fifth wheel ball placement

case685 · Feb 11, 2008

Hi I have 1999 GMC 4by4 1/2 ton that I pull a 5th wheel 3 horse Sundowner with. When I bought the truck I mounted the 5th wheel ball 2" behind the axle. After I connected the trailer I saw that the truck was sitting low in the back (lower than my 1990 GMC 2wd did with the trailer mounted to it. I had the ball mounted 2" ahead of the axle on it). That was a year ago and I've had the transfer case go on me and now the rear end. I'm wondering if the ball placement is causing extra strain on the driveline. The truck steers and brakes fine with the trailer on it.
Can anyone offer experience/suggestions regarding this. Thanks. Gerry

Diamondpilot · Feb 11, 2008

Not to get in a brand bashing issue here but that era GM drive line was a weak point. I had the transfer case go on my Chevy at 18,000 miles, the drive shaft break not long after then the engine went all before 36,000 miles. I am guessing you have quite a few miles on the truck so I figure its just time.

Chris

Z-Michigan · Feb 11, 2008

I suspect the fact you're using a 1/2 ton for this job is more likely the problem than where the gooseneck hitch ball was located. I pull basically the same trailer you have with a 3/4 ton diesel 4x4 (it happens to be a Dodge, but I don't think that's important) and I would not be happy pulling it with a 1/2 ton of any brand.

For your next truck, I would mount the hitch ball 1-2" ahead of the rear axle, or wherever the hitch manufacturer tells you to. We had ours (B&W turnover ball) professionally installed and it's about 2" ahead of the rear axle. We are completely happy with how it tows in all respects. I know some people swear by mounting the ball perfectly over the rear axle, but I've never heard of mounting it behind the rear axle before. I guess that if you are happy with the steering, brakes and handling with trailer attached, the location is probably not much of an issue, though hearing that the rear of the truck sits low makes me think you may have too much weight on the rear axle.

Eagleview · Feb 11, 2008

Move the ball ahead of the axle . With the ball at the rear your putting all your trailer weight (as well as some of the transfered vehicle weight as the nose lifts)on the rear axle instead of sharing the load with the front axle . Also when you make a turn , say to the left your ball is pushing your trailer nose to the right because your rear axle is the pivot point . If your ball is in front of the axle on the same turn the ball will pull the nose of the trailer around to the left . Yes it would cause driveline damage as your pinion angle would be excessive as well as the damage the extra weight would cause . My ball is 6" in front of the axle .

case685 · Feb 12, 2008

Thanks for the replies. I will move the ball ahead as much as possible. Its a short box ext cab so I don't think I can move it too far forward.
Yes there are some contributing factors here- the trucks got 200,000 miles on it, also my daughter has a bad habit of turning down the brake controller when she uses it.
Z your right I wish I had a bigger truck for this. Of course, the people who sold me the trailer did tell me a 1/2 ton would handle the trailer easily.

Diamondpilot · Feb 12, 2008

I would just leave the hitch alone and get the transmission fixed. 200,000 miles is what these trannys are good for max. So what I am saying is with a 1/2 ton truck and running gear you did good to get 200,000 miles.

Chris

Z-Michigan · Feb 12, 2008

case685 said:
Yes there are some contributing factors here- the trucks got 200,000 miles on it, also my daughter has a bad habit of turning down the brake controller when she uses it.
Z your right I wish I had a bigger truck for this. Of course, the people who sold me the trailer did tell me a 1/2 ton would handle the trailer easily.

Ah, salesmen.

Anyway, I would tell your daughter that if she likes being able to move horses around, she can use the brake controller properly. If it's loaded when she's using it, the controller needs turning up if anything. I know when my wife pulls horses around she goes into crazy-obsessive mode as if the horse was more delicate than an egg in a stamping press and worth more than an aircraft carrier. But at least she leaves the brake controller alone!

Oh, BTW, our Sundowner 3-horse slant gooseneck weighs about 4800lbs empty. Figure at least 7500 with 3 horses, and 9000lbs is entirely possible with bigger horses or some tack. I suspect your 99 Chevy 1/2 ton has a tow rating of around 7500lbs or less, or at least it would have if it were sold in the US (I don't know if Canada has the same or different towing standards). So, at best, you're right at maximum weight when towing 3 horses, and likely over.

Eagleview · Feb 12, 2008

The further you move the ball rearward of the rear axle the more your trailer will behave like a bumper pull , think about it . Im betting that whilst reversing , your trailer is slow and unresponsive in turning compared to your previous truck .

Mahana79 · Feb 13, 2008

B&W have a ball placement at 44.25" from the rear edge of the bed Not sure where that puts the ball in relation to the axle

http://www.turnoverball.com/download.asp?id=61

Eagleview · Feb 13, 2008

I forgot to mention that with the ball forward of the rear axle your truck will squat squarely when the trailer is loaded . With the ball rearward of the axle your trucks nose will lift and the tail will go down . This will change your kingpin inclination on the front axle and cause your steer tyres to scrub .