will_drift_4_food Posted May 16, 2011 Share Posted May 16, 2011 Okay. This is my first post, and though I did quite a lot of searching before starting it I was unable to find an answer. Other forums I looked at seemed to point me in the direction of HybridZ. I am a RWD Toyota enthusiast, and am putting a Blacktop (s13) SR20DET into my AE86 Corolla. I have purchased a complete SR swap, with long-tailshaft FS5W71C transmission. I have also procured a short-tailshaft FS5W71C transmission from a Hardbody pickup, unsure of year but I am sure I could find out. I am thinking that is irrelevant, though. I bought the short trans so that my shifter would come through the floor in the same place as the T50 transmission that I removed, saving me having to cut a new hole and modify my center console. I was in the process if swapping the bellhousings between the Nissan transmissions when I found what appears to be a "missing" bearing on the countershaft of the short tail trans (see pictures). Top picture is my short tail and the bottom is the long tail. The new transmission attached to the SR is extremely clean inside (and has a bearing installed where the other does not), so I want to know if I can just swap the output shafts between the two transmissions and use the front mainshaft and countershaft assemblies from the SR trans. I have compared the exploded gear component diagram for both the long and short transmissions, and it appears that the output shaft from one is simply longer than the other; the gear spacing is the same. Can anyone confirm or deny this? Also, the shift forks in the long tail (newer) transmission seem beefier. This is my other motivation for wanting to swap the shafts. Any ideas or input welcome. Jason Quote Link to comment Share on other sites More sharing options...
rossman Posted May 16, 2011 Share Posted May 16, 2011 You have both transmissions so why don't you measure the gear spacing yourself? Quote Link to comment Share on other sites More sharing options...
will_drift_4_food Posted May 16, 2011 Author Share Posted May 16, 2011 (edited) You have both transmissions so why don't you measure the gear spacing yourself? Only because I ran out of time before having to report back to work for the week. I plan on doing that as soon as I get the chance, but I thought someone else here might know something that would clear things up for me, like "That truck tranny never came with a countershaft bearing" or "that'll never work because the rods that hold the shift forks are a different diameter", etc. With most Toyota transmissions, swapping the bellhousing does not require opening of the case, so this is uncharted territory for me and I'm not sure I know what to look for from a compatibility standpoint. Nice build thread, BTW. Edited May 16, 2011 by will_drift_4_food Quote Link to comment Share on other sites More sharing options...
will_drift_4_food Posted May 16, 2011 Author Share Posted May 16, 2011 I'm not sure I know what to look for from a compatibility standpoint. A better question might be, what is required to remove the output shafts from these transmissions? Complete dis-assembly of the mainshaft? Or is there a trick to be learned here? If complete dis-assembly is required, I'll need some bearing and gear tools. What specific tools (at a minimum) would be required? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Nigel Posted May 17, 2011 Share Posted May 17, 2011 I'd be really shocked if there was no bearing at the front of the counter shaft. What does the inside of the truck bellhousing look like? Here's a picture of the inside of a long shaft box bellhousing: At the very least, I would expect a bushing in the truck bellhousing where the 62mm dia countershaft bearing would ordinarily go. If you were to try to swap the gearset from the long shaft to the short shaft, you would have to pretty much completely disassemble both transmissions. You can download a 240SX service manual for free from http://carfiche.com/manuals023/cars/, which have transmission rebuild instructions so you can get an idea of what's involved. Keep in mind that the 71C transmission continued to evolve even though the designation didn't change. The later model boxes have significantly wider gears than the earlier one for example. So there's no guarantee that a gearset from one would work on the other mainshaft from the other or from a long shaft to a short shaft box. You'll probably just have to try it and find out. On a side note, it's interesting how much bigger the 3/4 shift fork is in the SR box. To the best of my knowledge, the SR and KA 5 speeds have the same gearsets, but it looks like the SR is beefed up in some other ways. I wonder what else is different? Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
