WHGuy413 2,690 #1 Posted May 11, 2023 Hey all, I’ve scrolled back several pages and didn’t see what I’m looking for. I have a 1971 Bronco 14 that I had previously swapped out the SUNDSTRAND transmission years ago. The old one leaked like crazy and I stupidly tore it apart and never put anything back together. The current transmission came out of a different model tractor but they look the same and has worked great for years. Today while mowing it started going up hill really slow. When I was headed down the hill it would speed up to normal speed. As soon as I turned and headed back up the hill it would slow down again. I’m guessing it’s probably about half the normal full speed. There are no odd noises, the transmission fluid looks good and is on the dipstick the hydro lift that’s attached to the transmission works perfectly fine all along. Has anyone experienced any of this before? I’m sure I am missing the posts. Anyone have any suggestions? Share this post Link to post Share on other sites
mrc 812 #2 Posted May 11, 2023 daveoman has posted some excellent pics of how to repair the hydro's. from his past descriptions sounds like the swash plate and pistons are scored. this allows the fluid to bypass. thus, you get slower speeds especially when the tranny is warmed up. unfortunately to fix the tranny must come out, be split open and the pistons and swash plate lapped. good luck regards mike 2 Share this post Link to post Share on other sites
WHGuy413 2,690 #3 Posted May 11, 2023 33 minutes ago, mrc said: daveoman has posted some excellent pics of how to repair the hydro's. from his past descriptions sounds like the swash plate and pistons are scored. this allows the fluid to bypass. thus, you get slower speeds especially when the tranny is warmed up. unfortunately to fix the tranny must come out, be split open and the pistons and swash plate lapped. good luck regards mike Thank you Mike. I was hoping I could get away with not opening it but looks like I may have to. Share this post Link to post Share on other sites
mrc 812 #4 Posted May 11, 2023 does the tranny have motor oil in it? 10W30??? if so, try switching to a thicker viscosity. it is a band aid fix but, worth a shot. does it have atf in it? buy a bottle or two of lucas tranny fix. comes in a 24 ounce bottle. years ago i had a ford escort station wagon.. the tranny started slipping. i dropped the pan, drained all the fluid, cleaned and replaced the filter. added fresh atf. still slipped. re-dropped the pan and drained. added 2 bottles of lucas and topped off with fresh atf. drove the car another 3-4 years till the rear axle broke free of the body mounts due to rust. tranny was still working great. be aware the lucas is red like atf but pours out of the bottle like molasses. the escort tranny after the lucas treatment always made a whining sound but, worked for many years and miles. if you decide to do the daveoman fix be warned that your repair area when lapping must be VERY clean. tiny dirt can score the pistons/swash plate. 1 Share this post Link to post Share on other sites
daveoman1966 3,752 #5 Posted May 11, 2023 This is the Sundstrand HydroGear overhaul .pdf file referred to above. I made this file a few years back... and have offered it to everyone as an aid in restoring the power to their tractors. One must keep in mind that these tractors are nearly 50 yrs old...wear and tear happens... and the only real fix is to overhaul. This file applies to Hydrogear models 90-2046 used in Charger Bronco 14 and others. It also applies to the model 90-2062 used in the GT14. Hope it helps.... SUNDSTRAND HYDROGEAR refurb.pdf 2 1 Share this post Link to post Share on other sites
953 nut 55,280 #6 Posted May 11, 2023 10 hours ago, WHGuy413 said: started going up hill really slow Is the speed reduction on a hill the same in reverse as it is in forward? The fact that your lift works well leads me toward the acceleration valves. The spring on the acceleration valves will break and limit the ability of the transmission to transfer power. Lowell @wheelhorseman sels the springs. https://wheelhorsepartsandmore.com/product/transmission-acceleration-springs-2-7052-9215-2-7264-9858/ 1 Share this post Link to post Share on other sites
WHGuy413 2,690 #7 Posted May 11, 2023 3 hours ago, 953 nut said: Is the speed reduction on a hill the same in reverse as it is in forward? The fact that your lift works well leads me toward the acceleration valves. The spring on the acceleration valves will break and limit the ability of the transmission to transfer power. Lowell @wheelhorseman sels the springs. https://wheelhorsepartsandmore.com/product/transmission-acceleration-springs-2-7052-9215-2-7264-9858/ Yes! It will barely creep going up a hill in reverse but if I back up going down a hill it’s normal. Share this post Link to post Share on other sites
daveoman1966 3,752 #8 Posted May 11, 2023 In conjunction with my HYDROGEAR REFURB.pdf , there is a 4-page OEM manual on the Automatics. Pages 1 thru 3 deal with the Piston-to-Piston models (90-1136, 1137, 1140 etc) and the 4th page alone deals with the HYDROGEAR. Here is that FOURTH PAGE... Sunstrand Hydro (part 4).pdfI am also posting a photo of the actual dampening/acc valves that 953 nut alludes to. NOTE that the cone valve (7050) is often damaged ...yet is machined to match the cone sleeve (7049). Get the springs from Lowell. I may have some replacements if you have damaged parts. Share this post Link to post Share on other sites
oliver2-44 9,756 #9 Posted May 12, 2023 (edited) A simple thing to check, is that all the linkage is clean and moves freely. Trash likes to build up in the tunnel in front of/below the seat. Then head to checking the acceleration valve springs. Edited May 12, 2023 by oliver2-44 Share this post Link to post Share on other sites
