With your tranny popping out of gear is the sheetmetal cover hitting the tranny shifter when the frame flexes? I really don't see any other way for the tranny to pop out of gear unless you have a tranny problem too. I don't think the castiron tranny case can flex at all. I'm thinking the driveshaft may bend causing the bending going into the tranny making it pop out of gear? I can't think of any other way it can happen.
Here are some of my thoughts,we need to figure out the root causes of the problems with the frame first before we redesign it to strengthen it. I'm talking setting up the frame for the FEL/backhoe. Not just fixing the rear part which is ok if your not adding the fel/backhoe and more weight.
I have a feeling my first int154 has a cracked rear section on the frame too.(maybe) When i put it in a off camber position while plowing dirt the frame seems to twist and i hear the fan hit the fan shroud. I inspected all 4 points of the engine mounts and it appears to be solid with no seperations or cracks. I have a few extra 154 fan assemblies too and on everyone I can see grooves were the fan has worn into the fan shroud. Or the frame is subject to a lot of normal twisting action the way its designed. We must remember something has got to give or flex in the structure or it will break. I think the two larger bolts with the spacers on the front of the tranny is actually holding the frame together when the back section cracks from twist. The front of the frame acts like a lever and hinges on the large bolt with the spacer so the smaller section in the rear cracks and seperates when the frame twists.
I have also heard from other int154 owners with FEL's the front axle is prone to split in half. This raises another thought is the front axle running out of room when the axle swings/ or arc's up and actually bottoms out on the frame and causing it to split in the middle?
Ok we need to design a subframe from the front to the rear. At the sametime we must make a note in our minds about watching the front axle swing and bottoming out so we don't split the front axle on uneven hilly ground. Even by adding a stronger structural steel axle we will only put the twisting forces in another place and cause more problems down the road. Since i'm adding larger tires on my 154 it will make me remove the front axle bracket and lower it a channel box to make the tractor still sit level. At the sametime the front spindles need to be addressed too so there stronger too. Power steering too.....
Off the top of my head thinking;
I wouldn't box the frame yet, i would add a 1/4" or 5/16" thick vertical plate to the front part of the frame making it a double wall frame. From the front to were the frame bends to go narrow. This can be bolted using grade 8 bolts and tac welds like i explained before by putting heavy beads about 1" long and 1" to 2" apart on the top and bottom of the frame. Using this method nothing can seperate or bow because the bolts are holding the middle section too.
With the very last part of the rear frame i would do the same by adding a vertical plate too.
If you have a 3pt hitch you will need to connect the plate to it.
Then we need to connect the front plate to the rear plate but keeping in mind the mid rocker shaft if you still plan on using it for mowing. On the rear upper section i was thinking of using a thicker larger angle that would strengthen the horizontal and radial twist too for the backhoe frame. Since i'm not using it for mowing i'm going to add a cross beam under the FEL uprites to connect the right and left plates on the frame.
Now you could look closely at the inside of the frame channel to see if it could be boxed in certain places to strengthen it too.
I believe the orginal IH 154 bracket pics shows it goes under were the foot rests are and connects to the rear.
By now i'm sure everyone is thinking its too heavy. We need to make it stronger yet keep it light as possible too weight wise. In your vertical plates you can add lightening holes too and it will keep its structural integrity.
I think it can be done successfully, we'll see soon. I'm starting to disassemble my int154 today. As soon as the snow starts melting i'll be cutting steel. I'm hoping to have all my steel cut so i can start welding it when it warms up.
On the http://www.machinebuilders.net/
site these gurus are putting FEL's & backhoes on most garden tractors so why not an int154 cub too?
I just got thru looking at my newly purchased int154 cub today for the first time upclose. I removed the S/G they had hanging off to the side to make room fore the 10si alternator they had on it too. Right now the frame looks to be free of all cracks. This doesn't appear hard to do and it should move quick once my parts are fabricated ahead of time. Then all i have to do is to weld everything up so its lined up and square. I guess i'll make rough drawings of each part i fabricate so it can be copied if you want to build an FEL or backhoe on your 154/184/185 the concept should fit all 3 tractors.
If anyone wants to add any ideas its ok too i'm sure i can miss things at times too after all there is a lot to cover when designing and building this. I also learn something new everytime i fabricate something too.