Severe Fishtailing

So yesterday I took my friend's trailer up and gathered firewood. This is a great custom built 3,500 lb axle trailer with full size tires. I've used it for years with no problems - until yesterday. I loaded it up with firewood about 18" high from front to back. When I went much over 60 mph the thing would start to fishtail severely. It was scary. After 2 events I got off the freeway and stayed under 50 mph. I swear I had the thing loaded with 60% of the weight in front of the trailer axle - maybe not. Also, the hitch height is just right so the trailer sits level.

This is this is the first time firewood cutting that I didn't fill the bed of the truck with wood. I just put the lighter stuff like my chainsaws, tools, chairs, lunch, etc. Going up to the mountains I whipped down the freeway sometimes over 80 mph with the trailer empty and it behaved very well. On the way back the trailer was heavy but the truck was relatively light in the bed.

Question: Does having a light rear end on the truck and a heavy trailer affect fishtailing or it is pretty much the load distribution on the trailer?

Thanks for your advice.

 

It's all about the 'tonque weight'

You might have had too much weight at the back of the trailer and not enough at the front of the trailer (nearest the hitch).

I used to tow a jeep on a trailer. The tonque weight was critical to keeping the trailer stable. We had the trailer marked so we knew exactly where the jeep had to sit on the trailer for proper tonque weight. If the jeep was off by a few inches - you could feel it while driving.

 

Yes. Plain and simple. By having a trailer with an acceptable tongue weight is good, that weight can push the back end of your truck if it has an empty bed. When you have an empty bed, the best way to distribute weight on a trailer would be 90/rear and 10/front. This reduces the "push" that occurs. Also tongue HEIGHT is a huge factor. You want a hitch that does not push "upward" on the bumper because this will lift the back of the truck slightly when braking, and can cause excessive sway, push, or loss of brake force on the back wheels. Next time you go cutting wood, fill the bed up, then load the trailer.

 

Physics, it's fun! Figure a long trailer with all the weight on the backside. Any time there is force applied to the trailer you have it basically lifting the back of the truck and pivoting on 1 point. That puts more of the trucks pressure on the front wheels, that also pivot. It doesn't take much of a push in any direction to get that pivot point to move, there is a lot of leverage on it. That = oversteer, constantly.

Or you go tongue heavy, which sinks the rear end of the truck but lifts pressure off the front, so your steering and braking is less effective. That = understeer, constantly.

Both make the tow more dangerous than need be. Couple either with a short wheelbase or light tow vehicle, and it's a lot more interesting.

Properly loaded, the effects are still there but are minimized generally just making extra care required.

 

I tow all the time with nothing in the bed at all. My boat and my snowmobiles. Never been a problem but mine are likely longer length trailers. Maybe the axle got knocked out of alignment?

 

Check your tire pressure...in both the trailer and your Tacoma.

 

yeah, I tow trailer with firewood, atv's, mowers (not the 300lb things at lowes) tractors... and with unloaded truck. Tongue weight is what the problem is.

 

its also possible that the axle is too far forward as well

 

Its all about correct tonque weight and weight in your bed. When I pull my Scamp 16 foot with my dad's Sierra 2500HD sometimes the trailer starts to sway if its not loaded correctly. That sway doesn't transfer to the truck because its so big and heavy, but it would affect a lighter truck alot more. This is what happened in your case, trailer wasn't loaded properly.

Also, if you are overloading or pushing a single axle trailer to the limit they are just junk. Sitting on only one axle is just weak especially for a smaller truck.

Example: I owned a 7X18 dual axle 7k gvw flat bed and own a 7X12 single axle 2 foot tall side with drop down gate trailer. The dual axle both loaded and unloaded tows 100 times better with my 05 regular cab at ANY speed. At 55 mph the single axle is already starting to sway and that's unloaded.

Maybe your friends trailer works better for his specific truck but it's just not the best for yours.