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I swapped a remanufactured AX15 into my 87 YJ a few years ago to replace the BA 10 since it was a no-go for my project. I also replaced the internal slave with an external slave bellhousing. The AX15 has performed excellently with one exception: it consistently grinds going into reverse. I have zero shifting problems in forward gears, but even at a fully warmed up slow idle it grinds a bit shifting into reverse. Worse at a fast idle. I got the conversion kit from Advanced Adapters, including the hydraulic clutch assemble. Bleeding it was a huge PITA but it’s been a good three years now so air in the system isn’t the issue. If considered one of Novak’s adjustable throwout bearings since I can only assume that I’m just not getting enough clutch movement. Thoughts?
 

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Here are some of my observations:

With the reverse gears not being synchronized I typically pump my clutch till I am able to get a smooth transition into reverse, another method I have used is to drive slightly forward then transition into reverse.

As of late on various occasions most commonly in colder weather these problems are exacerbated, of which could be the condition of the fluid or the slave cylinder.
 

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2016 JK w/ Snowplow & Trailer Hitch 7-Pin
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"Grinding into reverse" means you are not pushing the clutch in far enough and/or not waiting for the input shaft to stop spinning.

Adjust your habits. You've gotten spoiled by syncromesh 1st gear.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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^^What IRQ said about the synchros and temp above. Mine does the same depending on how I roll up to a stop. like when I pull into garage and shut the motor off because it's on a slight hill pulling in I guess. I developed a habit of dropping it into 4th, then looping into reverse rather than using the double clutch, works every time for me
 
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Every jeep I've driven needs help getting into reverse. I go into first, then into reverse. It also helps to get moving the tiniest bit forward to spin the gears around.
 

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Here are some of my observations:

With the reverse gears not being synchronized I typically pump my clutch till I am able to get a smooth transition into reverse, another method I have used is to drive slightly forward then transition into reverse.

As of late on various occasions most commonly in colder weather these problems are exacerbated, of which could be the condition of the fluid or the slave cylinder.
Yeah, Same here...
Even with a new master and slave cylinder--Reverse is iffy to land smoothly most times.

John D
 

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Wait. They’re not supposed to grind going into reverse!?!
Lol, I do what’s been mentioned, usually shift to 4th first and it does the trick!


Sent from my iPhone using Tapatalk
 

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Wait. They’re not supposed to grind going into reverse!?!
Lol, I do what’s been mentioned, usually shift to 4th first and it does the trick!


Sent from my iPhone using Tapatalk
I learned that way, way back when I was a kid, hot-rodding flathead Fords. If you were rolling backwards (say backing out of the driveway) and shifted into second before shifting into first while still rolling backwards you wouldn't grind when the shifter went into first gear. You could do like they did in the movies. You didn't even have to step on the brakes.
Same thing applies to the AX15 where reverse isn't synchronized. First gear in the old Fords wasn't synchronized either, but by shifting into a synchronized gear before shifting into a non-synchronized gear seems to be magic.

The way I believe it's supposed to work is stop all vehicular motion (fore or aft) and make sure the clutch is completely depressed to the floor. Then slowly and carefully shift the transmission into reverse. Nobody does it like that though, because it takes too much time and we're all too much in a hurry. JMHO

Good Luck, L.M.
 
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The way I believe it's supposed to work is stop all vehicular motion (fore or aft) and make sure the clutch is completely depressed to the floor. Then slowly and carefully shift the transmission into reverse.
Nobody does it like that because in doesn't work. If the car is fully stopped and the input shaft has stopped. Unless the gears are perfectly aligned, the tranny won't go into a non-syncromesh gear.

The trick for non-syncro R or 1 is to have the least little bit of motion and quickly move the shift lever. Don't let it grind. Push hard when you feel the gears mesh.
Or, as others have recommended: 1) Full stop of all parts 2) slide into a syncro gear 3) move lever to desired non-syncro gear.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Or for uncoordinated people, buy an automatic....
 

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Or for uncoordinated people, buy an automatic....
I'd call sacrilege on that but an automatic on the rocks or really hard stuff sure makes things easier. Now, if I only had 3 feet....

Good Luck, L.M.
 
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I'd call sacrilege on that but an automatic on the rocks or really hard stuff sure makes things easier. Now, if I only had 3 feet....

Good Luck, L.M.
I found a cheap pair of narrow, lightweight, sneakers at Walmart for $10 that are horrible to walk around in, but really agile on the pedals, I I call them my "Driving" shoes, Wife thinks I'm nuts, I told her to try and play brake, clutch,gas,clutch,brake,gas, in work boots and then try and make fun of me. You can keep your automatic...LOL
 
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I'd call sacrilege on that but an automatic on the rocks or really hard stuff sure makes things easier. Now, if I only had 3 feet....

Good Luck, L.M.

LOL, Yeah! stall! hold position with toes on brakes, start, heal on throttle, clutch out, ease off the brake, on the throttle "heal-toe"
It gets tricky all while looking at sky😬

John D
 
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I found a cheap pair of narrow, lightweight, sneakers at Walmart for $10 that are horrible to walk around in, but really agile on the pedals, I I call them my "Driving" shoes, Wife thinks I'm nuts, I told her to try and play brake, clutch,gas,clutch,brake,gas, in work boots and then try and make fun of me. You can keep your automatic...LOL
+1 Race car drivers do it.
Better feel with light shoes and no heal rise...
I also learned in the rock gardens where bouncing around really upsets your throttle control to stuff the outer edge of my foot up against the center well as an anchor and foot higher up so I am using my heel instead of toes. Then roll onto the pedal. Actually, the motion is more like moving knee left or right to roll the heal to apply more or less throttle.

John D
 
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Except I'm anything But a Race Car driver, I do it out of necessity. Size 13 feet make it tough for fancy footwork down there. lol
 
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