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Cat D7F Feedback/Advise

ja_cain

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Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
So, decided to start a separate thread for this D7F since I decided to pass on the D6C I looked at last Friday. This one is also in WV but a little further south, so not as much of a commitment to drive there.

Looks to be a former military machine, obviously. Seller has a winch on another D7 that he would be willing to sell too. He says it has the DI 3066 and I've heard that it is pretty common for the military to swap out/upgrade these dozers while in their possession to include going through their complete frame up rebuild process around 96. I have requested a video of the dozer operating and hope to get one soon and share it here. My biggest is concern, based on reading older threads, is the older 7E transmission that these military machines came with. Hopefully I can figure out a way to verify which one is actually in the machine before I commit to going up there. Hopefully it went through the rebuild process and got the newer D6C type transmission.
 

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ja_cain

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Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
More pictures
 

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Vetech63

Senior Member
Joined
Aug 10, 2016
Messages
7,120
Location
Oklahoma
I've seen a few military machines in my life. The biggest issues I ever found was the fact that a lot of them can sit in storage..........for years. Usually mechanically sound but leaks were profound on most of them. I rebuilt a gen plant engine years ago for the local Air National Guard.........an Allis 3500MK II. It had sat in storage for so long that when they fired it up.........it leaked oil from literally every gasket. All I had to do was re-gasket the entire engine.
 

OzDozer

Senior Member
Joined
Jan 18, 2007
Messages
2,262
Location
Perth, Western Australia.
Occupation
Semi-Retired ..
All the military D7F's went through what was called "SLEP" - Service Life Extension Program, in the early 2000's.
The tractors essentially got stripped to the last nut and bolt and rebuilt with all new bearings and seals, plus any other parts/components that showed wear were replaced.

All the D7F's that went through the SLEP program were retrofitted with later model 3306 engines, with later type fuel injection systems and other additions - and they were boosted to 200HP. In effect, they all got D7G engines. The SLEP engine ID is described in the photo below.

NO military D7F's got the later model, upgraded (2P prefix) transmission that is fitted to the D6C.
The reason being it is virtually impossible to change the transmission from the early type to the later type without incurring massive costs.
There were so many engineering changes between the two transmissions, I'd need more room than one posting to catalogue them all.

Large amounts of piping and hoses were changed. The reduction gear on the rear of the transmission was changed, because the later 2P transmission spins at much high rotational speeds than the early transmission. The driveshaft between torque converter and transmission was different. The transmission gear selector controls were different. It goes on and on. It's been over 30 years since I last worked on D7F's, and 51 years since I first worked on them, so my memory is fuzzy on many fine details.

One day, I'll try to find the Product Release bulletin on the changes, but I need some time to search through my Cat microfiches.

The early style transmission also went numerous upgrades, and the military tractors would have all of them. One of the upgrades was the fitment of a modulating valve in the transmission control valve body, which reduced transmission clutch pressure momentarily between gear changes, to smooth out transmission gear change jerkiness.

These early transmissions work just fine if you don't want to do full time, heavy duty dozing and ripping, or working on rock - and modern oils have also improved greatly in the last 25-30 years, with better additives and better lubrication.
We used to use engine oils in the Cat transmissions in the 70's and 80's, which was Cat's recommendation at that time.
Nowadays, Cat recommend specific transmission oils which provide longer transmission life, and less transmission problems overall.

The only information available for the 61G Ser. # prefix is that all the 61G military tractors fall into the equivalent civilian tractor range between 94N1 - 94N5191 - which are all fitted with the early-type transmission.

screenshot-of-slep-png.288553



1704891897568.png
 
Last edited:

Nige

Senior Member
Joined
Jun 22, 2011
Messages
33,165
Location
G..G..G..Granville.........!! Fetch your cloth.
As I pointed out in your other thread……

“Don’t let the fact that a particular D7F doesn’t have all the latest bells & whistles put you off. Even the early ones weren’t bad tractors, just that the later ones were a bit better - but remember that was in a contractor production environment working Lord knows how many hours/day 6 or 7 days a week. You’re not exactly planning to do that I would imagine….”
 

