Frame Extension

It's variable. A 24' may use the stock wheelbase or may be extended. The rear extension length depends completely on the body builder.

Just crawl under and take a look, you can see the factory thicker frame end and the lighter frame begin, its usually not over 3 foot long but on a 24 footer you might not have one.

My 24' Winnie has an unstretched frame but there are rear extensions. You can usually figure out if it's stretched by looking up the wheel base for the unit. Current production Fords are manufactured with a 138", 158" or 176" wheel base. If the RV wheel base matches one of these, it's very unlikely that the chassis has been stretched.

I'm shopping for a class c, don't have one yet. I know different manufactures do have different designs. I'll probably buy a 24 ft. and am wondering what people are actually seeing on their own rigs. The reason has to do with installing a hitch and whether or not an extension will be a problem. Maybe no one looks under their rig and checks? Anyway, thanks.
Stan

Here is a link you might want to dig around in. Can't remember exactly where but they had some remarks about frame stretching and length to handling etc

https://www.fleet.ford.com/truckbbas/

https://www.fleet.ford.com/truckbbas/topics/bodybuild.html

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

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.

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

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.

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.