C.A.R. Posted October 29, 2008 Posted October 29, 2008 (edited) I thought I'd post this up here as I've had a few people ask about the conversion & I've gotten sick of directing people to the FAQ thread on Ozdat... Please note: the S13/R31 gearbox is only a evolution of the Zed box.Meaning it's only marginally stronger than a 240/260Z box. But it does provide a cheap & readily available conversion. Please note:If you have an early Zed ('70 - '71) that was originally equipped with a 71A gearbox (gearbox cross-member bolts are bolted vertically into the car), you'll need to use the S13/S14 gearbox. If you have a later 240Z/260Z that was originally equipped with a 71B gearbox (gearbox cross-member bolts are bolted horizontally into the car), you'll need to use the R31/R32 gearbox as it is 40-50mm shorter & allows the shifter to come out in the correct spot..BIG thanks to Dave & Richard for writing the article!SR gearbox onto L tutorial.Parts Required:L6 gearboxSR/CA gearboxNew L6 gearbox countershaft bearing (optional) Part Numbers: 63/22C3, TMB3/22C3, or 22BC0655X. Call CBC (www.conbear.com).Specific Tools Required:16mm drill bitDremel with a small grinding disc.Optionals: 16mm H7 reamer bit, 41/64ths drill bit.Step 1:Remove L6 bell housing from gearbox. To do this unbolt the bolts halfway on the gearbox that go from the extension housing through the sandwich plate to the bell. Also unbolt the cover on the inside of the bell that the clutch arm sits on.You will then need to remove the circlip on the front of the input shaft bearing. Use circlip pliers and a screw driver.Put everything aside as you will be using some of it again.Remove SR/CA bell housing from gearbox following the same procedure.Step 2:Remove the SR/CA countershaft front bearing using two chisel point screw drivers to get it started, then lever it off against the bearing (as opposed to the gear) so you don't ruin the gear.Step 3:Reinstall the 240Z countershaft bearing. Either reusing the one from the L6 box, or a new one. Gently knock it down with a rubber mallet.Step 4:Drill out the 1st/2nd selector shaft hole in the L6 bell housing using a 15 or 16mm drill bit then a 16mm H7 reaming bit. Or you could try a 41/64ths bit if you happen to have one lying around (thats what I ended up using).Step 5:Get a dremel/rotary tool and grind away 1mm or so from the countershaft casting on the inside side of the gearbox bell housing. This is necessary as the casting has been modified between the 71B and the 71C to accommodate the wider gears assumedly.You also need to put a chamfer on the edge which is square standard. I made this chamfer between 1 and 2mm big.Step 6:Trial fit this bell onto the SR/CA gearbox being careful of the oil supply cup on the upper passenger side just above the 1st mainshaft gear. Rotate the input shaft by hand. If it is very difficult to turn you need to die grind some more off the countershaft casting in the bell.Step 7:When you can bolt the gearbox up and rotate the input shaft easily you are just about ready to bolt the box together.You could possibly have trouble with the 1st/2nd input shaft not wanting to go into the bell housing because this metal doesn't have any oil sitting on it, I suggest you squirt a dab in there. If the selector doesn't go in it can slide backwards (engaging 1st gear).If this happens and the gearbox shifter is not in the 1st position you won't be able to select any gears (except 5th/Rev) from then on. If putting some oil in the 1st/2nd selector shaft hole doesn't solve the problem, you can put the gearbox in the 1st position before you bolt it up and it will be fine. Worked for me atleast.Step 8:Reassemble the gearbox as you took it apart and you're ready to go. Don't forget the circlip on the mainshaft bearing. Use the L6 front gearbox cover, clutch arm and throw out bearing carrier.Additional issues:The SR/CA gearbox has the bolts for the gearbox x-member around 35mm further back than the 71B box. Depends on your car what you do to fix this. Here is what I did, tad dogey, but it works.This gearbox is also 50mm longer at the end of the tailshaft. I took a tailshaft that was used on a 71B box and had it shortened by 50mm and it fits just fine (after you remove the cover for the front spline as it doesn't fit into the gearbox).Big thanks to Mad1600 for helping me and motivation. Dave (Thehelix). Edited September 27, 2016 by Lurch ™ locklock and Ponyo240z 2 Quote
