1969 Mack R611T official thread

[doubleclutchinweasel]

Kinda hard to see, but here is a typical wiring diagram for an R of that vintage...

[Robo987]

I’ve been on the fence about changing it over to  negative ground. I was surprised to see it was a negative ground. Trying to keep it as original as possible.
 

i really like the light green, the dark green isn’t as appealing to the eyes IMO.
 

I’ve worked on a lot of stuff but old trucks and equipment are not things that you come across often in a day to day mechanics job. At least in what I do. So some of this stuff is foreign to me and I learn new things every time I work on it.

[Robo987]

8 minutes ago, doubleclutchinweasel said:

Kinda hard to see, but here is a typical wiring diagram for an R of that vintage...

That’s awesome thanks! Luckily my phone zooms in good enough to just make out most of it.

[doubleclutchinweasel]

1 minute ago, Robo987 said:

I’ve been on the fence about changing it over to  negative ground. I was surprised to see it was a negative ground. Trying to keep it as original as possible.
 

i really like the light green, the dark green isn’t as appealing to the eyes IMO.
 

I’ve worked on a lot of stuff but old trucks and equipment are not things that you come across often in a day to day mechanics job. At least in what I do. So some of this stuff is foreign to me and I learn new things every time I work on it.

They are actually fairly easy to work on.  Very well designed beasts.

The biggest issue I saw when one was changed to negative ground was that some of the gauges would not work correctly.  For instance, I had to change the volt meter on mine, because it was not possible to reverse the gauge (single wire, ground through case).  Had to get a 2-terminal gauge so I could connect the wires to the terminals with the correct polarity.  Also, I think the fuel gauges did not like being reversed.  But, I am fuzzy on that one.  Light bulbs do not care.

Nothin at all wrong with positive ground.  Just have to isolate any add-ons that you have (like radios or phone chargers).

[doubleclutchinweasel]

3 minutes ago, Robo987 said:

That’s awesome thanks! Luckily my phone zooms in good enough to just make out most of it.

I have airline schematics, too.  Not sure what kind of parking brake setup you have on there.  Mine came with DD3 brake units.  Very complicated system with extra air tank and an "inversion valve" (see pictures).  I swapped it over to regular spring brake chambers, which was very easy.  It also eliminated a bunch of hoses and stuff.  Worked better, too.

[Freightrain]

4 hours ago, Robo987 said:

What is an esi option?

Extended Service Interval.

Had three filters and a larger oil pan for more capacity to go longer on oil changes.

[Freightrain]

4 hours ago, Robo987 said:

Would that alternator have been a 6v alternator? If that was even a thing. Because it at one point had to 6v batteries and was converted over to one 12v.

It was a 12v generator originally, now it has a 12v alternator.   The running system was 12v.  It took the two 6v batteries on each side and put them in series for 12v to run the truck.  The S/P switch make them all in series to make 24v for the starter.   It gave better cranking amps to start using 6v batteries.  Now it is obsolete.

 

The 24v start was good for the day but could be finnicky.  I changed mine out the first year due to not being reliable.  Now I put air starter on it!  Just because they are cool.

 

[doubleclutchinweasel]

9 minutes ago, Freightrain said:

It was a 12v generator originally, now it has a 12v alternator.   The running system was 12v.  It took the two 6v batteries on each side and put them in series for 12v to run the truck.  The S/P switch make them all in series to make 24v for the starter.   It gave better cranking amps to start using 6v batteries.  Now it is obsolete.

 

The 24v start was good for the day but could be finnicky.  I changed mine out the first year due to not being reliable.  Now I put air starter on it!  Just because they are cool.

 

The R611 I drove for Shuler had the 24V starter on it.  Had a push-button to engage the starter.  It was basically a manual relay that put the 12 volts from each side in series to the starter.  The one thing I will say is this...it would ALWAYS spin the motor over!  Even when the batteries were low, it still had enough power to turn that pig over on the coldest days.

Of course, my more-recent R611 had the basic 12V setup, and I never had more than one 12V battery in it.  And it did fine too.  Only saw a couple of really cold mornings where it said it hated me.  But, plugging in the block heater allowed us to come to an understanding, and away it would go!

And, yes, air start is still cool!

[70mackMB]

On 5/4/2023 at 12:28 PM, Freightrain said:

Extended Service Interval.

Had three filters and a larger oil pan for more capacity to go longer on oil changes.

My '77 R600 had the ESI and l think it was 54qts +/- in the pan. l remember the oil pan was big enough to bath a small kid. lol    .....Hippy

Edited May 6, 2023 by 70mackMB
Changed amount of oil in pan. 34 to 54qts

[mechohaulic]

with the phasing out of generators the alternator of factory install was the Leese/ Neville (as pictured) , built in regulator on top cover . plastic cover screw removed take small screw driver to adjust voltage.

[mechohaulic]

1 hour ago, 70mackMB said:

My '77 R600 had the ESI and l think it was 34qts in the pan. l remember the oil pan was big enough to bath a small kid. lol    .....Hippy

some where along the way the 3 spin on set up with large oil  pan was 51 qts  ??? possibly that 51 was total capacity including filters. unofficially there was a problem with the large pans  developing cracks , something with the manufacturing /casting process. brazing didn't work for repairs.

[doubleclutchinweasel]

51 minutes ago, mechohaulic said:

some where along the way the 3 spin on set up with large oil  pan was 51 qts  ??? possibly that 51 was total capacity including filters. unofficially there was a problem with the large pans  developing cracks , something with the manufacturing /casting process. brazing didn't work for repairs.

