67RModel

I asked this same question a while back and mostly heard crickets for any type of response. I'll tell you what I have found out and learned thus far on the subject. My truck is a 1960 B81 that has S cam brakes with manual slack adjusters, much like a modern truck, however, it has rotochambers of some variety (I think type 20 or type 30) to actuate the slack adjusters. The brackets attached to the axle housing the rotochambers bolt to are extremely close to the tire/wheel assembly. The center to center measurement of the bracket hole centers are the same as any modern mounting bracket and will accept any modern brake chamber, however, the diameter of the new compound brake chambers don't allow them to be installed without interference with the wheel. Modern chambers are also much too long, causing interference with the wheel at the back of the spring chamber as well. I first tried a 30/30....not even close. I then tried a 24/24 and it fit, however, it was so close to the wheel you may have been able to fit a sheet of paper between the two. I was not comfortable with this amount of clearance. The only other option I have found but not tested yet are Haldex I Series Maxibrake chambers, specifically part number MA15770. They look to be esentially a type 20 rotochamber with a small little spring brake chamber on the back that is smaller in diameter than the service chamber so clearance should not be an issue. The only downside to these (assuming they fit as planned) is the cost. I priced two of these out a few months ago and my parts place wanted somewhere North of $400.00 apiece for them, and I could not return them if they did not work. I just could not bring myself to spend the money on them at them time with the risk of not being able to return them. I will probably bite the bullet and buy one to test and then buy a second one if it works out. I figure for a show truck that only ever bobtails one axle with spring brakes should be sufficient. Below are two pictures of my current stock setup and you can see how close the service chambers are to the wheel.

I have an NTC 855 Big Cam 350 horse if you are interested. It has an eaton fuller double overdrive 13 speed still bolted to the back of it as well. They have been sitting in a warehouse for the better part of 30 years. The set came out of early to mid 80s international cabover that had 93,000 original miles. I have all the information and VIN number of the truck it came out of if you ever needed to get parts for it. I know its not an NH220 but I figured I would throw it out there. I have no use for it and need to get rid of it. I am 20 minutes from Pittsburgh.....near the airport. Thanks.

Release the parking brakes. Yellow air valve on the dash. If you are doing this already ("push in the brakes") then the rear brake shoes are most likely seized to the brake drums from sitting.

Thanks for all the info. At least I know it can be done and the correct part number. I am going to run it as is for now and see how it works out. Braking power aside, I would think they would have come standard to help get the rpms down faster when upshifting with those huge rpm drops in the t2070 and t2080 transmissions 😄. Who knows, if it ends up being a good reliable truck, and I am looking for something to do next winter in the shop maybe it will happen. Thanks again for the information.

Yes full mechanical EM7-300 with the 1750 governed rpm

Can anybody answer the question of installing a Jake brake on this engine?

Yes, They are both still available. Thank You.

Yes it is an EM7-300

Hello All, I just picked up a very mint condition 1994 RD steel body tri axle dump truck for local dirt work. I searched for a long time to find the specs I was looking for and this truck finally popped up, however the only thing it does not have is a set of Jake Brakes. It is a fully mechanical EM7 with a Mack T2070 transmission and 6.06 Mack rears on 46k Camelback suspension. Can this version of the E7 be set up with a Jake Brake? Does the slow speed 1750 governed rpm prohibit the installation of a Jake brake? I realize braking power would be less than a 2100 rpm engine, which is why I'm guessing a lot of the EM7s were never equipped with them from the start. But I have also heard that taking this engine to 2100rpm is not overrevving it. If jakes can be installed can you run this engine to 2000 - 2100 rpms on a downhill?

Unfortunately no. Bill of sale only for the blue DM. There is a title for the DM 800.

Yes I agree. The cabs are rough as well too. Very poor floors. I see the value in the engines, and drivelines as they both ran like sewing machines when they were finally parked. Its just a shame to see them get scrapped considering they are good running engines, transmissions, and rear ends.

Here are some pictures of the chassis...

I will get some more pictures today and post them up tonight.

Not sure of the years but pre 1973 as they both have steel dashes. They both have 237 maxidyne engines. The blue DM600 has a 6 speed and the DM800 has what I believe to be a quadruplex. Both trucks ran very good when parked but have been sitting for several years. The DM600 has a jake brake but the DM800 does not. 6 is a triaxle and the 8 is a tandem with obviously very heavy rears. Probably 58,000 pounds or more. 12.00x24 rubber and Mack axles on camelback suspensions. Both trucks are pretty rotten and too far gone for any kind of restoration (in my opinion), however the engines, transmissions and drivelines are all good parts. They are essentially good complete parts trucks. Looking to get scrap price or maybe a little better if possible. Just trying to save them from the torch if somebody can use them. Located in the Pittsburgh, PA area. Please do not ask if I will export these or deliver them to a port. I will not deal with exporters. Thank you.

What do you mean by not wanting to idle? Like starving itself for fuel to a stall, or running at higher than normal rpm at "idle"? If it truly is an all mechanical injection pump it may be the linkage. It could be out of adjustment or getting jammed up somewhere. You could disconnect the throttle linkage from the injection pump and manually open the fuel rack all the way by hand and have somebody watch your tachometer to see if it is still stopping at 1600. Just a thought.

Ebay Listing for a B-61 and Trailer. Located in Missouri. https://www.ebay.com/itm/B-61-Mack-with-1944-Fruehauf/324398244494?hash=item4b87a4628e:g:uV0AAOSwi3BfxSv5

Do you know what they each had for power?

Found these two trucks in an upcoming auction listing in the central Ohio area. They look to be in great shape and say they have been stored inside. https://www.kaufman-auctions.com/project/details/54569

Holly cow! Can you scan and send the whole magazine? I'm not sure how many pages they are. I'm actually interested in an article about a former local concrete supplier overhauling old Colonial mixers from Jersey that were originally WWII Mack LMSWs.

Does anybody have one or know of a source where I can get an original or copy of the 1977 4th quarter edition of Mack's Bulldog Magazine?

Not really sure what they are worth. Probably not much even though they are a pretty unique item. $100 for the set.

I have two new old stock 6.5-16 Lee brand tires for sale. These are still in their original wrapping and have been stored inside forever. They are still very soft and have no dry rotting whatsoever. I am guessing they are from the 30s or 40s. Although too small for what most people on this site have, I don't want to throw them away as someone could possibly use them on a restoration project. Pittsburgh, PA area.

I have a B81SX with single acting service brake chambers on the tandems. The truck utilized a hand brake that engaged a brake drum on the drive shaft for parking. From the attached pictures does anybody know if there is a parking brake chamber type that is a direct bolt on? The current setup only utilizes one bolt to secure the chamber to the axle housings. All the spring brake chambers I have seen have two bolts. Has anybody ever done this change to older trucks that were not originally equipped with spring brakes? I realize there is air line plumbing involved and a valve needs added in the cab, however I believe that to be the easy part of this job. My concern is with being able to mount a spring brake chamber to the axle housings. This truck is 90% restored and is used only for show, however, the lack of a good functioning parking brake is somewhat of a liability in my eyes. Let me know if you have any ideas. Thanks in advance.

Thanks for the response. I am going to pass though. I need to have a Rest Rite for the restoration I am working on. They were manufactured a short distance from where I live and were very popular in this region at the time. From what I have researched they actually made sleepers OEM for Mack up until maybe the early / mid 90s.

I am in search of a Rest Rite sleeper from the 60s, 70s, or 80s. Preferably a 48" or 36" but a 24" would be OK too. Any leads or information would be helpful or if you know of a junk / parts truck with one still attached. PM me any and all information. Thanks. Neil