Any foreseeable problems or concerns with this Trailer Hitch Suspension?

[tta71]

Disclaimer: I am not an engineer nor did I play one on TV. However, I am In the process of restoring a 2000 Bushtec Roadstar and have read a lot of information about the hitch attaching directly to the swing arm. I was looking for a way to provide at least a small amount of travel/relief to the hitch point using an extended hitch pin and springs. Before actually towing this down the road, I was hoping I could get some feedback from those of you who have more insight/experience with this sort of thing. The hitch pin is a 3/4 grade 5 bolt machined to 5/8 to fit the heim hitch. The springs are springs for a 3d printer. (NOT 3d printed springs). Any foreseeable concerns or problems I should be aware of. Thanks for any insight!

 

[Mrmikey]

The top of the bolt isn't supported, correct? Least ways in the pic it looks like it isn't.
I'd be concerned about the bending force applied to the 1/4" thick tab the bolt is fastened thru. It'd be even worse when the tow hitch is at the top of its stoke i.e. when the bike's rear tire drops into a depression in the road for example. If you happen to be applying the brake or accelerating at the same time there's a good possibility, in my mind anyway, of forcing the vertical post forward or rearward.
As for a grade 5 bolt... mehhh, I don't think.
Just my two cents worth.

 

[Knizar]

I pull an Aluma trailer on a 1 7/8" ball and have not had any problems over hundreds of miles.
Been on some very rough roads and don't hardly know it's back there.
I don't believe that your set-up would improve my ride.

Try it if you want, maybe it works different on your trailer.

 

[EdMat]

At least add a gusset on each side. Interesting concept.

 

[BCNewell]

Neat idea. Two things I’d change. First - those springs appear to be plastic. If so, I wouldn’t trust them. That hitch is probably making hundreds of small bumps up and down per minute. Second - I would replace the top nut with a jam nut (about 1/2 the thickness) to bring your springs/tongue down lower; the lower that heim connection point is, the stronger it’ll be.

 

[Snoking1127]

Disclaimer: I am not an engineer nor did I play one on TV. However, I am In the process of restoring a 2000 Bushtec Roadstar and have read a lot of information about the hitch attaching directly to the swing arm. I was looking for a way to provide at least a small amount of travel/relief to the hitch point using an extended hitch pin and springs. Before actually towing this down the road, I was hoping I could get some feedback from those of you who have more insight/experience with this sort of thing. The hitch pin is a 3/4 grade 5 bolt machined to 5/8 to fit the heim hitch. The springs are springs for a 3d printer. (NOT 3d printed springs). Any foreseeable concerns or problems I should be aware of. Thanks for any insight!

View attachment 254362

How is the "hitch piece" attached to the U shaped piece that goes the the swing arm. I agree that hitch piece and its attachment should maybe reinforced. And maybe switch to flange nuts and thicker washers on the vertical pin.

 

[tta71]

The top of the bolt isn't supported, correct? Least ways in the pic it looks like it isn't.
I'd be concerned about the bending force applied to the 1/4" thick tab the bolt is fastened thru. It'd be even worse when the tow hitch is at the top of its stoke i.e. when the bike's rear tire drops into a depression in the road for example. If you happen to be applying the brake or accelerating at the same time there's a good possibility, in my mind anyway, of forcing the vertical post forward or rearward.
As for a grade 5 bolt... mehhh, I don't think.
Just my two cents worth.

Thanks for your thought. You are correct. No support at the top of the bolt/pin. Just a coupler lock to hold it together. Haven’t measured, but I believe the plate where the shank of the hitch pin attaches is a little thicker than 1/4 inch but I do see your point and that was one of my concerns. I chose the grade 5 bolt as it supposedly has a tensile strength upwards of 100K psi. Not saying it’s right, just my thought process.

I pull an Aluma trailer on a 1 7/8" ball and have not had any problems over hundreds of miles.
Been on some very rough roads and don't hardly know it's back there.
I don't believe that your set-up would improve my ride.

Try it if you want, maybe it works different on your trailer.

Thanks for your reply. This will be the first time I have towed with the Spyder. I will most likely try it both ways and see if there is a noticeable difference.

 

[tta71]

Neat idea. Two things I’d change. First - those springs appear to be plastic. If so, I wouldn’t trust them. That hitch is probably making hundreds of small bumps up and down per minute. Second - I would replace the top nut with a jam nut (about 1/2 the thickness) to bring your springs/tongue down lower; the lower that heim connection point is, the stronger it’ll be.

Springs do look like plastic but are actually metal with a max load of 158lbs with max compression of 50%. Great idea for the thinner jamb nut. Back to the hardware store again this afternoon!!

At least add a gusset on each side. Interesting concept.

Thanks for the reply. Looks like you are right down I20 from me. Exactly where would you put the gussets? Between the plate where the hitch pin attaches and the main frame?

How is the "hitch piece" attached to the U shaped piece that goes the the swing arm. I agree that hitch piece and its attachment should maybe reinforced. And maybe switch to flange nuts and thicker washers on the vertical pin.

The hitch itself is a Show Chrome model. The hitch piece is welded on both ends on the side closest to the tire. Thx for your thoughts.

 

[Snoking1127]

The hitch itself is a Show Chrome model. The hitch piece is welded on both ends on the side closest to the tire. Thx for your thoughts.

Would not hurt to add a little more beads.

 

[BajaRon]

Very interesting concept. If it works as intended, it should make for a better ride. Both for the bike and the trailer. I'm wondering what the friction component will be at speed. Greasing the shaft would be an option, but messy. I would go with a very thin layer of clear, fully synthetic grease as a first try if you decide to go this direction. This is a grease that I like to use for some applications.

I would also be tempted to put an O-Ring above and below the hitch on the bolt to see what kind of travel in both directions you might be getting. I might also be tempted to thread the top of the bolt giving me the ability to add tension to the springs. Though shimming with additional washers might accomplish the same thing.

A Go-Pro videoing the action would be awesome!

I do agree that some attachment to the top would be a good idea. I don't think it would take much. Something posted up from the hitch would do it. You could incorporate it into the pin assembly at the top.

I really like the idea. Hope it works out for you.

 

[Snoking1127]

He might also want some spring with never rates to play around with. The GoPro camera will tell a story!

 

[Redbeard]

I would be concerned about the bolt strength. Going from old memory grade five bolts are only "case hardened". Machining from 3/4" down to 5/8" took most or all of the good strength away, basically back to a grade 3 bolt. If one started with a grade 8 that is heat treated all the way through, machining a bit off would retain full strength through the bolt. For the weight of these trailers, I wouldn't think a spring hitch would gain you much better ride on the trailer than the normal setup.
Just my 2 cents.

 

[EdMat]

Thanks for the reply. Looks like you are right down I20 from me. Exactly where would you put the gussets? Between the plate where the hitch pin attaches and the main frame?