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Old 07-17-2018, 03:11 PM   #1
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Shank length/ball distance from TV

I've noticed that the 'suck' from large trucks passing is noticeable on my 23D, never noticed it on my 23FB, which had 200 lbs less tongue weight.

For those that have their ball mounts at home and not in storage, a favor please. What is the distance from your back bumper on your pickup trucks, to the center of the hitch ball? My shank is waaaaay long. 11.5 inches from the bumper to the ball center. I could shorten it 5.5 inches (by having another hole drilled in the shank, it's solid), bringing the trailer that much closer to the truck's rear axle. This is with my jack head turned so I could still open the tail gate. Research I've done (including asking Can-Am, who despite the criticism they often receive, overall really know their business when it comes to hitching) indicates that handling, sway control, and weight distribution is all much better with the ball as close to the TV as possible with the shank as short as possible.

If I move mine in 5.5 inches, it will be 6 inches from the bumper instead of 11.5 inches. If I forego opening the tailgate, I could bring it in even more, as much as about 7 inches or so with about 4.5 inches distance from bumper to ball. Would sacrifice clearance on tight turns of course. For what it's worth, Can Am also says to tilt the ball back as far as possible while still maintaining adequate (4-5") ground clearance of the WD bars (when they are hanging, not installed to the A-frame).

I use a standard WD hitch setup, not a Pro-pride/Hensley type deal. Hoping to avoid a debate on hitches on this thread...just keep it to feedback on ball distance from TV. And yes, only one chain shown, took other off for the photo. And part of this process will be to size chains appropriately so I can 'cross' them.



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Old 07-17-2018, 03:50 PM   #2
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My hitch was set up by Can-Am. The distance from the end of the receiver (bumper) to the middle of the ball is 9 1/4". It can't be any closer because of my spare tire mounted on the tailgate. I can jack-knife the rig without my spare tire touching the propane cover (barely.)

I travel at about 60 mph on the IS and when a truck passes at 70-75 mph, I can tell it is there (the same as if I were being passed solo), but there is no movement of the trailer.
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Old 07-17-2018, 03:54 PM   #3
PKI
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Shortening the TV overhang is a good thing. One of the reasons CanAm recommends the Eaz-Lift hitch is that it moves the ball closer to the TV than other hitches. Testing your turning clearance is a good starting point.

Pat
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Old 07-17-2018, 03:54 PM   #4
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What you are looking at is the length of the "lever arm" from the trailer ball to the center of the truck rear axle. The longer that lever arm, the more influence the trailer can have on the front axle. When the trailer sways, it can push the front axle around, and screw up directional control.

If you shorten that lever arm by shortening the hitch shank as you suggest, the trailer has a harder time pushing the front axle of the truck to the left or right, with the rear tires acting as the fulcrum.

The Hensley design hitches use their trapezoidal mechanical links to make the pivot point (the ball) appear to be at or very near the center of the rear axle. Very short, to NO lever arm, therefore no fulcrum, and no sway effects.

There is another older hitch design that has a track the shank rides on to literally make the pivot point the center of the rear axle. No lever arm whatsoever. Again, no fulcrum, no sway effects..

Fifth wheel trailers are typically rigged to get the pivot point and the load right over the rear axle center. Again no lever arm at all, and no fulcrum, no sway effects.

Trailer towing is all about the leverage and the forces. Control the sway forces properly, and there will be no chance to get into an uncontrolled sway situation, where everything goes to heck and beyond for you....
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Old 07-17-2018, 03:59 PM   #5
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Hi

As long as you can still make a reasonable turn, there is no downside to reducing the distance from the truck to the ball. The key parameter to look at is the center of the rear axle to the ball. Shortening that by 10 or 20% is in the "maybe you can" range.

Bob
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Old 07-17-2018, 04:29 PM   #6
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Not being to open the tailgate is a real pain in the......
However, other than that, I don't see a downside to shortening the shank by drilling another hole. (not that easy).
You're limited by the "gusset" since the shank won't slide in past that.
I'm surprised you can go forward that much! Your tailgate must be relatively short.
Mine setup looks similar and I can't open mine. I know from the pin hole to the mounting holes is about 9". I'm thinking of going to 12" but I don't want to lose stability.
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Old 07-17-2018, 04:35 PM   #7
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In looking at the photo I posted, I had a 'duh' moment and realized that due to the reinforcement at the inside 'corner' of the shank, the most I can shorten it is about 4 inches, which is 35% shorter. That would bring it in to 7.5 inches from the bumper, from the current 11.5 inches--and still allow for the tailgate to open.

