RKTJeep Posted February 20, 2019 Share Posted February 20, 2019 I'm currently working on finishing up my AX-15 swap in my 88 Comanche. I went with a complete kit from Novak transmission, which has been good so far. However, I've encountered an issue with the clutch not fully disengaging. I've blead the clutch multiple times and made sure the Novak (3/4 bore) slave cylinder/piston is not bottoming out. Novak included a replacement master cylinder which appears to be the the same as the stock '88 (11/16 bore). I've measured the travel of the slave piston with the pedal fully depressed and I'm getting 0.718" of travel, this means that the throw-out bearing is only pushing in the pressure plate fingers 0.359". Which doesn't seem like enough to fully take the pressure off the clutch. I did install new carpet with the during this process but that may only be removing about 0.5" of pedal travel at most. I'm used to clutches disengaging within the first half of pedal travel so I would expect that last but to make or brake me. At this point it seems like either the pushrod of the mast cylinder is too short. Leading to a low clutch pedal, idk? I've tried to find information on the Luk clutch to see how much travel is needed to compress the pressure plate for full disengagement, but haven't had any luck. If anyone has some info or insight on this I would appreciate it. I have been in contact with Novak and they recommended bleeding and pushing the piston as far back as possible. Which I was skeptical of since I had already check for it bottoming out. I performed this today and it made no difference. I'll be calling them again tomorrow. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 20, 2019 Share Posted February 20, 2019 I assume you are using a stock bell? stock slave and master? Is there a metal plate between the slave and bell? If so remove the plate. Is there a nylon end to the slave shaft? a ball the goes into the fork? Is your fork pivot ball in good condition? What TOB are you using? Anything other than a Mopar master and slave totally sucks.......FWIW. And just curious, why did you go Novak for a stock trans? Link to comment Share on other sites More sharing options...
RKTJeep Posted February 20, 2019 Author Share Posted February 20, 2019 The Master cylinder appears to be a stock replacement for the original setup. I'm using Novak's external slave and a new external slave bell housing. The slave cylinder is in the link below, but it bolts directly to the housing without a bracket. https://www.novak-adapt.com/catalog/clutch/kit-hcr3/kit-hcra/ I went with Novak for convenience of not piecing everything together, searching for used parts. I also got a brand new transmission, transfer case rebuild kit and proper shafts to make it all work. Everything has has gone together fairly smoothly up to this point. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 20, 2019 Share Posted February 20, 2019 Post pics of what you have., Link to comment Share on other sites More sharing options...
Eagle Posted February 21, 2019 Share Posted February 21, 2019 I'm surprised that the slave cylinder is larger diameter than the master. The master may simply not be moving enough fluid. I would double check with novak to be sure they sent you the correct parts. Link to comment Share on other sites More sharing options...
RKTJeep Posted February 22, 2019 Author Share Posted February 22, 2019 Talking further with the support at Novak it sounds like the master cylinder that they include is for a YJ (~87-89) this makes me suspect that the pedal assembly is probably different which may mean that the master cylinder shaft may have a different length to account for different pedal travel distances. I just measured the old master cylinder rod to the center of the hole and it's about 3.75 in, the one from Novak is 3.125 in. Aside from that, there's almost no visible difference. From full extension to bottoming out the pedal on the floor, with the Novak MC, I get about .75 in. of travel at the MC Rod. Tomorrow I'll install the old MC, I'm thinking the additional .625 may be enough for full actuation. Link to comment Share on other sites More sharing options...
OldManComanche Posted February 22, 2019 Share Posted February 22, 2019 I too had similar problems with the clutch not releasing after all new parts (pressure plate, disc, throwout bearing, and plastic bushing on the pedal end of the pushrod). I found that removing the carpet would allow the clutch to fully disengage. I made the pushrod adjustable and problem was solved. I found that adjusting the pushrod about 5mm longer gave me a clutch engagement at about half pedal travel. (89 Pioneer, 4.0, AX15 4x4) Link to comment Share on other sites More sharing options...
RKTJeep Posted February 23, 2019 Author Share Posted February 23, 2019 Problem Solved: This evening Installed the original Master Cylinder that was used for the internal slave cylinder on the BA10-5 (stock). Since the stock one has a 5/8" longer rod (than the YJ MC) it gave me more than enough travel to disengage the clutch. No adjustable rod was necessary. I've included a photo of them side by side, the stock MC is on the bottom. Link to comment Share on other sites More sharing options...
Eagle Posted February 23, 2019 Share Posted February 23, 2019 I'm happy that you got it solved, and many thanks for posting the solution so other people can benefit from your experience. Link to comment Share on other sites More sharing options...
Jeep Driver Posted February 24, 2019 Share Posted February 24, 2019 The 'solution' is sourcing the correct parts to begin with. The only reason this interested me is when I do my SBC swap I'll have to decide on Novak or Advanced Adapters, I'm torn on which to use. But I keep reading about the BS with Novak. I'd still like to know/see which slave was used here. Link to comment Share on other sites More sharing options...
RKTJeep Posted March 2, 2019 Author Share Posted March 2, 2019 On 2/24/2019 at 3:48 PM, Jeep Driver said: The 'solution' is sourcing the correct parts to begin with. The only reason this interested me is when I do my SBC swap I'll have to decide on Novak or Advanced Adapters, I'm torn on which to use. But I keep reading about the BS with Novak. I'd still like to know/see which slave was used here. Knowing what the correct part IS, is most the battle with a conversion. I posted a link to the Novak slave cylinder page, above (3/4"). Good luck with your research! Link to comment Share on other sites More sharing options...
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