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1993 Breakaway Top Speed
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Picture of David Andrews Jr.
posted
Hello Barth Family,
First time posting here, but I need some advice. We have a 1993 Barth Breakaway 30 Foot. Cummins 6BT 190HP with the Allison AT542- 4 speed transmission. Love the coach, owned her since 2016. On the highway, flat ground, not towing, I'm doing 62-63mph, at 2600-2700 RPM. This is with the pedal to the floor. I've been told by our diesel mechanic this is pretty much the max power this coach will make.

I do understand this is an economical coach, I drive professionally for a living. I have driven school buses with this exact setup, and can easily hit 65-70 mph no issue.
 
Posts: 9 | Location: Millville, NJ | Member Since: 11-19-2015Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 1/19
Picture of Steve VW
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Given the rpm you have you are probably topped out. This is the downside to the 4 speed trans. The rear axle ratio is the limiting factor also.

Good to see another Barth here. Thumbs Up


9708-M0037-37MM-01
"98" Monarch 37
Spartan MM, 6 spd Allison
Cummins 8.3 300 hp
 
Posts: 3951 | Location: Kalkaska, MI | Member Since: 02-04-2011Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 6/19
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Thank you Steve I was thinking the same.
 
Posts: 3748 | Location: Northeast , Ohio | Member Since: 07-29-2012Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 1/18
Picture of Dana
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Gives you an idea of the difference the drive train makes.

In DBarth I have a 5.9 at 268 hp, the Allison MD3060 6 speed, the beefier Eaton rearend. I have seen 85 with no problems with engine temp or exhaust temp. It is not something I do with regularity. I cruise at 70-75 often if in a hurry.


Dana & Lynn
1997 38ft Monarch front entry
Spartan Mountain Master Chassis
Cummins 8.3
Allison MD-3060 6 speed
22.5 11R
Cummins Factory Exhaust Brake
9608-M0022-38MI-4C
Christened Midnight

1972 22ft
Christened Camp Barth
 
Posts: 928 | Location: Waseca, Minnesota | Member Since: 12-09-2010Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 1/19
Picture of Pgh. Pirate
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Have same drivetrain. At about 2300rpm @ 55mph. Believe providing a public service - admiration time. Appropriately have a SMV reflective triangle mounted on my ladder.

BTW, very economical - always 13+ mpg, except in mountains.


'92 Breakaway
Diesel Pusher, Cummins 190hp,
No Modifications
Allison AT542
Floor Plan 30-BS-11B
9205-3798-30BS11B
 
Posts: 233 | Location: Pittsburgh, PA | Member Since: 11-07-2014Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 10/08
Picture of MWrench
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quote:
Originally posted by David Andrews Jr.:
On the highway, flat ground, not towing, I'm doing 62-63mph, at 2600-2700 RPM. This is with the pedal to the floor.

Most Breakaways of the late 80s early 90s 5.9L Cummins go into what is called "de-fueling" at 2400 RPM. This will lesson the HP the engine can produce. This combination is at best a marginal compromise between acceleration in 1st gear and top speed in 4th gear.

My 30' Breakaway has the 230 HP Cummins 6 speed Allison and Eaton rear diff identical to Dana's coach. Our rear diff ratio is 4.11 but the trans 6th gear ratio is 0.65:1 over drive. Both 5th and 6th are are overdrive ratios.

I drive routinely at 70-75 MPH, engine RPM from 1900 to 2100 and fuel mileage is right at 10.1-10.4 doesn't matter if I am towing or not.

There also appears to be a "sweet spot" around 2100 RPM where the engine will give a higher MPG, Steve and I are testing out this theory this summer.

Wordy but hopes this helps.


Ed
94 30' Breakaway #3864
30-BS-6B side entry
230 Cummins, Allison 6 speed
Spartan chassis
K9DVC
 
Posts: 2131 | Location: Los Gatos, CA | Member Since: 12-08-2005Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 6/12
Formally known as "Humbojb"
Picture of Jim and Tere
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I can see it now, Ed and Steve running down the interstate, side by side, slide rules in hand. ROTFLMAO
jim


Jim and TereJim and Tere

1985 Regal
29' Chevy 454 P32
8411 3172 29FP3B
Gear Vendor 6 Speed Tranny
 
Posts: 3507 | Location: madisonville tn usa | Member Since: 02-19-2005Reply With QuoteReport This Post
Picture of David Andrews Jr.
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I appreciate the responses!
Thank you everyone!
 
Posts: 9 | Location: Millville, NJ | Member Since: 11-19-2015Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 3/19
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quote:
I have driven school buses with this exact setup, and can easily hit 65-70 mph no issue.

I'm glad I don't have any kids using school buses any more.
Oh! Millville, N.J. .........never mind!!! ROTFLMAO






29' 1977parted out and still alive in Barths all over the USA
 
Posts: 1011 | Location: Floral City FL | Member Since: 04-25-2008Reply With QuoteReport This Post
Picture of David Andrews Jr.
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Being said, those speeds were done on highways like I95 with the school bus.
 
Posts: 9 | Location: Millville, NJ | Member Since: 11-19-2015Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 3/19
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Tooling Along Thumbs Up






29' 1977parted out and still alive in Barths all over the USA
 
Posts: 1011 | Location: Floral City FL | Member Since: 04-25-2008Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 4/08
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The school bus probably had 22" tires rather than 19.5. I had the same setup before changing transmissions. Overdrive and lockup torque converter allows about 70 mph at 1800 rpm.


'92 Barth Breakaway - 30'
5.9 Cummins (6B) 300+ HP
2000 Allison
Front entrance
 
Posts: 1003 | Location: Minneapolis/Yuma | Member Since: 08-17-2006Reply With QuoteReport This Post
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