Doesn't seem to be a downside to this assuming the clearance is ok when jackknifing. Thanks for the feedback thus far.
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Old 07-17-2018, 04:40 PM   #8
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Quote:
Originally Posted by Mollysdad View Post
...
You're limited by the "gusset" since the shank won't slide in past.
Have a machine shop cut off the excess shank and drill a new pin hole.
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Old 07-17-2018, 04:48 PM   #9
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Originally Posted by Mollysdad View Post
Not being to open the tailgate is a real pain in the......
However, other than that, I don't see a downside to shortening the shank by drilling another hole. (not that easy).
You're limited by the "gusset" since the shank won't slide in past that.
I'm surprised you can go forward that much! Your tailgate must be relatively short.
Mine setup looks similar and I can't open mine. I know from the pin hole to the mounting holes is about 9". I'm thinking of going to 12" but I don't want to lose stability.

Good catch. I actually had noticed the gusset issue and posted a new comment. I was only looking from the top, where it appeared I had up to 11 inches to play with. Once accounting for the thickness of the vertical part of the shank, plus the reinforcement...I'm suddenly limited to more like 4 inches that I can shorten by. The good news is I'll still be able to open my tailgate. I have 6.5 inches clearance to the jack (turned 90 degrees) now; I'll still have 2 inches clearance if I shorten the shank 4 inches. There is a local machine shop that said they can easily drill a new hole for me.
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Old 07-17-2018, 05:05 PM   #10
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Originally Posted by pcskier View Post
The good news is I'll still be able to open my tailgate. I have 6.5 inches clearance to the jack (turned 90 degrees) now; I'll still have 2 inches clearance if I shorten the shank 4 inches. There is a local machine shop that said they can easily drill a new hole for me.
Winner, winner!
When I said it's not easy to drill, I meant at home with a hand drill and a worn bit. Even with a drill press, it's still a lot of steel.
+10 on machine shop.
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Old 07-17-2018, 05:05 PM   #11
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Funny to see this right now. I literally just finished drilling a new hole in my shank to move my ball closer to the receiver by about 3" per Andy's recommendation. As was mentioned above, the gusset determined how far I could go. And yeah, I would not have attempted it without a fairly large drill press and machining vise to hold it.
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Old 07-17-2018, 05:49 PM   #12
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And a good supply of fresh cutting oil to keep from burning out that drill bit...
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Old 07-17-2018, 06:38 PM   #13
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" ---- 'suck' from large trucks passing is noticeable on my 23D, never noticed it on my 23FB, which had 200 lbs less tongue weight. ----"

So, "WHY?"

Data:
- did you weigh the coaches or assume the dry weight info from AS?
- were the coaches loaded or dry?
- were the tanks dry or full - fresh tank location on D? FB in front of axles.
- was there a difference in wind velocity or direction?
- are the tires the same or different? Inflation pressure?

Notes
- the axles are about a foot further back on the D than they are on the FB.
- the FB is 9" longer than the D, so less lateral surface area on the D.

The above questions are only offered only as a trigger for your thoughts, not a request for info. Your shank change will address stability, but the reason the coaches differ is worth understanding. Would appreciate your thoughts. Pat
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Old 07-17-2018, 06:49 PM   #14
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Originally Posted by PKI View Post
So, "WHY?"

I have given it thought. Unfortunately, no hard data. Just Anecdotal. A year and a half towing the 23FB, in various states (loaded/unloaded/full tanks/empty tanks etc) and never noticed any 'sucking' when passed by semis on the highway.



On my couple of trips in the 23D, I suddenly noticed. But not enough A/B data to try to figure out why the difference. It simply got me wondering that whatever the reason was, if shortening the shank might help (along with overall better handling by moving the ball closer to the truck's rear axle.)
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