Community Forums

phil-t · 05-27-2018, 10:00 AM

Thanks, TeJay. I will take that into consideration. We still have several thousand miles ahead of us; could still change my mind. It is the Roadmaster Reflex Steering Stabilizer that I was looking at, just before this trip.
My question is, with a good stiff crosswind, you will need to apply counter force to the steering wheel; then the stabilizer is constantly trying to bring the system to center, and you need to fight that as well? I just need to experience it, I guess.

TeJay · 05-27-2018, 12:34 PM

Think about that a bit longer. Remember what the RSSA coil spring is doing. When a wind hits the left side of the MH it's trying to push the front end to the right. That movement wants to turn the SW to the right or towards the right shoulder. You want the SW to stay in the center.

When the wind hits the RV on the windy side the spring is resisting being compressed and the spring on the lee side is resisting being stretched. Together those two forces will add resistance to the SW reducing greatly the SW movement.

That's really confusing but I think I have it right. Either way when the SW moves off center the spring resists compression and stretching.

Don't forget these two factors. If you do have to provide some left or right rudder you have power steering so it's much easier. The point (MPH of the cross wind) at which you need to add rudder may be 30 or 35 or 40 MPH as opposed to what it might be if you had no system to center the SW. I can't help but think it' a win win situation.

I just ordered the RSSA stabilizer from Amazon. I checked again and the price went from $309.95 to $290 over night. That still included free shipping. The bracket kit is $90 but I have brackets from my original DIY steering shock that I'm sure I can re-fab to fit.

Enjoy your trip and travel safe!!!!

IggyTech · 05-27-2018, 03:03 PM

Quote:

Originally Posted by F53Challenge

What percentage of the rear axle weight should the front be carrying? I have lowered the front air bag pressure with the rear increased and did not notice a difference. Of course when doing that one decreases the positive caster. I had the caster set to 5 degrees positive. Do you have some experience that would point to something other than 5 degrees positive?

Ford says:
40% weight on front axle
60% on rear axle

F53Challenge · 09-13-2018, 08:00 AM

Quote:

Originally Posted by IggyTech

Ford says:
40% weight on front axle
60% on rear axle

Where can I read where Ford states these weight percentages for front and rear axles?

TeJay · 09-14-2018, 07:22 AM

We bought our RV from a dealer in Forest City IO and had it weighed (front axle, rear axle and total) before we left town to head home. This is an 18,000 LB 31' chassis and nothing was added except a full gas tank.

FRONT 5,450 33%
REAR 11,000 67%

TOTAL 16,450

This is not an exact 60/40 % split but darn close. That's maybe how or why Ford came up with these percentages.

triplewide · 09-14-2018, 09:44 AM

From another thread:

8-31-2017

I was curious how the modifications and additions to the coach had changed the gross weight. Weighed it today, below are the results of weighing when first delivered, followed by today's weights. (both CAT certified scales)

4/2/2015

Weights at CAT Certified scales:
Steer axle: 5,780 lbs 37.2%
Drive axle: 9,740 lbs 62.8%
Gross weight: 15,520 lbs

Propane full
Fresh water full
Holding empty
Gasoline full
100 lbs baggage
1 passenger

8/31/2017:

Weights at CAT Certified scales:
Steer axle: 6160 lbs (+380 lbs) 37.9%
Drive axle: 10,100 lbs (+360 lbs)62.1%
Gross weight: 16,260 lbs (+740 lbs)

Propane full
Fresh water Empty
Holding empty
Gasoline full
Baggage: Loaded for two week trip
1 passenger

18K chassis, 30' long

TeJay · 09-14-2018, 10:23 AM

Can't argue with those results. Very close to the 60/40 split. Even after you added your stuff.

I still find this interesting. The rear carries more weight. In fact it's in the neighbor hood of double in all three cases.

The rear has 4 tires to carry the weight which makes sense and yet the rear stabilizer bar (SB) is smaller 1.42" as opposed to the front which is 1.50".

