ktm Posted February 12, 2008 Share Posted February 12, 2008 I have really been struggling with the decision to upgrade to an LSD differential or stick with open. I am running a 3.54 R180 (dead diffy spinning at my power levels, or so I've read) behind an L28ET with around 320 wheel ft-lbs of torque. I do not Auto-X nor do I plan to, I may hit up Speedventure a few times a year and I may hit the strip a few times a year, that's it. Current plans are to invest in meth injection and a Lone Wolf intake. I just do not know if I would really see the benefit of an LSD diff. I've been doing quite a bit of reading and have explored all of my options. Cost really is not an issue as much as spending money that I am not going to realize the full benefit. I live in So. Cal. and do not drive the car in the rain (all 20 or so days we get ). Thoughts? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 12, 2008 Share Posted February 12, 2008 An LSD makes a HUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUGE difference in how the car drives, and with the amount of torque you've got I'm sure you'd notice it right away. No more one wheel peel, and the car will pull out of a corner so much harder you'll be shocked. Get an LSD! Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted February 12, 2008 Administrators Share Posted February 12, 2008 Borrowing an old cliche... Just Do It. JM hit the nail on the head. You wont even believe its the same car. Its a 'must have' if the funds are available. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 12, 2008 Share Posted February 12, 2008 Its a 'must have' if the funds are available. Its a must have after you make the car safe and reliable and before you spend a dime modifying anything else on the car. It helps handling and acceleration regardless of how much power you're making. Quote Link to comment Share on other sites More sharing options...
mcmike280z Posted February 12, 2008 Share Posted February 12, 2008 I have had two 76's and they both had stock lsd's that would leave beautiful dual patches where ever I went.....ahh bliss. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 12, 2008 Share Posted February 12, 2008 I have had two 76's and they both had stock lsd's that would leave beautiful dual patches where ever I went.....ahh bliss. Probably not. The 76's didn't come with LSDs stock (none of the Z's did until the 87 300ZX Turbo), and the Datsun IRS will leave two stripes most of the time without an LSD. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted February 12, 2008 Share Posted February 12, 2008 I think the LSD is definitely a must investment at your power levels. Adding more power is nice, but not if you can't hook. Datsun IRS will leave two stripes most of the time without an LSD. I have noticed that too, why is that? Quote Link to comment Share on other sites More sharing options...
mcmike280z Posted February 12, 2008 Share Posted February 12, 2008 ? Jon... does a non LSD diff leave two burn out marks? I will research this but I do believe both 75's and 76's came with r200's that had some type of "posi" system. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted February 12, 2008 Share Posted February 12, 2008 They did not. First LSD for a Z car was the 1987 300zx Turbo. My most recent 240z purchase leaves two black marks, it is the stock R180 open (confirmed by axles turning freely when jacked up in the air). Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 12, 2008 Share Posted February 12, 2008 ? Jon... does a non LSD diff leave two burn out marks? I will research this but I do believe both 75's and 76's came with r200's that had some type of "posi" system. Not usually, but the IRS that we use does. There haven't been any in a while, but I've seen probably 10+ posts over the years that say "My Z has a posi!" and then they figure out that these cars will just leave two stripes. The better test is crank the steering wheel all the way and then try to leave two stripes. 75's and 76's definitely did not come with any sort of LSD, at least in the US. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted February 12, 2008 Administrators Share Posted February 12, 2008 ? Jon... does a non LSD diff leave two burn out marks? They can, and often do, in a straight line. I will research this but I do believe both 75's and 76's came with r200's that had some type of "posi" system. Sorry, not from the factory. Quote Link to comment Share on other sites More sharing options...
mcmike280z Posted February 12, 2008 Share Posted February 12, 2008 Thanx for the input guy's... every now and then you go through life thinking you new something than wham! it hits you. Your not as think as you smart you are. LOL! I always thought the "limited" in limited slip meant your rear end would lock up in a strait line but free wheel one side or the other through the corners. I have had several vehicles that have only spun a single side no matter how you pointed them. Quote Link to comment Share on other sites More sharing options...
