67RModel

My 1994 RD690S is a monster single frame, which is one of the main reasons I bought it. It was originally from Virginia and a one owner unit with low miles and no frame rot to speak of. The Maxitorque T2060, 2070, and 2080 all have a 0.6:1 overdrive to get road speed out of the very slow rears they had in them. An Eaton trans will have a 0.71:1 overdrive and the rears will be somewhere between 4.17 to 4.88:1.

Yea I was going on the fact that its a RD690....690 indicating a maxidyne engine. When trucks get to be this old and passed through many owners anything is possible though.....

It worked for me. Looks like a decent truck. Just looking at it quickly it doesn't look to be in as nice cosmetic or maintained shape as the 2000 you looked at earlier but that doesn't necessarily mean this one is a bad egg by any means. Some pics of the frame rails and chassis condition would be a good starting point. The Eaton transmission may be a transplant. An EM7 (Maxidyne) engine would have most likely come with a Maxitorque transmission. The Eatons were usually paired with an E7 350 or E7 400 engine.

I was going to say this. I know in Massachusetts you can gross something like 100,000 on a 5 axle combination. The most you will probably get on the steers is 14,000, which leaves 85,000 total and around 43,000 far each set of tandems. So in this example 38,000 rears would be pretty undersized. Now if you are pulling one of those Michigan specials with a bunch of axles on the trailer to shoulder the weight, the weight on the drive tandems may only be around 34,000 or so in which case you would be fine. I always though the rating of the rears was the weight carrying capacity of the axle set. I don't think it has any reference to the amount of weight you can gross on a combination setup. Plus you say you are just rolling down the highway with it.....not a really demanding use case.

You can copy and paste the web address of the Facebook listing into the text of your comment here on the forum and it will show up as a hyperlink. Or you can take screen shots of the listing and post them as pictures here. They both work.

A stated by others in your other thread. Its the ECM. The engine has the mechanical ability to run but the computer is not satisfied somewhere along the way and is derating and/or shutting you down. Its that simple. Maybe take it back to whoever deleted it and have them "fix" it.

Does India even require Tier IV emissions controls? I can't imagine they do. Is there dealer support for these systems over there yet?

Yes my story about backing was with a DT12. I tried to like them and give them the benefit of the doubt and have an open mind regarding the automated transmissions but they are not for me. As an owner operator now in a vocational application I can't see their benefit as they are much more expensive initially, much weaker (1 countershaft), and seem to be too complex electronically to have long term reliability (higher operating costs). They may save on driveline abuse with an inexperienced driver off-road. Also if your running a fleet they probably help to attract new and younger drivers that don't know how or don't want to drive a manual.

I know a lead mechanic at a mostly Mack fleet runnning a lot of MDrives and a lot of the failures they were seeing were from from one of the wiring harnesses (I think on the left side of the unit) were getting corroded somehow and causing all sorts of weird symptoms. This was several years back now but I know they had they exact same thing happen on a few of their trucks. It could possibly be a technical service bulletin by now. These are rebadged Volvo I Shift transmissions with different software programming to match the programming and characteristics of the Mack MP engines. Maybe check some of the Volvo forums (if they have one) to see if there is any information there?

Most likely so it would save a an extra thimble full of fuel every week and so they could say it gets up to 3% better fuel economy than the previous iteration. I have driven these and the Detroit DT12 transmission and from a drivability standpoint they really are less than desirable. Yes they make going down the road a little "easier" since you don't physically have to go up and down through the gears but once you get into any type of tight quarters that requires a lot of slow speed backing or maneuvering they absolutely suck. I've had several instances where getting a 53' trailer into a super congested terminal that was designed for 32' trailers the air actuated clutch was working so much the low air alarm came on. I personally have no use for these Volvo I shift (I mean Mack M drive) transmissions. Plus you guys say they have poor longevity.....Its amazing to me what people will give up for convenience.

Both of those trucks have V8s. The one with the dump body looks like an 864 or 865 V8. The one without the body looks like a transplanted E9.....

That is a Penn body. They were a dump body manufacturer from Johnstown, PA. Long gone and out of business. They may have been acquired by and/or became Thiele Bodies. That one looks to be in extraordinary shape. That thing would cost a fortune to get fabricated today. Would be a nice as a period correct body for a dump restoration project if somebody needs one.

I fixed it. I suspect the buyer was after the body mostly. We all love a nice Superliner on this forum (especially a superdog with a cat under the hood) but to most landscapers / environmental companies a chassis like this is just a liability to them.

I'm willing to bet that truck is coal hauler in West Virginia or Kentucky. Most of the coal haulers from that area run trucks like this. Enormous beds on tandem axles with spokes.

