D4 vs. D4d

Like most Caterpillar machines there are updates all through the model run, serial #'s tell the story. There were many updates to both D4D and D47U tractors, later D4D's had heavier final drives & more horse power and were relatively trouble free. You have some homework to do to make fair comparisons.

Wombat is correct, the D4D is a fine machine, fixing some of the issues found with the 7U, eg., weak rear end castings that almost always cracked especially if a winch was fitted. At one time I had three casings each of which was totally ruined due to cracks. It took me over a year to find one that was not cracked to replace mine.

Sure you are not thinking if the D4C wrt the engine?

I know three people with D4Ds and they have had really good runs from them all, even when subjected to very heavy workloads, eg., logging. In one case the bull gears wore out (same as in the 7U) but that's all, other than normal track wear.

The D is a much easier machine to operate a that a 7U, especially with power shift and electric start. Track adjustment is easier too with hydraulic adjustment rather than threads and nuts that always seize up.

The Ds do have a tendency to spread their legs tho. Something that can be fixed with a slide arrangement like the Inters had. If this happens they will crack the dead shaft which is a real PIA to replace.

Did the 7u crack even with just a drawbar.

I don't think any of them could be tore up on drawbar use only. What s/n D4D are you looking at? If I was looking I'd want a s/n beyond the D330A engine (D330C or 3304). One of the key items to check is the frame rail bolting to the steering clutch case. Rough service units are known to crack at this location. All of them have their good and bad points. No such thing as a perfect tractor.

Did the 7u crack even with just a drawbar.

I am using a 1949 D4 7U once in a while for excavating and pushing after repairs to the blade and hydraulic rams. It is what I have, runs good, and seems to have plenty of power. The main problems are keeping batteries charged for the electric starting system, sticking steering clutches, and grabbing brakes (the clutches and brakes seem to work better after some use). However, it could use more weight. The tracks are in good shape, but will spin when trying to push the blade into hard, dry ground or when trying to move rocks. Neither of these were a problem when using a larger machine, and may be caused by my own operator errors or expectations. My father got the D4 to pull a home-made brush crusher. Then the tractor turned out to be too light to control the crusher on hills. I think the lesson here is to make sure the whole machine can do the job.

JRMunn

Can someone give me info on this d4. It is the one that needs a engine. I'm wondering if it was made in Mexico. I'm also woundering if it is the faster or slower 1st gear.

None of the D4 "U" models were made in Mexico. That just happens to be where the trade mark is registered.
4H9275 transmission group has the standard 1.9 mph 1'st gear (high speed). Later s/n D4's improved items for the better but that tends to make them a little less common as far as parts interchange with earlier models.

I tend to look at the 78A's as experimental for the "D" series. Lots of changes and upgrades through the series as was typical for all manufacturers through the 60's.

Magnet can you tell what engine series the d4d has. 78a2376