Pans are a “deep draw” product. The metal can pull extremely thin during the manufacturing process. That is a common cause of cracks in the thin areas. 

[Robo987]

14 hours ago, doubleclutchinweasel said:

I have airline schematics, too.  Not sure what kind of parking brake setup you have on there.  Mine came with DD3 brake units.  Very complicated system with extra air tank and an "inversion valve" (see pictures).  I swapped it over to regular spring brake chambers, which was very easy.  It also eliminated a bunch of hoses and stuff.  Worked better, too.

I’ll take whatever info and schematics you have. The more the merrier. I’ll get pics of the brakes chambers when I get a chance, I haven’t really looked at those yet. The brakes worked so I moved on to more pressing matters.

Edited May 5, 2023 by Robo987

[doubleclutchinweasel]

8 hours ago, Robo987 said:

I’ll take whatever info and schematics you have. The more the merrier. I’ll get pics of the brakes chambers when I get a chance, I haven’t really looked at those yet. The brakes worked so I moved on to more pressing matters.

First thing I did on mine was replace every air line on it, the slack adjusters, and the brake chambers.  Got rid of the rotten hoses on the frame and replaced with DOT air line tubing.  After that, I felt a lot more comfortable driving it!

With all the collective knowledge of the guys on here (you know who you are!), there's not much you can't find out on this forum.

Keep posting pictures!  We love pictures!

[Robo987]

On 5/4/2023 at 10:28 AM, Freightrain said:

Extended Service Interval.

Had three filters and a larger oil pan for more capacity to go longer on oil changes.

I should have known that haha. the guy that originally bought this truck was very serious about his equipment and didn’t just go with anything. So it’s no surprise that it is setup the way it is. 

[Robo987]

On 5/4/2023 at 6:30 AM, doubleclutchinweasel said:

They are actually fairly easy to work on.  Very well designed beasts.

The biggest issue I saw when one was changed to negative ground was that some of the gauges would not work correctly.  For instance, I had to change the volt meter on mine, because it was not possible to reverse the gauge (single wire, ground through case).  Had to get a 2-terminal gauge so I could connect the wires to the terminals with the correct polarity.  Also, I think the fuel gauges did not like being reversed.  But, I am fuzzy on that one.  Light bulbs do not care.

Nothin at all wrong with positive ground.  Just have to isolate any add-ons that you have (like radios or phone chargers).

I think just for the sake of keeping it as original as possible I’m going to keep it positive ground. 
 This thing does have speakers in it it that I think went to a cb, I don’t think it had a radio. But I’ll cross that bridge later.

[Robo987]

On 5/5/2023 at 5:38 AM, doubleclutchinweasel said:

First thing I did on mine was replace every air line on it, the slack adjusters, and the brake chambers.  Got rid of the rotten hoses on the frame and replaced with DOT air line tubing.  After that, I felt a lot more comfortable driving it!

With all the collective knowledge of the guys on here (you know who you are!), there's not much you can't find out on this forum.

Keep posting pictures!  We love pictures!

Yes this is an awesome forum! It’s great to have places with guys that have legitimate knowledge and not just spewing a bunch of backyard crap.

[mowerman]

I’m planning on doing same thing eventually all in good time … I wouldn’t be surprised if some of them ,, Air and fuel lines were original… been starting it every Saturday… starts rite up ,, otherwise I have to blow air into the fuel tank because it looses prime if it sits too long… Bob

[mowerman]

22 minutes ago, Robo987 said:

I think just for the sake of keeping it as original as possible I’m going to keep it positive ground. 
 This thing does have speakers in it it that I think went to a cb, I don’t think it had a radio. But I’ll cross that bridge later.

Don’t bother I’ve been running CB since 1976 there’s nobody on it now… bob

[mowerman]

That’s only if you were considering it????? Lol

[mowerman]

On 5/4/2023 at 5:30 AM, doubleclutchinweasel said:

They are actually fairly easy to work on.  Very well designed beasts.

The biggest issue I saw when one was changed to negative ground was that some of the gauges would not work correctly.  For instance, I had to change the volt meter on mine, because it was not possible to reverse the gauge (single wire, ground through case).  Had to get a 2-terminal gauge so I could connect the wires to the terminals with the correct polarity.  Also, I think the fuel gauges did not like being reversed.  But, I am fuzzy on that one.  Light bulbs do not care.

Nothin at all wrong with positive ground.  Just have to isolate any add-ons that you have (like radios or phone chargers).

After all that I am thinking of doing the same thing going to 12 V negative ground thanks for all that. Bob

[mowerman]

What about the heater? I doubt I’ll be ever using it anyway or the electric horn steering wheel???? Bob

[mowerman]

I switched an old Chevy pick up years ago from 6 to 12 V I really don’t even really remember how I did it or hooked it up it was also 40 years ago ha ha

[mowerman]

Sorry, didn’t mean to squash your tread. I should’ve put that somewhere else.

[Robo987]

On 5/6/2023 at 7:49 AM, mowerman said:

I’m planning on doing same thing eventually all in good time … I wouldn’t be surprised if some of them ,, Air and fuel lines were original… been starting it every Saturday… starts rite up ,, otherwise I have to blow air into the fuel tank because it looses prime if it sits too long… Bob

I need to change fuel filters and put fresh fuel in mine. It runs but it’s not super happy about it.