JD 450C Engine Frame Rail Replacement

[Powderhorn Jim]

I have a JD 450C dozer with a right side cracked engine frame rail. We've tried gusseting and welding it, but the piece that actually bolts to the transmission is cracked horizontally so the welds break at the top, down to the crack in that piece.

Bottom line, the frame needs to be replaced. We have a ranch and I do a lot of work on farm equipment. I've found that it is a lot easier once you've done a repair than starting out blind. John Deere's tech manual on this machine pretty much glosses over how to approach replacing this part.

I'm sure more than one of you have replaced the frame rail, particularly the right side as it sounds like that is a weak point in the 450 dozers. Advise would be helpful. A step-by-step sequence would be extremely welcome.

[JWB Contracting]

We just did the same repair on a 350 dozer.

Best bet is to remove the hardnose, fenders, hydraulic tank. It is really difficult to remove the frame rail if the dozer or loader is left on, but it is possible. Also, unbolt the frame rail on both sides of the track frames (from the sides and bottom). Loosen the cap bolts on the rear crossmember on both sides (large round bar) and then jack up underneath the tramission. This should rotate the machine away from the undercarriage. You need a little bit of separation as the frame rail needs to come out forward aways before you can wiggle it out. You will need some long extensions and a swivel socket.

You will need to determine what the extent of the damage is. If the mounting points in the transmission case are dammaged you are in for a complete disasembly. May need to drill and rethread to a larger size. Problem is if you don't have all the bolts in place and tight, you will keep running into the same situation. Usually if 1 bolt breaks the other are not far behind. On machines that we work, we only use new high grade bolts of maximum length and also weld a bar accross the bolt heads so that can come undone. Usually not a lot of cash cost just an incredible amount of labour.

Best to buy the JD technical manual, cheap on EBAY and do some reading.

[Powderhorn Jim]

Thanks. That is pretty much what I thought I'd need to do but with a job like this, one always hopes that someone has discovered an easier way. On my dozer all the bolts are intact. The faceplate of the frame rail is cracked through behind the brake band adjusting bolt. It is likely that the dozer fell off a truck (or rocks, whatever) onto its right side as there are other signs of damage, all of which was successfully repaired except the frame rail.

The first thing I buy for all my equipment is the tech manual. In this case JD has a very short reference to this part.

Thanks for the information.