olie05 Posted February 12, 2008 Share Posted February 12, 2008 In defense of lower powered cars at high speeds: [quote name=Nick Adams' date=' Vehicle Development Manager for the Fed. Elise On Limited Slip Differential] The Elise was always designed from the outset to work without an LSD. We have recently started to offer an LSD as an option on the Toyota engined cars, primarily in response to market demand from the Autocross enthusists in the USA, who need one to be competitive when accelerating away at full throttle from very slow, tight corners in first or second gear. In this type of competition they do not tend to run high speed (100mph +) corners and therefore the increase in understeer on this type of corner which you get with an LSD is of little negative consequence to them and they therefore are better off with an LSD. In our experience an Elise or Exige equipped with an LSD is at a disadvantage to one without an LSD on a typical European race track. On top of that the LSD bluntens the steering feel and repsonse of the car which we don't like. If you want an LSD then by all means fit one, but please understand that there are negative as well as positive effects. In the instance you describe, instead of spinning the inside wheel as you accelerate away at full throttle (which can be easily fixed by modulating the throttle! Very Happy ) a car with a 2:1 LSD like the obne we supply will provide twice the torque to the outside wheel as it does to the inside one. This will increase the slip angle of the outside wheel and the car will tend to oversteer heavily on corner exit, requiring a reduction in throttle if you are not to spin.... It isn't much quicker, honest. The optional diff we supply is a Torsen unit, the aftermarket unit supplied by Motorsport is a plate diff, with a similar 2:1 bias and no preload so in terms of action it mimics the Torsen closely. I know this only applies to light, low powered cars, at higher speeds, but there is something to be taken from this excerpt. non-open type differentials do tend to bring the car back to a straight line under full traction in the middle of a corner. With the rear suspension designed NOT to lift the inside wheel (soft or no rear sway bar) in theory good traction can be had, and a limited slip type differential is not necessary. Of course, in practice, and in the world of high powered zcars, everything is opposite Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted February 12, 2008 Administrators Share Posted February 12, 2008 Olie, Interesting article. In general, there is some truth (with respect to autocrossing), but its just not reality in most cases. Have a look at National results. There are no 'fast' cars with open diffs. Not FWD or RWD. Admittedly, some people are successfull on 'light' diffs, but not commonly with open diffs. Its very rare. An example might be open-wheeled cars, with their low CG's/wide track/aero, but production based cars, overall, need LSD's to be competitive. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted February 12, 2008 Administrators Share Posted February 12, 2008 I have had several vehicles that have only spun a single side no matter how you pointed them. Live-axle cars are notorious for that. Quote Link to comment Share on other sites More sharing options...
zedevan Posted February 12, 2008 Share Posted February 12, 2008 i was debating to get an LSD or not too, best money i've spent on the car and that was while using a mostly stock l26! the car behaves the way you expect/want it to instead of occasionally having its own mind. what convinced myself to get one was all the ae86 people talking about just how different their cars feel with one, and how if ppl want to have fun in a ae86 they should put in an lsd before a decent engine. and if you regret it you can always sell it? Quote Link to comment Share on other sites More sharing options...
johnc Posted February 12, 2008 Share Posted February 12, 2008 In our experience an Elise or Exige equipped with an LSD is at a disadvantage to one without an LSD on a typical European race track. On top of that the LSD bluntens the steering feel and repsonse of the car which we don't like. The original 140hp Elise's did not need a LSD on most race tracks for the reason's descirbed above. Similarly a lot of open wheel race cars (Formula Fords, Formula Vees, etc.) that run a lot of aero downforce also run open diffs. But, with the newer Toyota powerd Elise's... here on the West Coast of the US, all of the Elise drivers I know and have worked with have reduced their lap times by installing a LSD in their Elise. Quote Link to comment Share on other sites More sharing options...
ktm Posted February 13, 2008 Author Share Posted February 13, 2008 Thank you all for the comments. I've decided to go ahead and track one down. I had one all lined up and a check cut, but then I was involved in a minor fender bender and had to cancel the purchase. I am now in a position to find one again.....if I can only find one again. Quote Link to comment Share on other sites More sharing options...
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