Datsun Roadster Forum-311s.org

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Alvin,


I am pretty positive that gear set is NLA and to find a used one is like finding the holy grail. If by chance you do find one it should be no problem with a five speed, however a 4 speed would pull some higher rpms enough that highway driving, in my opinion couldn't be achieved.

That being said I have seen 4.11 r and p going for around 500.00 to a 1000.00 bucks. I paid 750.00 for my 4.62 from Nismo Japan thats without a diff. Best of luck though

Russell

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Alvin.

You don't want that diff for the street do you? Herb was running a 4.11 with the KA and he had to shift it into 2nd within 10 feet of moving. Too low geared! With your setup a 3.9 would be about as low as you would want to go on the street.

My S2000 had a 4.11 I think, but it also had a 6spd.

Alexi

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Alvin.

you have to take into consideration that the roadster is about 800 lbs lighter than the car the motor came from. Your not holding anything back. You are simply changing your rpm range. You will take away your top end and cause your motor to rev more.

Alexi

Alvin,

First of all give me your tranny type I need to know if it is a 5 speed or a 4 speed then give me your tire size, next I need to know what your max rpms will be. That way I can compute your different top speedswith the different rear end ratios.

I'll give you an example of what I am talking about, my car which runs about 12.5 to 1 compression, can pull about 6500 rpms on the long front straight on one of my courses with a 4.62 rear end is going around 120 mph.

First of all I wouldn't even consider doing that in a street roadster, just for safetys sake, second unless you just have the money to burn I would leave the diff open.

Give me those figure and I'll do the math.

Russell

Personally, I love how quiet the engine and tranny are with the 3.7 on the freeway. The car just glides along...

I know I am giving up a bit of acceleration, but I am not autocrossing the car.

Alvin, with your commute and quantity of daily driving, I'd stick with a 3.9 or 3.7. A 4.11 would give you a bit better accel, but lets be serious...How often do you drag race versus drive? I'll give up the portion of a second in the ten seconds acceleration time from 0 to freeway speed for all of the hours of constant speed driving time behind the wheel.

Personally, I'd leave the real high ratios for the guys that are racing...TR

After going back to the 3.9 on my car, it is quite a bit better around town. I can easily get by with 3rd where as I was in 4th before. With the 4.11, I would go about 10 feet before having to find 2nd, now I can get almost 3/4 of the way across the intersection before needing to shift. I can actually use gears below 4th now. It could be that I need to make some tuning ajustments (I haven't really touched the car since the end of september), but the car is a little slower off the line. I can't wait to try the freeway with a 5th gear, perhaps by the end of the year....

Will

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I hear you about the LSD, I am sure the car will launch out of turns much better (Or spin out!).

The best way to make sure about a gearset is to learn from other's mistakes, find other people on a run that have the gearset you are interested in and swap cars for a bit...

There are enough people that want a solid LSD option that we should find a rear end shop and order a bunch at once. We could probably save serious cash since the custom machining would be much, much cheaper...I am saving car funds for the 510 right now, but I would really consider it if we could get a good price.

TR

Alving,

I'll run the numbers today when I get in from work, at a glance I can tell you already that those gear ratios and r&p( your current set up) are GREAT! leave them alone. I wouldn't go higher than a 4.11 if you just have to do it.

I'll give you an example( TR is right) my first gear is a 2.08 to be usable with the 4.62 you willshoot out of the hole but have to shift darn near immediately.

Just my two cents worth


Russell

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Listen to TR, and save yourself the money. In driving any car it is 90% operator and 10% car. So bone up on your techniques instead.

Alexi

alvin,

Thats a great resource you should be able to know and play around with different gear ratios. Drive what you have before you spend money.

Russell