neotech84 Posted August 20, 2009 Share Posted August 20, 2009 Ok so I have searched and read a lot of useful threads about gear ratios from the different rear ends. I know what models they come from and some general information on each. I am not an expert nor have I experienced many of the choices out there. I am looking for your opinion on gear ratios. I have most of my knowledge from these helpful threads: The sticky about general options and basic knowledge, http://forums.hybridz.org/showthread.php?t=114798 The still growing list of options and the source, http://forums.hybridz.org/showthread.php?t=103512 I want to know what you have (or rode in). Please list your specific details (engine tranny ect.) and..... 1. What ratio you have now? 2. What ones you have used? 3. Why you picked it? 4. What would you change? 5. Are you pleased with it? Any other USEFUL information ect. This is not to find the "BEST" but to find what your general opinion is, positive and negative, on each ratio. Please help me out here I think this will be a great tool for others and not just to answer my questions. If this thread dies how sad, but if you think its good the by all means keep the info coming!!! Quote Link to comment Share on other sites More sharing options...
zedman240 Posted August 20, 2009 Share Posted August 20, 2009 With an L28 and approx 240ish Hp, and a 260 gearbox with the 2.9 1st, had a rear end ratio of 4.3 that was great for accelarating but for some long tracks, ran out of rpm's! Settled for a 3.9 which is a good all rounder. Ultimate would be to swap between a 4.1 - 3.9 depending on the track. Both are CLSD's. It all depends what you want to do with the car and engine/drivetrain combination you have. Quote Link to comment Share on other sites More sharing options...
neotech84 Posted August 20, 2009 Author Share Posted August 20, 2009 Good info! thanks The 3.9 is a favorite for most with a N/A L serries. Quote Link to comment Share on other sites More sharing options...
Mayolives Posted August 20, 2009 Share Posted August 20, 2009 Your particular application would determine the required ratio. Drag racers normally run lower ratios in order to be "wound up" at the end of the track. Road racers with high hp, na setups or turbo engines can benefit from higher ratios (3.7, 3.54 3.??). I'm getting good results with a 3:54. The tall ratio allows more time for the turbo to stay spooled up. For street applications where gas mileage is a factor, the higher gear sets would help but you may suffer with less "instant on" power when you put the right foot on the floor. Quote Link to comment Share on other sites More sharing options...
zedman240 Posted August 20, 2009 Share Posted August 20, 2009 I know the V8 guys like to run high ratio's like 3.5 or even down to 3.3 but unless you have massive amounts of torque, letting the engine spin abit more helps on the circuit. With my L28, if I had a 3.5 ratio on most tracks I'd only end up only using 2nd and 3rd gear where i should be using 5th! Like we said, depends on what the car is being used for. Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted August 20, 2009 Share Posted August 20, 2009 For my Z and what it'll be built for (mostly street driving and a bit of track days/drag racing) I really want a late 280zx 5 speed and keep my 3.545 rear end. Right now for street use my trans/diff is ok, but 1st and 2nd are really short, and the transition from 2nd to 3rd is such a big drop that it really drags down. A 3.9 might be better overall, but once I build the turbo engine (aiming for roughly 250whp) i think the 3.545 would be a bit nicer overall. Quote Link to comment Share on other sites More sharing options...
Iceman Posted August 20, 2009 Share Posted August 20, 2009 I have the 3.90 diff (guy I bought it from said it was the 4.30, but I dunno about that) and an N/A L28 in a '70 240Z. Not certain which tranny I have (i think it's from an '83), but it has a REALLY high 5th. Low/High... I always get those confused.. anywho, 5th gear is like 2500RPM at 75MPH. Generally speaking, having a rear ratio around the 3.0-3.5 range is good when you have more HP, but I will be keeping my 3.9 since my 5th gear is so high. Quote Link to comment Share on other sites More sharing options...
HS30-H Posted August 20, 2009 Share Posted August 20, 2009 These anecdotes about diff ratios are relatively meaningless without the inclusion of the tyre ( tire ) diameters used. Quote Link to comment Share on other sites More sharing options...
