Howdy, guys!

I have an 2002 F150, 3:55 Locking rear end, HD springs (full towing package). Whenever I pull ANYTHING (from an empty 16' flatbed trailer to a 4800 lb boat) the damn truck feels like something is slamming on the brakes for a split second. I thought it may be the trailer brakes from the boat, but I pulled 3 different trailers and it does the smae thing on all 3. There is no RPM changes, no specific time that it does it, and it does it when either on the gas or coasting. I checked the reciever and nothing is loose. The hitch fits right, and is relatively new. It just feels like something is "grabbing" it and immediately releases. The guy at the shop said it was probably my fuel filter, but it runs great without a trailer. Any ideas? Thanks!

 

Its not the drawbar just moving around is it?

 

Thanks for the response. I'm not 100% sure what a drawbar is? If it the hitch mount that slides in to the mount on the truck, then I don't believe it's that. I checked the hitch on other trucks (A Chevy Z-71 and a F250) and it fit the same on all of them. Is that what you mean? I feel like a dumbass!!

 

Yes the Drawbar/Ballmount/thingy that slides into the square hole with the round shiny bally thingy on it was what I was refering to. I have had mine bang around giving the feeling that something was jerking the truck, usually a trailer with a decent amount of weight but not alot of tongue weight. If you take and slide the thingy (got to love those technical terms :P ) in you will notice that it does move around. I'm not really sure why manufactures designed them this way, so maybe someone else can step in on that. One thing you can try is to get a shim like you would use to level a door and wedge it in the top of the hitch on the top of the drawbar and maybe one on the side. Be sure to wrap tape around the shim and the drawbar to keep the shim from flying out. This effectively takes up the slack between the shank of the drawbar and the extra space in the hitch so that it won't move around as much and will allow you to see if this is infact what the problem is. Keep in mind this will probably crush the wooden shim so it is just a temporary fix that is cheap so you don't waste money on anti-rattle devices incase this isn't the problem. Clear as mud?

If that isn't it I don't really have an idea of what could cause the issue that would only do it when the trailer was attached. Everything I can think of that would cause the truck to jerk would affect normal driveability without the trailer.

 

I have been thinking about your post and I can't think of anything that it would be besides what F.L.U.F. talked about.

If a guy at the shop thinks it may be the fuel filter, well I would go ahead and change that if you haven't previously, just because it might need it and its an easy fix.

Good luck.

 

A little more info, please...
Are you using an electric trailer brake controller? or do the trailers have surge brakes?

Does it do it when driving along a flat straight road?

Does it ever do it under braking? Heavy or light braking?

When you crest hills? going over bumps in the road?

 

COOL, guys! I appreciate the hell out of the shim idea. I'll try that!

The trailers, one has surge brakes and the flatbed had no brakes at all. It happens all the time...slowing down, speeding up, on a flat road...BUT, it really doesn't do it when braking at all. It does do it coasting, though. Someone said it may be the torque converter. Dammit!!

 

Just out of curiosity, what size ball (singular) do you have (on the receiver)? Could the ball be too small for the trailer receptacle and cause this?

Dunno.

 

If it does it when the truck is coasting, it's not the torque converter.

There is often an adjustment on the latch of the trailer that controls how tight the trailer is to the ball (you have to look underneath where the trailer slids on the ball). You might try tightening it and see if it helps. I guess it could be too loose on both trailers...
Does anyone else have this problem when they tow the trailers w/ a different truck?

 

Not the convertor? Phew!

it's a 2" ball and a 2" reciever. The boat tows good on a 90 model C1500. Someone else at work told me it may be axle load. the springs are loading up and releasing. Anyone else heard of this or had it happen to them. i thought about getting some helper springs, but sure could use you guy's input. Thanks again for all of the responses.

 

I'm not an engineer or anything, but your "springs loading up" did catch my attention. Could it be the spring shackle is rotating (loading up), pivoting on the rear spring attachment and the rear shackle bolt attachment points and causing the issue?

I don't know if they could be lubricated, although I might hit the urethant/rubber components with silicone spray lubricant , or if you have slammed the back of your truck with a drop kit. What do you think?

This IS an interesting issue!

 

I'll hit it with some silicon lube. I'm pulling the boat to the lake this weekend, and we'll see what happens. I'm doing the fuel filter tonight, putting shims in the reciever, and hitting the bushings in the springs with soem lube. Hope one of those will work. I'll keep y'all posted. Thanks!

 

With and empty trailer, I would't think that the springs loading up would be a problem.

As for the tolerences of the 2" receiver and drawbar, I now have a small Travel Trailer with about 450lbs of tongue weight, and no longer have an issue with the effects of a loose fitting receiver/drawbar, but When I used to pull a very small Tent Trailer with about 80 lbs of tongue weight, I had a welder friend of mine weld 2 beads accross the top of the draw bar, about 2 or 3 inches apart. These beads were high enough that the draw bar would no longer fit in my receiver, but then I took my grinder to it and ground them down just enough so that I could slid it in nice and tight... anyway, that was the end of that problem. But if you are getting this surging whether the trailer is loaded or not, I can't see it being your problem.

Make shure your tongue weight is in check. Usually around 10 to 15% of total trailer weight.

Dpostman

 

I'll weld a few beads on the hitch tomorrow. That was a good point about the springs. Come to think about it, I hauled 2 yards of dirt in it last month, which is probably at least 2000 pounds, and had no trouble at all. I'll bet its the damn hitch. I'm pulling the boat this weekend and I'll let you know. Thanks again, guys!

 

Oh yea, one last thing.....Here in Austin, It's pretty flat (until you cross the dotted line in the hill country). I plan to tow with the OD on, unless it starts shifting alot, then I'll turn it off. Is that about right? Damn, with all of these questions I'm asking, I might owe someone a beer or four.