Yes, another 'wandering' rant...er ... post...

[goufgators]

Probably the most discussed topic on this forum and likely others is that of the notorious steering wander on Ford F-53 chassis’. Judging from the number of requests for advice on remedying the problem, it seems to be close to a universal problem. My 2017 Winnebago, Sunstar with less than 4K miles is not an exception. Why I did not recognize this problem when test driving it is a mystery. I was probably too engrossed with gadgetry in the coach such as a flat screen that comes up out a counter area, electric sun shade that coves the windshield, bed that comes down over the front seats, air mattress in sofa and other items that are mostly to guarantee a sale…well, you get the idea. I have done practically everything that has been recommended on this Forum such as: Front-end alignment, weighing the coach then airing up in accordance with Goodyear’s PSI chart, installed steering stabilizer, installed rear trac bar and had caster adjusted to (I believe) 6 or 7 degrees positive. Thinking about next having toe in adjusted to Ford’s max 3/32. All of these things have been recommended by, I believe, well meaning members of this forum and there has been a bit of improvement but remains a difficult, tiring drive. I’m thinking now about having a Steer Safe installed but wondering can one be installed when there is already a steering stabilizer? Also, I’m still open to suggestions (actually pleading for) …maybe something you did to correct this problem on your coach short of trading it in for a diesel pusher (admittedly, I’ve given that some fleeting thoughts) ?.

[goufgators]

Dale.Traveling wrote:

goufgators wrote:

zigzagrv wrote:
A couple questions: what is the length of your motorhome and chassis and what are your tire pressures?

32', rear 85, front 90

Sunstar rigs are all built on a 18,000 GVWR chassis with a front axle rated at 7000 lbs and a rear at 12,000 lbs. No idea why the GVWR is derated by 1000 lbs. The tires size will be 245/70R 19.5.

Front axle pressures are way too high for the axle and can cause straight line handling problems. At that pressure you have a load capacity in the tires of 7780 pounds. Dropping to 80 PSI cold, the low limit of Goodyears chart, which still gives you a tire load capacity of 7280 pounds, 280 beyond the axle limit.

Same for the rear. 85 psi = 14060 capacity with a 12,000 pound axle. Drop to 80 psi cold also which will give you 13,666 pounds. Lot a wiggle room with tire capacity if weights getaway from you. I suspect you'll find the coach will be a lot easier to drive.

Couldn't agree more! We're thinking alike. I will be dropping the cold psi as you suggested. Even so, road and ambient temps in Fl will cause the pressure to rapidly increase from the cold settings. However, they will not as high as with my current settings. Aside: Had toe in adjusted by 1/16th yesterday and the short drive home seemed to have made a positive difference. But, it was a short drive and I'll not know until I drive it a longer distance. I do expect dropping the cold pressures will make the most noticeable difference. Thanks for your input!

Goodyear Inflation Tables (PDF)

[Dale_Traveling]

goufgators wrote:

zigzagrv wrote:
A couple questions: what is the length of your motorhome and chassis and what are your tire pressures?

32', rear 85, front 90

Sunstar rigs are all built on a 18,000 GVWR chassis with a front axle rated at 7000 lbs and a rear at 12,000 lbs. No idea why the GVWR is derated by 1000 lbs. The tires size will be 245/70R 19.5.

Front axle pressures are way too high for the axle and can cause straight line handling problems. At that pressure you have a load capacity in the tires of 7780 pounds. Dropping to 80 PSI cold, the low limit of Goodyears chart, which still gives you a tire load capacity of 7280 pounds, 280 beyond the axle limit.

Same for the rear. 85 psi = 14060 capacity with a 12,000 pound axle. Drop to 80 psi cold also which will give you 13,666 pounds. Lot a wiggle room with tire capacity if weights getaway from you. I suspect you'll find the coach will be a lot easier to drive.

Goodyear Inflation Tables (PDF)

[dodge_guy]

Wild Bill 888 wrote:
One day I was driving along a beautiful, narrow and mostly straight road in southern Utah, and noticed that I was making a lot of steering inputs. I focused on how the vehicle responded to them. Then I tried reducing the magnitude of the corrections by half, and removing the corrections as soon as it began to respond. In a few minutes I was staying centered in my lane with very little steering wheel movement.

Sometimes modifying the brains transfer function is easier and cheaper than modifying the vehicles transfer function.

Yes funny how that works! I think part of my issue also is the steering wheel was down on the left, my brain was wanting it to be centered. Also with where you place your hands on the spokes of the wheel with it down on the left makes the wheel naturally want to center which makes the MH go right. Once o get the wheel centered and with the proper toe adjustment I think I will be all set!

[Wild_Bill_888]

One day I was driving along a beautiful, narrow and mostly straight road in southern Utah, and noticed that I was making a lot of steering inputs. I focused on how the vehicle responded to them. Then I tried reducing the magnitude of the corrections by half, and removing the corrections as soon as it began to respond. In a few minutes I was staying centered in my lane with very little steering wheel movement.

Sometimes modifying the brains transfer function is easier and cheaper than modifying the vehicles transfer function.

[dubdub07]

way2roll wrote:

zigzagrv wrote:

goufgators wrote:

zigzagrv wrote:
A couple questions: what is the length of your motorhome and chassis and what are your tire pressures?

32', rear 85, front 90

I meant to ask the wheelbase on your unit, but I'm assuming it is the 208" wheelbase. Also, if you have the Goodyear GS670 tires, they are a harder compound than other tires and can ride a bit harsh. I would suggest dropping the front tire pressure to 85 lbs. Good Luck.

