Frame Extension

We had a 24-ft C on 158" WB. It drove very well, but it was the pre-1992 chassis. Front Axle was Twin I Beam but it had kingpins not ball joints. Along with a better front sway bar arrangement than 1992-2007 E-Series.

I don't hear the handling complaints about the 24-footers that I do from owners of longer coaches. Biggest mistake Ford owners do, is air up the front tires to the pressure on the sidewall, or the door jamb decals.

As others've said, be sure the tires haven't aged out of usefulness. If they're Load Range "D" with a max pressure of 65 PSI, I'll guess those tires are OLD. Just about all the new ones are "E" and 80 PSI. 65 would be max load on the front axle, 4600 lbs, and I'd guess you have 1000 less than that on that 24' coach. I'll look up the Michelin RV tire pressure chart and link it. You'll see what I mean. The tires can be a different brand, so long as the specs match. Be sure to use "Single" info for the front and "Dual" for the rear.
Michelin Chart

All good stuff J-D, thanks. The coach I’m looking at right now is a low mileage 99 24ft. Minnie. It does have a 3500 lb. hitch so I’ll throw my “brake in a box” in the Honda along with the tow bar in case I decide to buy it. It’s over 3 hours away so had my daughter who lives nearby look at it and take a bunch of pictures. Pictures show it setting pretty level but it’s hard to with photos. I’ll make them an offer subject to my inspection and see what happens. The frame extension and hitch information from you and Mich was just what I was looking for. I’ve had two Class A’s, my present one is 34ft and I’ve got it loaded with enough good stuff that we can make it two weeks without hookups. This little Winnebago looks so small and unadorned that I’m not sure what my wife would think if I buy it. I don’t think the original owners did anything to update it. My daughter said it was very clean inside and out. She likes my Class A so she wasn’t very impressed. Oh well, I’ll see what happens.
Stan

rice_classic wrote:
With your application and low amount of tongue weight it's doubtful to be an issue. The primary reason for reinforcement/strengthening is the lever affect from the tongue weight.

Agreed. We have a 3500 hitch, I don't remember or care the tongue weight because a towed vehicle, four down, has essentially Zero tongue weight. The vehicle we tow, weighs right at 3500. Like rice_classic, I don't think you have an issue.

Gotta say, though, on our coach, right at the hitch but on the coach body, sits a decal warning that the coach's braking system is designed for the weight of the loaded Vehicle (GVWR), NOT to work at the Combined weight of coach and towed whatever (GCWR). You NEED a braking system on whatever you're going to tow beyond a motorcycle trailer, small boat, etc.

I have another soapbox to jump onto: Weight DISTRIBUTION! If a Class C doesn't have a large enough portion of its loaded weight ON the Front Axle, it won't handle right. Will wander all over the road and particularly if it's a Ford. Ford says at least 32% of loaded weight should be on the front axle. I believe that might be OK for box trucks but not so much for RV's. Box trucks almost never have the rear overhang Class C's do, for one thing. Some of the guys here say at least 75% of the front axle's rated capacity. I have this to say:

1. Wheelbase seems to be determined by floor plan, not drive-ability. The worst offenders seem to be in the "upper 20's" length wise. I believe it takes a 31- or 32-footer to drive properly with a full queen walkaround bedroom. When the front office wants that feature on a 26-27-28-footer, there isn't enough coach FORWARD of the axle to balance the long bedroom (ours is 11-feet too, like Mitch's) behind the axle. Not only that, but the REAR axle may be Over Loaded, at the same time the Front is Under Loaded. Now it not only won't track on the road, it'll blow rear tires. Many times there's not enough storage area forward to be able to shift enough weight to get the axle loadings right.

2. What to do? WEIGH IT!!! I know the builders are now posting as-built weights. You can use that to see if you have enough TOTAL weight capacity for people and stuff. BUT!!! if that label doesn't show Front and Rear Axle weights, individually, you can't be sure the coach has a proper weight distribution. If it's a new coach, include a Travel Center (political correct speak for Truck Stop) in your test drive. Spend $10 to weigh it on their CAT Scale. Then go to the air station and set tire pressure so the Front is inflated according to Scale Weight and the Rears are likewise. Or at least equal. You may find it drives better. But if it's tail-heavy, Disqualify It!

3. Hint: Look at a Class C from the side. Not counting the part over the cab, does the House part look like it's balanced on the rear axle? If it does, this coach is likely going to be Front Light, Tail Heavy. If it looks like more House is in front of the Axle, and less behind it, coach might be OK.

