Gap Between Cab And Dump Bed

[tylerstanley]

We are looking at ordering a few new trucks this winter, and we have been talking to our dealer about the gap between the cab and the dump body (ox bodies) that is caused by the exhaust sticking too far back. Is there a fix to this problem? I know Internation, Volvo and Kenworth with dump bodies are right next to the cab (3-4" between) Our CV713's have like a 10-12" gap..... Can mack not do any better? they could move the exhaust more twards the side of the cab and do better. Or be like International and mount the muffler under the cab and run the pipe up the truck... thanks for your help.

[MACKS]

In my opinion the real problem is the width of the newer cabs,on my cl dump I'm running a straight pipe because if I use a muffler it's gonna stick out to far for my liking,I don't want to have to try to see around the muffler when ever I look in the mirror and I know I wouldn't, like the way it would look sticking out way past the cab and the dump body.Anyway I'm looking to try one of those dynaflex mufflers it should give me the sound reduction im looking for and wont stick out much more than a straight pipe.Also I wouldn't, mount the body 3 or 4 inches behind the cab I think that's to close for comfort,I was always told about 6-8 inches is the rule of thumb.One thing I miss with the older cabs,there really is no reason to have a cab that's 7 foot wide for a dump truck. Good Luck with what ever you buy.

[tylerstanley]

In my opinion the real problem is the width of the newer cabs,on my cl dump I'm running a straight pipe because if I use a muffler it's gonna stick out to far for my liking,I don't want to have to try to see around the muffler when ever I look in the mirror and I know I wouldn't, like the way it would look sticking out way past the cab and the dump body.Anyway I'm looking to try one of those dynaflex mufflers it should give me the sound reduction im looking for and wont stick out much more than a straight pipe.Also I wouldn't, mount the body 3 or 4 inches behind the cab I think that's to close for comfort,I was always told about 6-8 inches is the rule of thumb.One thing I miss with the older cabs,there really is no reason to have a cab that's 7 foot wide for a dump truck. Good Luck with what ever you buy.

I never thought about the cab being so wide that you cant mount the exhaust all the way on the side of a 7 foot cab. I guess thats why kenworth can pull it off with their t800 because they dont have a full width cab and can stand to mount the whole thing on the side without blocking vision. We still have a R model with a narrow cab.... like you said, you dont need a full width cab for just the day and a dump truck.

[mackdaddy1911a1]

The problem isn't the muffler it's the D.P.F. filter....it's made to look like a big fat muffler but it is the D.P.F. unit. I saw one of the first pre production units several years ago at Mack of Charlotte. I don't think vulva engineers care about the eye appeal value of a truck. That is where they put the damned things on their trucks and that is where it is on Mack. Why do you think they put the vulva battery box on the Pinnacle axle back trucks and that upsidedown mushroom ahead of the fuel tank on the right side on all the sleeper cab models? It is a vulva chassis with a Mack cab and sleeper. Doom on you vulva.

[daveigou]

Published BOC (back of cab) interference for GU's is 9" for trucks equipped with Mackcap DPF (under RH cab door) & single exhaust, and 11" with dual exhaust. Add 2 more inches for body clearence. Penn DOT trucks use a vertcal back of cab DPF so they can mount wing plows, and that leaves about a 2-3 foot space between body and cab , which looks pretty dumb.

A 10" or 11" space between cab and body is the best you can do. Watch your weight distribution on a straight truck!

Starting in 2011 model year (EPA 2010), the big problem will be frame space for fuel tanks, hyd tank and so on. I hope your salesman knows what he's doing.

Mack is building some EPA 2010 (model year 2011)(SCR) trucks now, and I believe all the EPA 2007 (model year 2010) line slots are sold out, and full EPA 2010 priduction will start in April 2010.

Dave

Edited November 20, 2009 by daveigou

[tylerstanley]

Published BOC (back of cab) interference for GU's is 9" for trucks equipped with Mackcap DPF (under RH cab door) & single exhaust, and 11" with dual exhaust. Add 2 more inches for body clearence. Penn DOT trucks use a vertcal back of cab DPF so they can mount wing plows, and that leaves about a 2-3 foot space between body and cab , which looks pretty dumb.

