Ive got me a mid 70's 580ck backhoe. Its got the shuttle trans in front with a 4spd trans behind. It slips out of 1st gear gradually within about 60 seconds of use. Does the same in 2nd just takes a couple minutes longer. If i hook a bungi cord on the gear shifter it will stay in the gears while using. Is there a simple fix for this or will this require tranny disassembly?
There are several possible causes. Worn detent on the shift rails. Does the shift lever feel like it wants to hold the transmission in gear with the shuttle in neutral ? You should feel the detent ball fall into the groove on the rail. A broken spring may prevent the ball from staying in the rail groove. I would suggest that you remove the shift mechanism and inspect the rails and spring loaded balls. #18 & #19 in the top image. Extreme wear on the gears. A broken or dislodged snap ring on the mainshaft. #11 is the snap-ring in the lower image. Usually that causes the transmission to jump into neutral violently.
I remember in my first car, a 1981 Honda Prelude, it would occasionally fall out of gear. It wasn't often enough to get me to fix it but the temporary solution was basically what the OP said, tie the shift lever off to something. Is there a danger of making something worse by doing that (uh, in the backhoe) or is that the simple solution they were asking about?
Hi Tinkerer Sorry it took me so long to respond. Ive been rebuilding the brakes on thay old girl and I had my hands full. I did pull the top of the tranny off. I have not taken the rods out snd checked the springs and detents. If the detents have gone south do you just replace the rod? Also looking at my gears there are a couple that have slightly rounded teeth edges. Not sure how much rounding it would tske to cause the gears to walk? I will let you know what i find with the rods snd springs.