Class C rear end sag and banging!

[rgnprof]

Just got back from a 4,000 mile plus journey to the great northeast - had a great trip and for the most part a pretty uneventful RV time.

I have a '93 29ft Class C on a Ford E350 chassis with the 460 motor. Pulled my 2014 Subaru Forester 4 down and averaged 6 mpg. RV ran great...but the banging on some really crappy highways was pretty loud - interstate transitions, particularly at bridges were especially problematic. An ex RV mechanic in Gettsyburg mentioned new leaf springs indicating that he thought the rear end was hanging pretty low. So I crawled under and starting looking around and reading some on the internet. My camper has about a 10 ft rear tire overhang and it's "only" (??) got a 3 leaf spring system installed and they're pretty much flat or arc slightly in a 'frown'. The rubber bumper stop that is pressed against the frame is pretty squashed...

I have Firestone Air Bags but I noticed they weren't making much of a difference in ride height. The banging problem has been prevalent since I purchased the RV about 10 years ago - PO even commented on it when I drove it - but I am pretty sure the rear end is sagging more over the past couple of years.

I read somewhere that Ford 'experimented' with a 3 leaf spring system and that it didn't really work out. I'm having trouble sourcing replacement springs and not sure of what to get. I know someone is going to mentioned rear axle weight, but I don't know it.

Any thoughts? Thanks in advance!

Ryan

[carringb]

rgnprof wrote:
So what do you all think of the 'add a leaf spring' option? Several online companies sell these and they're similarly priced - sounds like it would increase the support by about 2300 lbs.

Probably will replace the shocks as well, although I see no signs of leaking etc...

Add-a-springs would have been a decent option when your rig was new. But your rear-end has been overloaded all its life. You really just need new, better spring packs for your rig. Keep the airbags for fully loaded travel, bu the leaf springs should be able to support the empty rig at proper ride height.

FWIW - I bought replacement springs for my rig at my local salvage yard for $50.

[rgnprof]

So what do you all think of the 'add a leaf spring' option? Several online companies sell these and they're similarly priced - sounds like it would increase the support by about 2300 lbs.

Probably will replace the shocks as well, although I see no signs of leaking etc...

[rjstractor]

whemme wrote:
Your 29' Class C built on a Ford E350 chassis is most probably significantly over loaded on its rear axle. The E350 chassis uses a Dana 70 rear axle rated at 8500 lbs. Your 29' should have been built on a E450 chassis that uses heavier rear leaf springs and a Dana 80 rear axle rated at 9600 lbs. Have you weighed your RV to determine the actual weight on the rear axle alone?

The E450 did not exist in 1993. Some longer Cs were built back then on the E350 with a tag axle but apparently the OPs was not. You are correct, the rear axle is likely grossly overloaded.

[whemme]

Your 29' Class C built on a Ford E350 chassis is most probably significantly over loaded on its rear axle. The E350 chassis uses a Dana 70 rear axle rated at 8500 lbs. Your 29' should have been built on a E450 chassis that uses heavier rear leaf springs and a Dana 80 rear axle rated at 9600 lbs. Have you weighed your RV to determine the actual weight on the rear axle alone?

[SidecarFlip]

30K on a set of shocks, any brand, any price with the abuse you are giving them, are shot.

[DownTheAvenue]

You should consider adding Sumo Springs. They can do wonders!

[pianotuna]

Hi,

Next winter I'll be replacing my E450 springs with some from a wrecker--from an F 550.

Check the welds on the air bags. Mine gave up the ghost.

[rgnprof]

Thanks for all the quick replies!

I ran the air bags at about 80 lbs - this typically raises my coach only about 1 1'2" - maybe 2"...

My shocks are Bilsteins - I installed them around 2011, 2012 and about 30k miles ago.

I have called 3 different online places, the last being Deaver (thanks bear). They were very helpful and to confirm Drew, they said that it's hard to just look at the springs and see a problem and that most likely the problems with these springs are the bushings! They said from new they have little "curve" to them...

He actually suggested adding a leaf - they have a kit specific to my application. Replace the bushings if needed, but he said they frequently don't because they're ok. The factory tapered 3-leaf spring is rated at 3450 lbs, so it's likely the coach has always been 'under springed'...

I'm strongly considering this route.

I would like to find some replacement rear frame rubber bump stops - mine have clearly taken some punishment. But, I'm having trouble finding these - my Ford dealers around are pretty much a waste when it comes to parts for this old coach.

[DrewE]

Note that the rear leaf springs on (some? all?) E series chassis of that vintage are rather flat by design, and appear on casual inspection to go straight on a slight diagonal rather than having much or any obvious smile shape. I'm not suggesting you don't have some spring issues to look into--it certainly does sound like you very well might; but going merely on the spring shape can be misleading on these vehicles if you're not familiar with the design.

If the shocks are worn, it would be a good idea to replace them as well. A weak or worn shock is going to allow the suspension to bottom out more easily on a sudden transient than a new one (among other things). The rear shocks are not hard to replace on the Ford E series unless the motorhome builder has done something silly to limit access.

[the_bear_II]

Try Deaver Springs they manufacture aftermarket springs.
https://deaverspring.com/

[Hank85713]

If nothing else take measurements of the spring pacs and then research what model springs will work. Find some in a wrecking yard and have them install. The air bags should lift the rear as they are probably the 5000 lb type. You didnt say how much air is in them. I run 55-65 in mine and yes you will get occasional hard hits but nothing is a sure thing. Are you sure they hold air?

Go here and ask about the springs, folks are pretty knowledgeable:

https://www.ford-trucks.com/forums/forum128/

Also look in some truck magazines, they have ads for springs and stuff and would be a good start on finding replacements. Dont forget new hangers and bushings.

https://search.yahoo.com/search?p=rear+springs+ford+van&fr=uh3_groups_web_gs

[carringb]

The "banging" is almost certainly the airbags bottomming out. What PSI are you running? They should go up to 100 psi.

And yes, new leaf spring will do wonders. Your cheapest option would be take offs from a salvage yard E450. The 3-leaf setup normally was only used on E350s with an under 6,000# RAWR, and your rear axle weight I bet is at least 8,000 pounds.

[opnspaces]

You might try just a general internet search for a spring shop in your area. They should be able to build you some new spring packs, and it might be cheaper than you would have imagined. But I can guarantee you they will need the motorhome weights before they can build anything,