More than everything you always wanted to know about wheel bearings

The Macgregor trailers use an 3500 lb axle which uses standard bearings. The spindle is made to use a standard seal but many use Spindo Seal which I will describe later.

outer bearing --------44649  
inner bearing --------68149  
Transcom seal- # 1.720" 17255 standard
National seal-- # 1.720" 473336 standard
NOK seal ----- # 1.720" AD2548E standard
seal ---------- 1.860" ???? ----Spindo Seal
The bearings can be bought at an auto parts house or from a marine supplier. West Marine, Boat/US and most mail order places sell a kit which contains the parts for one wheel (both bearings, a new seal and a new cotter pin). They are sold as a size 1 3/8 X 1 1/16. The seal in these kits is the standard size (1.720) which fits an axle which doesn't have Spindo Seal.


On an axle which uses a standard seal, the seal rides on the spindle. Since the spindle is steel it can rust and pit. This will wear the seal out rapidly and let grease leak out. The Spindo Seal kit is a stainless ring and a special seal that is used instead of the standard seal. This gives a surface for the seal that will not rust and pit. Macgregor has used Spindo Seal on many of his trailers. I don't know what years he used them but my trailer and many others that I have seen came with them.

When working on the bearings this complicates things because the seal is special and can not be bought in an auto parts store or catalog.(The seal has to be taken out to replace the rear bearing and is not supposed to be reused.) Spindo Seal is Made by UFP (Unique Functional Products) They have a web site The kit that is used on Macgregors is #2. The kit consists of two seals, two stainless rings for the seal to ride on and two rubber o-rings which seal the rings to the axle.

Removing Spindo Seal
If you want to remove spindo seal you can. Just remove the parts and use the standard seal. Make sure to check the axle and make sure the area where the seal will ride is smooth and not rusty. If necessary it can be polished with fine emery cloth.


If the trailer has brakes, it still uses the same bearings seals and spindle as one without brakes. If you want to add brakes to a trailer which has none the axle must have been made with a flange where the backing plate bolts on. It is not practical to add this flange later.

The brakes on Macgregor trailers are not galvanized and after a couple of years of being periodically dipped in salt water they will be in sad shape. The brake shoes rust and break the lining off, The springs rust and will not retract the shoes and the wheel cylinders will freeze up. Fortunately there are replacement sets that are available. They are all galvanized and use stainless steel springs. It is well worth it to buy the replacement sets. There are even "free backing" brakes available. These brakes are sold in the marine catalogs. (about $125)

I would suggest also buying silicone grease and anti seize compound from an auto parts store. Apply the silicone grease to the piston in the wheel cylinder and the anti-seize to the bleeder screw, hydraulic line fitting, star wheel adjuster, where the shoes rub on the backing plates and also the mounting bolts for the backing plates. This will keep things working.

a site that has instructions on packing wheel bearings

ChampionTrailers a parts source

Eastern Marine a parts source.

The last place I know where Spino Seal was available is Boat/US special order Dept. Kit #2