A 10" or 11" space between cab and body is the best you can do. Watch your weight distribution on a straight truck!

Starting in 2011 model year (EPA 2010), the big problem will be frame space for fuel tanks, hyd tank and so on. I hope your salesman knows what he's doing.

Mack is building some EPA 2010 (model year 2011)(SCR) trucks now, and I believe all the EPA 2007 (model year 2010) line slots are sold out, and full EPA 2010 priduction will start in April 2010.

Dave

thats our problem with weight right now. Our Cv's are tri-axles, but we cant get much weight on the front axle because the dump bed (16') sits so far back past the rear tandems. If a truck gets loaded too far in the rear it feels like your doing a wheelie down the highway, plus its a crappy ride, and a crappier truck to handle. This problem could be the nail in the coffin for our Mack truck run..... Kenworth has their gameface on with the t800.

[HK Trucking]

thats our problem with weight right now. Our Cv's are tri-axles, but we cant get much weight on the front axle because the dump bed (16') sits so far back past the rear tandems. If a truck gets loaded too far in the rear it feels like your doing a wheelie down the highway, plus its a crappy ride, and a crappier truck to handle. This problem could be the nail in the coffin for our Mack truck run..... Kenworth has their gameface on with the t800.

Just spec a longer wheelbase to get the drives further to the rear, resulting in less overhang of the dump box past the rears, and more weight on the steer.

Very simple.

[daveigou]

I don't know the reason for the 16" gap. Sounds like a screw up to me. We like to set dump bodies with about a 10 -11" gap,and a 22 to 24" max overhang at the back for dumping into a paver, less if you can get away with it.

In our region, operators prefer a 17'6" body. I think they should think about going to an 18 or 18 1/2' body in the future.

Don't give up on the Mack. Every brand is going to have their challenges. I've heard Kenworth & Peterbilt are sitting on a pile of Cat engines, and are pretty aggressive on pricing, but the GU Mack's with MP power are fine products.

Specing a new truck is more difficult than ever, do your homework.

Edited November 21, 2009 by daveigou

[tylerstanley]

Just spec a longer wheelbase to get the drives further to the rear, resulting in less overhang of the dump box past the rears, and more weight on the steer.

Very simple.

that would work. but we want the shortest total length possible. Would that affect the total length? Or just move the tandems further back? It gets tight in some of the places we go. But we did talk about that solution.... thanks for the idea though. Some of the International 7600 we work with have the rear wheels almost right at the tailgate. the only overhang is the dump apron. Has any other people with other bodies (garbage,concrete) had problems with this?

Edited November 21, 2009 by tylerstanley

[theakerstwo]

Just spec a longer wheelbase to get the drives further to the rear, resulting in less overhang of the dump box past the rears, and more weight on the steer.

Very simple.

That is what i would do.Mt truck is alot longer than that and i dont have any trouble with the turning.

[cgallamore]

i drove for a company called midwest hauling they had 35 triaxels we ran into the same problem they tried one with the drives to far forward it did not work at all could not get close to leagel. no weight on steer. they kept it around for new hires for a couple years and sold it cheap. back of drives even with the inside of tail gate works the best every time.dont let some slick salesman bull s%#t you. i have seen it tried many times, but never seen it work!

[cgallamore]

knapheide has a good t-5 bed the frount corners are cut back at an angle to help with exhaust clearance and i guarantee you will like it better than an oxbody it cost a little more but when you set them side by side you can see why.

[HK Trucking]

i drove for a company called midwest hauling they had 35 triaxels we ran into the same problem they tried one with the drives to far forward it did not work at all could not get close to leagel. no weight on steer. they kept it around for new hires for a couple years and sold it cheap. back of drives even with the inside of tail gate works the best every time.dont let some slick salesman bull s%#t you. i have seen it tried many times, but never seen it work!

