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Increasing rear ride height
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Supporting Member of Barthmobile.com 03/22
Picture of MWrench
posted
When I first got the Breakaway, I had noticed that the rear seemed a bit lower than the front. Measuring around the coach along the horizontal trim piece confirmed that at the wheels, the rear was 1 inch +/- lower than the front. I had also noticed there was air assist bags on the rear.

Over time I played with air pressure in the bags and found that at best with 80 lbs pressure in the bags the most I could raise the rear was only 1/2 inch. Still not level but most importantly, the ride got very harsh!

Later I examined the bags and found that the bags are not correctly mounted! The bags should be mounted directly over the axle or behind the axle. The bags were mounted ahead of the axle and therefore had a very short arm to work with the load and pressure. I checked with "experts" and confirmed that this air assist was indeed incorrectly installed and would not be satisfactory. Because the shocks and other frame mount devices were aft of the axle, the air bags could not be mount correctly so they were installed ahead of the axle.

I checked the springs and found that they were good and had no sag, re-arching them could improve ride height but would be an expensive heavy proposition. Looking at the spring perches I noticed that there was a 3/8 inch spacer plate between the spring perch and the frame. I reasoned that if I were to put in thicker plates I could raise the height of the frame.

I was able to get some 3/4 inch material and would double up so I would gain 1 1/8 inch. I would not use the 3/8 inch plates. At the last GTG, I noticed on Richards coach there was a 1 inch spacer on one side so I knew this was standard procedure to adjust ride height.

Yesterday I finished the installation, WHEW, big job! Cutting the plates, drilling the plates, was easy. The problem was that the bolts were very hard access, the attach points were blocked by the storage compartments and the black tank. Working around those heavy springs and steadying the coach is not easy and does require some special equipment.

It took me most of the day once I started. However, the job is done! Measurement has confirmed the coach is level now with no air in the bags. Ride with 10 lbs in the bags is so smooth, even on our well know California roads! I can now go across drainage dips and not drag the hitch.

I will not remove the bags yet and will continue to research the possibility of moving the bags behind the axle.

For those thinking about the effect on the drive line, here is the change. I used spacers on all 4 corners so the diff pinion angle in respect to the Trans output has not changed. Yes the drive shafts angle has changed and is almost straight, BUT, the diff pinion is located off center in respect to the trans output so the "u" joints will be operating at an angle. "U" joints don't care if the displacement is horizontal or vertical, there just has to be a slight displacement for good reliability.

Pictures later


Ed
94 30' Breakaway #3864
30-BS-6B side entry
New Cummins 5.9L, 375+ HP
Allison 6 speed
Spartan chassis
K9DVC
 
Posts: 2151 | Location: Los Gatos, CA | Member Since: 12-08-2005Reply With QuoteReport This Post
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Hello Ed, I know it was a long time ago
but I was wondering if you still around
in this forum and if you had pictures ?

Stay healthy and safe


Thank You

Rico & Carmen
 
Posts: 42 | Location: Houston Texas  | Member Since: 12-03-2019Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 03/22
Picture of MWrench
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Hi Rico, I do have pictures but are not on my server, I will get them transferred this week and post a better reply.

Adding spring perch spacers is not a big issue but in my case difficult. You will, (or should) add spacers to all 4 rear spring perches to keep driveshaft "U" joint angles acceptable. In my change, I used two pieces of 3/4 inch material total 1.5" total each spacer thickness as it was much easier to cut and drill.

What model Barth do you have?

I may be coming thru Houston this spring

More later


Ed
94 30' Breakaway #3864
30-BS-6B side entry
New Cummins 5.9L, 375+ HP
Allison 6 speed
Spartan chassis
K9DVC
 
Posts: 2151 | Location: Los Gatos, CA | Member Since: 12-08-2005Reply With QuoteReport This Post
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It’s a Breakaway 30’,
the rear leaf springs run under the
rear axle, I just realized it won’t work.
D'oh

Thank You
 
Posts: 42 | Location: Houston Texas  | Member Since: 12-03-2019Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 1/21
Picture of Duane88
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Rico, that is why you need to put the spacers on the chassis spring perch!!


Barthless!!!
 
Posts: 1835 | Location: Clinton Iowa | Member Since: 04-02-2017Reply With QuoteReport This Post
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Can you send us pictures please when you find them ?

Thank You again

Rico
 
Posts: 42 | Location: Houston Texas  | Member Since: 12-03-2019Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 03/22
Picture of MWrench
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Here are pictures of my spring perch spacers and the final installation. The original is 3/8" thick and the two replacements each corner are 3/4 " so the actual height increase is 1 1/8" over stock.




Ed
94 30' Breakaway #3864
30-BS-6B side entry
New Cummins 5.9L, 375+ HP
Allison 6 speed
Spartan chassis
K9DVC
 
Posts: 2151 | Location: Los Gatos, CA | Member Since: 12-08-2005Reply With QuoteReport This Post
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Thank You Ed, another dumb question,
Can this spacers be installed in the
rear as well as in the front part of
the leaf spring’s perches ?

Thank You
 
Posts: 42 | Location: Houston Texas  | Member Since: 12-03-2019Reply With QuoteReport This Post
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We are going to go look down under there
to see ?..
 
Posts: 42 | Location: Houston Texas  | Member Since: 12-03-2019Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 1/21
Picture of Duane88
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quote:
For those thinking about the effect on the drive line, here is the change. I used spacers on all 4 corners so the diff pinion angle in respect to the Trans output has not changed. Yes the drive shafts angle has changed and is almost straight, BUT, the diff pinion is located off center in respect to the trans output so the "u" joints will be operating at an angle. "U" joints don't care if the displacement is horizontal or vertical, there just has to be a slight displacement for good reliability.


From ED's post


Barthless!!!
 
Posts: 1835 | Location: Clinton Iowa | Member Since: 04-02-2017Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 03/22
Picture of MWrench
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By putting spacers on all 4 corners I mean at the front AND rear of both rear springs. That way the angle of the rear axle will change in respect to the transmission but both ends of the driveline will change at the same rate. That is needed to keep the "U" joints working together without fighting each other.

You will find it is very difficult to remove the 4 bolts holding the spring perches to the frame because the big ends of the spring are in the way. I removed the spring from the perch to get access to the bolts but the chassis side of the bolts was hard to get to because of the black tank in the way.

You will need longer bolts to accommodate thicker spacers.

Your springs may be a bit smaller than mine, I have the Allison 6 speed transmission and an Eaton axle which is quite a bit bigger than the Dana 80 used with the Allison 4 speed.


Ed
94 30' Breakaway #3864
30-BS-6B side entry
New Cummins 5.9L, 375+ HP
Allison 6 speed
Spartan chassis
K9DVC
 
Posts: 2151 | Location: Los Gatos, CA | Member Since: 12-08-2005Reply With QuoteReport This Post
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