MR688S frame work

[JoeH]

So we bought a 2003 MR688S, and are prepping it for a brand new CemenTech volumetric concrete mixer.  Have about a month to complete the following:

Pull frame rails, separate, sandblast and paint.  Reassemble.  (One side at a time.)

Shorten wheelbase by approximately 16.5 inches. (Slide tandem forward, shorten driveshaft, possible relocate crossmembers)

Add 20k lb lift axle. Truck was a tandem axle trash truck, 20k front axle, 44k rear tandem.

Replace driver door shell (fiberglass PoS cost $2,000)

Paint cab.

Trying to figure out how to post pictures.

[JoeH]

Currently the left frame rail is out & sperated.  So much work just to alleviate less than 1/4 inch of rust jacking.  Monday will be sandblast the frame in the rain. Will tent it with the boom of our crane and a 30x50 tarp, then run it inside the garage for paint. Then crank up the heat and cook the paint!

 

Edited December 24, 2021 by JoeH

[JoeH]

In my lifetime to date, (I'm 32) we (I'm 3rd generation) have only had R models and a DM.  This is our first MR cab, and so far this has been a dream to work on.  All the cab electricals are under a massive plate in the middle of the cab that completely comes out to give access to everything. Terminal blocks, circuit breakers, dash switches, etc.  6 screws and you're into everything. The cab tilts forward and you can get to everything on the engine. You can get to the front of the engine, the back of the engine, both sides... Truly the easiest truck I've ever had to work on.  Our DM is easily the worst I've ever worked on, you can barely even get to the sides of the engine.  We have yet to drive this truck on the road, I'm hoping it will be a relatively smooth ride, but I'm expecting it to be a bit rough.  I may wind up only buying MR's from here on out, these things are that nice.  I'm sure there's very few MR fans on here, but no one will argue that these trucks are built with the same great reputation we all know Mack had.  The R model will always hold a place in my heart, but the MR is moving in next to it!  The mixer body going on requires 168 inches from "back of cab" to center of tandem, which on a traditional cab would be far too long for the type of maneuvering we have to do every day.  Thus in keeping with traditional Mack philosophy: Out with driver comforts, In with functionality!

 

Merry Christmas!

[1965]

I’m thinking & hoping you will like that automatic 

[Joey Mack]

I know what you mean about having room to work...  I have done a boatload of work on MR's and LE's...  it's really great compared to other truck's Iv'e had the diss-pleasure of working on...  The 2000'ish DM cracks me up.... I had to remove  the right corner cab mount and jack the cab to get the engine brake spacer out of the rear head..  I thought it was a joke... but my co-worker said.. yep, that's how you do it.. I was just doing a valve adjustment..  I still think there was a worn out cab mount or something... but I would still work on one today..  great trucks.. and as you know, pulling a transmission in an 'R' chassis  is much more work than many other trucks, even if they have a wet system.. I have a KW W900 at my shop with a 3406.. I have to run the valves, and whatever else I find..  you know... open the hood... and there it is..  Almost as much room as a superliner.. jojo...

[JoeH]

1 hour ago, 1965 said:

I’m thinking & hoping you will like that automatic 

I think I will too, I've driven automatic oil/propane delivery trucks and they're easy.  What I'm nervous about is off-road capabilities.  We get in people's back yards and find soft ground sometimes.  I need to inspect the automatic power divider.  Full lockers would be sweet but they're hard to come by.  Truck has Automatic Traction Control, piggy backed into the ABS system, which I had hoped was on all 4 drives wheels, but it's only on steer and rear drive axle.  I may buy toner ring hubs for the intermediate axle and steal the steering ABS sensor system for the intermediate axle so I have traction control on 4 drives.

[Joey Mack]

How about buying an air locked power divider housing and shift fork assembly, and the cam drum, peanuts and inner cam, and building it and shimming it to fit back into the carrier housing, then get  the drive shaft shortened by the difference between the auto power and the air locker set up? then you can run an air switch to the dash and hook a light or buzzer to it so you know if it's locked in..  you can use the current bevel pinion that is in the carrier and set tooth pattern the normal way after you convert the housing..  jojo

[JoeH]

An interesting proposition, perhaps a project for down the road.  Budget and time don't allow for it now, truck needs to be in Iowa in February to get the body mounted on.

