axle attachment question

[FAC]

on my trailer the leaf springs are bolted to a piece of angle iron (red) that fits on the c channel frame (blue) i woud like to put a bolt (yellow) through these instead of using a u bolt is this feasible or just ridicules?

 

[kabcpapc]

Re: axle attachment question

I have the same arrangement on my Little Dude trailer that has a 14' CollinsCraft fiberglass boat with stick steering and a 25hp Merc. Mine has two bolts, one at each end, and the bolts are also used to attach the fenders. I don't know what size boat you have but I would say you can use the bolts if they at least grade 5.

 

[Blujay96]

Re: axle attachment question

Bolting would be fine but I would put some in the side and the bottom depending on the thickness of the angle. I think they use the ubolts for adjustability.

 

[Frank Acampora]

Re: axle attachment question

Putting bolts in the side stresses them in shear while the U bolt method stresses them in tension--which is stronger. In your case though, it really doesn't matter because the load will almost always be downward into the angle iron--unless you keep your trailer in the air a lot. The only shear moment will be the force acting to move the angle backward on the trailer and as long as the bolts are tight, friction between the angle and the frame will be enough to prevent any movement. Be certain to use self locking nuts! It is really not much different than attaching a coupler with bolts on the side.

 

[FAC]

Re: axle attachment question

thanks its a 15' fiberglass tri hull with a 25hp johnson so i think i will be okay

 

[Silvertip]

Re: axle attachment question

The reason "U-bolts" are used is to allow fore/aft movement of the subframe (the axle) so you can adjust tongue weight. Nothing wrong with bolting the subframe but use the proper hardware and by all means adjust for proper tongue weight first.

 

[FAC]

Re: axle attachment question

adjusting for tongue weight is exactly why i will be bolting now, i broke two of the u bolts when i loosened them so i could move the axle forward

 

[Silvertip]

Re: axle attachment question

I understand your methodology but if you buy a different boat and keep the trailer, you now have to readjust and end up with a bunch of rusted bolts, unused holes and a bunch of new ones, all of which weaken the frame. Use the proper "U-bolts" to maintain the functionality of the design. If you do decide to bolt it, what size bolts do you have in mind?

 

[FAC]

Re: axle attachment question

i was thinking somewhere in the 1/2" range and grade 5 as suggested above

 

[yfzjim]

Re: axle attachment question

If you bolt it, bolt thru the sides of the frame, not the top or bottom of the c channel as this can weaken the frame.

 

[smokeonthewater]

Re: axle attachment question

I agree... the strength of the channel is in the top and bottom. bolt it through the side.... I had a 20' cuddy that sat on a 78 shorline trailer since new..... It was the same as yours except with a hole drilled every 12" through the side for adjustment of the axle position.... when I sold it last year it was 31 years old and no problems..... It had 6 1/2" galvanized bolts holding the tandem axle subframe to the trailer main frame

 

[Blujay96]

Re: axle attachment question

I disagree about the strength being in the top and bottom. Your strength comes from you vertical wall not your top and bottom. Just like on I beam. your top and bottom help from side to side strength. And with your angle on the channel you will not weaken it from putting a few 9/16 holes in it. Most of your load is being pushed down on the frame. Adding the bolts to the bottom helps to take the pressure off from on leg of the angle. It also spreads out the whole on side and top. How long is the angle that the leaf springs are attached to.

 

[FAC]

Re: axle attachment question

the piece is 3 feet long

 

[Blujay96]

Re: axle attachment question

I would put three in the side and two in the bottom