D7F serial number

[LCA078]

Wow- first hand experience! Do you remember if the dozers were torn down to the frame and all new bearings/seals/etc. were installed in all major components? There's lots of speculation of what SLEP really entailed so insight from someone who actually turned a wrench on 'em would be great.

 

[Nige]

To the best of my knowledge the D7F SLEP program was no different to a Cat Certified Rebuild (CCR). just dressed up in a different suit of clothes for the military so they would think they were getting “special treatment”. It was all done under the auspices of Cat Defense Solutions. From what I know the only major iron change (if it hadn’t been done already on a specific tractor) was the replacement of the D333C engine with a direct-injection 3306.

 

[pittsburgh cat man]

Cat determined what was to be done on each tractor like I said they sent parts and military manuals with what was to de done to that specific tractor I don’t remember a lot of undercarriage work they all seemed to have very good track and rollers the thing I got a kick out of was they would tell you to replace the wiring harness and they would just send you a roll of wire I think they did rebearing and reseal engine torque tran clutch’s and finals and a paint job be aware though some things on them are not the same as a regular tractor batteries and wiring comes to mind

 

[pittsburgh cat man]

Cat Certified Rebuild was a lot differant when you tore a certified down you had a empty bay frame went to sand blaster major parts went to componet shops updates were done on every thing they even got a new serial number where as the milatary rebuilds weren't that involved like i said very little work on under carrage I do remember changing rad cores

 

[LCA078]

Interesting differences between the CCR and SLEP efforts. I personally know that the military uses terms like repair, rebuild, refurbish, reset, and many others to describe "fixing" equipment to a higher state of mechanical wellness. While I've seen written definitions of all these terms used to try to differentiate the levels of improvement, I've also seen so many different realities of what really happened to the military equipment that I just don't trust the definitions anymore. In other words, unless you have the signed-off work orders for that particular piece of equipment, there's no guarantee of what "fixing" was actually done to it.

@pittsburgh cat man Thanks for sharing your first hand knowledge as it helps improve all our knowledge in this area.

 

[Nige]

Having been involved with quite a few CCRs I was under the impression that a CCR and a SLEP were civilian and military versions of the same thing. Obviously not the case from what @pittsburgh cat man posted. Seems like the SLEP is more like a few parts here & there and a new coat of paint to justify all the taxpayers’ dollars that were thrown at a machine.

 

[.RC.]

Didn't they retrofit a modulation valve as part of SLEP? That was part of the problem with the transmission. No modulation valve.

 

[pittsburgh cat man]

I'm not sure what you are calling a modulation valve. Nothing pops up in my head but I'm old it's been know to take up to 3 weeks for it to come to me

 

[.RC.]

The modulation valves slowly raise the clutch pack (why do they call them clutches when they are actually brakes?) pressure to make smooth engagement of the transmission.

Really early powershift transmissions did not have it and they clutch packs just slammed together. Probably was not an issue on the D7E with it's big slow motor.

 

[D6 Merv]

They all had modulation valves; ie speed clutch engaged before direction clutch. It was just the way is was done that was different. D9G, D8H D7E early D7F used the same basic layout of transmission hydraulic controls. D6C used a different layout with a presssure valve setup with a sequence relief valve.
When the D7F went to the 2P design transmission it used this D6C style pressure control system.
Consequently all the transmission hydraulic control systems are different between early and late D7F
If you study the transmission pressure testing and adjusting diagrams you can see how they are different

 

[D6 Merv]

The testing and adjusting diagrams also give you serial numbers where transmission changes happened; ie mid range D6C with trans oil water cooled, and later ones added a air to oil cooler as well to the layout.
Later D7F were a perfectly good tractor; but the bad reputation had stuck.
Cats next generation of machines the D9H, D8K and D7G all came out around 1974 with integrated clutch and brake steering controls aand pilot operated implement hydraulics.
D7G was a nice machine, and i cerrtainly would have liked one; but ended up with D6D which have done most of the work i needed.

 

[Nige]

Thanks for bringing a sense of sanity back to the thread Merv.......