will_drift_4_food Posted May 17, 2011 Author Share Posted May 17, 2011 (edited) I'd be really shocked if there was no bearing at the front of the counter shaft. What does the inside of the truck bellhousing look like? Here's a picture of the inside of a long shaft box bellhousing: At the very least, I would expect a bushing in the truck bellhousing where the 62mm dia countershaft bearing would ordinarily go. Well, though I don't want to admit it, there apparently was a bearing on the countershaft. Apparently it fell off during disassembly when the tail section was lifted off of the bellhousing. It must've rolled underneath the dolly and we didn't see it until today. I suppose that it isn't good that it just fell off, either. After I tap it back on, it comes off easily when I pull on it. At any rate, I'm still very interested in reusing the internals from the other transmission, I just need to make sure that the component spacing and shaft diameter are the same. Is there any chance that the output shaft from the shorter transmission can be welded to the mainshaft of the SR transmission? At this point, it would be nice to just be able swap the shaft for the shifter extension and change the output shaft to a shorter one. I'd also have to tap the case somewhere for a vent since the current vent tube (for the SR trans) is in the rear housing of the transmission. Picture with bearing reattached: And the inside of the truck bellhousing (irrelevant now, I am sure): And the inside of the SR20/180sx bellhousing (housing rotated 180deg): Interested in the general community consensus of cutting/welding the output shaft vs swapping components between shafts. What does everyone think the best plan of attack is here? Cut and weld? Disassemble mainshaft components and reassemble new components on old (shorter) shaft? Also notice in the pics of the front covers, only the SR20 has a visible ring where the countershaft bearing was. This ring is absent in the photo of the short transmission, which is another reason we thought that it might have just been "missing". Thanks in advance. Jason Edited May 17, 2011 by will_drift_4_food Quote Link to comment Share on other sites More sharing options...
rejracer Posted May 30, 2011 Share Posted May 30, 2011 I would not weld on the shaft, rather swap components assuming they are compatible. Once you get into teardown, it's not that bad. I am assuming that when welding the shaft, you would have it torn down anyway. Shafts are not just like welding normal steel if you want them to be strong. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted May 30, 2011 Share Posted May 30, 2011 (edited) I think the truck transmission is called the FS5W71G. Edited May 30, 2011 by HowlerMonkey Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 30, 2011 Share Posted May 30, 2011 The truck transmission is still the FS5W71C, the G suffix is for the transmissions that have a bolt flange for the transfer case. There is also the FS5W71H, which is also used in the trucks and 200SX cars, but I'm not sure if that denotes short-tail/long-tail/adamantium gearset/butter syncros etc. Quote Link to comment Share on other sites More sharing options...
Xnke Posted June 17, 2011 Share Posted June 17, 2011 Ok, my bad. The designations are, as best I can find in dealership reference books and transmission rebuild books, as follows: "G Box"-this is the Xterra version of the trans "E Box"-this is the Newer Frontier version of the trans "H Box"-This is the 240SX version of the transmission, used with the KA24, and also with the SR20 "C Box"-This is the 200SX/300ZX/Hardbody transmission, used in the 200SX, 300ZX, and pickup trucks from 1984-1988 Other than specific chassis modifications, your best bet is to take both transmissions apart completely, lay them out side by side, and move everything over one part at a time and build a transmission from the parts on hand, to the spec you need. All the revision letters are available in long tail and short tail, and all of them could be had with integrated transfer cases; depending on the market and model. Quote Link to comment Share on other sites More sharing options...
will_drift_4_food Posted June 17, 2011 Author Share Posted June 17, 2011 (edited) Thanks for that info. I decided to swap the bellhousings and see how long my used truck tranny lasts. It's good to know that the short tail transmission came in a variety of vehicles. I think I will likely source another one and rebuild it after I get the car up and running again. Also, where can I find these Adamantium gear sets? FWIW, I'd prefer them to be straight-cut gears, with diamond synchros. If this is not currently in production, I will immediately begin AD synthesis and call my new company Weapon-X. Edited June 17, 2011 by will_drift_4_food Quote Link to comment Share on other sites More sharing options...
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