C.A.R. Posted November 4, 2008 Author Posted November 4, 2008 Guys, I want to keep this as 'factual' as I can. If you've got hard facts, please add them here & I will update the first post. Please don't post general questions & chit-chat. Thanks Quote
waxhead Posted May 29, 2009 Posted May 29, 2009 How much power can this gearbox handle before it splits down the middle and you end up walking home. Quote
dat2kman Posted August 24, 2009 Posted August 24, 2009 The RB20 DE and RB 20 DET box has the same lenght extension housing as a regular L series type extension housing, so, you dont need to worry about getting a tailshaft shortened. The difference between the DE and DET, is the DET ( turbo) box has thicker selectors forks in 1/2 and 3/4, with a better reverse/fifth slide selector mechanism The RB 20 DET come out of the R32 skyline rearwheel drives with the 2 litre six cylinder RB motor ( not the RB25 or RB26 models) The FJ20 DET will also suit this conversion, its ext housing is the stock lenght, it hasn;t got the big selectors that the rb20dethas, but, the same as the rb20de ( non turbo) Bugger, I have like nine assorted boxes all of the above all pulled apart and I should take some pics and LEARN HOW TO JOLLY WELL POST THEM Also I have made up a very neat simple mount to fit these later type box ext housings to our Late 240/260 shells, using the STOCK gearbox metal cross member, two bits of 12mm thick rubber, and a bit of 5mm thick steel plate Quote
Whittie Posted July 15, 2010 Posted July 15, 2010 I followed this procedure and then some when I did my conversion. I have compiled a document about the procedure including missing information around gearbox varieties, gear ratios, fitment, modifications, miscellaneous gearbox information and data and lots of pictures. Unfortunately the document is 1073kB in size (even with ridiculously low picture quality) and I can only upload 1024kB of data to this post. I have uploaded the document to HybridZ and just wanted to share it here as well. The thread can be found here: http://forums.hybridz.org/index.php?/topic/75401-l28-transmission-swap-options/page__view__findpost__p__881963 Quote
juz0 Posted April 27, 2011 Posted April 27, 2011 Just chucking this up for a bit more info I found. detailed step by step (using pictures) on doing an s14 5 speed swap http://www.motortopia.com/cars/1973-datsun-240z-11118/car-pictures/240sx-transmission-swap-14041 Quote
waxhead Posted March 10, 2012 Posted March 10, 2012 300hp at the wheels is about the limit of these gearboxes. Some people will get higher but thats the generally accepted limit Quote
Magnet Posted October 21, 2012 Posted October 21, 2012 How long the these boxes last has more to do with your clutch type, driving style, car weight and grip levels moreso than just a power figure. I've blown several 5 speeds because of running a twin plate with not much power. With a nicer clutch, and slightly careful shifting, anywhere upto 300rwkw(400hp) is doable(with around/just under 400nm torque). Most people swap to a z32/r33 box for piece of mind but they can handle some power. Even 6 speeds which have a rep of being weak can be used for upto 300rwkw with a nice clutch and driven carefully, I recall one guy who was doing just over 300 with a twin plate clutch and not even the circlip mod, pretty impressive. Drifting sorts them out quickly though. Quote
mossy Posted July 29, 2013 Posted July 29, 2013 Going to do this conversion shortly when I rustle up some more funds, I found this link to the conversion with pics which might help noobs like me. http://home.comcast.net/~zheimsothtn/transmission.htm Quote
twoforty z Posted February 1, 2016 Posted February 1, 2016 Ok sorry for a silly question, Once you've done this, you use the L series flywheel and clutch? Not the SR or Rb clutch/flywheel Quote
dat2kman Posted February 1, 2016 Posted February 1, 2016 Yes, leave the L fly and clutch on engine Quote
