Reply
 
Thread Tools Search this Thread Display Modes
 
Old 05-21-2016, 05:40 PM   #29
2 Rivet Member
 
2011 Interstate Coach
Evansville , Indiana
Join Date: Sep 2015
Posts: 74
Quote:
Originally Posted by Mr. B View Post
Need an advice from your experience Mike,

as I don't want to mess up with my perfect alignment,
and because I am satisfied with the handling of the bus,
and since I just need to make a rear ride softer,

what if I just will:
1) replace rear stock shock to gold Koni,
2) insert the rubber so-called Sumo "springs",
3) and install the rear sway bar.

Would these three things improve the rear ride on the road bumps? If yes, don't I really may not do the wheel alignment after these things installation?

If anyone also know it, please comment!
Thanks everybody,
Mr. B,
None of those items will improve the ride in the rear. If you are happy with the front alignment and handling, I would not add anything, unless you get a shop like the Sprinter Store in Oregon to install the full air suspension.
__________________

__________________
BurntAsphalt is offline   Reply With Quote
Old 05-21-2016, 05:56 PM   #30
4 Rivet Member
 
PSchw's Avatar
 
2005 39' Skydeck 390 SD
Livingston , Texas
Join Date: Mar 2013
Posts: 445
Images: 4
Mr. B,
No luck there you may improve sway side to side but not the comfort in the back.
Rear shock is easy to install and does not need any alignment.
Improve right quality sitting in the back the only thing is air ride unless somebody can figure out how to put the back bench on air cushion.
Peter
__________________

__________________
PSchw is offline   Reply With Quote
Old 05-22-2016, 12:08 AM   #31
4 Rivet Member
 
Moon , Moon
Join Date: Jan 2016
Posts: 343
Thank you Gentelmen, your advises saved me from spending money for unnecessary task.
__________________
Mr. B is offline   Reply With Quote
Old 05-22-2016, 01:50 PM   #32
Rivet Master
 
Boxster1971's Avatar

 
2013 Interstate Coach
Fulton , Maryland
Join Date: May 2010
Posts: 1,781
Quote:
Originally Posted by Mr. B View Post
Need an advice from your experience Mike,

as I don't want to mess up with my perfect alignment,
and because I am satisfied with the handling of the bus,
and since I just need to make a rear ride softer,

what if I just will:
1) replace rear stock shock to gold Koni,
2) insert the rubber so-called Sumo "springs",
3) and install the rear sway bar.

Would these three things improve the rear ride on the road bumps? If yes, don't I really may not do the wheel alignment after these things installation?

If anyone also know it, please comment!
Thanks everybody,

I don't think any of those things will smooth out the ride. I changed to Koni shocks to firm up what I thought was a bouncing ride. But now I have doubts that it helped much. I don't have any experience with the Sumo spring, but I would be worried that they might damage the frame at the bump stops. A stronger rear sway bar will increase the roll resistance but won't smooth out the ride. If I had to do it again I'd just leave the suspension stock unless I was willing to spend the big $$ for full rear air suspension.

I have found that adjusting the tire pressures to 55 psi in the rear seems to help make the ride a bit less harsh.


- - Mike
2013 Interstate Lounge EXT on 2012 Sprinter
__________________
- - Mike
--------------------------
2013 Airstream Interstate Lounge EXT
Boxster1971 is offline   Reply With Quote
Old 05-22-2016, 04:04 PM   #33
4 Rivet Member
 
Moon , Moon
Join Date: Jan 2016
Posts: 343
Yes what I am also thinking is to lower rear tires pressure. I wish to lower it for 45 PSI because we have four wheels there, but Protagonist urged me to have all tires at 61.
__________________
Mr. B is offline   Reply With Quote
Old 05-23-2016, 04:28 AM   #34
Figment of My Imagination
 
Protagonist's Avatar
 
2012 Interstate Coach
Metairie , Louisiana
Join Date: Dec 2011
Posts: 9,089
Quote:
Originally Posted by Mr. B View Post
Yes what I am also thinking is to lower rear tires pressure. I wish to lower it for 45 PSI because we have four wheels there, but Protagonist urged me to have all tires at 61.
There are formulas/tables for determining exact air pressure required for a given load on a given brand and size of tire, but using them requires that you weigh the loaded van by axle.

