89 MJ Posted June 18 Share Posted June 18 I don’t think anyone thinks that your clutch itself is bad, there’s just most likely issues with the hydraulic system. Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted June 18 Author Share Posted June 18 3 hours ago, 89 MJ said: I don’t think anyone thinks that your clutch itself is bad, there’s just most likely issues with the hydraulic system. Okay, good to know! Honestly just trying to get as much knowledge as I can and fix this issue, and hydraulic system meaning the slave cylinder? So my best bet would be to replace the slave cylinder??.. and see if that fixes the issue?.. after my fluid change of course. Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted June 18 Author Share Posted June 18 14 minutes ago, InTacosWeTrust said: Okay, good to know! Honestly just trying to get as much knowledge as I can and fix this issue, and hydraulic system meaning the slave cylinder? So my best bet would be to replace the slave cylinder??.. and see if that fixes the issue?.. after my fluid change of course. Any recommendations on a good throw out bearing and p/n? or is the internal slave the “throw-out bearing” of so still would love any good recommendations as well Link to comment Share on other sites More sharing options...
ghetdjc320 Posted June 18 Share Posted June 18 Looks like Timken has one. The hydraulic system includes the master cylinder, slave cylinder (with integrated throw out bearing) and all associated hose and fittings. I’d start by looking for leaks and possibly bleeding it for any trapped air first. That may fix the problem Link to comment Share on other sites More sharing options...
ghetdjc320 Posted June 18 Share Posted June 18 10 hours ago, InTacosWeTrust said: You have me curious on what other problems may occur since I’m over 8 inches lol, I have a Dana 30 in the front, and the 8.25 in the back and I am re-geared to 4.88. With working 4wd. Just trying to see what I missed and needs to be covered What are you currently running for steering and brakes? 35’s are about the upper limit for what the Dana 30 can handle even in upgraded form. 8.25 is getting up there also at 35’s but probably could run 37’s if needed. Steering, brakes and suspension geometry would be my primary concern. If you lifted 5-6” and fender trimmed to accommodate 37’s, that is a viable option, but one that still calls for extensive brake, steering and front axle upgrades. Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted June 19 Author Share Posted June 19 On 6/18/2025 at 6:47 PM, ghetdjc320 said: What are you currently running for steering and brakes? 35’s are about the upper limit for what the Dana 30 can handle even in upgraded form. 8.25 is getting up there also at 35’s but probably could run 37’s if needed. Steering, brakes and suspension geometry would be my primary concern. If you lifted 5-6” and fender trimmed to accommodate 37’s, that is a viable option, but one that still calls for extensive brake, steering and front axle upgrades. I replaced my whole suspension recently, all components except for the axles which were put on by po, po also said it has a lunch box front end whatever that means.. it was on a 6 inch and 35s before i replaced it with the 8in Rusty’s long arm, I replaced my steering box with a read head 4 turn, replaced the steering arm and link, new: steering box mount, steering stabilizer, over the knuckle steering system, upper and lower ball joints, wheel bearings, brake rotors and pads, upgraded brake master cylinder and BB, axle shafts and the 8inch long arm. most everything came from Rusty’s. New 35s and wheels as well. Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted June 19 Author Share Posted June 19 22 hours ago, ghetdjc320 said: Looks like Timken has one. The hydraulic system includes the master cylinder, slave cylinder (with integrated throw out bearing) and all associated hose and fittings. I’d start by looking for leaks and possibly bleeding it for any trapped air first. That may fix the problem Okay, that’s what I thought just sucks that I just did that a year ago Link to comment Share on other sites More sharing options...
Htchevyii Posted June 19 Share Posted June 19 3 hours ago, InTacosWeTrust said: Okay, that’s what I thought just sucks that I just did that a year ago The internal slave in my LUK kit lasted 10,000 miles before catastrophically failing. It made me so mad after it ruined our trip that I did the external swap. Even new, they were failure prone enough that Jeep redesigned and changed to the external setup. 😡 Link to comment Share on other sites More sharing options...
