M416 Trailer wobble at highway speeds

[wvtradbow]

I feel the answer is obvious But .. I added a bumper to my 416 with a spare tire carrier,and ever since i've done that i'm getting a high speed wobble so I guess the answer is; the tongue is too light or the back is too heavy.. I have a heavy deep cycle battery in the tongue box and that doesn't do anything..Any of you guys that have a 416, know that space is valuable so aside from carry a spare inside, whats the answer? Is there a formula for trailer balance or does anyone have pics or writeups how to mount the spare under the body/frame? My last resort is to go back to my original set up carrying the spare inside... If there's an answer,I'm sure someone here figured something out..Here were the before and after pics.... Thanks

 

[vintageracer]

Too much weight on the rear of the trailer and not enough tongue weight.

Redistribute weight on trailer with more tongue weight. Spare tire to the front.

 

[WillySwan]

I am very familiar with trailer sway with a M416 that does not have enough tongue weight. When I overhauled my M416 a few years ago, I made the decision to locate the spare under the frame in front of the axle. It fits my needs perfectly, but the tradeoff with this is reduced ground clearance.

Here are a couple of pictures showing the work-in-progress and the finished product. I used an F150 tire hoist. It is a cable hoist. It works well, but it was a very tight fit. If I were to do it again, I would look into using a chain-type hoist from a Toyota pickup or something similar. The chain hoists appear to be more compact.

 

[NatersXJ6]

It should be pretty easy to get your trailer weighed and then figure out how to move stuff around to balance. I’m a fan of water tanks up front because they adjust weight easily and it never hurts to carry more water.

You probably have a matching trailer spare. Maybe consider a donut spare or just carrying a patch kit? Trailer tires are likely so lightly loaded that a minimal amount of attention can prevent sidewall blowouts and you’re just left with punctures to deal with.

 

[mep1811]

I am very familiar with trailer sway with a M416 that does not have enough tongue weight. When I overhauled my M416 a few years ago, I made the decision to locate the spare under the frame in front of the axle. It fits my needs perfectly, but the tradeoff with this is reduced ground clearance.

Here are a couple of pictures showing the work-in-progress and the finished product. I used an F150 tire hoist. It is a cable hoist. It works well, but it was a very tight fit. If I were to do it again, I would look into using a chain-type hoist from a Toyota pickup or something similar. The chain hoists appear to be more compact.

I did the same with my 416. I also did a spring-over and gained several inches of ground clearance.

 

[SgtMac]

I mounted my spare underneath as close to the axle as I could place it, it does restrict the clearance a bit, but it actually touches the underside of the bed. I built a mount across the front of the bed on the tongue, the mount holds two 5 gallon scepter cans and a 50 cal ammo can for tools between the cans. The 10 gals (full) and full ammo can seem to have stopped the sway. The weight down low also helps with the weight of the RTT.

 

[wvtradbow]

Great advice,I never did have it weighed but I'm not sure with the tongue box i'd have enough room since I really didn't add any length.. WillySwan your trailer looks awesome,you did a great job.. Looks like something is gonna have to be redesigned..I really like the swing open spare and even put a shelf on the inside BUT if I can't tow it properly, It's all for not..

 

[Walkers]

Spare carried over the tongue makes more sense. If you really want to keep it as is, and cant find a way to balance the load better, you can relocate the axle further to the rear.

 

[calicamper]

Wind drag load on the tail end can also add to the weight effect. So not only mor tongue weight but if the spare is grabbing lots of air at higher speeds that can add a load effect beyond the static weight when sitting still?

 

[Peter_n_Margaret]

I suggest this is a yaw inertia problem.
Too much weight at the ends of the trailer instead of over the axle, even if the ball weight is good.
Move weight away from the ends towards the centre and as close to the axle as possible.
Caravan Stability Studies - YouTube
Cheers,
Peter
OKA196 motorhome

 

[50 fiver]

Sounds like you know that there isn't enough tongue weight, I made a frame for a cooler on the tongue and added a cj7 tire carrier on the back, I haven't had any issues towing it, but I did extend the tongue by several feet.

Sent from my SM-S908U using Tapatalk

 

[Peter_n_Margaret]

Extending the drawbar is helpful for stability, but keep the hitch as close to the rear axle of the vehicle as possible. Excessive overhang of the hitch behind the axle can have a dramatically bad effect on stability, particularly with a short wheel base vehicle.
Cheers,
Peter
OKA196 motorhome

 

[billiebob]

Move the axle back.

Honestly if you like the spare on the back,... we all do... and the rack is heavy but does it all...
just move the axle and fenders back. The weight is no longer too far back, the light stuff and tongue stay as is. You only change the leverage of the rear weight bias.

Keeping the same wheelbase / hitch distribution and adding weight to the tongue only adds to the polar moment.

You want the rear overhang weight closer to the trailer center and moving the trailer axle back does that.