toyoz Posted January 4, 2008 Share Posted January 4, 2008 I am in the planning and parts collecting stages of building a '71 240Z with a Lexus 4.0 engine (eventually to be twin turboed). I have a mildly built 700R4 that I plan to use. What I would like to know is (I have done a search, unsuccessfully) has anybody tried to use a C4 Corvette rear end? I know some people have used the entire Corvette assembly, but I would like to do is cut off the existing arms and machine the rear cover flat (would require some spacers in some areas) and manufacture a mustache bar to fit. I would then use the stock Corvette/Camaro ladder bar to connect the engine/transmission to the rear. By doing this, one would eliminate the rear transmission mount and front rear end mount. This would free up more room for exhaust. I haven't actually measured yet, but there may be room to run an exhaust over the inboard rear axles by machining holes through the mustache bar. There would be a lot of advantages in doing this -- instant correct rear end alignment/weight/more ratios, and, of course, positraction. For those of you running mega-power, you would have the option of running the big Dana 44 rear. Adapting the rear swing arms and axles shouldn't be any problem. I would appreciate any thoughts on whether or not this seems like a feasible option. Thanks. Ernie P.S. So that you will know that I am not a total pipe-dreamer, pictures of my 240 and the Lexus engine and some of my other cars are at www.kaneva.com/mytoys Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted January 4, 2008 Share Posted January 4, 2008 Hey Ernie, how's it going! I'm glad you started your Z project, can't wait to see it! Scottie used a C4 rear in his Z. Here are his links: http://home.cfl.rr.com/scottiegnz/gnz.html http://www.turbobuicks.com/members/scottiegnz/vette-irs-swap.htm Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted January 4, 2008 Share Posted January 4, 2008 The few documented swaps have used the whole assembly (like Scottie). But I do remember an ad for a Z with just the Corvette pumpkin and the stock Z everything else. The ad included pictures. However I have never seen a write up or any details of what is involved with that swap. So yeah, it can and has been done, but not a lot of details on this site. That should tell you something. You might be better off sticking with a positraction R200. Or an R230 if it just has to be bigger. Quote Link to comment Share on other sites More sharing options...
V8ZRACER260Z Posted January 4, 2008 Share Posted January 4, 2008 Scottie's set up is great for drag racing as we all know. Also his set up does not require as much surgury as mine. I have a C4 diff but I went with a new subframe, set up more for road racing. It raises the diff higher to lower the center of gravity. You could do it as a back half without the ful tube frame. The rear subframe was built by Randy Hunter of Hunter Kit cars located south of Ocala Fl. Either set up will work just depends on what you goals are for the car. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted January 5, 2008 Share Posted January 5, 2008 There was a gorgeous blue V8 Z at the inaugural SEZ that had exactly what you are looking to do. Did not get a chance to check it out closely and do not believe he hangs out here. Only thing I remember is that he was using the stock Z halfshaft and broke it. What a surprise My FC RX7 had exactly what you are trying to do with custom inner stub axles, (see pic below) allowing use of stock RX7 TurboII CVs which are very strong. I understand what you are trying to accomplish but not sure if it is the best option for you. I did it because I needed a very high ratio (3.07) with an LSD. The DANA36 diff was only available with 2.59, 2.73 and 3.07 ratios. There was supposedly a rare 3.20s ratio but never seen or heard of anyone having one. Aftermarket 3.54 ratio is available for about $400. Yes, the DANA44 is stronger and has more availble ratios but you will need a king's ransom to get one. Fitting the moustache bar assembly on the D36 rear cover is probably not doable as the mounting holes in the center of the cover are probably not strong enough. See the pic below. You do have other options in the Ford 8.8 used in the T-Bird SC and late Explorers which is also aluminum case. Your other option is sticking with the R200 if you can find a LSD. None of the options are easy/cheap. The D36 diffs are cheap but will require a lot of mods to make it fit and tricky/expensive to solve the axle issues. No point in doing this and end up using stock halfshafts. The 8.8 diffs are even cheaper and should be easier to mount the moustache bar assembly but you have the same CV/axle issue. The R200 is the easiest but probably the most expensive as you need to find an L$D, R&P if you need taller than 3.54 and the CV adaptor kit. Not trying to discourage you in anyway just pointing out the reality. Unless you are a fabricator and can weld aluminum and have access to inexpensive machine work, the R200 might be your best option since you can get the car going for nothing and keeping searching for the necessary parts. Good luck. Quote Link to comment Share on other sites More sharing options...