If you don't weigh the van and use the formulas or tables, it's best to stick with 61psi all around. A blowout from running under-inflated is not a price you want to pay just to try to improve rear-seat ride quality.
__________________
WBCCI #1105
TAC LA-4

Engineering: Finding complex solutions to simple problems you didn't even know you had.
Protagonist is offline   Reply With Quote
Old 05-23-2016, 10:44 AM   #35
4 Rivet Member
 
Moon , Moon
Join Date: Jan 2016
Posts: 343
Quote:
Originally Posted by Protagonist View Post
There are formulas/tables for determining exact air pressure required for a given load on a given brand and size of tire, but using them requires that you weigh the loaded van by axle.

If you don't weigh the van and use the formulas or tables, it's best to stick with 61psi all around. A blowout from running under-inflated is not a price you want to pay just to try to improve rear-seat ride quality.
Yes, but the formulas assume there is two wheels in the rear, not four. For example, a Sprinter 2500 has single wheel rear, and my logic says to divide our pressure by two.

Also please see what other Sprinter owners say:
Attached Thumbnails
Click image for larger version

Name:	image.jpg
Views:	76
Size:	268.5 KB
ID:	263060  
__________________
Mr. B is offline   Reply With Quote
Old 05-23-2016, 11:12 AM   #36
Figment of My Imagination
 
Protagonist's Avatar
 
2012 Interstate Coach
Metairie , Louisiana
Join Date: Dec 2011
Posts: 9,089
Quote:
Originally Posted by Mr. B View Post
Yes, but the formulas assume there is two wheels in the rear, not four. For example, a Sprinter 2500 has single wheel rear, and my logic says to divide our pressure by two.
There are formulas for duals as well.

Your logic is mistaken. The math does not lie. From a previous post of mine on the "Fans of Airstream Interstate" thread:

Quote:
The gross vehicle weight of a long-wheelbase Sprinter 3500 is 11,030 pounds, divided unevenly between front and rear axles.

According to the Sprinter owner's manual, the gross front axle weight of a Sprinter 3500 van is 4410 pounds.
4410 (GFAW) 2 (tires) 61 (psi) = 36 square inches of contact surface with the ground, per tire.

The gross rear axle weight is 7720 pounds.
7720 (GRAW) 4 (tires) 61 (psi) = 32 square inches of contact surface with the ground, per tire.

You will note that the amount of contact surface is almost the same on each tire, within a few square inches, which is exactly as it should be.

When we say 61psi per tire, we mean 61psi in each and every tire— not divided by 2 for the duals.
So when you calculate tire pressure for weights under the gross weight, you should still end up with nearly the same amount of contact surface, 36 square inches of contact surface per tire for both tires in front, 32 square inches of contact surface per tire for all four tires in the rear.

If you treat pounds per square inch as the unknown value, then actual rear axle weight, divided by 4 tires, divided by 32 square inches of contact surface, tells you how many psi you need per rear tire.
__________________
WBCCI #1105
TAC LA-4

Engineering: Finding complex solutions to simple problems you didn't even know you had.
Protagonist is offline   Reply With Quote
Old 05-23-2016, 12:49 PM   #37
4 Rivet Member
 
Moon , Moon
Join Date: Jan 2016
Posts: 343
In a possible occasion I will go to the trucks Weigh Station to weight measures...
Will report to you then )
__________________
Mr. B is offline   Reply With Quote
Old 05-23-2016, 02:42 PM   #38
Rivet Master
 
Boxster1971's Avatar

 
2013 Interstate Coach
Fulton , Maryland
Join Date: May 2010
Posts: 1,781
Quote:
Originally Posted by Protagonist View Post
There are formulas/tables for determining exact air pressure required for a given load on a given brand and size of tire, but using them requires that you weigh the loaded van by axle.

If you don't weigh the van and use the formulas or tables, it's best to stick with 61psi all around. A blowout from running under-inflated is not a price you want to pay just to try to improve rear-seat ride quality.

Protagonist is correct. I weighed my van at each axle and also side to side to get good idea of weight on each corner. Then I used the Michelin tire pressure chart for duals on my rear axle and singles on the front. As I recall it said I could go as low as 50 psi, but I used 55 for some added margin. Also I noticed my front tires are starting to wear more on the outer edges, a sign that their pressure is too low. I'm going to boost the fronts to 60 psi.

45 psi is probably too low.


- - Mike
2013 Interstate Lounge EXT on 2012 Sprinter
__________________
- - Mike
--------------------------
2013 Airstream Interstate Lounge EXT
Boxster1971 is offline   Reply With Quote
Old 05-23-2016, 09:34 PM   #39
Rivet Master
 
73shark's Avatar
 
2011 Interstate Coach
Overland Park , Kansas
Join Date: Aug 2011
Posts: 2,595
Quote:
Originally Posted by Boxster1971 View Post
. Also I noticed my front tires are starting to wear more on the outer edges, a sign that their pressure is too low.