I'm pretty sure anything after the E7 Etech engine (1998-2002) are not really E7s. The engine in a 2006 is the ASET (application specific engine technology) and are not very well liked by most. The block and rotating assembly might be an E7 Etech but that's about it. There are two versions of the ASET: The AC and the AI, which pertains to internal EGR cooling vs. external EGR cooling. There are a slew of other differences too. A road tractor is usually the AC version. There are a lot of other guys on here who are much more knowledgeable on these early emission engines who will chime in.

I see you are in NC but not sure where in the state. JoeyMack has a shop and a service truck in NC. He has been responding to this thread. If you are close to him he may be able to come to you if you cant get it sorted out. Just a thought...

It would be really sweet to own that lone RS800 or at least even see it. I wonder who it was built for and why they only made one of them. 800 series DMs were fairly common. Did Mack build any R800s in Allentown?

Or maybe there is break or leak in the line feeding the secondary system supply tank. It may be hard to hear or unnoticeable with the engine running. Look for the simple stuff first.

The orange needle is for the secondary air system. Usually the low pressure indicator (buzzer) is tapped of the secondary system supply tank. There is a one way check valve at the inlet of the both primary and secondary tanks to prevent supply air coming from the compressor from flowing back into the compressor and/or air dryer and/or wet tank. It sounds like the check valve at the secondary tank is stuck or failed.

That is about the exact use case that 690s was specd for....

The pattern is literally like a 5 speed pickup truck plus you have the two under gears in holes 1 and 2 which you probably wont use that much. The big difference between them and a Fuller or even the 9 speed you are driving now is the rpm drops between gears. Once you understand it and get used to it they are very humbling and pleasant to drive.

Having more gears on the high side is always more helpful than not having them. If you are purchasing a used transmission from a salvage yard there is no guarantee about what you are getting. If you are getting a reman unit they probably will not accept your 10 speed as a core so there may be more cost involved. the 13 will require a different stick or a at least a new knob than what you have in addition to a little more air plumbing to the knob. Also, the 13 speed is longer than a 10 speed due to the auxiliary box. You will need to have your drive shaft shortened if you switch to a 13. I'm not sure if the mounting locations and cross members are the same for each transmission but that is another thing to check before you make a decision. Do you have an Eaton or Mack Transmission currently?

Its one of those universally unanswerable questions. It depends heavily on region, type of truck, future usage of truck, budget, cash flow, and your mechanical skill. For instance I would be more uneasy about a steel body dump truck with 500,000 miles that spend its entire life in Pennsylvania versus a highway road tractor with 500,000 that ran the interstate between Arizona and New Mexico. For me regardless of type of truck I seek out an example that has no rust or corrosion and good sturdy frame rails for the application. After that I look for the powertrain that meets my specifications and then evaluate the mileage after these criteria are met. If a truck has been maintained and cared for higher miles should not necessarily scare you away. There will come a time however, where everything will need worked on or replaced its just a matter of when. Also, with 20+ year old trucks there is no guarantee the ecm mileage is correct either. The ecm could have just as easily been replaced as odometer gauge at this point.....

It looks like you are allowed 34,000 on the rear tandems and 18,000 on the front for a total GVWR of 52,000. You are not limited to a lesser GVW by the components of this truck since it has 44k rears and an 18k front axle with 385 float tires. If we assume it weighs 28,000 you can net 24000 pounds, which is 12 tons....I assume if it was a triaxle it would be allowed to gross 73,280 lbs which is how it is in PA. With a drop axle it would be around 30-31,000 pounds. 73280-31000 is 42,280 pounds or 21 tons. "Legally" for hauling weight a tandem is kind of useless as you can see. The truck will easily haul much more than 12 tons as is but you wont be legal. And as stated previously the drop axle provides the additional carrying capacity to get to 73280 GVW as well as additional braking power to stop it.

I don't know where you intend to run this truck (which state). I see its being sold In Arkansas. I'm not familiar with the axle requirements for Arkansas or whichever state you live in. But yes in my opinion for a truck that clean and well kept $38,000 is a reasonable asking price if it were a triaxle (having a drop axle) in my area. Tandems have a purpose but they are not as sought after and in my area they are almost non existent. You could add a drop axle but that is a whole different subject. Yes a drop axle allows you to carry more weight but more importantly provides more braking. If a tandem suits your needs and you can make money with one I wouldn't hesitate for a second if everything checks out. I would definitely rather have a nice old girl like this in my stable over one of these new fangled, over engineered, sensor laden piles of rolling crap they sell new as trucks for a cool $150,000+. At least you can fix it yourself and won't be riddled with weeks of downtime while the stealership "technicians" try to figure out which loop of electronic wizardry caused you to go into limp mode while pulling a 8% grade fully loaded........That truck is a literal block of granite and will probably outlast most of us if taken care of and looked after.