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Discussion Starter #1
I have a jeep. A 1995 YJ wrangler with a 4.0L a swapped in NV3550 out of a TJ rubicon, and factory air conditioning (no releveance here, I just like bragging since I have owned it since new). After years of hard abuse my original Ax15 lunched a main gear shaft and was completely undriveable in anything below 3rd gear and I swapped in a 30,000 mile NV3550 from a TJ that had been in a fire. The tranny was always questionable because of the fire but it has held up for years without issue. However, lately there has been the slightest crunch going into third gear and I noticed the other day I can grab it and snatch it out of gear even when on a load. I think the synchro is shot. This is actually common with the NV3550 - they were the 3/4 ton truck tranny (NV4500) guts shoved into a jeep specific aluminum case.

As this is my daily driver, and I have owned the truck since it was new I try to keep the costs and time off the road to a minimum while still trying to do everything myself. I swapped the tranny in so it is no biggie for me to pull it.

costs for a rebuild kit is between $300-$400, tools are $150. A reman tranny is $850 with a one year warranty. A new one is about $1500. From what I am reading online I should just suck it up and put in Redline MTL fluid and live with it until the tranny has "real" problems like broken shift forks or blown 1st and 2nd gear sycnhros.

so what do you guys think? am I kidding myself here? or go for it?
 

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if it doesnt make weird noises....I would probably slip it out, slip it apart and slide a synchro on 3rd, preserving any shims for endplay etc. in the process and leave everything else alone. replace what gaskets you have to if it uses any. it feels like "patching" but since its yours it isnt a big deal.


is that tool the one to set up the mainshaft endplay?
 

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Discussion Starter #3
define weird nosies. The tranny is not so affectionalty nicknamed "the box o' rocks" for a reason, most of that sound related.

There are a few special bearing cup installers, a few tranny specific pullers just to get it apart and I know I need a press for at least on of the steps (but I can outsource that).

From what I am reading online I may just need to run Redline MTL. I had been using pennzoil in the tranny before and it had a drain and flush about a month ago. I am going to try that first.

One of the motivators for swapping to the nv3550 was eventually I want to put a SBC into the truck when the 4.0L decides it has had enough. The ax15 was rated at 270-280ft lbs and the nv3550 was rated at 300ft lbs. neither is ideal but ideal requires an automatic or fab work and I am willing to do neither.
 

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I haven't done a Jeep but manual is easier to re-build than an auto in my opinion (even though the first time I did one it took me about 10 hrs :rolleyes:)
 

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I have an '85 Corvette with the 4+3 transmission. It's essentially a Borg-Warner Super T-10 4 speed manufactured by Doug Nash, coupled with a Nash overdrive unit. I've owned it since '04. Over the last couple of years, I've noticed a tendency to do the same thing you're describing when upshifting to 2nd. Not bad, and only sometimes, but enough to be annoying. I have no doubt it could use a set of blocker rings...it is an '85 with 140,000 miles after all. Last winter I read about Red Line's MTL and thought I'd give it a try just to see what happened. MTL is actually a GL-4 oil, while what my application called for was GL-5. Re Line 75/W90 (here: Red Line Synthetic Oil - Gear Oil for Manual Transmissions - 75W90 NS GL-5 Gear Oil) is similar to MTL, but is a GL-5 lubricant. I put it in this spring and can honestly say I've noticed a big improvement. I'm not saying it fixed worn parts, I know it still needs new blocker rings, but I'm pleased with the result!
 
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