- - Mike
2013 Interstate Lounge EXT on 2012 Sprinter
Or the camber is too positive which is usually the case unless the AI has been aligned since it left the factory. After reading how a lot of folks were experiencing outer edge wear and noticing the same thing, I had the front end aligned and rotated the tires/wheels. Front tire wear is now uniform. YMMV

My theory is that the extra weight added to the rear causes the front to raise slightly which would increase positive camber.
__________________
Glass half full or half empty to an engineer is the glass is twice as big as it needs to be.

PM me for sale info on my 2011. SOLD!
73shark is offline   Reply With Quote
Old 05-24-2016, 01:49 AM   #40
4 Rivet Member
 
Moon , Moon
Join Date: Jan 2016
Posts: 343
I like your theory Mark it sound logic )
__________________
Mr. B is offline   Reply With Quote
Old 05-25-2016, 12:52 AM   #41
4 Rivet Member
 
Moon , Moon
Join Date: Jan 2016
Posts: 343
Today I weighted the vehicle, and scale shows:

Front is 3,520 lb (with myself)
Rear is 6,510 lb (with wife and the entire trip luggage)
On the time of wheighting the vehicle was with full tank of diesel, half-tanks of water/fluids and gas, full kitchen stuff, and full fridge of food and beverages. This is how I usually use it.

Now, following Protagonist's math, we can count my tires pressure by his table:
Front - 3,520 lb : 2 wheels : 32 sq. in. = 55
Rear - 6,510 lb : 4 wheels : 32 sq. in. = 50

It is coming the figures of:
Front tires pressure as 55 PSI in each tire,
And for the rear is 50 PSI in each of four tires.

Protagonist, please confirm??

However, the Michelin site table says for rear is even lower pressure, i.e. for my rear weight is 45 PSI in each of dual wheels. Table is below.

So, Gentelmen, I am confused of which the lowest pressure in rear wheels I can use safely?

Attached Thumbnails
Click image for larger version

Name:	image.jpg
Views:	76
Size:	88.9 KB
ID:	263173  
__________________
Mr. B is offline   Reply With Quote
Old 05-25-2016, 10:32 AM   #42
Rivet Master
 
UKDUDE's Avatar
 
2014 Interstate Ext. Coach
Sedona , Arizona
Join Date: Jul 2008
Posts: 948
Quote:
Originally Posted by Mr. B View Post
Today I weighted the vehicle, and scale shows:

Front is 3,520 lb (with myself)
Rear is 6,510 lb (with wife and the entire trip luggage)
On the time of wheighting the vehicle was with full tank of diesel, half-tanks of water/fluids and gas, full kitchen stuff, and full fridge of food and beverages. This is how I usually use it.

Now, following Protagonist's math, we can count my tires pressure by his table:
Front - 3,520 lb : 2 wheels : 32 sq. in. = 55
Rear - 6,510 lb : 4 wheels : 32 sq. in. = 50

It is coming the figures of:
Front tires pressure as 55 PSI in each tire,
And for the rear is 50 PSI in each of four tires.

Protagonist, please confirm??

However, the Michelin site table says for rear is even lower pressure, i.e. for my rear weight is 45 PSI in each of dual wheels. Table is below.

So, Gentelmen, I am confused of which the lowest pressure in rear wheels I can use safely?


Mr B, the chart you attached is for XPS RIB tires, and they are probably not recommended for the rear axle on a Sprinter since they are extra heavy duty and probably won't make the rear ride softer under any circumstances. Also the tire dimensions are non-standard: should be 215.85 x 16 I believe.
Incidentally, that chart shows the total rear axle weight, no dividing by 4 is necessary here.


Sent from my iPad using Airstream Forums
__________________

__________________
UKDUDE is offline   Reply With Quote
Reply


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


Similar Threads
Thread Thread Starter Forum Replies Last Post
how to improve fuel efficiency of Chevy 350? turfclubroad Mechanics Corner - Engines, Transmission & More... 28 02-10-2014 08:17 AM
Improve Fuel Efficiency by over 15%??? Relentless Tow Vehicles 19 04-08-2010 09:03 AM
Improve seat comfort of 2004 F150 ? Ken D Tow Vehicles 8 02-07-2010 12:16 PM
looking to improve on height with new axles slvrbulit Axles 19 04-12-2009 07:27 PM
How to improve the WBCCI azflycaster WBCCI Forum 87 07-15-2007 03:53 PM


Virginia Campgrounds

Reviews provided by



Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 01:57 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.