Straight 450 frame repair. Any experience/ideas?

[Jim S.]

I am trying to resurrect a 450 loader. Got the engine running and was about to install it but discovered the left side main frame channel is broken where the frame flange bolts to the transmission case.

Background: a previous owner rode this machine hard and there are lots of ham-fisted repairs. For example, the main front load bearing cast iron frame member was welded to both the track frame and the side frames. Not surprisingly, the welds have broken, allowing the entire frame structure to twist. The large grade 8 bolts which attach the side frame channel to the bell housing have also broken.

The first major challenge is to repair the broken weld which attaches the flange to the rear of the side frame channel. I can do the welding easily, but ensuring alignment with the bell housing bolts is the challenge. Deere originally welded the flange to the channel and then milled the face of the flange that bolts to the transmission. Clearly was to ensure a perfectly flat face and provide proper alignment with the spacer which attaches the front of the frame to the bell housing.

My plan is to tack weld the frame channel to the flange in-situ while the spacers align the front of the channel to the bell housing. My concern is that the heat and stresses from welding will slightly modify the correct alignment achieved when tacking it up.

Any better or other ideas?

The photos better show the problem. The first shows the broken weld between the frame channel and the flange. Previous repair attempt is visible. Second photo shows where the frame was welded to the cross-bar casting. Third shows the broken bolts that attach the channel/bracket to the bell housing. Other two photos show other previous "repair" attempts. The term ham-fisted is being kind, IMO.

Jim

[jtrichard]

Never heard that one "ham-fisted" had to look it up .....Define ham–fisted: awkward or clumsy. ... awkward, butterfingered, cack-handed [British], graceless, ham-fisted, ham-handed, handless, heavy-handed,

[DBaker98]

My clutch disintegrated so had to remove the engine. Then discovered both my rails were broke. Removing the engine and rails I found several broke bolts. Puddle welded sacrificial nuts to the broke studs and were able to remove them. So far holding up good [/img]

[Jim S.]

DBaker,
Did your frame rails break, like mine shown above, or were the cap screws that attach the frame/flange to the transmission just broken?

If the frame broke, how did you accomplish alignment when welding back up?
Thanks,
Jim

[jtrichard]

HI From you other post "I also found the two large special grade 8 bolts which attach the frame channel to the left side of the bell housing were broken. Since the counter bore in the bell housing and the frame channel bracket were wallowed out, Im having to make new bolts oversize and reaming both bores to fit. These are dowel like in function and have to be fully torqued to prevent movement and loosening."

Since you are making NEW bolts for the bell housing I would look into making the thread portion the next size bigger also... It is very common that they break and any other bolts you can up size I WOULD.... JD is know for using to small of bolts on some of there older machines

[Jim S.]

jt,
Thank you for the good suggestion. I have considered increasing the thread size in the bell housing but currently do not plan to.

1. Drilling and tapping it out to the next size (7/8") by hand will be iffy, in my experience. The threaded length is 2" + and if the hole and tap are not in near-precise alignment, I would risk tap breakage, I think.

2. I believe that I have found the cause of breakage. PO installed the bracket backwards which mates to the bell housing with the special cap screws and then connects to the bottom of the channel. The bore in the bracket is stepped, as are the two ground-smooth shanks on the special cap screw. Being backward allowed about .030" play between the bore and pin when it should have been a light slip fit. I believe the assembly was also not torqued adequately which allowed the cap screw to bend and quickly break.

3. Once the cap screws let go, the bending force on the flange at the rear of the channel would have been enormous, which let to its failure.

4. My repair will involve replacing the grade 8 special cap screw with one made to L9 specs, 180Ksi strength. To ensure I dont strip out the threads in the bell housing, I will increase the thread length to a full 1 3/4" vs the 1" on the OEM.

5. Using a higher strength fastener and fully torquing should provide assurance that the cap screw will not slip and back out. Tightening torque should be 300 + lb-ft, which I will have a challenge meeting.

Does anyone know whether this is a common failure area on 450s?

And, BTW, ham-fisted is a kind way of describing the abuse inflicted on this machine by a PO. Fortunately, I will be the only operator of this and it is for use on my property. I doubt I will put more than 10 hours a year on it. I can treat it kindly, if needed.

Thanks,
Jim

[jtrichard]

YES many posts about the frame rails and some with the same bell bolts broken http://www.jdcrawlers.com/messageboard/ ... ight=bolts
and
http://www.jdcrawlers.com/messageboard/ ... ight=bolts

[Jim S.]

jtrichard,
Thank you for the links. I am now rethinking whether to drill and tap bell housing for 7/8". Fortunately the engine is out so I have decent access to everything.

Regards,
Jim

[Jack-the-Ripper]

jim

it seems you have a pretty good handle on the forces and stresses involved

I left a welding note on your other post

My thought - after you tack in place, preheat with a rosebud where you will weld in depth, then heat all your finished welding again with the torch to release any stress and maybe even allow the parts to flow back into alignment a little bit

btw leaving all punctuation marks out per stand suggestion is allowing me to post with no problems