ja_cain

Well-Known Member
Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
I've seen a few military machines in my life. The biggest issues I ever found was the fact that a lot of them can sit in storage..........for years. Usually mechanically sound but leaks were profound on most of them. I rebuilt a gen plant engine years ago for the local Air National Guard.........an Allis 3500MK II. It had sat in storage for so long that when they fired it up.........it leaked oil from literally every gasket. All I had to do was re-gasket the entire engine.
Thanks for the info and this confirms what I've been seeing in my own research on these military machines. Will definitely check it over real good for leaks before and after I operate it.
 

ja_cain

Well-Known Member
Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
All the military D7F's went through what was called "SLEP" - Service Life Extension Program, in the early 2000's.
The tractors essentially got stripped to the last nut and bolt and rebuilt with all new bearings and seals, plus any other parts/components that showed wear were replaced.

All the D7F's that went through the SLEP program were retrofitted with later model 3306 engines, with later type fuel injection systems and other additions - and they were boosted to 200HP. In effect, they all got D7G engines. The SLEP engine ID is described in the photo below.

NO military D7F's got the later model, upgraded (2P prefix) transmission that is fitted to the D6C.
The reason being it is virtually impossible to change the transmission from the early type to the later type without incurring massive costs.
There were so many engineering changes between the two transmissions, I'd need more room than one posting to catalogue them all.

Large amounts of piping and hoses were changed. The reduction gear on the rear of the transmission was changed, because the later 2P transmission spins at much high rotational speeds than the early transmission. The driveshaft between torque converter and transmission was different. The transmission gear selector controls were different. It goes on and on. It's been over 30 years since I last worked on D7F's, and 51 years since I first worked on them, so my memory is fuzzy on many fine details.

One day, I'll try to find the Product Release bulletin on the changes, but I need some time to search through my Cat microfiches.

The early style transmission also went numerous upgrades, and the military tractors would have all of them. One of the upgrades was the fitment of a modulating valve in the transmission control valve body, which reduced transmission clutch pressure momentarily between gear changes, to smooth out transmission gear change jerkiness.

These early transmissions work just fine if you don't want to do full time, heavy duty dozing and ripping, or working on rock - and modern oils have also improved greatly in the last 25-30 years, with better additives and better lubrication.
We used to use engine oils in the Cat transmissions in the 70's and 80's, which was Cat's recommendation at that time.
Nowadays, Cat recommend specific transmission oils which provide longer transmission life, and less transmission problems overall.

The only information available for the 61G Ser. # prefix is that all the 61G military tractors fall into the equivalent civilian tractor range between 94N1 - 94N5191 - which are all fitted with the early-type transmission.

screenshot-of-slep-png.288553



View attachment 302693
Excellent info and really appreciate you sharing it. That's great they implemented the modulating valve too.
 

ja_cain

Well-Known Member
Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
As I pointed out in your other thread……

“Don’t let the fact that a particular D7F doesn’t have all the latest bells & whistles put you off. Even the early ones weren’t bad tractors, just that the later ones were a bit better - but remember that was in a contractor production environment working Lord knows how many hours/day 6 or 7 days a week. You’re not exactly planning to do that I would imagine….”
Thanks Nige! Feeling much better about the dozer after you and OzDozer weighing in, as long as everything is sound.
 

ja_cain

Well-Known Member
Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
Based on the dozers current configuration, should anyone know what the estimated weight might be? Would possibly pick up a winch from him too if he doesn't want an arm and a leg for it.
 

OzDozer

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Joined
Jan 18, 2007
Messages
2,262
Location
Perth, Western Australia.
Occupation
Semi-Retired ..
All military construction machines are normally fitted with a prominent information plate with their dimensions and shipping weight listed on it.
They also have lifting eye attachments at the four corners of the tractor, to facilitate movement onto ships.

In the link below is a military 61G series fitted with a ripper, that sold at auction. The military info plate says it weighs 54800lbs (GVW). You can open the photos in a new window and click on them to get them full-size.

The ripper reportedly weighs 6100lbs, so that would make the tractor you're looking at run to about 48,700lbs.