Titus_RacerX Posted January 5, 2008 Share Posted January 5, 2008 that's too nice of a car to cut up! Leave it as Nissan designed it! Nice Mustang btw! Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted January 5, 2008 Share Posted January 5, 2008 that's too nice of a car to cut up! Leave it as Nissan designed it!Nice Mustang btw! I thought this is Hybrid Z? Quote Link to comment Share on other sites More sharing options...
toyoz Posted January 5, 2008 Author Share Posted January 5, 2008 Guys - Thanks for the input. Scottie - I have a lathe, mill and mig & tig welders at home. The plan is to cut off the arms and mill the rear housing as flat as possible and manufacture spacers for the lower holes. You could conceivably use every hole as a mounting hole for the new mustache bar. The new bar would no longer be in flex as the rear end would be bolted to the transmission via the ladder bar. The only welding that would be necessary would be to the axles, drive shaft, and possibly the ladder bar. I hope this makes sense -- it is hard for me to verbally explain exactly what I have in mind. The car is primarily going to be used for street use and will probably never see any type of competition. I have a brand new 8.8 Cobra rear end with 3:27 positraction sitting on the shelf here at home, but after doing a lot of looking and measuring, I still think the Corvette would be the easiest option. Again, thanks for everyone's input. Ernie Quote Link to comment Share on other sites More sharing options...
Titus_RacerX Posted January 6, 2008 Share Posted January 6, 2008 Dang Six_Shooter, I forgot what forum I was on. My bad! Cut away! Quote Link to comment Share on other sites More sharing options...
quicker240 Posted January 6, 2008 Share Posted January 6, 2008 That car ,until a month ago, belonged to a aqaintance of mine.He started with the Vette diff only and a shortened to fit rear mustache bar.He was destroying halfshafts at will.He had custom HD axles built.Started breaking stub axles(like he did at SEZ1).Installed some Cryo-treated 280Z stubs.Could never launch the car without breaking something,but he was hell from a 30mph roll.A few weeks ago,I see the car again.Its on the lift.The rear diff housing(the gear case part) is broken in half.Needless to say,when it let go,it tore up most of the custom parts at the rear of the car,axles,diff mount,mustache bar etc,etc,.Sonny,the owner, had broken it,got pissed,sold it broken to a friend of his for 16k.The new owner had it fixed within 2 weeks.As far as I know,its back on the road.A real nice car and a good deal for the new owner.The moral of the story is,if you are going with an independant rear end and plan on launching the car regularly,you can expect some breakage.Ind. rear ends work great for road cars,not so great for drag cars.Although members here have done much development and improvement,there still is not a real "bulletproof" set up,at least for any senseable amount of money.Sub 1.4-1.5 60' time put huge stress on the rear.With Turbos and and auto,you will likely not be stressing it quite so bad as the Clutch Dumpers,but add a big stall converter and/or a trans brake and you're in for breakage.Just my .02cents... Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted January 6, 2008 Share Posted January 6, 2008 quicker240Z, sorry to hear Sonny had so much problems. I ran the D36 diff in the RX7 until a coule of weeks ago then retired that setup. Never broke a outer stub or CV but the FC RX7 units are stronger. Over the last couple of months I broke teeth of a ring gear and then off spider gears. Nothing wrong with the setup but with an estimated 650rwhp and a 100-shot off the line, I was way past the limit of the D36. Ernie, I know exactly what you are saying and glad we can talk on that level. I understand exactly what you are thinking and assume by "ladder bar", you mean a torque arm in the tranny tunnel. I still would not mount the rear of the torque arm on the rear cover though. Here are a couple of other ideas: Forget about the moustache bar and hang the diff with brackets to use the diff cover eyelets either like I have in the picture in my 1st post with the cover shortened. You could also leave the batwing uncut and hang it like I have in the pics in this post. Uncut, the batwing eyelets end up under the longitudinal frame rails and you can see how I made those brackets. Sorry I do not have better pics of that but sure you will get it. For the torque arm, consider making the original C4 aluminum torque arm work. It goes over the nose of the diff and connects to a TH700. It is kinda big and might not fit in the tunnel. We tried that on FD RX7. If it does not fit, you could mod it to fit. If you do not have access to one, I have one you can use for trial fit if you pay for shipping it to you. You might also consider making your own torque arm similar to the one in the pic. That is what I will be using on my 8.8 solid rear swap i am working on. Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted January 7, 2008 Share Posted January 7, 2008 That's a great looking solid set-up there Scottie! I have no doubt that Ernie can make it work, what ever it is! You should see his other cars! Quote Link to comment Share on other sites More sharing options...
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