Bar Nuthin 808 #1 Posted December 6, 2024 What is the difference between the three model numbers of the piston-piston Sundstrand hydros? My C-120 has a 90-1136. I have a lead on useable 90-1140. I would like to keep the tractor in service while I overhaul one (or the other). Are they interchangeable with my current transaxle? If there is a difference in models, which one would be considered better to overhaul (assuming they are in similar condition) Share this post Link to post Share on other sites
953 nut 56,244 #2 Posted December 6, 2024 Both of them were used on the 1976 C series tractors so there shouldn't be a problem. Perhaps one had the set-up for a hydraulic lift and the other didn't, or could be the pulley shaft isn't the same or something like that. Take a look at the manuals section, The 12 HP models 61-12KSO1, 61-12KSDO2, 61-112KSO3 AND 61-12KSO4 ALL HAD THE 1136 AND THE 16 HP units of the same number sequence had the 1140. I seem to recall a thread not too long ago about the input shaft on the 16 HP Sundstrand being splined rather than keyed. Perhaps @ebinmaine or @daveoman1966 can give some more information on this. 1 1 Share this post Link to post Share on other sites
Bar Nuthin 808 #3 Posted December 6, 2024 (edited) @953 nut Thanks. I've been studying a parts list from another thread, trying to detect any differences. All three models use the same parts list, so I feel like I'm missing something. I'm not sure who compiled the parts list, but they seem to have done a thorough job. SUNDSTRAND PUMP & MOTOR Parts list (1).pdf Edited December 6, 2024 by Bar Nuthin Share this post Link to post Share on other sites
pfrederi 18,023 #4 Posted December 6, 2024 The key vs splined is probably the only significant difference. 2 Share this post Link to post Share on other sites
gt14rider 809 #5 Posted December 6, 2024 Daveoman posted this in one of my post.ill look for more information. 1 1 Share this post Link to post Share on other sites
953 nut 56,244 #6 Posted December 6, 2024 57 minutes ago, pfrederi said: The key vs splined is probably the only significant difference. If you get the pulley with the Sundstrand you buy then all is good. 1 Share this post Link to post Share on other sites
gt14rider 809 #7 Posted December 6, 2024 My post was. (90-1136 teardown question), has some other information, hope it helps. 1 Share this post Link to post Share on other sites
Bar Nuthin 808 #8 Posted December 6, 2024 53 minutes ago, gt14rider said: My post was. (90-1136 teardown question), has some other information, hope it helps. Excellent reading! Thank you! Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,146 #9 Posted December 6, 2024 All the 16hp C-series used the 90-1140 hydro and the hydraulic lift shows as being standard equipment on all. The smaller hp hydros used the 90-1136 and the hydraulic lift shows as being optional. 2 Share this post Link to post Share on other sites
Bar Nuthin 808 #10 Posted December 6, 2024 50 minutes ago, gwest_ca said: All the 16hp C-series used the 90-1140 hydro and the hydraulic lift shows as being standard equipment on all. The smaller hp hydros used the 90-1136 and the hydraulic lift shows as being optional. So, I'm guessing I would need to confirm that the charge valve and implement valves are in the correct ports for manual lift. (Unless someone has a good deal on the parts needed to convert to hydro-lift ) Share this post Link to post Share on other sites
gt14rider 809 #11 Posted December 6, 2024 This was what I found 2yrs ago. 2 Share this post Link to post Share on other sites
ebinmaine 68,986 #12 Posted December 6, 2024 14 minutes ago, Bar Nuthin said: So, I'm guessing I would need to confirm that the charge valve and implement valves are in the correct ports for manual lift. (Unless someone has a good deal on the parts needed to convert to hydro-lift ) You MIGHT be able to swap parts from one to the other for manual vs hydro lift. 2 Share this post Link to post Share on other sites
ebinmaine 68,986 #14 Posted December 6, 2024 @gt14rider Me n you may have a chat in the next few weeks so I can clearly see what those pics mean. I have a 1978/79 C121 with manual lift I'll be making into a hydro lift. I should have all the required parts here in/on a 78 C141 1 Share this post Link to post Share on other sites
gt14rider 809 #15 Posted December 6, 2024 (edited) Not a 100% on this I plan on switching one on my 73nn. If you don't have a lift you should have cone,spring,maybe a shim pack, o ring and cap (right side) and nothing on left.(see pics) to get the lift. Take spring #55 on right and move to the left add (ball #48). Add new spring #49 to right side. Am I making any sense. If there is anyone out there who knows please chime in. Edited December 6, 2024 by gt14rider 1 Share this post Link to post Share on other sites
gt14rider 809 #16 Posted December 6, 2024 I've been playing around with a parts list for the piston to piston sundstrand. I'm not a good typist and I have a attention span of a nat,so still a work in progress. Trying to get good part#s and were to purchase still have a lot to do but what do you think of a complete overhaul kit. 3 Share this post Link to post Share on other sites
ebinmaine 68,986 #17 Posted December 6, 2024 54 minutes ago, gt14rider said: but what do you think of a complete overhaul kit. Excellent idea! 1 Share this post Link to post Share on other sites
pfrederi 18,023 #18 Posted December 7, 2024 Check out the pinned post on Sunstrand O rings top of this section 2 Share this post Link to post Share on other sites
ebinmaine 68,986 #19 Posted January 4 Do any of you know if a hydro pump from a 1970 Charger with hydro lift would be able to give me the appropriate springs etc for my 1978/9 C121 to change the C121 TO HYDRO LIFT? Share this post Link to post Share on other sites
pfrederi 18,023 #20 Posted January 4 31 minutes ago, ebinmaine said: Do any of you know if a hydro pump from a 1970 Charger with hydro lift would be able to give me the appropriate springs etc for my 1978/9 C121 to change the C121 TO HYDRO LIFT? Qualified yes. At some point they changed from balls to cones for the charge pump relief. However there was no change to the pump body so I would think that either ball or cone would work.. 1 1 Share this post Link to post Share on other sites
Bar Nuthin 808 #21 Posted January 4 1 hour ago, ebinmaine said: Do any of you know if a hydro pump from a 1970 Charger with hydro lift would be able to give me the appropriate springs etc for my 1978/9 C121 to change the C121 TO HYDRO LIFT? I'll be watching for details on your conversion. I'm down to waiting on the spring (25-2480) which shows as "shipped" this morning. Probably won't attempt the conversion until the chance for winter snow has passed. The rock shaft looks like the trickiest part of the swap. 1 Share this post Link to post Share on other sites
ebinmaine 68,986 #22 Posted January 4 3 hours ago, Bar Nuthin said: The rock shaft looks like the trickiest part of the swap I'd agree. That rock shaft is WELL known for being a rust frozen PITA to remove. My C121 in particular won't be an issue because it was only put on a year ago. My parts tractor on the other hand... who knows? 1 Share this post Link to post Share on other sites