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03-08-2007, 05:51 AM
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#1
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Silver Mist
Currently Looking...
Riverhead
, New York
Join Date: Aug 2006
Posts: 3,011
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Down angle
Anyone know how much the height changes of the trailer if you increase the angle say 2, 5 or 7 degrees greater than the 22 1/2?
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Bob
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03-08-2007, 06:28 AM
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#2
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Silver Mist
Currently Looking...
Riverhead
, New York
Join Date: Aug 2006
Posts: 3,011
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Leo, what I'm trying to ask is if I have new axles made with an angle greater than 22 1/2 standard how much will the height under the belly or axles increase at various increases in the torsion arms?
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Bob
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03-08-2007, 06:50 AM
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#3
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Just an old timer...
2004 22' Interstate
Tipton
, Iowa
Join Date: Mar 2003
Posts: 4,760
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Bob, the 22.5* axle will deflect with weight as will the other angles. It's difficult to say how much gain you'll have in ride height as the axle GVWR and your trailer weight will influence that as well. I don't think anyone can give you a definitive answer of "5.75" inches for example.
Andy may be able to give the best estimate as he does this all the time and he may have some "norms" figured out.
Depending on how worn out your current axle is though, you may see an increase in bottom-of-coach to street height of several inches with a new 22.5* and perhaps up to another two inches with a 45*, again depending on the way the axle is rubbered.
Roger
Roger
__________________
havin' to fix my broken Airstreams since 1987...
AIR 2053 Current: 2004 Airstream Interstate "B-Van" T1N DODGE Sprinter
Former Airstreams: 1953 Flying Cloud, 1957 Overlander, 1961 Bambi, 1970 Safari Special, 1978 Argosy Minuet, 1985 325 Moho, 1994 Limited 34' Two-door, 1994 B190 "B-Van"
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03-08-2007, 06:55 AM
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#4
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4 Rivet Member
1984 34' International
1977 Argosy 24
Central
, Georgia
Join Date: Jun 2006
Posts: 492
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Bob,
Using some basic geometry the important number in the following formula will be the length of the articulating arm. (the connecting arm from the center of the wheel to the axle beam) I did not go out and measure but for our example we will use 12".
example: if the articulating arm is 12”
you multiply 12" times the sine of 22.5 degs (.38268)
The sine of 22.5 deg. is .38268 multiplied by 12 equals 4.59"
The sine of 24.5 deg. is .41469 multiplied by 12 equals 4.97"
the sine of 26.5 deg. is .44619 multiplied by 12 equals 5.35"
So… each 2 degree increase will give you a rise of .38 inches.
To make the example work in real numbers you need to know the actual length of the articulating arm.
I think...
em.
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Travelers by aluminum roadships, loyalists to one species,
masters of convenience, herdsmen steeped in maintenance and restoration.
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03-08-2007, 07:15 AM
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#5
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Rivet Master
1991 34' Excella
Princeton
, New Jersey
Join Date: Aug 2003
Posts: 7,070
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The other consideration that influnces the height of the trailer is the load rating of the axles. I just changed mine from the original 2800 lb. axles to 3200 lb. axles and raised the trailer about 3 in. I my case the the original axles had gone to a negitive angle because they were under rated when originaly installed at the factory.
If you are using Henschen axles they can give you good advise on angles and loading.
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WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles
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03-08-2007, 08:33 AM
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#6
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Silver Mist
Currently Looking...
Riverhead
, New York
Join Date: Aug 2006
Posts: 3,011
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Ok, great info that what I was looking for.
I think I'll add 4 degrees to get about 3/4" more ground clearance than stock.
Who knows it may extend the point in time they need to be replaced again????
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Bob
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03-09-2007, 05:48 AM
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#7
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3 Rivet Member
1973 23' Safari
Maryville
, Tennessee
Join Date: Nov 2006
Posts: 167
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I was told going from 22.5 to 32.5 raises the trailer about an inch....about an inch for a 10 degree difference.
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03-09-2007, 07:37 PM
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#8
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2 Rivet Member
1993 30' Excella
1993 19' "B" Van Airstream 190
Apache Junction, AZ
Join Date: Dec 2002
Posts: 30
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Changing from stock to 35 degrees raised our 30' about 1 1/2 - 2 inches, but we had failing axles when I first measured. Henchen has charts (or did) on their web site which you can use to calculate the lift. The axles are only available in standard angles...you can't specify the number of degrees you want (or so I was told).
Terry
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03-09-2007, 08:14 PM
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#9
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418
2007 25' Safari FB SE
1958 22' Flying Cloud
1974 29' Ambassador
Yucca Valley
, California
Join Date: Jun 2002
Location: 1963 26' Overlander
Posts: 4,804
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I went with 32.5 down angle, and it raised my 63 Overlander an approximate actual 1.75in.
This is hard to answer precisely, since the axle rating and load in the trailer also change the ride height. But for a given set of weights in a given trailer, exoect an ride height increase of about 1.5in for a 10degree increase in down angle.
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03-09-2007, 08:48 PM
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#10
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Rivet Master
1962 22' Safari
2016 30' Classic
Southeast
, Michigan
Join Date: Mar 2004
Posts: 2,986
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Quote:
Originally Posted by HowieE
I my case the the original axles had gone to a negitive angle because they were under rated when originaly installed at the factory.
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I don't remember the dates exactly, but I think around 1980 or so Airstream changed the down angle of their axles from the old 22.5 degress to something like 10 degrees. This lowered the trailer heights relative to earlier years. And since axles are rated for the unloaded angle, once the trailer (and contents) are put on the axles, their resting angle changes quite a bit (I think more than 10 degrees is typical). Anyway, I mention this, because I have never seen a 1980's or newer Airstream with a positive axle angle, even pretty new ones. They are all negative and yet the amount of tire showing in the wheel well looks correct. I do not believe the old adage that "your axles are shot if they have a negative angle" applies to 1980's and newer Airstreams. That of course doesn't mean that they are not shot if the angle is negative, it just means that this method of determining if they are shot is not valid. If you put a 22.5 degree angle axle under a 1980's or newer Airstream, I think you will raise it above the original factory height. You can verify this if the ball height ends up more than 18.75" with the trailer level. As I remember it (didn't check recently), either the Henshen or Dexter web site lists both original and loaded angles for their axles.
In any case, since your trailer is a 1991, the angle may not have indicated that your axles were shot. Of course if they were over loaded, they may have sagged more than usual.
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Joe
Wally Byam Caravan Club International Historian
Vintage Airstream Club Historian
WBCCI/VAC #702 & #6768
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03-09-2007, 11:06 PM
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#11
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418
2007 25' Safari FB SE
1958 22' Flying Cloud
1974 29' Ambassador
Yucca Valley
, California
Join Date: Jun 2002
Location: 1963 26' Overlander
Posts: 4,804
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Another fact to consider is that some Airstream axles had high profile axle brackets, which raised the frame about 1in over the axle tubes. This might not apply to trailers built after 1980, because I have only seen these brackets on late 60's and early 70's trailers.
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