Pivot Design DIY for tyre carrier, etc - Australian Sizes [part 1] (1 Viewer)

[bgennette]

Here is what I built, with instructions following.
(As the site limits attachments to 3 per post the 6 pictures will have to be spread over 3 posts)



There are 2 parts to making one of these – a stub axel and a hub to hold the axel bearings.
These instructions apply to Australian sourced parts. I’m sure parts in other countries will be similar, though maybe not exactly the same, . . . so maybe someone who knows can supply the exact Bearing Part numbers and pipe sizes to suit for common American our European, etc trailer hubs and stub axels.

The Stub
In Australia the most common trailer hubs fit stub axels that were used on Ford and GM designs from the 1970s. The inner diameter of the bearings are different by 1/8” (Ford is bigger) but the trailer hubs (due to careful selection of roller size) can use the same outer diameter bearing races so that the ‘standard’ trailer hubs fit both types of stub axel. The hub described here will fit either the GM or Ford stub axels too (when the appropriate bearings are used).

GM is also known as LM stubs using LM11910/11949 outer bearing, LM67010/67048 inner bearing and LM28560 seal
Ford is also known as SL stubs using LM12710/12749 outer bearing, LM68110/68149 inner bearing and LM28600 seal

The finished hub will be about 70mm in diameter by 102.5mm high and you will need at least 10mm clearance height below the oil seal support and 40mm clearance above to fit the nut and dust cover (so total clearances are about 75 x 155mm (3” x 6-1/4”).
Select a bearing type (either Ford or GM will be more than adequate), buy a stub axel from Super Cheap, etc, and buy a set of matching trailer bearings (including top cover) at the same time. Weld the stub into an appropriate position in a solid rear bumper (taking the clearances and swing path into consideration).

The Hub
DO NOT cut the flanges off of a cast iron wheel hub and then attempt to weld to it – welding is almost impossible with cast iron, and certainly unattainable for an amateur.

A hub can be made quite easily from a few short pieces of steel pipe. Unfortunately only the middle section will fit ‘as is’ while the other three pieces will have to be fabricated, pressed into a curve and welded into place. This is not as hard to do as it may sound, 30 minutes or so with a hacksaw, file, hammer, a strong vice, arc welder and a bit of patience will create the four pieces. A drill may be required for optional plug welding and grease seal pining.

Sizes Table


Next part is fabrication

 

[bgennette]

Pivot Design DIY for tyre carrier, etc - Australian Sizes [part 2]



The middle section (80mm or 3‑1/8”) and upper bearing ring (38mm or 1‑1/2”) are made from a short length of DN50 [2”] pipe (OD - 60.3mm or 2‑3/8”, ID – 53mm or 2”) with Medium wall thickness (3.6mm or 9/64”). The 38mm ring needs about 25mm (1”) cut out before squeezing in to fit inside the top of the middle section. This will result in an inner diameter of ~45mm (1‑3/4”).

 

[bgennette]

Pivot Design DIY for tyre carrier, etc - Australian Sizes [part 3]




Make the bottom piece 80mm (or 3‑1/8”) high from DN65 [2-1/2”] (OD - 76.1mm or 3”) light grade pipe so that side loading is through the upper bearing (see drawing). Alternatively the bottom section can be fabricated from a 190 x 80 x 3mm (7-1/2 x 3-1/8 x 1/8”) plate strip or a 30mm (1-1/4”) if loads will be low. Pipe needs a piece cut out so that it will just fit around the outside of the middle section. Tack weld this ring in the middle to hold its shape during assembly. Also drill some holes for plug welds 33mm or 1-1/4” from the bottom if making it 80 mm long.

The cut out from the middle section can be used as a former to create the 45mm ID upper bearing ring (fitted inside) – see pictures. The middle section itself can be used to shape the 60.3mm ID lower bearing ring (fitted to the outside).
The outer bearing races should be fitted and the final shape of the tubes around them ‘adjusted’ with judicious hammer taps (and maybe a few well placed steel shims) before welding. Don’t make them too tight a fit though, the bearing preload (when you tighten the stub axel nut) will hold them in place even if there is 1mm ‘rattle’ spacing. Remove the races before welding. Re-adjust the ‘fit’ before painting (see below).

The upper bearing ring is welded flush with the top (Welds 1 & 2) and the upper bearing support is welded at the bottom of the ring (Weld 3) to hold the bearing ~25mm from the top. Ensure Weld 3 penetrates into both Weld 1 and into the wall of the middle section. Grind or file Weld 2 flat on top.

The bottom section is attached 22.5mm (7/8”) lower than the middle section and welded all around. If using an 80mm section it will overlap 57.5mm (2-1/4”) (to Weld 4 position) with the plug welds lining up at the Weld 6 position, if using a 30mm section it will overlap ~8mm (3/8”) (at Weld 6 position). Either way the whole hub ends up being 102.5mm (4‑1/4”) tall and the spacing between the bearing supports is 65mm (2‑9/16”). Finish the seam (Weld 5) with penetration into the middle section (but NOT into the bearing ring).




After removing any weld spatter do the final fit of the bearings. For light loads (one spare wheel, two fuel cans, etc) the bearings can be fitted ‘loose’, but for heavier loads (or just for peace of mind) you can fit some thin brass shim metal between the outer bearing races and the bearing rings to create a tight fit (advised). Note – brass won’t permanently bond with steel, you’ll be able to change the bearings at a later date; steel wedges and shims however could rust together – you have been warned.

Don’t rely on the pivot to hold all the load; fit a (plastic or rubber covered) support under the carrier frame near your latch or under the heaviest part of the load.

After welding on your carrier frame grease and fit the bearings, protect the inside of the hub with a coating of grease, protect the outside with paint. If the seal isn’t being retained properly use 3 self tapping sheet metal screws to secure it at the bottom of the hub – this is essential, no grease on bearings, no pivot! Dirt in grease, no pivot! Water inside = rust, no pivot! Also seal the cap in place with some silicon after you are sure the axel nut is tightened properly. Again – dirt in grease, no pivot! Water inside = rust, no pivot!

 

[bhmmapping]

Thanks for sharing! there is a lot of information in those three posts.

 

[mudgudgeon]

or you can buy bare cylindrical steel hubs (no flange) and spindle/stub axle purpose made ready for welding in for around $80

 

[VETTE60]

here's what I use. have built several bumpers with this set up

Fabricator Parts for Do It Yourself - Tire Carrier Hinge Kits and parts