Iceman Posted August 20, 2009 Share Posted August 20, 2009 These anecdotes about diff ratios are relatively meaningless without the inclusion of the tyre ( tire ) diameters used. True.. but they are pretty accurate considering the possible sizes running on a Z. Not likely that anyone is running truck tires on their Z nor tires with a 14" OD. This should be of some help though for more specifics.. Z Transmission Calculator Quote Link to comment Share on other sites More sharing options...
neotech84 Posted August 21, 2009 Author Share Posted August 21, 2009 Thanks guys I hope that I am not the only one that finds other opinons helpful. I know how they work and that there are other things that factor into the whole package. I want to leave those out for now, just simple facts on what you have and how you like it..... Thanks Quote Link to comment Share on other sites More sharing options...
DekThaiG35 Posted August 21, 2009 Share Posted August 21, 2009 Thank you for creating this thread, since I had been looking into 300zx TT LSD, the CV shaft are so hard to find and very expensive if find one, so with these info, it will help me decide what to pick and maybe I should be ok with R200 300zx N/A as well. *Edited* What do you guys about what LSD I should get? I'm planning to put 2JZ TT to my car and will be around 460 HP, street car. thanks for the input. Quote Link to comment Share on other sites More sharing options...
zedman240 Posted August 21, 2009 Share Posted August 21, 2009 Alan, with every wheel/tyre combo I use, I always do my best to get as close to the original rolling radius of the 70 series tyres. I may be wrong but from memory, I think it was around 614mm? Its always +/- 2-3mm. I used to have a 225 50 on a 15" rim which is too small. 225 50 x 16 is almost right. Then again it all comes down to the accuracy of the tyre manufacturer. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 21, 2009 Share Posted August 21, 2009 25.2" tall tire. 4.64 ratio Quote Link to comment Share on other sites More sharing options...
John Scott Posted August 23, 2009 Share Posted August 23, 2009 Very happy with my 3.7 Trans 2.97:1, 2.07:1, 1.43:1, 1.00:1, 0.80:1, 0.62:1 Tire 225 50 16. This makes for a 2.29 effective ratio in 6th. Highway cruising 2500 rpm or so @ 80. Often drive in town 35-40 in 4th with out lugging 1500-2000 I had a 3.54s, but the 3.7 made it a touch snappier, and still nip 140 in 4th a touch over 7000. For my set up a nice compromise for street, highway, and 1/4 mile play. These anecdotes about diff ratios are relatively meaningless without the inclusion of the tyre ( tire ) diameters used. http://www.wallaceracing.com/gear-speed.php Quote Link to comment Share on other sites More sharing options...
neotech84 Posted August 24, 2009 Author Share Posted August 24, 2009 Thanks John Scott. I am guessing you are running an L serries? what mods do you have? Quote Link to comment Share on other sites More sharing options...
John Scott Posted August 25, 2009 Share Posted August 25, 2009 Thanks John Scott. I am guessing you are running an L serries? what mods do you have? Sorry, no, 383 sbc. Quote Link to comment Share on other sites More sharing options...
jnjdragracing Posted August 25, 2009 Share Posted August 25, 2009 We presently are running the 3.54 gear ratio in our R200. We use a 2 speed power glide with the 1.82 1st. We were using a 3.90. We tried the 3.54 and it picked up our et. This was with the 355 SBC with the 6-71 supercharger. Now with the 412 sbc and NOS we still use the 3.54. We would probably pick up some et if we switch back to the 3.90 on HP because it is slow moving but on the NOS it runs good. If we put the 355 SBC with the supercharger back in we will probably try to higher in the 2.?? ratio if we can find it. I guess the higher HP you have the less gear you need. John Quote Link to comment Share on other sites More sharing options...
MikeBZ Posted August 26, 2009 Share Posted August 26, 2009 In my current Z I have a 3.90 R200 with the stock 4 speed. It made a big difference over the stock gears that were in it (3.36's) I have an L28. My prior Z had 4:11's from the 200sx turbo and 1st gear with the stock early 4speed was a little too tall for me. I swapped in a 83 5-speed and it balanced out the gears nicely. Quote Link to comment Share on other sites More sharing options...
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