I've posted this before and nobody has responded with any suggestions or answers.

THenne1713 · 09-14-2018, 10:30 AM

THOUGHT: Have you tried driving w/ empty water & waste tanks? The influence of 520# WATER (64gx8#) and another 640# of FUEL (80gx6.4#) sloshing side to side, or front to rear maybe your biggest issue? and depending on tank locations, maybe even influence of VARYING front axle loading while driving? THESE ARE (DESIGNED) TO RUN on smooth, flat roads, not the wavy, rolling highways (even brand new) I am seeing for the past few years. and lord help you if any tank anchors are loose

TeJay · 09-14-2018, 03:14 PM

Tom,

You may be correct about the rear SB arms. If we think about why no link extensions are needed on the rear it's the placement of the link arms on the frame. They should know what they're doing. That's why they get the big bucks!!!!

SimRacer · 09-14-2018, 03:23 PM

Tim
I deleted the post because I could not find any documentation for what I thought I remembered. There was speculation on the differing size bars but no hard proof.

Tom

Dav L · 09-14-2018, 07:55 PM

Quote:

Originally Posted by TeJay

I still find this interesting. The rear carries more weight. In fact it's in the neighbor hood of double in all three cases.

The rear has 4 tires to carry the weight which makes sense and yet the rear stabilizer bar (SB) is smaller 1.42" as opposed to the front which is 1.50".

I've posted this before and nobody has responded with any suggestions or answers.

Because the RV is moving forward, when you turn into a corner, the front leads in and dives. The total weight of the RV (not just the front) is moving forward. The front bar takes that brunt. As the RV rotates into the turn, the weight starts to stabilize and the weight starts going outboard. Then, the rear bar starts to take effect to keep the top from swaying out.

And if you happen to be trail braking into the turn, even more of the effect.

It's a dynamic system which makes tuning difficult. But, RVs aren't exactly critically tuned like a sports / race car. But the dynamics are similar.

If you were going in constant speed circles then the two bars could be more balanced.

A stiffer front bar promotes understeer. A stiffer rear promote oversteer. Ideal case is balanced, but the err on the side of understeer. If the tires start to slip in a corner, most let up the throttle and get adhesion back. If in an oversteer condition, it takes more driving skill to bring things back in line. So, most all vehicles are tuned for slight understeer.

911 Porches with their rear engines were known to be naturally oversteer as the engine weight swung the back out. That made the car hard to drive at it's upper limit because when the rear looses it's traction, then things happen quickly. They typically had light rear bars and significant fronts.

A hollow bar has more twist resistance for the same weight solid bar. But, less resistance for the same diameter solid bar. Not aware of any hollow RV bars because weight ain't no big thang in an RV like it would be in a race car.

Poly bushings, because they deflect less, provide in effect more sway bar effect. And, since they replace packed down rubber OE mounts, they fit better too and the sway bar has more immediate effect once the weight starts to transfer ie: more sway protection.

TeJay · 09-15-2018, 09:30 AM

Dav L,

Thanks for the suspension analysis.With the adjustable plates on front and rear I'm able to increase the SWAY control 1" more than the CHF position. This gives me more SWAY control from the stock SB SWAY adjustment than most any other RV on the road. I have little trouble cornering most turns even when I underestimate the sharpness of a corner.

We travel many of the back roads here in AR and they are hilly and curvy. If you've ever traveled into or around Eureka Springs and Branson you now what I mean. It's not unusual to see a yellow sigh that looks like a snake and says "25 Mph" and means it.

Your comments on the poly bushings is another plus. You are absolutely correct. I've often suggested to any RV owner that has an RV that is on a 2011 F-53 chassis or older to change from the old rubber bushings to poly urethane for better SWAY control. I've compared it to a baseball player batting with hands that can't hold the bat tight. The bushings must hold the twisting SB firmly or things won't work efficiently.

