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

[77rollalong]

Our 1977 26 foot e-class ford had firestone 5000lb air bags in the back to help.. due to there age I replaced them with a set of PacBrake and it makes a big difference in the ride and the ride level as well

[pianotuna]

Hi Phil,

I've never owned an RV with a built in generator.

[pnichols]

pianotuna wrote:
Hi,

This morning I took my ride into a spring shop. They suggested the best route was to add a leaf or two on both sides. I had weight measurements for them--and they will "beef up" the driver's side to compensate.

They were not happy with the 11.5 foot overhang which is increased by my generator cage (offset to the passengers side to try to shift some weight). But there is no way practical way to fix this. Fortunately the wheel base to length ratio is about 53%, so driveablity is not too horrible.

They will be welding the broken air bag brackets on both sides.

Thanks to this thread for making me rethink just going to E-550 springs.

Don ... what happened to your built-in generator ... or is that what you meant by "generator cage"?

[pianotuna]

Hi,

This morning I took my ride into a spring shop. They suggested the best route was to add a leaf or two on both sides. I had weight measurements for them--and they will "beef up" the driver's side to compensate.

They were not happy with the 11.5 foot overhang which is increased by my generator cage (offset to the passengers side to try to shift some weight). But there is no way practical way to fix this. Fortunately the wheel base to length ratio is about 53%, so driveablity is not too horrible.

They will be welding the broken air bag brackets on both sides.

Thanks to this thread for making me rethink just going to E-550 springs.

[ron_dittmer]

rgnprof wrote:
added a new leaf to each side, about 1100 lbs additional support per side

ryan

1100 pounds per side is significant. Good for you!

I do wonder what the actual load is on your 4 rear tires. If you get the rig weighed and discover they are over-loaded, there are available E-rated tires designed to handle 600 extra pounds (per tire) over the typical E-rated RV tires most of us have.

Keep that in mind, just in case.

[rgnprof]

Finally had a chance this fall break to try out the RV with the new add-a-leaf spring. I went with an add-a-leaf that I bought from ATS out of the Philadelphia area (they are great to work with and I can highly recommend them).

Anyway, added a new leaf to each side, about 1100 lbs additional support per side...installation was pretty straightforward and we drove the rig this weekend about 500 miles. Definitely made a difference - ride is better and sits a little higher in the rear, which was very noticeably with my Subaru connected and when I pulled out of backed in to my slightly inclined driveway.

I still get a "BANG" sometimes on pretty abrupt transitions in the highway, but seems better. Not sure how to address that problem.

Overall, I'm pretty satisfied.

ryan

[Chum_lee]

The problem with buying/using/replacing your springs with "used springs" is that they fatigue over time. For the most part, IMO, you have no way of knowing the condition of used springs without trying them out on your rig. (unless you KNOW the condition for sure) Class C E350's are real tough on springs because they are almost always overloaded or close to it. Age is another factor. Adding "helper" springs to already worn springs may be of little long term help but that's your choice. There's nothing like the ride of a new vehicle which usually comes from replacing ALL the worn suspension/steering parts. IMO, making the suspension "too stiff" is something you'll probably regret later. You all ready know what it's like when it's too soft.

Chum lee

[pushtoy_2]

rgnprof wrote:
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.

a company called sumo makes heavy duty bump stops

[rgnprof]

After a lot of reading and talking with folks - and not having much success tracking down anything used - I have decided to try the add-a-leaf option. I have had numerous conversations with the guys at ATS Springs in Pennsylvania and they've been very helpful. Ordered a kit with one leaf per side rated at 1150 lbs each...Also bought a new polyurethane bushing kit from Energy Suspension - not sure if should or will replace the bushings yet???

Has anyone done this on an E350 chassis? Any trick to it?

Doesn't look that hard, but every time I start a project thinking that, something always seems to come up!

Thanks,
ryan

[Hank85713]

look at craigslist for dal/ftw and other local areas. I saw some parts vans there with mainly frame and suspension parts. Might require a road trip on your part but...............

[pianotuna]

How about jumping to the 550 from an E-450?

Will the F-550 fit?

carringb wrote:
Yes, just find any E450. They all have the same 9450 spring rate, so that makes it easy.
From '92 to '19 models, all E-series cutaways have the same spring mounts, so that makes it super simple.

[ron_dittmer]

Hi Ryan,

carringb is this forum's resident expert on "everything E-series".

With that said, for reference I went on Rock Auto's website and called up a 2005 E450 chassis rear leaf spring pack. Keep in-mind that you would need two packs.

CLICK HERE to see many Rock Auto options as low as $331.79 per pack, and as high as $577.79 per pack. I think the 5100 pound pack is the one to consider. The 7200 pound pack will be way too much for a 29 foot motor home. Too much capability will vibrate, shake, and bounce your house to death.

carringb's junk yard idea, $50 for two used packs is so much cheaper. Call around for any junk yard E450. They should pull the parts and have them on the office floor waiting for you.....maybe with the bump stops if you ask to include them. Like carringb says, preferably from a shuttle bus that is rarely loaded to capacity. Unfortunately many shuttle buses have air-ride rear suspensions that have gone bad. We get that kind often at our church's auto charity HERE where I volunteer at.

New or used, changing your early 3 layer E350 rear leaf springs to a full 11 layer E450 version makes the most sense to me. Any truck suspension shop should be happy to swap them at a reasonable price. It's what they do, and do it well. Then get a 4-wheel alignment and you will have completed the project. Many truck suspension shops do 4 wheel alignments too.

When all done, you can pitch the air bags leaving you with one less thing to think about.

[carringb]

rgnprof wrote:
I'm not sure what I would be looking for and what would be a good swap - are you saying that most leaf springs - even from a later model 450 will fit my E350 chassis?? How many leafs should I be looking for?

Not opposed to the salvage yard route (love going to my local Pull-a-Part), but I just don't know what I'm looking for.

Yes, just find any E450. They all have the same 9450 spring rate, so that makes it easy. Just find the newest set you can. They did offer the E450 with varying leaf numbers over the years, but it doesn't matter since the spring pack rating was always the same. I'd try to find something lower mileage so they won't already be tired, and try to find a set from a body that isn't also over loaded (i.e., take a set from a shuttle bus or box truck rather than a motorhome).

You could go with newer E350 springs, but you'd still likely be overloading them. And since they came with RAWRs from 6,080 to 8,500 pounds, finding the set you want will be harder than just using an E450 set.

From '92 to '19 models, all E-series cutaways have the same spring mounts, so that makes it super simple.

[rgnprof]

I'm not sure what I would be looking for and what would be a good swap - are you saying that most leaf springs - even from a later model 450 will fit my E350 chassis?? How many leafs should I be looking for?

Not opposed to the salvage yard route (love going to my local Pull-a-Part), but I just don't know what I'm looking for.