Hi, Josh.
Quick 'kwesrtyun': will the traxcavator idlers swap over to the recipient machine's idler mounts?

A kew-ree-yuus mind would like to know - maybe several of 'em.

Just my 0.02.

I don't know.
You might be able to do that with the addition of a couple spacers, but one would need to see all the parts side by side to see what fits and if the shafts are the same, there is mention of adapting one of the big idler groups with the addition of 4H2020 arm, but that is not one of the idler groups used on the loaders.
There were lots of different of options and changes over the years on the D4 and loader parts,
putting on a big idler transfers a lot of load onto the front of the track frame, and for at least most of the U series, it calls for heavy duty track frames to be used with big idlers.

Hi, Josh.
Thank you, Sir. I did not know that there was heavy duty track frame used with the big idlers. Many people seem to have the idea that the big and small ones are interchangeable with the removal or addition of one track link.

Just my 0.02.

Ok thanks for all the information. My machine is very early 7u loader. I don't know if it is big or small idler. I will check.

Hi, Jimmy 977.
I could be wrong - I dimly remember it happening once - LOL - but I think the loaders all came standard with the big idlers - helped to make them more stable fore-n-aft with a full bucket.

Just my 0.02.

I took some quick measurements on my 2 machines and the loader track frames are longer by about 7 inches.Center of axle to center of axle is about 4 inches longer.My 7u dozer has the big front idler and it looks like the loader idler is close to the same dimensions.I don't have a 7u book specific to the traxcavator so I can't cross part numbers but it would definitely not be a simple swap.As has been said I don't think you would gain anything from the longer frames or the hard bar on a dozer or ag tractor

Hi, d2gary.
You would definitely gain some stability on a dozer with a 5-roller track frame and a big idler and even with a big idler on a 4-roller track frame. That said though, the big idler would not be as much of a blessing on an ag tractor although the 5-roller track frame may well make it a smoother ride.

Again, I don't KNOW but I think the oil pans are the same for the 4-roller and 5-roller tractors with equalizer springs but different for the loader hard bar units. That said though, I would not think it would be all that hard to cut the hard bar mounts off and fabricate the spring mountings on the loader track frames if one was serious about doing the swap.

just my 0.02.

I have a 1957 977, hardbar is bolted on. The D4 loader is 1947, I'm not sure if it is welded or bolted. I will look when I get a chance.

Hi, Jimmy977.
I think it would be a pretty safe bet that it is bolted - - - - unless someone has done a 'butchershop' repair on it at some time.

just my 0.02.

I found an equalizer bar in the service manual for D4 ... 6U and 7U
I uploaded the Caterpillar Service Manual for models D4  4G, 2T, 7J, 5T, 6U, 7U to the library