madden87 Posted March 24, 2008 Share Posted March 24, 2008 I am picking up a 240z this week. I already have most of the parts i need to complete the sbc v8 installation. Now I am trying to decide what differential to use. The motor I am puting in now have under 400hp, but the one I am building with be a little higher. I am not looking to go to a solid axle yet so what is the correct gear ratio I should use in the r200? I am using a t350 tranny. This will be a track car that I may drive on the weekend. I am not worried about freeway speeds because they are not close to where I live. I was looking at the 3.90 or the 3.70. I would appreciate any advise from people that have already tried these in their cars. Quote Link to comment Share on other sites More sharing options...
turbo81racer Posted March 25, 2008 Share Posted March 25, 2008 What kinda track use? Just the straight line or some road aourse action too? Straight line, go with a 3.90 to 4.10 if you can, if you are going to do some solo racing that does not usually reach high speeds (well the ones here by Dallas don't) the higher rear gear would be better for the quickness. But a real road course it might be to high. I use the stock r200 from my turbo 280zx behind my LT1, though I use the 4L60e tranny too so I have overdrive. Its about a 3.60 i believe. Its ok on the drag as well as the solo course, but I drive it daily so i like to cruise ok on the highway too. I do have a r200 from an infinity with 4.10 in it that i have thought of using if I go more track with the car. It really just depends on what you are going to do with the car to what rear gear to use. Quote Link to comment Share on other sites More sharing options...
Pyro Posted March 25, 2008 Share Posted March 25, 2008 get a 3.90. use the proper stall for the cam used automatics are better suited for drag racing. Quote Link to comment Share on other sites More sharing options...
madden87 Posted March 25, 2008 Author Share Posted March 25, 2008 This car is being built to go in a straight line. I will drive it on the weekends once in a while, but I live in Phoenix so it will be too hot most of the year. I was leaning towards the 3.90, but was not sure. The nice thing is if I change my mind and want to drive it on the street more after it is done I can always put in a 700r4. I just have a feeling I won't want to drive this motor on the street no matter what gear ratio I have in it. Quote Link to comment Share on other sites More sharing options...
Pyro Posted March 25, 2008 Share Posted March 25, 2008 if you put enough cam in it, it will not seem like it is over revving when going down the highway. a compcam 292H will pull to 7000 rpm with the right valve springs. That is about 140mph with a 3.90 gear, 26 inch tires, with a 1:1 top gear (3rd gear in a th350). that cam requires a 3000 stall and 10 to 10.5:1 cr and makes 400hp with almost stock heads Quote Link to comment Share on other sites More sharing options...
madden87 Posted March 25, 2008 Author Share Posted March 25, 2008 Its funny that you mentioned that cam setup. My buddy has been build chevy's all his life and is building the motor for this car. That is the cam he said I should run. Nice to here it from someone other than my chevy know-it-all buddy. I found a site yesterday that has all the diff's and cars they came in on it, but I did not bookmark it and now I don't know where it is. Anyone have this information? or at least which cars came with the r200 3.90. Quote Link to comment Share on other sites More sharing options...
Pyro Posted March 25, 2008 Share Posted March 25, 2008 81 to 83 280zx with 5 spds have the 3.90's. the 292H has a rough idle. makes great power after 3000 rpm. works great with a rpm intake and a 750 holley 3310. Quote Link to comment Share on other sites More sharing options...
Nealio240z Posted March 27, 2008 Share Posted March 27, 2008 Im running the exact same set up... 3.90:1 diff, th-350, 330hp sbc 350. 60 mph will put you at 3,000 rpm exactly for crusing. (27' tall tires) you will pull off the line like crazy, and go through all 3 gears before you reach the otherside of an intersection wit normal acceleration. Iv done many diff swaps in my car and i like the 3.90:1 diff the best. Its perfect for the track also... 6k rpm puts you at about 118-120 mph. Quote Link to comment Share on other sites More sharing options...
madden87 Posted March 28, 2008 Author Share Posted March 28, 2008 Thanks for that last reply. The set up seemed right to me, but I was hoping someone else has run it so I did not have to do what you did and try them all. What kind of time were you pulling at the track? Your motor sounds similar to the one I am putting in first. Quote Link to comment Share on other sites More sharing options...