ghetdjc320 Posted June 20 Share Posted June 20 3 hours ago, InTacosWeTrust said: I replaced my whole suspension recently, all components except for the axles which were put on by po, po also said it has a lunch box front end whatever that means.. it was on a 6 inch and 35s before i replaced it with the 8in Rusty’s long arm, I replaced my steering box with a read head 4 turn, replaced the steering arm and link, new: steering box mount, steering stabilizer, over the knuckle steering system, upper and lower ball joints, wheel bearings, brake rotors and pads, upgraded brake master cylinder and BB, axle shafts and the 8inch long arm. most everything came from Rusty’s. New 35s and wheels as well. Most of those items will let you run 35’s but that will still be upper limits for the Dana 30. The ring and pinion are just too small to take much more. But you should have a very capable rig as is Link to comment Share on other sites More sharing options...
ghetdjc320 Posted June 20 Share Posted June 20 2 minutes ago, Htchevyii said: The internal slave in my LUK kit lasted 10,000 miles before catastrophically failing. It made me so mad after it ruined our trip that I did the external swap. Even new, they were failure prone enough that Jeep redesigned and changed to the external setup. 😡 I was surprised to see different slave cylinders available starting in 91 on rock auto. Figured they would all have been the same for the ax15 up until they went external in 94. 91 is the first year the Timken version shows up. Realistically though, I’ve had the throw out bearing go bad as well in an external slave ax15. Same pain to swap it as well. I like the idea of eliminating the linkage and having that direct clutch engagement from an internal slave provided it was reliable. That eliminates a lot of small parts and linkage. It’s notable too that most performance manual transmission vehicles today use internal slaves. Seems the tech was sound, provided it was properly manufactured. Link to comment Share on other sites More sharing options...
Pete M Posted June 20 Share Posted June 20 have you tried bleeding the clutch? Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted June 22 Author Share Posted June 22 On 6/19/2025 at 8:26 PM, Pete M said: have you tried bleeding the clutch? I have not, it’s been running fine for a year, I honestly don’t think why I should, you know, but if you have any insight to why I should bleed the clutch after so long of everything working as it should I would love to gain that knowledge, not saying your idea is wrong in anyway, just want that knowledge Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted June 22 Author Share Posted June 22 On 6/19/2025 at 8:01 PM, ghetdjc320 said: Most of those items will let you run 35’s but that will still be upper limits for the Dana 30. The ring and pinion are just too small to take much more. But you should have a very capable rig as is What axles do you recommend? Or is there an upgraded ring and pinion set up I can get? Link to comment Share on other sites More sharing options...
89 MJ Posted June 22 Share Posted June 22 46 minutes ago, InTacosWeTrust said: I have not, it’s been running fine for a year, I honestly don’t think why I should, you know, but if you have any insight to why I should bleed the clutch after so long of everything working as it should I would love to gain that knowledge, not saying your idea is wrong in anyway, just want that knowledge Because it’s potentially a free solution. The line could’ve gotten an air bubble in it somehow, especially if the master was a little low on fluid. Link to comment Share on other sites More sharing options...
Eagle_SX4 Posted June 22 Share Posted June 22 2 hours ago, InTacosWeTrust said: I have not, it’s been running fine for a year, I honestly don’t think why I should, you know, but if you have any insight to why I should bleed the clutch after so long of everything working as it should I would love to gain that knowledge, not saying your idea is wrong in anyway, just want that knowledge Also sometimes air will be pulled in to the system with out leaking anything. I had that happen with a brand new brake master cylinder. Link to comment Share on other sites More sharing options...
Htchevyii Posted June 22 Share Posted June 22 On 6/19/2025 at 5:08 PM, ghetdjc320 said: I was surprised to see different slave cylinders available starting in 91 on rock auto. Figured they would all have been the same for the ax15 up until they went external in 94. 91 is the first year the Timken version shows up. Realistically though, I’ve had the throw out bearing go bad as well in an external slave ax15. Same pain to swap it as well. I like the idea of eliminating the linkage and having that direct clutch engagement from an internal slave provided it was reliable. That eliminates a lot of small parts and linkage. It’s notable too that most performance manual transmission vehicles today use internal slaves. Seems the tech was sound, provided it was properly manufactured. I know that they are common in other makes. Looking at one compared to a conventional one, it does seem like they would be more difficult to seal, you've got a donut shape to work with. I've had two bad internals, always the slave that fails. At least the first lasted over 100,000 miles. The last 10,000. I've never had a throwout bearing completely fail out of nowhere, most seem to get by for years even after that start to get noisy. I do remember that the original assembly was metal vs the plastic ones that are now available. I still am skeptical that Jeep would have engineered the system if it wasn't problematic, but if you're happy with it, great! Link to comment Share on other sites More sharing options...
