Fix Bend in Trailer Axle

[PeterInSA]

Have small wheels on our boat trailer and Disc Brakes, the wheel rim is to small to fit the brakes and hence the springs are further back. The axle is round solid steel. Because of the position of the wheel and the spring, more of the weight of the boat is transferred to the middle of the axle which is lower than the axle at the Spring/wheel.

Have seen single axle caravans that have a strip of steel 50mm off the underside of the axle to prevent this bowing of the axle. Under some caravan A Frames a similar set up is used.
Mate suggests I weld a 50mm by 50mm gal angle iron under the axle. Am not keen on the angle iron as it will hold water to rust the welds . In regard to the strip with a heavier welding process wary of impacting the strength of the axle.

Am probably only looking at doing a fix because of the look of the slight bend in the axle,
do not appear to have any major tire wear and has been like this since we purchased the boat/trailer new.

Peter

[FishHunter]

I cant make any sense of your description maybe upload some pics?

[finga]

Put a bigger axle on.
They're fairly cheap now-a-days and welding an angle under the axle for strength may be illegal.

[Mossy247]

Don't want it illegal and may void any insurance etc...

[tunaticer]

A replacement axle to the next size up would be a more cost effective solution in the long run. I can not understand how they can produce good quality lazy axles for the price they ask.
Check out Active Fabrications or Vehicle Components on the web, both are SEQ based, but i am sure there is an equivalent outlet near you that would be comparable price. You are probably staring at a U-Bolt replacement anyhow due to rust by now anyway.

Upon reading your post for a second time, I am now wondering just how far inside the tyres are the springs?? Could it be the axle is too long for the trailer chassis and the flex is generated more to the geometry of your trailer and the fulcrum effect?

[PeterInSA]

Jack, All
Re Upon reading your post for a second time, I am now wondering just how far inside the tyres are the springs?? Could it be the axle is too long for the trailer chassis and the flex is generated more to the geometry of your trailer and the fulcrum effect?

I think this is the problem, the outside edge of the spring is 15cm away from the inside edge of the trailer tyre and another 6cm to the studs to bolt the wheel on. This i think is the Fulcrum effect. Not sure whether the next axle size up would solve the problem though. In between the Spring and the wheel are a Torana Disk Brake setup.

Thanks for your replies.

Peter

[SunnyCoastMark]

Hey Peter,
Axles will always have a slight bend in them when they are under load. In saying that - Yes - your wheel is a long way out from the springs. We work on 35 - 50mm clearance between the chassis and wheel - depending on tyre profile. Add an extra 6mm for the spring hanger. and you are around 40 - 55mm. - 150mm is a long way.

What size is your axle and what weight is the boat? - If you don't know the weight - what is your rig? Also how much room do you have under the guards?

Standard rule of thumb for working out the Hub Face to Hub Face length of your axle is:-

Chassis Width + 70mm (2x clearance) + 2 x wheel backspace.

If you had a 1500 wide chassis and a wheel backspace of 120mm - (measured by laying wheel on ground face up and putting a tape measure through the hub bore to measure distance from ground to where the hub face would sit) Your Calc would be:-

1500 + 70 + 240 = 1610 Face to Face. -

Add 110mm for hub offset and you have an axle length of 1720 Tip to Tip.

hope that helps.

Mark (ex Rosewater boy;D)

[tunaticer]

As Sunny points out, bring your clearances down from 150mm to about 40mm each side if possible (could have a clash with the guards or wheels hitting the boat maybe???).
Whack up a couple of pics so we can see any problems that could arise from shortening the axle would probably be your safest bet atm. Just throwing in a heavy axle could well stop the bending if the axle was heavy enough, but probably not the best solution.

[PeterInSA]

Trailer purchased new about 30 years ago, probably was one of the first in Adelaide to have Disk brakes installed on small 10" wheels the Torana disk brakes are the reason for the wheels standing out. Am going on a trip will look at taking some pics late November/Dec.

Will also look at more modern Disk brake setups to reduce the width ( axle space)

Boat and trailer weigh around 730Kg.

Thanks

Peter

[cormorant]

With it being 30 years old and now flexing the axel I wouldn't consider any modifications to the existing axel. Have a experienced trailer repairer local to you have a look and he will tell you if the axel looks Ok or not. Many old trailer and axels are well overloaded and can be a disaster waiting to happen as boats get heavier and more overloaded.

If not I am sure he will be able to sort you out with a complete new axel to suit the weight and set up depending on how it is construncted.

All I can say is get it checked, don't oveload it and be careful.

Have a safe trip.

[PeterInSA]

Cormorant, all
Re the Bend, the trailer axle had the bend since new, its just that did not not bother about it and did not realise it was because of the Fulcrun affect until years later

Peter.

[Knotpretty]

Fit a new 45mm solid axle that suits Ford bearings if possible (cost around $200). Check to see if your hubs can take Ford bearings. This combo should carry 2ton. mojo

[FishHunter]

My old Tinka had the same setup just with 13' wheels. After costing the exercise to fit a new axle and brake setup I bought a new trailer instead of sinking money into a 30 year old trailer.

[PeterInSA]

SSmojo,
My Solid round axle is 50mm diam, would need to go larger/squarer than this.

Fishunter have not used the Boat/Trailer a lot in its lifetime at a guess 120times and always washed it down, am happy with the design and now it would probably be a specail build, so will look at replacing the axle. etc.

Peter

[cormorant]

50mm solid is very unusual. With one offs anything is possible. Back then there was a lot of hollow axels with solid ends. Not saying it isn't but there was a lot of very heavy wall tube axels. I think hollow axels were banned in the eastern states 10 years ago as they could rust from the inside and fatigue where they join I think I remember. It is not only the size of the metal but it's temper. That is what determins it's flex and resilience.
Bottom line just make sure it is safe.