I reinforced my rear SB brackets and when I installed them I noticed the one on the drivers side was torn. There was bushing rubber that transferred from the Ford stock poly bushing onto the SB. I had to sandpaper it off. I also added some poly lubrication and most of it was gone. Somethings not right in Denmark.

Our RV is a 2013 chassis so it has poly bushings. Why did the poly lube disappear, why has part of the bushing torn 1/3 of the way through and why did the poly bushing rub off and stick to the SB? The SB has to rotate within the bushing without causing a great deal of resistance.

I've contacted "Skuterdude" to see if he can custom make a set of bushings for the front and rear. I'm interested to know if his poly is different from what Ford provided?? We have been playing phone tag so we haven't talked about why this is happening.

I have seen this bushing material rubbing off and attaching itself to the SB before but didn't think to much about it until I noticed the tearing of the poly bushing. That has to be because of the increased resistance in and around the bushing and bracket. Maybe this is why so many brackets are coming loose??

When I first bought the tub of poly lube and lubed the Ford stock bushing I noticed that they were DRY. There was no lube on the bushings. We had maybe 10,000 mile on the RV at that time and now we have 30,000+.

In the first pic you can see the gussets welded to the bracket for strength and at the base of the bushing you can see the split put there by Ford.

The second pic shows a close up of that same split. This is on the passenger side.

The next two pics show the drivers side and how the bushing is actually torn and not just cut or split. The tear is ragged and not at the same location as the normal split which is used to install them onto the SB.

I didn't notice any problems with the passenger side but I really didn't look to closely. I will when the new bushing arrive and I do the R&R.

TeJay · 09-15-2018, 09:46 AM

Quote:

Originally Posted by phil-t

Thanks, TeJay. I will take that into consideration. We still have several thousand miles ahead of us; could still change my mind. It is the Roadmaster Reflex Steering Stabilizer that I was looking at, just before this trip.
My question is, with a good stiff crosswind, you will need to apply counter force to the steering wheel; then the stabilizer is constantly trying to bring the system to center, and you need to fight that as well? I just need to experience it, I guess.

When we travel with cross winds if you are driving a stock RV when the wind gust hits you steer into it with a left or right turn so you stay straight. When the wind slacks you ease off the SW. If you have no improved controls or MODS the sudden wind gust can scare you. I have had the SW (Steering Wheel) torn out of my hands for an instant. It i scary.

Install a steering shock or as with the RSSA a shock and a spring that will resist compression and expansion. Now when you encounter a moderate gust of wind the shock dampens, resists, or stops any sudden SW movement. With a moderate wind with the shock you may not even notice the RV move. At the same time the spring will resist any SW movement. So you don't have to do anything with the SW. If you only had a shock the RV might move. With the spring you might not notice any movement.

If the gust of wind is greater than the shock and spring combined can stop or resist at that point yes you have to turn the SW into the wind to keep the RV straight. You will not be fighting two forces but one. The spring is already fighting the increased force which is trying to move the RV. You will counter the force with a turn of the SW. The amount of turning you do now is significantly less than you'd normally do with all the MODS doing their job.

When everything: shocks, Track Bar (Front/Rear), SB, CHF, Steering spring/ shock you have more than one MOD designed to resist/control RV movement from wind gusts and it does just that. The amount of RV lateral movement is significantly less and the sudden sideways movement is not nearly as bad of a shock or scare to you the driver. It literally softens the wind gusts and sudden movements.

I realize it's confusing. As I'm driving I devote a lot of time thinking and analyzing what is happening as we encounter the outside forces. It's just in my nature to do that to keep my mind active.

Bob Hyatt · 09-15-2018, 09:29 PM

sounds like that RV is simply going to be a dog. The key number is wheelbase divided by overall length. You said 158" for wheel base, and 115" for rear overhang. If your front (in front of center of front wheel) measurement (to bumper) is only 36", you are barely over the 50% mark for wheelbase / length. That is considered undriveable. If center of front wheel to front bumper is more than 36", it is even worse.

short wheelbase + big overhang gives really bad handling characteristics.