 

ja_cain

Well-Known Member
Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
All military construction machines are normally fitted with a prominent information plate with their dimensions and shipping weight listed on it.
They also have lifting eye attachments at the four corners of the tractor, to facilitate movement onto ships.

In the link below is a military 61G series fitted with a ripper, that sold at auction. The military info plate says it weighs 54800lbs (GVW). You can open the photos in a new window and click on them to get them full-size.

The ripper reportedly weighs 6100lbs, so that would make the tractor you're looking at run to about 48,700lbs.

You are the man OzDozer. Really appreciate all the info you Nige and the others have shared with me.
 

D5Dan

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Joined
Sep 29, 2021
Messages
129
Location
Oxford, Maine
Here's a BEAUTYYYY I saw in the truck stop on its way to who-knows-where...

For a 2012 model it looked like it had pushed NOTHINGGGGGG - just look at the face of the blade alone. Damn cutting edge was stout and the track pads/grousers were mint

Thought it was cool they flipped the blade corners up to gain the c-hairs they needed to roll down the highway...although there was no rig/tractor attached to the trailer!?!?

Anyway, to OzDozers point, if you look at the tag on this one it tells weight, and of coarse the tie-down points are obvious. I wish I could have asked the number of hours on the machine; 200?? 400? Just out of storage/reserve with ZERO?!!
 

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ja_cain

Well-Known Member
Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
Here's a BEAUTYYYY I saw in the truck stop on its way to who-knows-where...

For a 2012 model it looked like it had pushed NOTHINGGGGGG - just look at the face of the blade alone. Damn cutting edge was stout and the track pads/grousers were mint

Thought it was cool they flipped the blade corners up to gain the c-hairs they needed to roll down the highway...although there was no rig/tractor attached to the trailer!?!?

Anyway, to OzDozers point, if you look at the tag on this one it tells weight, and of coarse the tie-down points are obvious. I wish I could have asked the number of hours on the machine; 200?? 400? Just out of storage/reserve with ZERO?!!
That's crazy!
 

ja_cain

Well-Known Member
Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
More info. Seller said he bought it around 6 months ago at a government auction. So, it most likely went through the SLEP program. He had to replace the radiator. Pretty sure the military models came with a steel unit.
 

OzDozer

Senior Member
Joined
Jan 18, 2007
Messages
2,262
Location
Perth, Western Australia.
Occupation
Semi-Retired ..
Yes, the military has a staggering amount of equipment just sitting around with zero to little use.
The sad part is no-one really looks after it, it's often just left to rot for years, then sold off.

I can recall seeing a big military JD wheel loader on offer from DRMO about 15 years ago. It had done around 300 hrs, had been stored in the open for maybe 15 years, and all the tyres were dead flat, and had been that way for years, and all the tyres were totally shot!

What a waste, you'd think that they could've at least arranged for someone to keep the tyres inflated, keep the tyres covered, and run it up every few months!
 

ja_cain

Well-Known Member
Joined
Sep 8, 2023
Messages
100
Location
Chesterfield, VA
Yes, the military has a staggering amount of equipment just sitting around with zero to little use.
The sad part is no-one really looks after it, it's often just left to rot for years, then sold off.

I can recall seeing a big military JD wheel loader on offer from DRMO about 15 years ago. It had done around 300 hrs, had been stored in the open for maybe 15 years, and all the tyres were dead flat, and had been that way for years, and all the tyres were totally shot!

What a waste, you'd think that they could've at least arranged for someone to keep the tyres inflated, keep the tyres covered, and run it up every few months!
I was in the USMC from 96 to 01. Did two deployments with the 24th MEU attached qith MSSG 24 Maint Platoon. We still deployed with hummers with ricochet holes in the undercarriage from the first Gulf War. I don't remember seeing a whole lot of heavy equipment like that just sitting around at camp Lejeune. Otoh, it wouldn't surprise me with larger organizations like the Army, Navy or Airforce.

It kills me knowing that there is so much waste in these large military organizations. I think there should be a program where veterans get first dibs on bidding for this equipment. The least the government could do for folks that sacrifice for their country.

The good old days. Semper Fi
 

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