Mercedes R320 CDI towing 31' '79 Excella

[andreasduess]

CanAm welds a supporting beam forward to distribute the fulcrum force of the weight distribution hitch. Where that beam is welded to depends entirely on the vehicle in question.

On my Honda, there was zero increase in noise. When I showed the install to my mechanic (I am friendly with the owner of the dealership) he declared it "very clever, the way they did it".

[dkottum]

Originally Posted by PKI

Would not the force be downward if weight transfer to the front axles is in play? Pat

Yes, downward or upward forces on the suspension carrier, the same forces the carrier is designed to operate with in a dynamic condition.

Has this even been an issue in the hundreds of vehicles with hitch reinforcement of this type, beyond the issues of normal bushing wear from suspension travel?

[dkottum]

Originally Posted by rostam

Welding a brace between the hitch and the axle carrier also causes you to bypass the rubber bushings and transmit road noise to the cabin.

Not sure what your point is. If the hitch connection produces road noise, then it is transmitted at the rear receiver connection. Honestly I've never heard any road noise difference hitched or unhitched.

But we should ask those with such a reinforcement; does this reinforcement produce more road noise?

[rostam]

The axle carrier is not directly connected to the frame. The bushings lie between the frame and the axle carrier, preventing road noise getting to the cabin. If you weld a brace between the axle carrier and the hitch (which is connected to the frame), the road noise will be transmitted to the cabin via the brace, by passing the bushings.

Now back to the game.

[dkottum]

It's not a game to the folks who actually tow Airstreams, there needs to be some basis in experience for this or it's simply fishing in a dry pond.

What is the noise transmission you suggest amount to, if any, from those who use this reinforcement?

That's what we need to know.

[rostam]

I was talking about the super bowl game

There is a master certified Porsche/Audi technician in the forum that posted about issues with the hitch reinforcement before.

[Knuff]

Originally Posted by dkottum

Not sure what your point is. If the hitch connection produces road noise, then it is transmitted at the rear receiver connection. Honestly I've never heard any road noise difference hitched or unhitched.

But we should ask those with such a reinforcement; does this reinforcement produce more road noise?

Nope - not more noise. The reinforcement is benign with respect to vibration and noise.

[Knuff]

Originally Posted by rostam

I was talking about the super bowl game

There is a master certified Porsche/Audi technician in the forum that posted about issues with the hitch reinforcement before.

Reminds me that Audi/VW/Porsche are indeed a different platform compared to the Benz. Still, after towing 25K miles, there are no issues... Bummer with the Diesel scandal. I was hoping for the 5L Diesel Cayenne with 850 lbs of torque...

[dkottum]

Originally Posted by rostam

I was talking about the super bowl game

There is a master certified Porsche/Audi technician in the forum that posted about issues with the hitch reinforcement before.

Yes, a mechanic with credentials and experience which is useful but more of an opinion about hitch reinforcement, possibly related to his experience with Porsche/Audi suspension carriers. Read it because we want to know if such a tow vehicle is a good choice.

This sort of speculation is interesting but we need more than that. Can-Am (as well as others) has been doing this reinforcement on hundreds of such vehicles for years yet I can recall no reports of suspension damage on account of it.

Keeping an eye on our own unreinforced Ram 1500 receiver, I get the impression the long reinforcing arm would have plenty of leverage to steady the receiver without severe force on the suspension carrier. What is your towing experience telling you on the subject?

[jcl]

Originally Posted by rostam

I was talking about the super bowl game

There is a master certified Porsche/Audi technician in the forum that posted about issues with the hitch reinforcement before.

Perhaps there was more than one master Porsche technician posting on the topic of hitch reinforcements and the problems he had seen with them. The one I recall posted on a thread about tow ratings for the Touareg, and said he had seen every Porsche failure point, but didn't comment on hitch reinforcements. Also no specific posts on failures seen related to towing. Link below, post 14. Do you have another link? I am interested in problems documented after installing a brace, not the theory of why such a brace may cause noise transmission, which we have already discussed.

http://www.airforums.com/forums/f238...ml#post1666916

Jeff

[guskmg]

Re; Post #6. The hitch frame has to be attached to sheet metal in the uni-body vehicle's construction. In order to do this correctly you need to attach to as many points as possible with welds and nuts/bolts to spread the load out over the uni-body along the hitch frame. When hitched up there will be loads in both up and down directions on the front as well as the rear of the hitch frame (think a "T", "H", or box shaped hitch frames). In my case when the vehicle pitched up going over the tracks it overloaded the front of the hitch frame and the frame tore loose from the uni-body and almost snagged a track rail. Just prior to that, the hitch force was in the opposite going up over the RR track. Good sheet metal attachment procedures require bolt holes no closer than three bolt hole diameters. Probably the best thing to do would be to interspace short beads of weld in between the bolt and nuts. You could do it all with bolts/nuts only, but be sure and use many more than what seems necessary to spread out the load over the uni-body that will be encountered. Many aircraft fittings are attached this way. Remember the attaching area must be capable of supporting the load on a sustained basis including any stress that could possibly be encountered.
guskmg

[Andrew T]

29 years ago when we first fastened the front of the receiver to a rubber isolated suspension cradle we were really concerned. We did it thinking this won't work but lets just try it and see what happens. There was no affect at all on road noise or vibration, at least nothing detectable. Since then we have done this on a couple of thousand vehicles. We had one Hyundai SUV about 10 years ago that had a bit 0f a rumble afterwards but that is the only one.

I think due to the length of the receiver tube and the width of the stock receiver there is enough flex in the hitch to absorb the movement of the axle carrier. When the weight distribution is done up it actually takes a little pressure off of the bushings. We have not seen any accelerated wear of the bushings.

The great thing about the axle carrier is it distributes the downward force to 4 or 6 separated body points. Since we are fastening between the wheels as opposed to behind them on a live axle vehicle it makes a very strong installation.

The ones that concerned me more are vehicles like my Jag or Road Rulers Infinity where the Suspension Cradle is aluminum so far though not an issue on either after several years.

The R Class in the pictures on Page 1 is friend of ours and it never had any issues. They have replaced it with a newer one while they could still get one but have 110,000 miles on the old one.

I have driven several hundred miles with their 34 Classic and I have to say it is likely the best tow vehicle I have ever driven. Absolutely rock solid on the road but with a very nice ride at the same time.

Andrew T

[Silverleaf]

I pulled my 30'' with the ML variant of this engine and Andy's mods. The Hensley that Andy probably recommended helped immensely. There are a lot of naysayers out there, and it's true that the feel of this combo is different than a LWB truck, but IMO it is safe and viable. I wonder if you might exceed 7200 pounds loaded for full timing, so be careful of that. Wishing you safe and happy travels.

[jrswann]

I towed a 2013 FC 27' with the same engine in an ML350. Towing is fine. Problem is that you reach the maximum weight rating for the vehicle real fast. Not much room to carry extra stuff inthe vehicle.