Thread: How To Measure Axle Length & Spring Packs

Active Fabrications at Beenleigh on the southside of Brisbane has a lot of information such as what you are asking (ie ratings, heights and ways of measuring) on their website and in their cattledog.
Active Fabrications Brisbane Gold Coast Queensalnd Australia

They also do mail order.

Originally Posted by bigboofhead

Active Fabrications at Beenleigh on the southside of Brisbane has a lot of information such as what you are asking (ie ratings, heights and ways of measuring) on their website and in their cattledog.
Active Fabrications Brisbane Gold Coast Queensalnd Australia

They also do mail order.

Thanks for the link. Had a quick look over brekkie.

Hope that the knowledge base comes back with the weld position answers too.
Cheers

Originally Posted by Bad Fruit

Needing to tap the knowledge base again .....

The axle supplier l have in mind has 40mm & 45mm sq axles (1100kg & 1450kg respectively with Ford bearings & hubs apparently). But the brake backplate flange is not welded on.
I'd be interested to know who this "supplier" is, that won't or can't weld the brake flange on. If you contact the actual manufacturer of the trailer axles, they can supply them with the flanges welded on, jigged up, and correctly located.

To get an 1100Kg rating on a 40mm axle, you will have a Ford outer bearing and a Holden inner bearing.

So a few Q's :
1. How do l design the axle length required? Where can l find out the various length data required. eg for a 5ft (1524mm) wide chassis frame what is the offset from brake backplate mounting flange to trailer centreline?

The two main measurements required to determine axle length are the width of the chassis, and the wheel and tyre dimensions, namely overall width and offset.

2. The supplier catalogue shows imperial measurements for axle length. They have a 77inch unit which is apparently ok for a 5ft chassis. But where would the 77inch be measured, end-end or flange-flange

These measurements are stated for overall length, tip to tip. HOWEVER... these generic lengths were calculated over 3 decades ago when the wheels and tyres available for fitment to Caravans and Trailers were generally 14" HT, 14" HQ and 14" Falcon wheels, each with a similar offset, running 185 to 195 tyres.

But now, with so many different wheel and tyre combinations available, ranging from 12 to 26" diameter, 145mm to 305mm wide, and zero to 50mm offset, you really need to determine what wheels and tyres you're going to use before ordering an axle.

3. I have to weld on the brake flange mounting flange. I plan to fit the hub and align the flange face with a dial indicator fitted to a magnetic stand.
Any better ideas would be appreciated.
I dont want to use the brake drum as l won't have the hydraulic lines done.
(see above about getting them already done.)
If you are determined to weld your own flanges on, the best way is to bolt the flange to the brake, assemble the brake inside the drum and adjust the brakes up to lock tight against the drum. Then install the drum and brake onto the axle. Tack the flanges on, remove everything, check the flange for square, and weld. The trick is not to have the flanges too far or too close so that the brakes are either ineffective, or rubbing on the drum.

4. Decision still to be made is 2000kg tandem load share suspension or 50mm 1450kg single axle using shackles not slippers.
I'm guessing the unladen mass of these would be about 125kg different all things being equal. Single 350kg, Tandem 475kg - both estimated.
Decision is down to storage and moving by hand vs load carrying.
I think I understand the question. For me, the decision is simple. For all your good intentions, one day you're going to load it with as much as you can fit, so I would build it with as much load capacity as you can afford. And when you have a big trailer, people will borrow it, and load it with as much as they can fit, regardless of capacity.

5. Is there a better axle to use in a single axle trailer to improve load carrying capacity?
Depends on your wheel and tyre combination. Anything bigger than a 1450Kg "Slimline" axle requires a 4WD or commercial rim with a centre bore big enough to accomodate a larger bearing (the snout of the hub becomes too big for a passenger car rim). Axles can be made for 2 tonne and 3 tonne single, but their cost jump is quite dramatic. You'll also require tyres with enough capacity rating to match.

6. Its been driven in not to weld the chassis/drawbar across the drawbar. Should l use the weldplate idea so all welds are vertical or fore/aft?
Good to see someone's doing their homework.
If you mean the triangular gusset at the join between the drawbar and front cross rail, thenYes, highly recommended, particularly for trailers with heavy load capacities.

7. Suspension mounts. Should these only be welded fore/aft or is cross chassis ok here?
Again, recommended. However, it partly is depends on whether the chassis is the main backbone of the trailer, such as a car carrier, or if the trailer has sides that give it extra rigidity. I only ever weld the hangers longitudinally (fore/aft) as makes them easier to remove should you ever need to replace them.

8. This supplier doesnt have sheetmetal sides and tailgates. Any idea where l can source them in Melb?
H.E. Brehaut or MTCS

9. Any other construction no, no's that l should be thinking about?

10. I know to tie in the drawbar to the front spring mounts but should l also add a centre spar to tie the drawbar front to a chassis crossmember.
If your drawbar is the correct size, and securely attached, then a centre spar on not required.

11. What is the nominal height from the leaf pack centre bolt to spring hangar mount surface for a tandem 5 leaf, 60mm pack with load share.
How long is a piece of string?
Depends on the spring manufacturer and the camber they put into their springs. One of the drawings I have has this measurement at around 170mm from spring bolt to chassis.

12. Any other Aus supplier websites that state this stuff would be greatly appreciated.
see Melbourne Trailers link above.
Thanks

I think I covered most of it...

Originally Posted by Yonnee

I think I covered most of it...

Yonnee, your a legend !
Thanks for taking the time to help out a newbee trying to sort the pitfalls.
I'll PM the axle supplier details to you as they are doing a favour (l think...)

Cheers