Chevy Chassis is out of control

[ericsmith32]

Frankly it doesn't seem any different than my grandparents E450 31ft but I'm getting tired of being pulled over! Pulled over outside of Jackson MS because the road suddenly started tossing the RV around and couldn't slow down quick enough (although the step was starting to come down so it was good timing). My wife got pulled over for the same but was the wind in KS. Starting to think it could be our age, grandpa never pulled over except speeding and he's worse than we are!

Planning on this in the following order.. Alignment.. Changing out the rear D Load Range with E's and pumping them up to 80lbs (front are already changed out)... Steering stabilizer up front .. and shocks last.

It does track straight and ride good for the most part but is easily influenced by wind and road conditions. And it does excessively bounce over the dips in the road. Typical RV's that I'm used to but has to be better. Thinking about a rear sway bar to but those are pricey for my budget. Anything I should look into?

[j-d]

You didn't photo all of Jayco's label, but they're only going to parrot the tire pressure for max axle load. 4300 GAWR means 2150 per single tire or 65 PSI.

Please Please Please lower that front tire pressure! I'd like to have you drop it all the way to 50. Go 55 if you feel better, but LOWER that pressure.

Our front tire pressure should be 65. Tire shop set to 80. It tracked poorly till we went down the steep grade from the top of a high bridge in a cross wind. At that point we nearly lost it. Stopped on the side of the road and lowered to 70. Got our tracking back.

Air's Cheap, probably Free. Let some out! You can always put it back.

[tenbear]

Mine came with load range D tires with a recommended inflation of 60 psi front and 65 psi rear (maximum for LR D tires). I have since replaced them with load range E tires and increased the pressure by 5 psi each.

[ericsmith32]

Some day wanting to change out the dinette for another sofa.. until then don't know of anyway of moving any weight forward.

I haven't bumped it up to 80 just left it at the factory specs. According to Firestone chart 1800/individual up front or at least 50psi .. 2105/individual back or at least 65psi. Going to drop the fronts down to 60 and the back's up to 65. Factory is the opposite. Unless I'm reading it wrong. Primewells should be similar.

http://commercial.firestone.com/content/dam/bcs-sites/bridgestone-ex/products/TechnicalInformation/T...

[j-d]

Your not overloaded from an Axle or Gross Vehicle standpoint. That said, I know that Ford wants at least a third (why they say 32% and not just 33% or a "third" kinda beats me) of the unit's loaded weight on the front axle. I calculated just under 30% from the numbers you provided.

"One-Third" is one rule of thumb. The other one I've heard is "75% of GAWR-Front" and you're above that at nearly 84%.

So, although I'd like to see you shift 200-300 pounds from aft of the rear axle to forward of the rear axle, I'm not convinced that weight distribution is the problem. On our Jayco, the fresh water tank is under the coach body, pretty much centered over the axle. So full or empty, it's a rear axle weight, but doesn't unload the front axle when full. But!!! Both the Black and Gray waste tanks are behind the rear axle, so we always try to run with those empty.

Since I think the issue is something else...

Did you adjust Tire Pressure according to the CAT scale axle weights? If you have Load Range E tires and they're inflated to the max of 80 PSI shown on the sidewall, I can PROMISE you that the handling is going to be squirrely. Read Michelin's Load/Pressure Chart and scroll to your tire size. If you match your size, the Brand doesn't have to be Michelin. The numbers still work. You should have NO MORE than 50 PSI front. Look up the rear, too, but overinflated rears just ride harder, don't do much to affect tracking.

Is there a damaged part in your steering, or even in your rear spring shackles and bushings? I think I mentioned front Idler Arm and its mounting bracket.

Then have its alignment checked/corrected by a truck shop. Fords benefit from the CASTER setting toward the upper end of the range, so we try to avoid having it set to midpoint. I don't know about Chevy, but Caster contributes to tracking.

Your coach should do better...

[ron_dittmer]

ericsmith32 wrote:
2k difference give or take.. Wonder what the true difference would be besides the rear-sway bar? Fully loaded it doesn't drop more than 1/2 inch. Don't know after the new shocks doesn't feel like it needs a sway bar! But in all actuality it would take corners alot better.. but if you do that things get to sliding (and breaking)!

Eric and community here,

It is not only a matter of improved handling. Most important, it is a matter of safety. It is not a question of "if", but rather "when" a motor home driver misjudges a curve in the road. It could be an on/off ramp of an interstate highway, it could be down in a canyon, it could be up in the mountains, but a driver will find himself or herself in a panic condition braking hard into a turn for one reason or another.

Under such a braking condition, heavy duty front & rear stabilizer bars will help immensely in keeping the motor home firmly planted on the road. All tires will grip the pavement better and therefore, the brakes will be more effective, and the rig will be controlled much better, easier to keep in between the lines.

Heavy duty front and rear stabilizer bars is cheap "safety insurance" with great benefits in reduced driver fatigue & passenger comfort, and even stability when parked. It's a win x4. I don't think people realize the multiple benefits with heavy duty front and rear stabilizer bars. They can be installed by the owner at a cost of around $175 per bar. Once the benefits are understood, I don't understand why it's so hard to spend $350 when there is so much else invested in the motor home, insurance, and most of all, the cargo.

[ericsmith32]

2k difference give or take.. Wonder what the true difference would be besides the rear-sway bar? Fully loaded it doesn't drop more than 1/2 inch. Don't know after the new shocks doesn't feel like it needs a sway bar! But in all actuality it would take corners alot better.. but if you do that things get to sliding (and breaking)!