Agreed, a 32' is likely to be well under the weight rating for standard RV tires and so the recommended pressure is probably more like 80-82. 90 in the front is going to ride like a brick and be a bit squirrelly. Of course you'd have to validate this by weighing your coach and adjusting accordingly. All that said, the F53 chassis is notorious for handling poorly and amplifying road imperfections. Some is just the nature of the beast. DP is a whole different ball game.

Yes it is....I have no such issues with my 41' DP. High wind, quartering crosswind......no issues. Maybe it is just the nature of the beast with the F53 chassis.

WW

[way2roll]

zigzagrv wrote:

goufgators wrote:

zigzagrv wrote:
A couple questions: what is the length of your motorhome and chassis and what are your tire pressures?

32', rear 85, front 90

I meant to ask the wheelbase on your unit, but I'm assuming it is the 208" wheelbase. Also, if you have the Goodyear GS670 tires, they are a harder compound than other tires and can ride a bit harsh. I would suggest dropping the front tire pressure to 85 lbs. Good Luck.

Agreed, a 32' is likely to be well under the weight rating for standard G670RV tires and so the recommended pressure is probably more like 80-82. 90 in the front is going to ride like a brick and be a bit squirrelly. Of course you'd have to validate this by weighing your coach and adjusting accordingly - I see you've done that but 90 seems like you have some extra in there. They probably heat up to 100-110 psi. All that said, the F53 chassis is notorious for handling poorly and amplifying road imperfections. Some is just the nature of the beast. DP is a whole different ball game.

[zigzagrv]

goufgators wrote:

zigzagrv wrote:
A couple questions: what is the length of your motorhome and chassis and what are your tire pressures?

32', rear 85, front 90

I meant to ask the wheelbase on your unit, but I'm assuming it is the 208" wheelbase. Also, if you have the Goodyear GS670 tires, they are a harder compound than other tires and can ride a bit harsh. I would suggest dropping the front tire pressure to 85 lbs. Good Luck.

[mikim]

This is where we took our 36 Tiffin Allegro Open Road.

https://www.hendersonslineup.com/

I found a similar company in Florida.

Josam Alignmant

407-438-7020
8849 Exchange Drive
Orlando, FL 32809

Hope this helps....it made a world of difference in the handling and comfort of our Class A.

[goufgators]

zigzagrv wrote:
A couple questions: what is the length of your motorhome and chassis and what are your tire pressures?

32', rear 85, front 90

[dodge_guy]

RLS7201 wrote:
It's amazing how the long over hang and short wheel base gets the blame for handling.
I drive what might be considered a worst case scenario for wheel base and over hang. 1995 33' F53 coach, 190" wheel base & 13' overhang.
It handles very well with having the toe in set correctly, a front pan hard bar and quality tires. I still work part time in the front end business and am very picky about how a vehicle drives.
Toe in can be easily and correctly set with a tape measure. Jack up the coach, scribe the tires and measure front and rear. Do the math and make the adjustment. I've never had a tape measure get out of calibration. GRIN
If your F53 doesn't drive well, your front end shop has not done their job.
Time to go to Henderson's Line Up.

Richard

I agree with the alignment shop not doing a 100% job. I have the print out of the alignment after the tires were installed. If the readings are correct the caster and camber are correct (caster was 6.2 and camber was .5 positive IIRC) but they set the toe out too much positive. And they never centered the wheel which only takes a few minutes after reading up how to do it on the 11 and up f53!

[dodge_guy]

goufgators wrote:

dodge guy wrote:

goufgators wrote:

rgatijnet1 wrote:
When you had the coach weighed did you shift items within the coach so that the front axle was close to the MAXIMUM allowable axle weight? A light front end will wander, even if the tire air pressure is set according to the weight.

Thanks for reply. No, did not shift anything around.

Yes, it’s the same as a trailer. You want more weight or the same on the front axle as the rear! I just bought a 2012 and it too was all over the road. A 3 hour drive home was a chore. I found out the coach has Hellwig sway bars, Sumo springs and a blue ox true center steering stabilizer. It also has 2 year old Michelin’s all around. I found the tow was out. 5/8 toed out. I reset it to 3/16 toed in. I haven’t driven it since because I have been getting it ready. I’m going to try and get it out this weekend for a drive!

Good luck! If you find the 'magic wand' solution, please let me know.

Will do. Don’t know about the magic wand, but hopefully I fixed the problem.
With my Excursion and trailer, it took a couple years to get it all dialed in, but in the end I got that setup rock solid and could drive upwards of 14 hours straight and not be beat up from driving. I’ll get this RV setup to drive perfect, it’s just going to take a bit, because you can’t drive it everyday to get a feel for things!

[RLS7201]

It's amazing how the long over hang and short wheel base gets the blame for handling.
I drive what might be considered a worst case scenario for wheel base and over hang. 1995 33' F53 coach, 190" wheel base & 13' overhang.
It handles very well with having the toe in set correctly, a front pan hard bar and quality tires. I still work part time in the front end business and am very picky about how a vehicle drives.
Toe in can be easily and correctly set with a tape measure. Jack up the coach, scribe the tires and measure front and rear. Do the math and make the adjustment. I've never had a tape measure get out of calibration. GRIN
If your F53 doesn't drive well, your front end shop has not done their job.
Time to go to Henderson's Line Up.

Richard

[zigzagrv]

A couple questions: what is the length of your motorhome and chassis and what are your tire pressures?

[azdryheat]

Take a look at the length (and weight) of the coach hanging out behind the rear axle. That right there will be the tail that wags the dog. When I was researching Class A gassers I found the cheaper coaches had shorter wheelbases than the more expensive models and, therefore, had more weight hanging out back to affect handling. Here's one of many stories on it: LINK