Numbchux Posted July 12, 2010 Share Posted July 12, 2010 Back Story (skip to the * for the basics and question): I've got an '88 XT6, as my profile says. I bought it with 2 teeth broken off 2nd gear. So, I bought a '94 impreza 1.8l AWD 4.111 transmission, and made a frankentranny. I used all the internals from the EJ transmission, as well as the 1-2 shift fork (slightly wider), speedo gear (smaller), and center diff housing. Well, when I put it back together, I did not use high-temp sealant for the case. This was not a problem for almost 10k miles. Last weekend, I drove across the state. mid 80* temps, car fully loaded, bike on the roof. apparently, I got an air bubble in the cooling system, which prevented the tstat from opening, as a result, I was able to keep the heat on to prevent the engine temp from getting too hot, but everything behind the engine got very hot, the speedo and clutch cables began to stick. Apparently it also cooked the transmission seals, as I checked the fluid before the trip and it was fine, and when I drained it later only about a half quart came out. * 3 days after returning, the rear bearing on the output shaft seized. I picked up an '01 2.5RS transmission locally. today I pulled the trans out, and got them both torn apart. I got the RS internals laid in the XT6 case and everything lined up perfectly. EXCEPT, the RS reverse idler gear is larger. too large, in fact. I swapped them, but found that if the input shaft is fully seated in the case, I cannot engage reverse. if I pull the input shaft a couple tenths of an inch off the case, it'll work fine. The only way I can imagine this to be an issue, is if the shaft for the idler gear is a bit further away from the main shaft. looking at the trans charts, it appears that all subaru 5MTs switched from a 3.416 reverse gear to a 3.333 (except the '97-'98 imprezas which had the 3.333 as well) in '99, so I suppose it's possible that the case changed. Am I missing something? I don't consider myself to be a tranny expert, but other than the fluid leak, the other setup worked wonderfully. What are my chances of getting away with using the smaller idler gear? it has the same number of teeth (26), and appears to mesh pretty well with the other 2..... Quote Link to comment Share on other sites More sharing options...
KiwiDan Posted July 12, 2010 Share Posted July 12, 2010 The reverse gears on the input and output shafts might be different diameters being a different ratio. If the teeth mesh and dont bind during several revolutions it will probably be ok to use the smaller gear. Its not like you will be doing high speed and milage in reverse. Quote Link to comment Share on other sites More sharing options...
Numbchux Posted July 12, 2010 Author Share Posted July 12, 2010 that was my thought as well. maybe I'll be sure not to pull anyone out of a ditch in reverse, or anything like that . Quote Link to comment Share on other sites More sharing options...
Numbchux Posted July 12, 2010 Author Share Posted July 12, 2010 bought a digital caliper. yep, the idler shaft is .04" further from the main shaft on the '01 case than it is on the '88 or '93. and it appears that the teeth on the reverse gear on the input shaft are larger on the RS. so even if I use the smaller reverse gear, I still have .015" less clearance than stock. I'm tempted to run them across the grinder for a moment.....what could go wrong? :-\ Quote Link to comment Share on other sites More sharing options...
Numbchux Posted July 13, 2010 Author Share Posted July 13, 2010 got out the dremel with a sanding drum on it.....and just finished. measured the depth between every tooth, and they all measured between 0.169 and 0.171 (used to be 0.186, old one was 0.170). Did a dry run. reverse engages, and I can spin the input shaft without any noise or binding. definitely an improvement.....I think I'll rock it and see how it works out. Quote Link to comment Share on other sites More sharing options...
Twitch de la Brat Posted July 14, 2010 Share Posted July 14, 2010 Good luck with that. Let us know if anything grenades Oh and if it does, pictures are a MUST. Just out of curiosity, what other differences are there between the two trannys? Twitch Quote Link to comment Share on other sites More sharing options...
idosubaru Posted July 14, 2010 Share Posted July 14, 2010 you're amazing, that's awesome chux, good job! weird subaru would make such a small adjustment. your thoughts on why they'd do that? think it's an RS/model change or newer updates? Quote Link to comment Share on other sites More sharing options...
Numbchux Posted July 15, 2010 Author Share Posted July 15, 2010 from what I can tell, all transmissions went to the taller reverse gear in '99, which is also the year that they changed the center diff. so I assume they're all different. result: something isn't working right. the shifter rod from the RS center section doesn't seem to engage the shifters in the XT6 front case. I'm not exactly sure what's up, but I've come to the conclusion that it won't work.... which means in order to get this car to work at all, I need to find another transmission, tear them both down, again, and install. and still have a car in need of a lot of work that will probably turn into a cloud of rust-dust in a year or so..... going to look at a '91 Integra tomorrow. XT6s are for sale as-is, otherwise I will probably part out the '88. Quote Link to comment Share on other sites More sharing options...
Gloyale Posted July 21, 2010 Share Posted July 21, 2010 EJ swap it and run the full RS trans behind the EJ. done Quote Link to comment Share on other sites More sharing options...
Numbchux Posted July 21, 2010 Author Share Posted July 21, 2010 EJ swap it and run the full RS trans behind the EJ. done logic > you Quote Link to comment Share on other sites More sharing options...
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