Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 12-20-2013, 07:25 PM   #57
Senior Member
 
Join Date: Feb 2010
Posts: 4,492
Read any manufacturer data sheet.

You weigh each corner for balance and to be sure each wheel is not overloaded.

If one is less inflated it will have different shape regardless of the load.

If large difference between sides it coukd be to how coach is built, spring rate shifting center of gravity, what is stored where or combination.

Ours has generator, water and fuel tanks between the frame rails, waste tanks and lpg are on sides but near rear axle so their offset weight is not as bad.

Check with majufacturer if arround for expected weights.
__________________

__________________
Tony & Lori
1989 Country Coach Savannah SE
TQ60 is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 12-20-2013, 07:29 PM   #58
Senior Member
 
jimbo2013's Avatar
 
Newmar Owners Club
Join Date: Aug 2013
Posts: 1,699
I would rather be in FL than what I'm heading into, but weather permitting I'll be back before New Years.

I have the ride height sticks cut ready but haven't had the time to crawl under, will do it soon.

But I did measure wheel well to ground the front was very close, the rear was off 5/8".

So I would be surprised if that needs to be adjusted, which I'll do myself with support blocks etc.
__________________

__________________
Newmar Ventana 3933 | Miata close behind
1,060 Watts of Solar | 8 T-105 RE Batteries | Outback controls
HR 38 Endeavor
jimbo2013 is offline   Reply With Quote
Old 12-20-2013, 07:45 PM   #59
Senior Member
 
Join Date: Feb 2010
Posts: 4,492
5/8 difference in the rear msy be clue.

Can it be weighed eith air dumped?
__________________
Tony & Lori
1989 Country Coach Savannah SE
TQ60 is offline   Reply With Quote
Old 12-21-2013, 02:04 PM   #60
Senior Member
 
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 1,714
I just went through the ride height measurements and adjustments. I had discussions with the manufacturer while doing it. From your posted weights, it appears that your front left and right rear are heavier than the opposite sides. This indicates that the right rear ride height is too high or the LF is too high. If you have a three valve system and the single one is in the front, then the RR height is too high, or the LR is too low. You can use the four corner weights to set the ride heights as needed to get the corners balanced even if it means lowering the RR below the required distance. There is a range allowed for the valves and you should be able to get the front weights within 50-100#s of each other. That will also take care of the rear differences as well. It's really very easy to do, but takes time.

Remember that the acceptable difference between the front tires is 500#s and the rear is 1000#s
__________________
Crasher is online now   Reply With Quote
Old 12-21-2013, 03:31 PM   #61
Senior Member
 
Fleetwood Owners Club
Join Date: Dec 2004
Posts: 527
The main reason for equal pressures in front left to right tires is to prevent pulling to the side. In the rear a ten psi difference is not going to harm anything.

The OP has already measured the ride height to a sufficient degree of accuracy. Additional precision just is not necessary since many fixed factors enter into the accuracy level. And as long as the tires are not overload, adjusting ride height to distribute the load between tires is going to cause more problems in the long run they what it solves. The only real beneficial way to change load difference is by shifting the weight inside the coach. Knowing what is inside the coach has many benefits. Also, if you do not know how the suspension system on your coach works, you will be driving yourself nuts changing and the reweighing before you accomplish your objective.
__________________
targaboat is offline   Reply With Quote
Old 12-21-2013, 04:34 PM   #62
Senior Member
 
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 1,714
I guess we have a difference of opinions. I doubt that enough weight can be shifted around in his or any coach to make a 1000# change to the front axle. You can, however, transfer enough weight from one side to the other with the ride height adjustment. Setting the RR slightly below and the LR slightly above the recommended distance would transfer weight to the FR and LR. This was the recommendation of my chassis manufacturer if needed. I have easy access to six position scales, so it was a simple job for me.
__________________
Crasher is online now   Reply With Quote
Old 12-21-2013, 04:51 PM   #63
Senior Member
 
Fleetwood Owners Club
Join Date: Dec 2004
Posts: 527
I am hung up on understanding the harm which the corner weight difference causes. Along with this the road surface is seldom level so that each corner of the coach is changing continuously as you move along the road surface. The only image is that of the the coaches I see during our travels that are not level. Did their owners adjust their suspensions heights. Another question is are you twisting the frame when your heights are not equal on the corners. This can not be good.

