AX15 Hard to Shift, Shuddering

[89xj]

I looked up the Redline MT-90 on Summit Racing's site and the is an additional information button with a write-up from Redline stating that the MTl and MT-90 are both GL-4 rated. Is this OK?

yes

 

[wavingpine11]

So looking back on it, I kind of shot myself in the foot putting in the oil that I did. I remember it getting harder to shift right after I put it in and thinking I must be crazy since the oil I used was the correct weight, then pursued further into the clutch system without full resolution. :doh:

But it makes sense now. . . initially I had hard shifts only when the system warmed up, and now it's mainly when the thing is cold. Oh, well, live and learn! I'm so anxious to see my other Jeep now, armed with a new bottle of oil!

 

[XJ AV8R]

Have you tried detaching the slave cylinder and compressing the piston fully to get rid of the bubbles? I did a conversion to an external slave cylinder on my '91 AX-15 a couple of months ago and that's how I did it. On the first try it still felt like it had air in the line. I don't think I compressed the slave enough. The second try yeilded a couple of small bubbles and I was good to go. The volume of the slave cylinder exceeds the volume contained in the line between the slave and master so you should be able to evacuate the air using this method.

 

[XJ AV8R]

I just read through some of the above posts and thought I would add my .02 on gear oil. As everybody knows, the manuals are wrong when they say to use GL-5 lubricant. It doesn't play well with the syncros. I use Redline MT-90 and it works great. It really improved my semi-hard shifting problems. My AX-15 is a little stiff from 1st to 2nd when it is cold but shifts like butter when it has warmed up. I attribute my worn syncros to the GL-5 I used to run before I knew any better. I am hoping to halt the wear by using the MT-90...210,000 and still going for now.

 

[wavingpine11]

Have you tried detaching the slave cylinder and compressing the piston fully to get rid of the bubbles? I did a conversion to an external slave cylinder on my '91 AX-15 a couple of months ago and that's how I did it. On the first try it still felt like it had air in the line. I don't think I compressed the slave enough. The second try yeilded a couple of small bubbles and I was good to go. The volume of the slave cylinder exceeds the volume contained in the line between the slave and master so you should be able to evacuate the air using this method.

Haven't tried that. I've bled it several times using the two man method, and then power bled it with the unit I got to bleed the brakes on my STi. It does brakes very well, but still didn't get my clutch working smoothly enough. Based on how the problem was exacerbated when I changed the transmission oil, I think I'm definitely having an issue there, but there may be an air-in-lines problem as well that remains unresolved. Full resolution of both issues would make me sooo happy.

Let me make sure I'm getting you on the bleed procedure: you're saying detach the quick disconnect fitting at the incoming line to the slave, compress the slave (not easy to do since I have the internal version) to get any air bubbles to come out the top where I detached it, and then reconnect? How do I assure that I don't get any air into the line going up to the master, then?

In my case, since I'm not willing to drop the transmission again until the spring, I should be able to approximate that by using the power bleeder at the bleed valve after breaking the disconnect. but would it be better to just reverse bleed the whole system as I was thinking before, so I can avoid accidental air ingestion by the master-to-slave line?

 

[wavingpine11]

Or did you mean detach the line at the master. . . ?

 

[lawsoncl]

I looked up the Redline MT-90 on Summit Racing's site and the is an additional information button with a write-up from Redline stating that the MTl and MT-90 are both GL-4 rated. Is this OK?

Yes. Neither has the sulfurs which are corrosive to brass synchros.

When I rebuilt my AX15, I initially filled it with cheap Napa house brand GL3 with the intent of running it for a few weeks to break everything in and then change over to the Redline. It shifted so bad, I thought I dorked up the rebuild and was almost ready to tear it apart again. It didn't get any better driving it for threee days either. Thankfully I decided to drain and refill with the Redline oil. I actually went with half MTL and half MTL90 as we do get well below 0*F in the winter. The difference was like night and day. It went from really hard to shift when cold to easy smooth shifting. A little stiff at first on the subzero morning, but it would shift at all before unless I let it warm up first.

Of course, I did make one mistake in the rebuild that bit me on the rump about 30k miles later. I assumed when the previous owner did the clutch, they also replaced the pilot bearing. Nope. When the pilot bearing seizes it tears up the tranny input shaft and input bearing. I now have an AW4 in there.

So yes, get a quality synthetic oil in there!

 

[XJ AV8R]

Let me make sure I'm getting you on the bleed procedure: you're saying detach the quick disconnect fitting at the incoming line to the slave, compress the slave (not easy to do since I have the internal version) to get any air bubbles to come out the top where I detached it, and then reconnect? How do I assure that I don't get any air into the line going up to the master, then?

Completely disregard what I said. This thread is old so I didn't take the time to read the above posts thoroughly enough. I thought you had an external slave cylinder. You're on the right track with the power bleeder on an internal slave setup. Sorry!:dunce:

 

[wavingpine11]

Yes. Neither has the sulfurs which are corrosive to brass synchros.

When I rebuilt my AX15, I initially filled it with cheap Napa house brand GL3 with the intent of running it for a few weeks to break everything in and then change over to the Redline. It shifted so bad, I thought I dorked up the rebuild and was almost ready to tear it apart again. It didn't get any better driving it for threee days either. Thankfully I decided to drain and refill with the Redline oil. I actually went with half MTL and half MTL90 as we do get well below 0*F in the winter. The difference was like night and day. It went from really hard to shift when cold to easy smooth shifting. A little stiff at first on the subzero morning, but it would shift at all before unless I let it warm up first.

Of course, I did make one mistake in the rebuild that bit me on the rump about 30k miles later. I assumed when the previous owner did the clutch, they also replaced the pilot bearing. Nope. When the pilot bearing seizes it tears up the tranny input shaft and input bearing. I now have an AW4 in there.

So yes, get a quality synthetic oil in there!

I'm convinced. Thanks everyone for clueing me in on the oil issue! I'm going to see my brother over Christmas and do the deed. I'm sure it'll make him happier, since he's the one dealing with it every day now.