[Joey Mack]

yes sir... My words make it sound easy... but it can be done..  it would be best to pull the carrier out and mount it secureley on a table, even if you made a 'jig'...  jojo

[Joey Mack]

there is always the option of buying a rear end with the correct ratio and of course in good condition, and building it on the bench..  The last 'whole' one I bought from Re-Mack was $4300.00....5 years ago..  don't know if they still offer them..  "Overdrive rebuilders" Is who I've been using since...  not sure if they are in your area, but it's a thought..  jojo

[james j neiweem]

I often wonder why the MR isn't used more broadly in the construction industry such as mixer(non pumper), dump and even HD tractor. As stated they are easy to service and work on. This would apply to Autocar and Paccar as well. I have seen some older MR dumps (Galasio from  East Granby)from time to time. We even have a twin steer White expeditor running around here in CT.🙂

[Mark T]

They'd make it much easier to get the weight on the steering axle if used in dump application.  

[mowerman]

wow i usually dont come to this section,,,,,thats way cool....ive always liked th MR,,,just a real neat looking ride.perfect for city work.     looks like your well on your way     .bob

[JoeH]

Left rail is primered painted and installed. Right rail has been removed and separated, tomorrow is hopefully sandblast, primer, paint.

Supply chain issues are a bit screwy. In our hurry to get going we have had to reuse a lot of bolts before sourcing new ones. Last truck we did like this was 10 years ago, and I dont think we had any trouble getting bolts.  

Pictures show left rails laying flat vs right rails still with rust jacking.

[JoeH]

Right frame rail has the cab tilt mechanism, and since the right frame rail isn't in the truck right now..... We had to improvise.  Left rail cab hinge is installed, right cab hinge is suspended by strap, and the cab gutter line is suspended from another strap, from beams going from our A frame to our pallet shelving. Redneck ingenuity is heavily at work here...

[JoeH]

Yes there is a wagon hiding in that last picture.  While most people set old wagons in their front yard to rot away we prefer to keep our 150 year old (rough estimate) wagon up high and dry in our garage.last time it came out was for Chalfont, PA's bicentennial parade in I believe 2002 or 2004. Next time it comes out will probably be my 4 year old daughter's wedding in 20 years.

[Hook n ladder 1]

Good luck with this project...you did a lot of work so far.  

I'm a big MR fan.  Drove one for Waste Management.  I did want to buy an MR tractor (old USPS rig) and either stretch it and make an RV out of it or put a sleeper cab on it.  I have a CH midrise sleeper that i was going to use but, there isn't enough time in the day.

[JoeH]

New Years Eve had the paint store closed, so we didn't get as much done last Friday as we hoped.  Finally got the right frame rails and about 10-15 miscellaneous brackets sand blasted and painted. Everything is sitting in the garage baking at 75 degrees overnight. 8am tomorrow starts the install process.  Should go smoothly, no reason for it not to.  Lift axle should arrive end of the week, hopefully the shortened driveshaft will be back soon too.  One of my tenants is a collision center, I may ask them to prep the cab for paint.  That's one task I don't enjoy so much. More pictures promised as progress continues!

[JoeH]

4 hours ago, Hook n ladder 1 said:

Good luck with this project...you did a lot of work so far.  

I'm a big MR fan.  Drove one for Waste Management.  I did want to buy an MR tractor (old USPS rig) and either stretch it and make an RV out of it or put a sleeper cab on it.  I have a CH midrise sleeper that i was going to use but, there isn't enough time in the day.

Sleeper would be interested on an MR, it couldn't mate to the cab as there's part of an engine in the way.  Would definitely be a neat rig if you could pull it off!

[Joey Mack]

that would be cool... you reckon youll need a cab jack from a fire truck??  jojo

[JoeH]

Today's progress: right frame rail installed, tandem slid forward to the new wheelbase. Miscellaneous brackets installed for bumper, skid plate, cab tilt, exhaust, fuel tank, etc. Shortened driveshaft should arrive tomorrow or Friday, hopefully the lift axle is coming by Friday, though the tracking number TForce Freight provides is bogus. All in all I think we've made a lot of progress in 2 weeks.

Won't be particularly pretty when it's done, but we've always had more interest in structural integrity than chrome. These trucks just get covered in concrete dust.  All this work is simply to eliminate the Rust Jacking in the frame, not to make it cute.

[keg1]

My nephew just bought 2 2008 garbage trucks which i believe are MR,s and he said when you turn the key off the 2 outside cab lights stay on you have to turn key back to acc then they go out. Ive never been around one so i was wondering if there's a seperate switch for the lights like how the R models have 2 switches. He said its a rotary style switch rather than toggle switches like the R model

 

 

[Joey Mack]

look for a battery switch on the batt box or near it... trash companies do that so the drivers cut the batts off after thier shift...   jojo

[JoeH]

Could be daytime running lights that stay on like modern cars do. You shut the car off, go inside, and the lights shut off after a minute. That's my best guess. This is my first MR too, haven't had much play time with it.

[keg1]

thanks for the replies. I'll  let him know