can anyone tell me what size the socket needs to be to adj the tracks on a 1937 rd4... it has a very large nut and a very large spring that need to be adj to keep the tracks on .. i think i'll need shims... thanks Doug

My Cat tool catalog says to use a 9F3869 wrench 2-3/4" size for the D4 and R4. I'd still check before purchase.

"Old wrote:

My Cat tool catalog says to use a 9F3869 wrench 2-3/4" size for the D4 and R4. I'd still check before purchase.

so good to hear from you again, old mag, you guys are amazing, thank you. I did take a reading on the nut from flat to flat, and it's big. i have heat and it's clean now after three days of power washing.... by the way the info i got last year when i ran it out of diesel was just the ticket... my air tank gauge was faulty so i had no air and didn't know it.... ouch... works great w/ a little air and like you said not too much and off we went... geez I love these old cats.... take care buddy ,,, i try to let you know how it works...thanks Doug

oh my ,,, just went to the cat tools page.... the wrench retails for over 750 dollars... yikes... sure glad my friend has one... there is one avail on ebay for a cool hundred.. this should be fun...

Buy an open end wrench at Harbor Freight, then cut the head and reweld at the angle you need or like!

If it's a before s/n 4G8790 a socket might work. Does look like there might not be enough clearance ahead of the sprocket though.

I tend to put an end on my wrenches for this kind of tightening that will accommodate a decent cheater bar - invariably these nuts tend to be stubborn if they have not been visited in a while and need some persuasion.

Mcmaster carr has them. www.mcmaster.com/wrenches/open-end-wrenc...pen-end-wrenches-11/

Some real ebay bargains on 2-3/4" slugging wrenches if your working with the early undercarriage. Again check sprocket clearance.