If that truck was otherwise spec'ed properly, why didn't the company just relocate the drives further to the rear?

Would've been better than selling an otherwise good truck at a loss.

.

[ThaddeusW]

that would work. but we want the shortest total length possible. Would that affect the total length? Or just move the tandems further back? It gets tight in some of the places we go. But we did talk about that solution.... thanks for the idea though. Some of the International 7600 we work with have the rear wheels almost right at the tailgate. the only overhang is the dump apron. Has any other people with other bodies (garbage,concrete) had problems with this?

No it will not effect the overall length as long as you have enough overhang of the frame rails. Wheel base is measured from the center of the front steer axle to the center of the rear driving tandems. So if you have lets say four feet of overhang on the frame from the back of the rearmost tire, you can slide the tandems back another three or so feet.

If the tandems were specked too far up then you had a bad salesman or unfortunately improperly specked the truck. Always do your homework and talk to your dealer. Make sure you feel that when talking to your dealer he/she is really working with you to give you the best truck for the job, not a truck off the lot that has been collecting dust.

[pmolitor]

My box is even with the back tires. I wouldn't have it any other way.

[HK Trucking]

No it will not effect the overall length as long as you have enough overhang of the frame rails. Wheel base is measured from the center of the front steer axle to the center of the rear driving tandems. So if you have lets say four feet of overhang on the frame from the back of the rearmost tire, you can slide the tandems back another three or so feet.

If the tandems were specked too far up then you had a bad salesman or unfortunately improperly specked the truck. Always do your homework and talk to your dealer. Make sure you feel that when talking to your dealer he/she is really working with you to give you the best truck for the job, not a truck off the lot that has been collecting dust.

Even if the truck has been sitting on the lot for awhile, as long as the basic specs of the truck are correct for the job, the frame can be shortened/lengthened, or drive axles moved to the proper location for correct weight distribution. Setting up a truck correctly involves more than just slapping a dump body on it, however some salespeople are either unaware of the proper parameters, or they just don't care as long as they can get their commission. Then again, a competent truck body installation shop should see a red flag when ordered to set up a truck with the drive axles incorrectly positioned.

.

.

[daveigou]

Another thing you can do is put a 6" slope on the tailgate. It makes the loader operators keep the center of the load front more, and the gate stays a little higher off the ground when you dump, and closes a little easier when the body comes down.

A 16' body on a tri axle is just too short, no wonder the truck handles poorly. Probably a proper weight distribution with the pusher axle down would show the end of the body should be about the center of the rearmost axle, or even farther front than that, and of course you can't do that.

As far as moving the axles back, with a Mack camelback you can probably move the axles back about 20-30" and still be in the original frame rails, but then you also need to move the pusher back, and add to the frame rails for the body hinge, and I have mixed feelings about that.

Nothing takes the place of gettin it right the first time!

Edited November 22, 2009 by daveigou

[tylerstanley]

Another thing you can do is put a 6" slope on the tailgate. It makes the loader operators keep the center of the load front more, and the gate stays a little higher off the ground when you dump, and closes a little easier when the body comes down.

A 16' body on a tri axle is just too short, no wonder the truck handles poorly. Probably a proper weight distribution with the pusher axle down would show the end of the body should be about the center of the rearmost axle, or even farther front than that, and of course you can't do that.

As far as moving the axles back, with a Mack camelback you can probably move the axles back about 20-30" and still be in the original frame rails, but then you also need to move the pusher back, and add to the frame rails for the body hinge, and I have mixed feelings about that.

Nothing takes the place of gettin it right the first time!

you got that right.... i hate to "rig" on stuff, espically if its new, or close to new. I know to move the drives back further, but its still just a bummer that you have such a gap between the cab and dump body. Everyone in our area uses a 16' body. So i dont know about that problem. On macks website, they are proud of their 'back of cab clearance." I think its a shame what they have done behind the cab.... Would people agree with me in saying that 70% of macks business is with some other "bodybuilder" adding on their frame?