Interest in a 3.00-3.20 ring & pinion

[redroadster]

https://m.alibaba.com/product/160030123 ... om=Android
Just wondering how many owners would want a higher gear ring and pinion around 3.0 ,if China comp.would produce one, with enough interests
Think this Ferrari 166 looks close to a 311 ?
https://www.classic.com/m/ferrari/333-sp/
@bottom of page

[jr02518]

The word I keep coming up with when I read this post is "compromise".

To review, the stock 1600 has a 3.9 with a 4 speed transmission, the 2000 has a 3.7 with a 5 speed. Both transmissions are one to one in the top gear.

The tires for both cars could be a number of combinations, 14" to ...

What you use your car for could have an effect on this. Getting up to speed, that will be effected.

Yes, not having a working tach in my 1970, 1600 is not helpful. But driving on the highway at 75 plus is not why have this car. I am willing to use the engine, keeping it "on the boil" as it were when driving. Going down hill. It is still just, a 1600.

[rwmann]

If memory serves, only the F5C71B Datsun Comp close ratio 5-speed had a 1:1 fifth gear. The OEM F5C71A was a 0.9:1 overdrive fifth, with a 1:1 fourth gear. Not sure why a much lower rear end ratio would be desirable in a sports car with this amount of power, though everything is an individual preference.

[redroadster]

If memory serves, only the F5C71B Datsun Comp close ratio 5-speed had a 1:1 fifth gear. The OEM F5C71A was a 0.9:1 overdrive fifth, with a 1:1 fourth gear. Not sure why a much lower rear end ratio would be desirable in a sports car with this amount of power, though everything is an individual preference.

Lower ratio gives higher speed
Higher gives lower speed more torque which if you can go up in tire circumference is great for a drag race , not so road racing
Manu's have been going slower speed ring and pinion ,to keep the cars on the road , it could certainly handle a 3.0 that should give 35 in 1st at 5k it would have a large pinion gear the case might not handle a Lemans Vette low ration did 80mph in 1st it said
Chevy Power glide 2 speeds had 283 , 189 ring gears
All you needed was a stick 45-50 in 1st
Also a small.ring gear gives a farther travel at a celeration at high speed when high torque isn't needed ....but looks like little to no interest , ,I guess using China these days isn't too popular. But we re still shopping Walmart

[unklpat]

I am wondering when the power vs drag would become a factor. It takes a bit to get over 100mph in my 2000, and I admit to not wanting (scared) to test the top speed claims made by Datsun. Maybe after better tires are installed. I am looking forward to the 3.9 installation added to my lightened flywheel making getting there more exhilarating. I can't imagine putting a 3.7 in a 1600, let alone anything lower. Just my opinion. Pat

[theunz]

You can’t reach max revs in a 2000 in fifth gear, so you wouldn’t gain any top speed with a lower rear end ratio. All you would do is kill your acceleration, so why bother unless you’re into hyper mileing.

[unklpat]

Have you tried or is it an assumption. I only want to make it more fun getting there. Datsun says 124 mph, maybe they were wrong. Could the stock cars not reach 124 mph in 5th gear? Pat

[JT68]

Both transmissions are one-to-one in the top gear.

correction, both are 1:1 in 4th gear. (when the input shaft is physically locked to the main shaft)

5th is overdrive in roadster 5speeds.


I think if you are going to go to the cost and expense of a R&P, I'd suggest either a 3.5:1 (helps the 4 speeds with the excessively low first and on the highway) or a 4.11 which is probably the most requested ratio (not that it is necessarily best for any particular purpose, it would sell well). I doubt you would ever recover the expense of a 3.0/3.2 since not many people would want one IMHO.

[redroadster]

Ya butt , not for running Le mans
My spl turns 4500 at 60mph with 185 70 14 s
You only need a low geared large ring gear to get off after that it's like trying to run as fast as you can but still only taking 18" strides, I used to have fun with the moded hodo civic kids on the high way with my 86 Z31 turbo and 3.54 and 225 60 16 s , they wanted me to slow down to 35 on the highway , I just slowed to 3rd gear they only hung with me for seconds before I watched them fade in the rear view mirror I'm telling you you put a 3.0-3.2 in and I bet you toss the 4.11 gear in a drawer for good
The RX7 has a 3.20 rear gear as I remember on the 1st generation rx7s which were dangerously fast

[rwmann]

With respect, unless you’re doing something magic to the engine, there isn’t enough power to make a low rear end work. At a given power, drag rises to defeat additional speed, and revs will drop below the useful part of the torque curve. A roadster is not a streamliner.

[JT68]

With respect, unless you’re doing something magic to the engine, there isn’t enough power to make a low rear end work. At a given power, drag rises to defeat additional speed, and revs will drop below the useful part of the torque curve. A roadster is not a streamliner.

Agree100%. The 3.7 works really well for normal street use with a 4sp (or 3.5 if you can find one). 3.7/3.9 is probably best for street with 5speed unless you want a couple hundred extra revs in all gears with 4.11(which is fine if that is what you want). Depends a lot whether you are normally under 60mph or on the freeway and your tire size. (tires are effectively gears too)

Track setups are totally different, usually 4.37,4.62,5.13.

From a practical perspective, JMHO, I think you are going to have production cost vs. production volume problem with anyone making a custom R&P (any ratio) for the roadster market.

[mikeb]

With respect, unless you’re doing something magic to the engine, there isn’t enough power to make a low rear end work. At a given power, drag rises to defeat additional speed, and revs will drop below the useful part of the torque curve. A roadster is not a streamliner.

Also agree. To add to the conversation, here's my personal experience from the early 1980's: Very healthy U20 - forged pistons, lightened rods, etc. Racer Brown cam, ported and polished heads, Solexes. Drivetrain - stock 5 speed, 4.62 LSD, running 195-60 tires. Comp suspension, Konis. One late night on an empty road I had the car redlined in 5th, speedo showed 130 (high due to tires), actual speed most likely around 120 (see gear chart attached). The car would easily do 8,000 rpms in lower gears, but as rwmann notes above, aerodynamics will end up being the limiting factor at speed with the roadsters. At the time, had I had more road I probably would have been able to hit 7,500 rpm's and 130, but to be honest that was more than enough for me. BTW, someone from the forum posted the gear chart attached many years ago, so attribution to whoever it was.

[Daryl Smith]

Irrelephant

[Daryl Smith]

Irrelephant

[unklpat]

I just wanted to kick start this topic. I will say that I am more than happy with the 6lb weight loss on my flywheel and will be changing to a 3.9. I would bet that most of us like the thrill of getting there more than the top speed of our cars. Pat