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JoeH

Pre purchase suspension conversion question

Question

Dad and I are getting ready to go test drive an air ride 2004 cv713 dump truck with 44k air ride. Air ride is a no go for us because it'll be converted to a volumetric concrete truck, top heavy and it'll get some off-road use, don't want to get stuck! We just retired a 1980 DM with 58k rears on 55k camelback. Any reason not to buy the truck and use our camelback to do a suspension swap? Are 55k springs too much shock for the cv713 double frame? The DM has a double frame but the frame under the cab to the lift axle is noticeably deeper than over the rears.  I'd hold out for a granite with camelback, but there's nothing else (in this century) in our price range. Salesman sold my dad his first Mack (79 R686ST, still runs most days) in 1986, so we're getting a good price on the granite.  Easy enough to get a cutoff with 44k camelback, but if I can use what I already have I'll save $2k.

 

Any other cautions to look for would be great! It has a 427 horse computer engine, I'll check for codes. (I bought the etech books a few years ago, they're priceless. They cover the etech ai and ac engines) and a maxitorque transmission, not sure how many gears. Are the modern maxitorques as bullet proof as our 2 sticks powered by Maxidyne 283s are?

Also how easy would the air ride sell here? Rears and all. Located in Bucks County PA.

Thanks!

Joe

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8 answers to this question

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Is the spread between the rails the same on both trucks to fit the Trunion in?

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We're going to compare those measurements when we go to test drive it. My assumption is that outer to outer all trucks should be the same. Inner I can see fluctuating due to rail thicknesses and quantity. We'll have to make new eagles for the camelback, rust has perforated the left one.

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IIRC around that time the Macks were switched over to the Volvo frame design, which IIRC is a bit narrower than the SAE standard 34" outer frame width.

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Good to know, it's a 12/2003 build date I think. I'll be careful measuring, may have to pick up a  cutoff from similar year.

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10 hours ago, JoeH said:

We're going to compare those measurements when we go to test drive it. My assumption is that outer to outer all trucks should be the same. Inner I can see fluctuating due to rail thicknesses and quantity. We'll have to make new eagles for the camelback, rust has perforated the left one.

What is a eagle on the suspension?     terry:MackLogo:

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It is a gusset section that basically acts as a third inner frame rail at the trunion cross member.  On this truck there are no sideways torque arms, just the ones from each rear to the trunion cross member.  The eagle serves to hold the trunion and the frame square, I assume before they started using sideways torque arms. It won't let me upload photos to show you.

This 55k suspension is massive. Inner and outer frame rails are 3/8th inch thick each, our 95 RD688 triaxle has a 5/16th outer frame and a 1/4 inch inner frame and different spacing on the rails.  There's almost a 1/4 inch less frame rail thickness on our '95 with 44k Camelback than our '80 with 55k camelback.

 

Back to my original question, is converting from air ride to camelback a dumb idea? Should I just look for a different truck? 

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