I stand by my previous recommendation, adjust the ride heights within the spec limits, verify that non of the your tires are over loaded, and adjust the airpressures to be over the load vs psi spec chart and go enjoy your coach.
__________________
targaboat is offline   Reply With Quote
Old 12-21-2013, 05:53 PM   #64
Junior Member
 
Rob-K's Avatar
 
Monaco Owners Club
Join Date: Jun 2013
Posts: 14
Quote:
Originally Posted by Crasher View Post
Remember that the acceptable difference between the front tires is 500#s and the rear is 1000#s
I have been looking for this lateral side-to-side information for awhile. Where did you find it? Can you post the link here?
__________________
2006 Knight 40PLQ
ISC 330
Rob-K is offline   Reply With Quote
Old 12-21-2013, 07:40 PM   #65
Senior Member
 
Join Date: Feb 2011
Location: Snowbird - Waterford Mi and Citrus Springs Fl.
Posts: 3,609
Quote:
Originally Posted by Crasher View Post
I just went through the ride height measurements and adjustments. I had discussions with the manufacturer while doing it. From your posted weights, it appears that your front left and right rear are heavier than the opposite sides. This indicates that the right rear ride height is too high or the LF is too high. If you have a three valve system and the single one is in the front, then the RR height is too high, or the LR is too low. You can use the four corner weights to set the ride heights as needed to get the corners balanced even if it means lowering the RR below the required distance. There is a range allowed for the valves and you should be able to get the front weights within 50-100#s of each other. That will also take care of the rear differences as well. It's really very easy to do, but takes time.

Remember that the acceptable difference between the front tires is 500#s and the rear is 1000#s
For what it's worth, I agree completely and would do it the same way. Necessary? Maybe not. Not going to argue the point. But it's what it's going to take for me to feel right about it. -Al
__________________
1997 37' HR Endeavor, 275hp Cat, Freightliner
03 CR-V Blue Ox, Ready Brake
ahicks is online now   Reply With Quote
Old 12-21-2013, 08:44 PM   #66
Senior Member
 
jimbo2013's Avatar
 
Newmar Owners Club
Join Date: Aug 2013
Posts: 1,699
This morning I aired (cold) up 85 psi all 4 rears, and 105 psi both fronts.

It felt fine from VA to NY, so following the advice I equaled tires on same axle.

I agree the ride height must be wrong in back end, I'll check it in the next few days.

I have the measurement sticks ready to go 9 3/4 & 10" Freightliner said there's 1/4" either way on those numbers
__________________
Newmar Ventana 3933 | Miata close behind
1,060 Watts of Solar | 8 T-105 RE Batteries | Outback controls
HR 38 Endeavor
jimbo2013 is offline   Reply With Quote
Old 12-21-2013, 09:40 PM   #67
Senior Member
 
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 1,714
Quote:
Originally Posted by Rob-K View Post
I have been looking for this lateral side-to-side information for awhile. Where did you find it? Can you post the link here?
I was given those numbers by the manager of the Powerglide Chassis dept at Tiffin. It is what they have found to work for them. I think they have the same rear tolorance for single and tag rear axles.
__________________
Crasher is online now   Reply With Quote
Old 12-21-2013, 10:04 PM   #68
Senior Member
 
Join Date: Dec 2013
Location: Lake Havasu City, AZ & Plover, WI
Posts: 1,714
Quote:
Originally Posted by jimbo2013 View Post
This morning I aired (cold) up 85 psi all 4 rears, and 105 psi both fronts.