[carringb]

IAMICHABOD wrote:
After reading your post on the weight,I see a difference in your 2005 and mine on a 2005 chassis. Is yours on a 2004 chassis?

My GVWR is 14050 compared to yours at 12300

He most likely has the Chevy-branded 3500 chassis, which is 12,300 pounds. Workhorse made structural changes to allow the Workhorse-branded chassis to carry the 14,050 GVWR (which GM later bought the intellectual property to and renamed it the Chevy Express 4500).

Workhorse 3500 =/= Chevy 3500.

[tenbear]

IAMICHABOD wrote:
Eric and Tenbear,
I find it interesting that both of you have no rear sway bar and mine does and the are all basically the same vintage.OFDPOS was the same but a few years away,j-d helped to install his.

Eric or Tenbear do either of you have a build sheet like this?

Mine has a data sheet inside a rear cabinet. It was put there by Four Winds. Here is the info.

GAWR front 4300 (All weights are pounds)
rear 8600

GVWR 12300

GCWR 17000

UVW 10568

SCWR sleeping 616

CCC 741

Water 325

LPG 51

Apparently my CCC is much less than yours. Probably compensated in part by the wife and my weight, much less than the SCWR and we rarely travel with the water tank full.

In any case, the RV has served us well for over 10 years.

Sorry I'm so late with this. Just saw your post today.

[IAMICHABOD]

After reading your post on the weight,I see a difference in your 2005 and mine on a 2005 chassis. Is yours on a 2004 chassis?

My GVWR is 14050 compared to yours at 12300

The front Gawr on mine is 4600 compared to your 4300

The rear Gawr on mine is 9450 compared to your 8600
I have the rear sway bar and wondering if just one year will make that much of a difference.

Fully loaded with full fuel,water and all the food and drink for a 2 week trip with 2 people on board I weighed it and got this.

Front 3880 and rear axle 7930 total of 11810.

I think that the addition of the rear sway bar will greatly help in the handling.

[ericsmith32]

Put 30 miles on or so on it today. The Bilsteins are quite the improvement. Seems to be more stabile all around and doesn't bounce. I did move the spare tire under the sofa from the very back and filled the propane so it put more weight on the front.

Also had it weighed..



And the stickers from the door and cabinet..





The gas tank was 7/8, propane and 2 water tanks completely full, 5 persons (usually just four) and I put 2 5 gallon jugs in the very back to simulate cargo. Feel fairly confident we've never overloaded it. And looks to me if I leave that one 21 gallon tank empty shouldn't be within or close to the limits pulling the Focus. I'll need to do the other calculation here later.

Still seems highly influenced by wind etc.. which would be normal. But think I can lessened it some. Scheduling a alignment next week and will get a stabilizer after that. It does have the factory blocks in place.

[IAMICHABOD]

Eric and Tenbear,
I find it interesting that both of you have no rear sway bar and mine does and the are all basically the same vintage.OFDPOS was the same but a few years away,j-d helped to install his.

j-d and Ron may of hit on something about the way the chassis is ordered from the factory,as we all agree, they will go the cheaper the better, both Ford and Chevy has these options

I think that the RV MFG has the option to go with the regular or the commercial version,as Ron and j-d pointed out.

Both of my build sheets identify mine as a Tioga Commercial,and it has the sway bars.It was ordered by El Monte RV from Fleetwood. This may explain some of it,I wonder if the Cruise America Fords have a rear sway bar. After all they are built for the commercial market,it would be interesting to know.

Eric or Tenbear do either of you have a build sheet like this?


As you can see in the top left it is identified as a Tioga Commercial
Just as the build sheet from Fleetwood.


Food for thought.:B

[tenbear]

tenbear wrote:

ericsmith32 wrote:
Mine didn't come with a rear sway bar. Tenbear does yours have one? Perhaps that the major issue handling wise.

I don't know if mine has a rear sway bar. I'm not sure if I could tell if it does. I didn't install one. In any case, there are a couple of inches of snow on the ground and it's raining, so I'm not crawling under it right now to see.

I did look and I do not have a rear sway bar.

[ericsmith32]

All comes down to the bean counters.. could care less about safety. Just for grins while at 4 picknpull's this morning looked at all the van's/van chassis. Not a single rear sway bar. Trucks also.

Called on alignment.. $99. I'll take it over after my business trip to Vegas. Still have the blocks in the caster adjustments.

[j-d]

We took a tour on a narrow gauge steam railroad. I mentioned to our guide the I'd heard narrow was preferred to standard in mountains because curves can be tighter. He told me "There are three reasons to build narrow gauge: 1. it's cheaper, 2. it's cheaper, and 3. it's cheaper.

Back to the load averaging idea - Some of us have smaller coaches on E450 chassis while most smaller ones are E350. I think it's usually safe for Ford to assume that when an RV company orders chassis, the E450 part of the order is intended, by and large, to go under coaches where E350 would be inadequate. Another reason for Ford not to deliver any of them, particularly E450, equipped like E250.

[tpi]

I agree with Ron's premise there is quite a bit of this could be easily fixed via calibration and not cost much at all. Stuff like OEM sway bars, shocks and springs. But it would take testing and engineering-with actual RV builds being tested. This on a platform that seems to get very little recent design time in general.

Perhaps too is most class C units are factory loaded way outside any sensible limits for CG and weight distribution..and Ford just doesn't happen to notice. Design for that and they'd be putting at least some kind of stamp of approval on it-something they don't want to do.

In general though motorhome chassis should be calibrated for typical motorhome weighting..and it isn't. In my opinion Ford's calibrations were way off for my class C. Aftermarket parts have proved very helpful.