Pyro Posted March 28, 2008 Share Posted March 28, 2008 I ran the 292H with a 350 (362 cid) 11:1 cr, rpm intake, holley 3310, full length 1-5/8 headers, dart 200cc iron eagle heads, 2-1/2 dual exhaust with areochambers, 3.90 r200, gm t5, 26x8 my drag tires on 15x 8 rims. ran 11.7's at 120 and 10.7 at 135 with 175 shot n20. 120 mph should be considered the safe limit for the stock rear end assembly. engine pulled hard to 7000 rpm but got my best et's with 6500 shift points. Quote Link to comment Share on other sites More sharing options...
Nealio240z Posted March 28, 2008 Share Posted March 28, 2008 I cant hook worth beans... On street radials I spin in first and secons, I can mash it in third and still manage a 13.4 @ 102. Going with full slicks this year- Im sure ill be in the 12's Quote Link to comment Share on other sites More sharing options...
Belvedere Posted March 29, 2008 Share Posted March 29, 2008 I have 700r4 tranny behind my 89 350TPI motor. Low gear in a 700R4/4L60E is 3.06 with an over drive of 0.70. Low gear in a TH350 is about 2.48 with high gear being 1:1. The V8 will have a little more torque than you think. I typically will leave in low gear and hit second about at just about the tree or even start out in second when I use street tires. Drag radials will allow you a little more room to stay in low before shifting. 3.54's will give you a fairly good launch with an overdrive transmission. Figure 3.06 x 3.54= 10.83 for launch ratio. To get that launch ratio with a TH350 you would have to have 4.36 gears. (10.83/2.48 = 4.36) Ok that's cool, now figure the over drive part of it. 3.54 x 0.70=2.48. So with a TH350 overall gear ratio in high would be 3.54 with an overdrive tranny it would be like having 2.48's in the rear. Therefore...sigh...if you use a TH350 I would go with low gears like 3.90 or 4.11 and complain about the gas miliage because you will buzz the V8 going down the highway. If you go with the over drive tranny use 3.54 or 3.70's, get a harder launch and better fuel economy. At 70mph I'm taching a little over 2000rpm. The only bad side to an over drive tranny is they don't like much over 450hp in stock form. They can be built for more. I also run a lock up 3000rpm torque converter built by Chance Racing Converters. It made my car launch a little too hard with stock tires, but softened the hard hitting shifts at low rpms around town. The shift kit is still quite present at upper rpms. The lock up converter helps out in overdrive and make passing up high price gas a little easier. My motor is bone stock (100k+ miles on it.). The car weighs 2805lbs. It runs 13.0s all day and has 1.75 sixty foot times. It also gets about 28mpg on the highway. For some real Banzia running find a set of 3.36 gears. That's like having 2.35 gears with the overdrive!!! Quote Link to comment Share on other sites More sharing options...
Phantom Posted April 3, 2008 Share Posted April 3, 2008 I'm running a T56 behind my 390HP LS1 so this won't be exact but I'd go with the 3.70's. My 280Z is porked out to 3,000 lbs with 1560 on the tail and I still can't control wheelspin/hop in first with a 3.70 LSD on street tires, even with a gentle launch. Second gear still has a significant amount of wheelspin but it's controllable. Might be OK if I was running slicks but then I'd be breaking u-joints on the half shafts routinely instead of just occaissionally. Quote Link to comment Share on other sites More sharing options...
Ptn.Ramsey Posted June 5, 2009 Share Posted June 5, 2009 Dont know if this helps but I have a differential from a 280zx and around 70mph it screams like crazy. Guess the t350 is working against it as well. Are differential shops able to rebuild our differentials Quote Link to comment Share on other sites More sharing options...
graphicjunkie Posted June 15, 2009 Share Posted June 15, 2009 Its funny that you mentioned that cam setup. My buddy has been build chevy's all his life and is building the motor for this car. That is the cam he said I should run. Nice to here it from someone other than my chevy know-it-all buddy. I found a site yesterday that has all the diff's and cars they came in on it, but I did not bookmark it and now I don't know where it is. Anyone have this information? or at least which cars came with the r200 3.90. [url=http://zcarpartsindex.com/index.php?title=Differential_Listing][/url]http://zcarpartsindex.com/index.php?title=Differential_Listing Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted June 20, 2009 Share Posted June 20, 2009 Diff info [url=http://forums.hybridz.org/showthread.php?t=145174][/url] http://forums.hybridz.org/forumdisplay.php?f=62 http://forums.hybridz.org/showthread.php?t=145174 Quote Link to comment Share on other sites More sharing options...
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