4. Still, Weigh it!

srd1941 wrote:
Thank you Mich
Very good information. I saved the Ford data in favorites for future reference. My problem is that my CRV weighs 3680 which is above the 3500 lbs. of most factory installed hitches. While I have no doubt that a 3500 lb. hitch will safely tow the CRV I really don’t like to be right at the upper limit. I’d rather have a bit of a cushion. My concern with the frame extension has been whether or not it is stout enough to install a heavier Class 3 hitch . With less than 3 ft. of extension I don’t believe there would be a problem. I would like to look at how the extension was constructed but I’m pretty sure Ford supplies the coach manufacture with specifications on how to do it and it would be more that strong enough to support a heavier hitch. One other thing that is not taken into consideration in regards to hitch rating is that towing a car places little to no tongue weight on the hitch unlike towing a trailer. The information I’ve been able to glean from the hitch manufactures refers only to towing trailers.

Just had to go through the Woodall's portal to post again ?

Any of the newer E350/E450 class C's will most likely have a 5,000# or 7,500# rated hitch. I believe some manufacturer says they have an 8,000# rated hitch, but that would be more than what Ford rates the chassis for.
I had a 1997 24' Coachmen Class C which came with a 3,500# rated hitch when built. It had a very short frame extension from the rear of the Ford chassis under the rear of the house. I had a local welding shop, which does this sort of stuff all the time, make up and install a custom hitch, which bolted into the frame rails forward of the frame extension. It was very inexpensive, less than what a lot of off the shelf hitches would have cost. That vehicle had an 11,500# GVWR and an 18,000# GCWR/
My current 32 1/2' Class C is rated to pull 7,500# as built by Ford. The wheel base was stretched to 220" and I have about 11 1/2' from the rear axle to the rear bumper. It came with a hitch rated at 5,000# and stickers saying not to exceed 350# tongue weight.

I'm doing this very thing shortly. There's a couple shops in my area (Tacoma WA) that do this very thing. I'm upgrading to a 10k hitch as I will be pulling a 7500# enclosed trailer. With the frame reinforcement + class IV hitch, one place quoted $1600.

With your application and low amount of tongue weight it's doubtful to be an issue. The primary reason for reinforcement/strengthening is the lever affect from the tongue weight.

Thank you Mich
Very good information. I saved the Ford data in favorites for future reference. My problem is that my CRV weighs 3680 which is above the 3500 lbs. of most factory installed hitches. While I have no doubt that a 3500 lb. hitch will safely tow the CRV I really don’t like to be right at the upper limit. I’d rather have a bit of a cushion. My concern with the frame extension has been whether or not it is stout enough to install a heavier Class 3 hitch . With less than 3 ft. of extension I don’t believe there would be a problem. I would like to look at how the extension was constructed but I’m pretty sure Ford supplies the coach manufacture with specifications on how to do it and it would be more that strong enough to support a heavier hitch. One other thing that is not taken into consideration in regards to hitch rating is that towing a car places little to no tongue weight on the hitch unlike towing a trailer. The information I’ve been able to glean from the hitch manufactures refers only to towing trailers.

MORE LATER... We were in a time crunch to get to church...

Look at the... Spec Pages that our members have graciously posted. You'll see that none of the chassis' have much frame at all BEHIND the axle. So whether stretched or not, pretty much ANY Class C will have a rear Frame Extension. Ford publishes a guide on how to stretch and extend and retain the rated capacity of the chassis. If you're looking at a Chevy chassis, I'm told the "stretchers" follow Ford's guide since GM doesn't publish one. I'd imagine that your "pull" rating will be preserved, up to the rating of the hitch. 3500 used to be common then 5000 became common but some now are 7500. That said, I believe that in EVERY instance, you will find that the "carry" rating (tongue weight) will be limited by the coach builder, even though the hitch itself bears a label with a higher tongue weight rating. The longer the frame extension (the one behind the axle) is, the more reduction you'll notice. So you might have a coach with a 5000 pull/500 tongue hitch and adequate Gross Combined Vehicle Rating (GCWR) to have 7000 of pull left. The most you should tow, is 5000 and the tongue weight might be only 300, limited by the coach builder to less than the hitch is marked.

There's "frame stretch" that extends the wheelbase. You can look in the door jamb find two labels. There'll be one from say Ford noting the wheelbase that Ford built the chassis at. Then another from say Jayco saying what wheelbase they built the coach at. The difference is the frame stretch. On ours, 158" and 218" respectively, meaning the wheelbase was stretched by 60", a full five feet. And probably another label saying who stretched it, Mor Ryde for example.

Look at the MORE LATER, gotta run

Many, maybe most, class C's come with a hitch installed by the maker, and the limits of the hitch are often in the specs they give. Frequently the tongue weight rating is limited, presumably because of frame extensions. Heavy tongue weights are also problematic due to the long lever arm, causing a larger weight shift towards the back (and off the front axle) than there would be with less overhang.

As stated above an E350 comes from Ford with a 138", 158" or 176" wheelbase. An E450 has a 158" or 176" wheelbase. A 24' motor home more than likely is on the 158" chassis. As you can see in this link a 158" cab and chassis supplied by Ford is 21.75'long (92.5"+100"+68.5"). Subtracting that from the overall length of the MH, should give you the length of the frame extension.
Ford E350 and E450 specs

Tried posting on RV Net - had to switch to Woodall's portal :S