Do You Know Which Axle & Differential You Have?

[CA Fisherman]

If you have never crawled under your GT XL you may be in for a surprise.

I own a 2014 GT XL 334QS. It is built on the infamous Ford F53 24K chassis, has a 228” wheel base, and came with Bilstein shocks. I have seen several of these chassis and felt I knew what I needed to know about my chassis. Using the VIN numbers as reference I ordered several items from Roadmaster including a steering stabilizer, rear anti-sway bar and trac bar. As preparations were being made to install things at the rear of the MH, it became obvious there was a problem. The axel housing is square not round as I expected and the differential is huge. Not large as you normally find with the F53 24K, but HUGE. I though perhaps it was a setup for the 26K chassis, however the leaf springs are stamped 24 not 26 so that is not it. The supplied brackets were for round axel housings, but a call to Roadmaster got brackets for the square axel housing. According to Roadmaster and a nearby Ford truck center, while it is rare, some F53 24K chassis are built with square axel housings and super heavy duty (and huge) differentials. Neither of them could offer any rhyme or reason for this, just that “sometimes it happens.” They both said I should be glad I have the much stronger setup.

Someone in this forum probably knows why this happens, however for the rest of us, before you order anything to attach to your chassis, you might want to take a look underneath to ensure you know what you have.

[Mickeystamper]

We have a 2013 378ts. A 24k chassis and a 244" wheelbase. I is actually a F550 chassis. Look at your VIN if it has F5D then it is an F550 motor home chassis. Search F550 on this forum and a link to F550 brochure I place there last year should pop up. These are a beast of a chassis.

[Iggy]

I also have a 378TS with a 244" wheel base and have the larger differential. I believe it is has a 6.17 ratio and is designed for GVWR 24,000lbs - 26,000 lbs .
The smaller one is 5.38 ration for GVWR 20,500 - 22,000 lbs
Then the really small one is 4.88 ration for GVWR of 16100 lbs - 18,000 lbs
You also have to understand what GVWR means.

Here are a few pictures of my round differential which is the biggest and has a 6.17 ration.

Now if you have the larger on it just may have been in the specs for that bare motorhome frame. Why lose any sleep over it as it is a much stronger differential.


It would be nice to see a picture of your data sticker on the wall behind the drivers seat.
This will show what you have in weight of your rig.
Also do you have 22.5" tires or the smaller ones?

[CA Fisherman]

Mickeystamper - I do have F5D in my VIN # and will search for the F550 brochure you posted. Thanks!


IGGY - I will take photos of the differential and the data sticker. My MH has 22.5 tires with suggested cold pressure of 100PSI.

[Iggy]

Correction above we have a 242" wheelbase not a 244"

[Mickeystamper]

Iggy Correct 242" WB not 244"

[mike.t]

Should have an ID tag on the 3rd member. (I think ;o) )

[CA Fisherman]

Mickeystamper - I found your past posting with a link to the F550 brochure. Unfortunately the link no longer works. However, I found the information on the Internet. Thanks


IGGY - Attached are photos of the data sticker and differential.

[Iggy]

Originally Posted by CA Fisherman

Mickeystamper - I found your past posting with a link to the F550 brochure. Unfortunately the link no longer works. However, I found the information on the Internet. Thanks


IGGY - Attached are photos of the data sticker and differential.

Looks like your differential is a Dana 135.
I also noticed you have a different sway bar than I have.
Your GVW is 24,000 lbs and mine is 22,000 lbs
Would like to know what is the difference in the differentials?


Your tires bigger 255/80/22.5
Mine are 235/80/22.5


Man what do you have in your rig rocks? Your weight and tires are the difference.
You must have tile floors and residential refrigerator.

Thanks for the pics.




Your rig is 24,000 lbs and mine is 22,000 lbs
My tire pressure is 90 and your is 100
You must have tile floors and that large residential refrigerator.


It still would be interesting in finding out what is the difference in differentials.

[CA Fisherman]

Yes I do have a tile floor and residential refrigerator. Actually I have two anti-sway bars, the original and a Roadmaster. I do not have a clear picture of the original at this time, but if you look at the picture below the red lines point to small visible portions of the factory installed anti-sway bar.

[Iggy]

Originally Posted by CA Fisherman

Yes I do have a tile floor and residential refrigerator. Actually I have two anti-sway bars, the original and a Roadmaster. I do not have a clear picture of the original at this time, but if you look at the picture below the red lines point to small visible portions of the factory installed anti-sway bar.

The interesting part is that your 2014 Georgetown 334QS is 34ft 11 in long and weighs 24,000 lbs and my 378TS is 37ft 4 inches long and weighs 22,000 lbs

[Mickeystamper]

Iggy my 2013 378ts is a 24k chassis with 255/80r/22.5 rubber. I think the later 378's had the heavier set up. The 1st 387 we looked at was 22k and 235 rubber.

[Mickeystamper]

CA Fisherman I tried the old link to F550 and it worked for me. Go figure, those electrons and 0's and 1's sometimes have a mind of their own! But glad you found the info.

[Iggy]

Originally Posted by Mickeystamper

Iggy my 2013 378ts is a 24k chassis with 255/80r/22.5 rubber. I think the later 378's had the heavier set up. The 1st 387 we looked at was 22k and 235 rubber.

2013 was when they added the residential refrigerator.

[Mickeystamper]

Iggy I think the original 2013 378 we originally looked at had a residential refer. and tile floor. We were going to make an offer but another couple beat us to it. The salesman said he had another 378 in stock but was a different color. He said it did have a 24k chassis instead of the 22k and 255 tires. That is the unit we purchased. Remember - he was a salesman!