69sroadster Posted September 4, 2013 Share Posted September 4, 2013 I've read about this in a few places and am pulling the trigger on trying it out. I have an SR20 in the ZX that has had previous abuse in Japan before delivery to my garage. I've also added some wear to it over the years and they don't have a good reputation for lasting very long in any car. A few places offer an adapter plate for putting a 350z 6 speed behind the SR motor which requires me to shave down the "new" transmission a bit to make up for the plate thickness. I get to keep the SR clutch. So I ordered a used 350 6 speed and driveshaft to get the output yoke swapped onto my existing hybrid shaft. I suspect I will have to rework the transmission mount and clutch line to get to the other side of the box. From research this transmission should be very stout and comes with a close ratio set of gears. I've always hated the SR 5 speed spread from 1-2. Maybe after I get this done it will cooperate and stay in the power band better at the local auto-x events with those tight turns. Either way I will be sharing how this adventure goes over the next few weeks. Total cost should still be below $1500 for the swap. -Sam Quote Link to comment Share on other sites More sharing options...
tooquick260 Posted September 4, 2013 Share Posted September 4, 2013 I put the S15 sr20 6 speed in my car. Really tight gear set, especially with a 4.09 rear dif from z32 n/a. Zenke on hybridz did the customization to make it fit for me. Spent about the same thing you are for tranny and altercations to bellhousing. Manual transmissions will hold up to alot of HP just can't handle maximum shock. Dad ran a stock VW transaxle with only a super diff in his VW's for years. 180hp he would end up spinning the 3rd/4th gears on the shaft (only pressed on). Did brake main shafts, first gears and rear ring and pinions. He said spin to win. If it ever hooked hard, start pulling the wheels off the ground breakage was certain. I ran that 6 speed in my 95 240sx with a 350(flywheel)HP no issues. The 350z should be almost bullet proof, just as all parts the weakest link will arise to the top. Good luck should be a fun install. Quote Link to comment Share on other sites More sharing options...
R3VO 3VOM Posted September 4, 2013 Share Posted September 4, 2013 I have a 240SX as my daily driver and am looking into all the SR stuff for that. From what I've read, the SR 6 speed is weaker than the 5 speed. Not sure if thats true or not, but just what I've heard. tooquick260, how did you get around the speed sensor with the S15 6 speed? Because isn't the speed sensor in the differential for those transmissions? Either way, 350Z 6 speed will be awesome. Expensive to buy all the parts though. Good Luck! Quote Link to comment Share on other sites More sharing options...
tooquick260 Posted September 4, 2013 Share Posted September 4, 2013 To solve the speed sensor issue for the 240sx I got a J30 rear LSD with ABS. I then bought a digital dakota converter. Plugged into the ABS sender on the snout of the diff to the converter. Then converter to the speedo input. Converter Has 6 settings that will get the signal close to the speed signal for your car. Then there is an up/down button that you fine tune with. I think I had it about 1 mph off of true mileage per gps. For the S15 Sylvia 6 speed that is in my 260z, Zenke was able to drill out the speed sensor hole and slide a gear from a frontier truck in for a mechanical drive. This allowed to screw the speed cable of the 260z directly into the tranny! Works well! Yes the speed sensor is in the nose of the rear diff and they are all helicoil lsd's I believe they have one now that doesnt need the input from a source but can coordinate with GPS! Thats the way I would go. Quote Link to comment Share on other sites More sharing options...
