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Old 11-11-2008, 04:58 PM   #1
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Transmission Question

Sooo. if you all remember, I had the issues with the rear differential (spider gear/pinion shearing off splines). I ended up getting the rear diff fixed. Great. However now it shows that I have a transmission problem too.

Basically, I can upshift no problem (normal driving), but when I go to downshift, I can't. So if I'm in 4th going like 60mph, and try to slow down to 40mph and downshift to 3rd to accelerate, it won't go into gear. period. It will only go into 4th or 5th. The only way I can downshift is if I come to a near-complete stop to go back into first. And then when I shift into first it grinds a bit before going in.

So it sounds like a tranny synchro problem, yes?

Now... the fun part. Is it better to just replace the whole damn thing rather than try to rebuild it? If so, does anyone recommend a good replacement tranny? It is for the 4.0L 6Cyl 1998 Wrangler (Sahara). I think the replacement I could handle on my own - rebuilding not so much. I may as well do the clutch at the same time since its been 120k miles and haven't had to do the clutch either.

Suggestions?

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Old 11-11-2008, 05:14 PM   #2
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Oh, and is the tranny that is on it the AX-15? I think that's what I've been able to dig up.

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Old 11-11-2008, 05:32 PM   #3
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Also, since I'm ripping all this out, what is a recommended aftermarket clutch/flywheel replacement?
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Old 11-11-2008, 07:02 PM   #4
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I wouldnt trust a junkyard tranny to be in perfect shape. If you can find one from someone you trust who said it worked perfectly before they took it out, I would buy it. Otherwise, the junkyard might have the same problems or even worse than yours. As for the clutches, I would say just stay away from cheap ones at autozone and places like that. I want to get a centerforce next time I replace my clutch but they are expensive.
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Old 11-11-2008, 09:17 PM   #5
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What tranny is in the 1998 Saharas? Is it the AX-15 or the NV3550?
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Old 11-11-2008, 09:59 PM   #6
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Being a manual I woould guess the AX15. I think the NV is automatic. Dont take my word for it though.
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Old 11-11-2008, 10:05 PM   #7
Knows a couple things...

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Your '98 has an AX-15 transmission, the NV3550 didn't come along until 2000.

Clutch-wise, I would only go with a Luk OE replacement kit, and avoid Centerforce. Centerforce clutches are designed with centrifugal weights that only help hold the clutch tighter at very high rpms. They are not a clutch that was designed for the typical uses a Jeep sees and they are WAY more expensive than a better suited clutch like Luk sells for. Despite their heavy advertising making them seem like the right choice, I strongly recommend against a Centerforce clutch for a Jeep Wrangler. Luk is the OE manufacturer of the TJ's clutch and most go well over 200K miles before needing to be replaced. I repeatedly smoked my Luk clutch with years of rock crawling and when I pulled it to replace as a precaution before doing a major rock crawling trail, I was amazed that with over 167,000 hard miles on it, it was still in great condition with at least another 20-30K miles of life left on it. I stayed with Luk with the replacement.

Here's one photo of one of the many times my Luk clutch got smoked and survived with no problem... the Gatekeeper opening to Doran Canyon in the deserts of SOCAL, near Calico Ghost Town. Yes, that smoke in the pic is from the clutch.
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Old 11-11-2008, 10:43 PM   #8
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Thanks for the info, Jerry. I've got 120k on this clutch so I figured while I had the tranny out I may as well replace it. I'll look for the Luk online.

I figured it was the AX-15. Once I get my skid plate off I'll verify before I order any parts.

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