It felt fine from VA to NY, so following the advice I equaled tires on same axle.

I agree the ride height must be wrong in back end, I'll check it in the next few days.

I have the measurement sticks ready to go 9 3/4 & 10" Freightliner said there's 1/4" either way on those numbers
I think you will find that the right is higher than the left, although both could be within the 1/2" range allowed. If that is the case, adjust the right lower and/or the left higher. You should stay within the 1/2" range, but they don't have to be even. This won't put any twist on the frame, but will cause the lighter corners carry more weight.

As targaboat has said, you could probably run the way you are as long as the tire pressures are the same on any axle and at least equal to the amount required for the heaviest tire and no tire exceeds it weight rating. There are a lot of MHs on the road doing just that. However, I feel that if I can get the corners balance properly, why not do it??

Regarding tire pressures, a Good Year and Michelin rep told me that as long as you start the day at any temp and have the pressures set for the min psi for the weight it is carrying, don't be concerned with a 25 psi or more increase (100 psi cold). That is perfectly normal and not harmfull to the tire. I have seen my front tires go from 115 Psi ( 5# above min) up to 141 psi on a day that started out at 50* and reached 85 by mid afternoon.
__________________
Crasher is online now   Reply With Quote
Old 12-21-2013, 11:13 PM   #69
Senior Member
 
VanDiemen23's Avatar
 
Join Date: Oct 2010
Posts: 778
Crasher has it right. His method was what I was trying to describe in my post above. In the car shown in my avatar, the rear spring rate is 1000 lbs/in. A 1/10 in difference in rear ride ht translates to 100 lbs of cross weight in the front. On that vehicle, as little as 50 pounds of cross-weight (5% of total weight) makes the car spooky.

To optimize handling in any vehicle you want the front wheel weights to be as close as possible - then having a single tire pressure - and a similar contact patch and rolling resistance - works. If the front weights are off by hundreds of pounds and you run the same pressure in each tire the contact patch and rolling resistance will differ from side to side and produce a pull. If you don't feel one, then it's likely because it is working in your advantage to cancel the effect of road crown - or some other aspect like alignment is having an effect.

The rear weights do not come into play in handling. There is so much weight on the rear and such a higher spring rate that the changes needed to transfer to a significant amount of weight to or from the front are hardly noticeable.

This is science, not some urban legend. Anyone who has engineered a fast car, used a good pressure gauge, a pyrometer, and kept good records of setups and measurements will have a similar approach.

Somebody earlier made a comment about different pressures making the rolling diameter of a radial tire different. That's wrong. As long as you are in the recommend pressure range the diameter change will not be measurable. Making a tire "grow" with pressure works with bias tires but not radials.
__________________
VanDiemen23 is offline   Reply With Quote
Old 12-22-2013, 07:02 PM   #70
Senior Member
 
Kuzzy's Avatar
 
Triple E Owners Club
Join Date: Jul 2013
Location: Nanoose Bay B C
Posts: 335
Quote:
Originally Posted by VanDiemen23 View Post

Somebody earlier made a comment about different pressures making the rolling diameter of a radial tire different. That's wrong. As long as you are in the recommend pressure range the diameter change will not be measurable. Making a tire "grow" with pressure works with bias tires but not radials.
Thanks for correcting me VanDiemen. I did a lot of reading and could not support my comment. It seems the deflection is greater when under inflated but the revolutions per mile is the same. I stand corrected. Thank you.
While doing this bit of research I stumbled across this site.
http://www.goodyearrvtires.com/pdfs/tire-care-guide.pdf
Page 13 has an interesting comment about storing your coach with unloaded tires and 25% more air pressure in them. I've never heard of this practice.
Does anyone do this and what's the purpose?
Dave
__________________

__________________
Kuzzy is offline   Reply With Quote
Reply

Tags
weight



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 03:31 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.