Xnke Posted September 5, 2013 Share Posted September 5, 2013 The Aisin AZ-6 6 speed transmission used behind the SR20 can reliably handle 300HP all day, every day, in a Z car. The problems with this transmission start with 4th gear, since it's reverse helical cut and is held in place by a funky little two-piece retaining clip, that will give way and allow 4th gear to walk forward INTO THE REVERSE GEARSET! This is just unfortunate design, but it is what it is. The 2-piece clip can be welded to the mainshaft (prevents any further rebuilds, unless you're magic!) and the transmission is as strong as the FS5W71C that is installed as the 5-speed option. Don't shock-load either of these transmissions or you WILL break them at the 300-350HP level. Tip: This 6 speed is the same unit installed in the NB Miata, the Scion FRS/BRZ, and the Toyota IS200. They are all internally similar, except the Toyota output shaft spline is different, the gear ratios vary between them, and ONLY the early SR20 or Nissan Competition transmissions can be modified to allow the Z's mechanical speedometer drive. Quote Link to comment Share on other sites More sharing options...
tooquick260 Posted September 5, 2013 Share Posted September 5, 2013 Thanks znke for clarifying the differences Quote Link to comment Share on other sites More sharing options...
69sroadster Posted September 5, 2013 Author Share Posted September 5, 2013 Thanks for all of the good info and the tips about possible ways to work another manual speedo sensor into the 350z 6 speed. I was just going to live without a speedometer after building a reference of speeds by gear/rpm and a gps. I thought about getting one of those GPS driver units but they're not inexpensive. From what I've seen those 350z transmissions have been standing up to a lot of abuse in 500+hp v-6's on the track. I know they've done some revisions to them over the years so will have to see if the used on I'm getting is okay or needs some technical service bulletin action. It looks like I won the ebay bid on it and it came to about $700 shipped. I've got the driveshaft too for another $80 to get the front yoke. Add in $400 for the adapter plate and a few more for the shave on the bell housing. We'll see how much work fitment will be for the mount/shifter. On the S15 6 speed is the clutch a pull type instead of the push type? Quote Link to comment Share on other sites More sharing options...
tooquick260 Posted September 5, 2013 Share Posted September 5, 2013 S15 wash same as the s130,s30 tranny. Quote Link to comment Share on other sites More sharing options...
Xnke Posted September 6, 2013 Share Posted September 6, 2013 After the bellhousing conversion, the AZ6 behind the L28 uses a stock clutch. You do not have an L28, you're using the SR20...so you could go either way. I do not convert the 350Z 6-speed currently, due to adaptor plate issues, however the 350Z uses a push-type clutch, same as the L28...I am running a 350Z clutch in my car currently. Quote Link to comment Share on other sites More sharing options...
69sroadster Posted September 12, 2013 Author Share Posted September 12, 2013 What is the diameter of the 350z clutch? I seem to recall the SR20 was 240mm. Quote Link to comment Share on other sites More sharing options...
69sroadster Posted September 21, 2013 Author Share Posted September 21, 2013 Just got the 350z 6 speed and it's mount and shifter in the mail. First glance it seems a little bit thicker height wise than the SR 5 speed. I have to wait on the adapter plate for a few more weeks to try all of this out. I also will be replacing the 7 year old SPEC clutch for the SR that is finally starting to slip. I can't remember what marketing gimmick "stage" it was but I can't complain that I beat on it for those 7 years. I'm going to use an ACT HD PP + 6 puck sprung clutch kit to replace it and be ready for the extra torque I'll have in a year or so. No better time I guess than while I have the transmission off anyways. Quote Link to comment Share on other sites More sharing options...
69sroadster Posted October 8, 2013 Author Share Posted October 8, 2013 Well, I need some recommendations on where to go and what to ask for to finish some of the drivetrain updates. All of the local machine shops are saying they can't help me out and don't offer any solutions. 1) The 350z 6 speed does not have a removable front bell housing and needs to be milled down about 5/8". Nobody thinks they can cut it back this way. 2) My Z31 cv axles need to be shortened and nobody wants to help cut them. I can disassemble them and have the actual shaft in the middle ready to go. From anyone who has done something similar or is a experienced machinist, what do you recommend I do now? Sam Quote Link to comment Share on other sites More sharing options...
tooquick260 Posted October 9, 2013 Share Posted October 9, 2013 Sent it to Xnke, He can do it! Quote Link to comment Share on other sites More sharing options...
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