with special bearing tools/slide hammer/press. Unlike some hubs that have gaps in the seat flange/stops, these were continuous with only a tiny edge/rim of the bearing visible to press/pull/pound out. I carry extra bearings, races, seals, and grease (mini 3oz. grease gun), but replacing races in my hubs would be very difficult in the field. If I had problems on the road, I would just swap hubs, and then take the faulty ones to a machine shop to have the old races removed/new ones pressed in (I also carry several sets of spare bearings/races/seals). After more than 7000 miles, I have had no problems whatsoever with bearings. I took my original bearings/races to my local automotive shop and cross-referenced the numbers/sizes to high quality automotive wheel bearings/races. These proved to be much better than the cheap import bearings I found at my local trailer shop. I was able to do the same for the inner grease seals (of which I bought quite a few). I did, however, purchase the spare hubs at the trailer shop. I pulled out the cheap races and installed the better ones. My guess is that the Trail-Rite for the M17 takes different bearings/races/seals. If you really get stuck trying to find them, Trail-Rite in Santa Ana, California can probably help you out. I watch my tire pressure very carefully. Underinflated tires will heat excessively, and this heat will be transferred to the hub, which in turn will heat and pressurize your grease (which can thin and escape past the seals). There are now oil-bath hubs available for many axles. These are complete replacement hubs that utilize heavy gear oil instead of grease. They are supposed to reduce friction, run cooler, and should extend bearing life. A clear cap on the outside (in lieu of Bearing Buddy) allows monitoring of oil level/contamination. I would at least investigate these if I were in the market for replacements. Finally, if you have trailer brakes, the bearing configuration might differ somewhat. Brakes can cause the hubs to superheat if not adjusted properly. Bearing failures on trailers with brakes are therefore more common, but not necessary if brakes are properly set-up. Here is a site with some visuals: http://www.easternmarine.com/em_showroom/tech_info/wheelhub_tech_info.html Scott Grometer, M15 #478 'bebe'