twoforty z Posted September 27, 2016 Posted September 27, 2016 (edited) Ok, ive almost completed this conversion using a R32 RB20det gearbox on an L28. My 1971 240z has a different crossmember than most which led me to find my own solution for the gearbox crossmember. Im pretty happy with it, so i thought id share I found a 1977 Datsun B310 Sunny gearbox crossmember and with a little modding now bolts straight up. Just need to pack the gearbox up above the mount about 5mm. Once its painted it should look pretty stock Edited September 27, 2016 by twoforty z Quote
C.A.R. Posted September 27, 2016 Author Posted September 27, 2016 Ok, ive almost completed this conversion using a R32 RB20det gearbox on an L28. My 1971 240z has a different crossmember than most which led me to find my own solution for the gearbox crossmember. Im pretty happy with it, so i thought id share I found a 1977 Datsun B310 Sunny gearbox crossmember and with a little modding now bolts straight up. Just need to pack the gearbox up above the mount about 5mm. Once its painted it should look pretty stock Why did you use the shorter RB box? An S13/14 gearbox is approx 50mm longer & would have been better centralized in the shifter opening. Quote
dat2kman Posted September 27, 2016 Posted September 27, 2016 The mount boss on both RB20 and the longer S13/14 boxes, are both in same position, relative to the front edge of the extension housing. Ie, set 30mm further rearwards. (71C "Stumpy" type are not !) The stick on the S13/14 s further rearward than the RB20, you also need to shorten tailshaft. RB20, you dont shorten tailshaft. This Sunny crossmember solves this issue on a 240Z type floorpan, other option is to drill to fresh holes into floor, use stock 240Z bx crossmember, but, a pair of 6mm 75x50 mm plates on the inside, is a good idea. Quote
twoforty z Posted September 27, 2016 Posted September 27, 2016 Why did you use the shorter RB box? An S13/14 gearbox is approx 50mm longer & would have been better centralized in the shifter opening. I had this gearbox on my Rb20 when that was installed, i know its got low kms and is in good condition so decided not to risk getting another gearbox. Shifter centralization wasnt a huge concern, with the RB in it was 30mm forward of where it sits now so its never been central to the original tunnel hole anyway Quote
twoforty z Posted October 8, 2016 Posted October 8, 2016 The finished product, very happy with how it came out Quote
Blue Z Posted May 22, 2017 Posted May 22, 2017 Hi All, I have an RB20 gearbox and I have done the following: 1) removed front cover plate, inside bell housing 2) removed bearing circlip under cover plate 3) removed bolts from sandwich plate holding bell housing on The issue is that I can't take the bell housing off, have I missed something? BlueZ Quote
C.A.R. Posted May 23, 2017 Author Posted May 23, 2017 Have you managed to get a gap to appear between bellhousing & the sandwhich plate at all?If not, the sealant & dowel pins will be holding it.Put the input shaft on a block of wood, hold the gearbox vertical & with a soft-face / copper hammer, hit the bellhousing downwards. Quote
Blue Z Posted May 23, 2017 Posted May 23, 2017 Thanks Lurch, Looks like need a big soft hammer to open it up, as you suggest, it hasn't moved yet. Quote
dat2kman Posted May 23, 2017 Posted May 23, 2017 holding it vertical and smacking it, bit like a newborn,,,, I just sit it on a bench, and using a decent soft hammer, work around the bellhousing, (at the bolt hole locations to back of motor) It eventually opens up just enough, to put a widest flat blade screwdriver or biuggered wood chisel, into the opening, and lever it around Quote
Blue Z Posted June 21, 2017 Posted June 21, 2017 Hi All, Good news I now have the bell housing off, I ended up breaking the seal by forcing in an window scraper blade. 1) As I have no shifter does anyone have a recommendation for a short shifter for the RB20 gearbox? 2) Any recommendations for the machining on the L series bell housing in Melbourne? Thanks Blue Z Quote
mossy Posted June 21, 2017 Posted June 21, 2017 (edited) I had my machining done by robco engineering. You could ask Les Collins for a short shifter, my LCR short shifter is very good. Edited June 21, 2017 by mossy gav240z 1 Quote
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