I am looking for a cat for my acreage and there is a D7F for sale that is local to me The fellow that owns it told me it’s a Japanese machine. Serial number 92E1533 I am aware of the transmission problems in the earlier D7F’s. I am curious if this machine came with the better transmission or the older D7E transmission. What should I look for when I go look at the cat in person?
You will need to lift up the floor plate in the cab. If it has the transmission derived from the D7E it will fill the space between the frame rails almost entirely. If it is the later transmission derived from the D6 you will almost be able to have a dance in the space around it. 92E is a Japanese-built tractor equivalent to a US-built 94N-prefix tractor. From the information I have all 92E tractors up to around S/N 1750 were fitted with the D7E-derived transmission.
Perfect thank you, that is extremely helpful
D333 engine as well. 92E1752 up is the changeover S/N to the 2P transmission arrangement.
Is the D333 something to stay away from? I mean I am expecting to do some work as it is a 50 year old machine. The undercarriage is in excellent condition which makes this dozer priced right for me
We’ve had this discussion before. If you are not working the machine hard 60-70 hours a week like a contractor would then IMHO the D333 engine/D7E transmission combination should work just fine. Yes the 3306 engine and the new-style transmission were an improvement but that does not make the previous setup something to shy away from.
I agree with the fact that the OP is not going to be hard on it, but who knows what the previous owner has done with it. FWD
I agree. A complete unknown. The only two things I am taking into consideration are the OP’s comments “I mean I am expecting to do some work as it is a 50 year old machine” and “The undercarriage is in excellent condition which makes this dozer priced right for me.” Most dozers the age of this one usually have the undercarriage hanging in tatters……..
What I find straight up bizarre is the magnitude of questions about the D7F and the lack of questions about the D7G, when the F series was only made for a handful of years. Surely there must be heaps more G's for sale then F's? Just by weight of manufactured units alone.
There have been tons of D7G for sale in alberta this spring and summer.... I found it funny...seems everyone here decided to sell them this year.
I suspect it is all down to the somewhat "chequered history" in people's minds regarding the D7F. All the talk about early/late transmissions plus the upgrade from the D333C to the 3306 with precups then a 3306 with direct injection has people asking all sorts of questions. Sometimes it appears that the only definitive information in respect of all those differences is here on this forum. In comparison all the various iterations of D7G/D7G Series II were pretty much the same from the time the model was first introduced until the time it was discontinued for the first of the high-drives. For example the same 9P-5382 Transmission Arrgt was used in every D7G tractor built.
You should see a tag on the transmission that looks like one in the pic I attached. I have a D7F with the "old" transmission. Sounds like the "new" transmission will start with a 2P. My guess is that most of the regular D7G's have been retired whereas a lot of the D7F's (the military ones) went through rebuilds, sat unused for decades, then hit the auctions as low hour machines in the past decade after units starting turning in old equipment from the wars. And there's been quite the number of ex-military D7F's at auction in the past few years. I assume that's generating all the questions
Only military 61G-prefix machines use the 5R-0862 Transmission Arrgt. A low S/N 94N with the "early" D7E-derived transmission will be a 9S-5250 Arrgt. A high S/N 94N with the "late" D6C-derived transmission will be a 2P-3670 Arrgt. To go from a 5R-0862 to a 9S-5250 involves a change of Planetary Transmission Group and a different Hyd Control Valve. There are significant differences in both of those components but I have no idea for the reason behind that.
I think the D7G were regarded as one of the best Cat dozers ever made and thus were a lot less problematic. Cat may have realized they missed the mark with the latter D7F models.
Nige- Your observation of differences in the planetary from the 5R to the 9S transmission makes me wonder if there is a deliberate difference in gear ratios across the drive system? Maybe the military realized the weakness of the 9S and requested better ratios that level the stress better across components in the older transmission system? I'm just completely guessing as I assume the rpms of the D333 and 3306 are fairly close in this application.
Don’t credit the military with that much intelligence…… Let’s face it they hung on to their D7Fs far too long in the first place and then piled insult on injury by refurbing them so that when they finally came on the market they were 30+ year-old technology. The only people who got anything out of it were those like you who managed to buy at the right price.
Haha- maybe so but it's also quite possible that Cat offered an improved gear solution since they originally sold a "weak" design to the military. I can easily see the military scrapping it's entire fleet of D7F's to be replaced by JD's because of an abnormally high transmission failure rate. Cat knows this is quite possible and thus offered a solution through SLEP that improved the reliability while also keeping acquisition costs low for the military. I don't know of a larger "fleet" of heavy equipment owned by one owner than the fleets in the military so there is substantial influence on the Cats, JDs, Boeings, AMGs, etc. to offer unique solutions. Again, I'm only guessing and have no factual information to back any of this up. Maybe it's just the optimist in me thinking the military did a few things right.
Did the SLEP program actually address the inherent design issues with the transmission.? I wasn’t aware that it did.
I have no idea if it the SLEP program addressed transmission design issues or not. I'm only speculating that the SLEP program probably wouldn't stuff different gears into the transmission unless there was some sort of upgrade or fix. Probably the only way to tell is compare the differences part by part and see if there is a change in tooth ratios.
We did quite a few of those Cat would send all the parts. I can’t remember much for transmission other than bearings seals and discs
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.
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.
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
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
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.
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.
Didn't they retrofit a modulation valve as part of SLEP? That was part of the problem with the transmission. No modulation valve.
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
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.
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
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.
Thanks for bringing a sense of sanity back to the thread Merv.......