149 hydro issue
 

I have downloaded and printed the information on hydro problems in the tech section, but had a specific question about my tractor. The hydro functions pretty normally when the throttle is about halfway or less. However, when the throttle is all the way open (cutting grass or blowing snow), the hydro will go full speed in a second! Even if I try to pull the lever back it will go back to full speed. Why is there a difference between WOT and halfway or less? Does it half to do with how much pressure is being generated in the hydro pump and different degrees of engine RPMs? I'd like to take some pictures and try to get this fixed up because this is my grass cutting machine.

Another quick question, with the hydro lever in neutral, should the big spring in the trunion be really loose (I can move it all around)? There are some grooves worn at the end of the trunion slot also. I am a novice welder. I read about using keystock to true up the slot dimensions. Would that be the preferred method for someone of my limited ability. I am sure I couldn't weld up the slot and file it back down without making a huge mess or wrecking something.
Thanks,
Jason

The big spring should be slightly loose. The small spring inside keeps the buttons tight. The grooves are probably the largest source of your problem.

My dad is a better welder than I am, so he welds up my trunions when I need them. We wrap a wet rag around the seal to keep the heat from melting it. We've been gas-welding them with hit-or-miss results, since an arc weld would be too hard to file. You can probably weld keystock on, but you'll have to make sure that you can still slide the outer bracket back on over the top.

Jfinney

I think you are talking about two different problems. In the first paragraph you say the hydro control is moving when you are at full RPM's and that can problaby be corrected with the speed control lever adjustment (under the dash) that you will find in the service manual. You need to check the manual as the adjustment is different for different serial number cubs.

In your second paragraph you mention the big spring and little spring. In normal operation the small spring controls the hydro control. Only when you make a quick movement of the hydro control does the big spring come into play and then once the hydro catches up the small spring takes over again.

Welding the trunion is not that bad of a job. Just take your time, weld a small amount then file and repeat until you get it back to the correct size. When I first started repairing the brackets I used keystock because I had seen others use it. It is overkill, looks like crap so I quit using it. If you just weld up the bracket it will last another 30 to 40 years.

Rchristensen,
Thank you very much. You were correct, the hydro needed to have the friction adjustment procedure done. I didn't have a pull scale, as per the service manual, but I snugged it up a bit and it is much better. I still have a slight issue with hydro lurch, but that I can handle for right now. I will deal with the trunion later...I needed the 149 on mower detail! Thanks to you and Matt for your help.
Jason