ghetdjc320 Posted June 23 Share Posted June 23 3 hours ago, Htchevyii said: I know that they are common in other makes. Looking at one compared to a conventional one, it does seem like they would be more difficult to seal, you've got a donut shape to work with. I've had two bad internals, always the slave that fails. At least the first lasted over 100,000 miles. The last 10,000. I've never had a throwout bearing completely fail out of nowhere, most seem to get by for years even after that start to get noisy. I do remember that the original assembly was metal vs the plastic ones that are now available. I still am skeptical that Jeep would have engineered the system if it wasn't problematic, but if you're happy with it, great! I’m wondering about the design/quality of the timken unit. It’s much higher in price than the others even on rock auto. Also curious why it’s not showing up for a 1990 but it does show up for a 91?? Link to comment Share on other sites More sharing options...
ghetdjc320 Posted June 23 Share Posted June 23 7 hours ago, InTacosWeTrust said: What axles do you recommend? Or is there an upgraded ring and pinion set up I can get? Lots of factors at play in that decision. Driving style, wheeling areas, tire size you want to run. Generally speaking, If you’re going 37’s -39’s, probably a high pinion Dana 44 like JK style axles. 40’s or larger may call for a D60 Link to comment Share on other sites More sharing options...
Htchevyii Posted June 23 Share Posted June 23 2 hours ago, ghetdjc320 said: I’m wondering about the design/quality of the timken unit. It’s much higher in price than the others even on rock auto. Also curious why it’s not showing up for a 1990 but it does show up for a 91?? Good question. I was told that my 1988 slave/bearing would work when I swapped to the internal slave AX15 25 years ago and it worked fine. Hard to say if the Timken is actually any better or comes out of the same Chinese plat as the rest these days. Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted Tuesday at 10:47 PM Author Share Posted Tuesday at 10:47 PM Yes, I’m very curious about the timken one as well! I’m honestly not sure which one I should go with, I want to have a good quality one. also on rock auto there is a clutch release bearing.. under the 92 Comanche, it looks like a slave cylinder idk if it’s the same thing just under a different name Link to comment Share on other sites More sharing options...
ghetdjc320 Posted Tuesday at 11:07 PM Share Posted Tuesday at 11:07 PM 19 minutes ago, InTacosWeTrust said: Yes, I’m very curious about the timken one as well! I’m honestly not sure which one I should go with, I want to have a good quality one. also on rock auto there is a clutch release bearing.. under the 92 Comanche, it looks like a slave cylinder idk if it’s the same thing just under a different name Post the part number or link. Probably the same thing Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted Tuesday at 11:11 PM Author Share Posted Tuesday at 11:11 PM 3 minutes ago, ghetdjc320 said: Post the part number or link. Probably the same thing Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted Tuesday at 11:17 PM Author Share Posted Tuesday at 11:17 PM Now the next question, when replacing the clutch master cylinder since I have the ax 15 trans in my 87, do I go for the 87-90 on rock auto or the 91-92 ones? Link to comment Share on other sites More sharing options...
Htchevyii Posted Tuesday at 11:27 PM Share Posted Tuesday at 11:27 PM 9 minutes ago, InTacosWeTrust said: Now the next question, when replacing the clutch master cylinder since I have the ax 15 trans in my 87, do I go for the 87-90 on rock auto or the 91-92 ones? The later ones use a different line configuration. I used the Advance Adapter braided line kit that allowed me to use the later slave with my original master. Link to comment Share on other sites More sharing options...
InTacosWeTrust Posted Tuesday at 11:44 PM Author Share Posted Tuesday at 11:44 PM 14 minutes ago, Htchevyii said: The later ones use a different line configuration. I used the Advance Adapter braided line kit that allowed me to use the later slave with my original master. The one I have now has that pin fitting style, do you have a part number for that AA one? Also the fitting size and line I need to get from master to slave? Link to comment Share on other sites More sharing options...
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