Good rear gear ratios. (By vehicle weight)?
So I recently started a project.
I'm dropping a 12a into a 78' Datsun 510 wagon. When it's all said and done, the total weight should be around 2300lbs. The Datsun rearend has a 3.30 gear in it. Thats a bit steep for a 12a street port IMO. I know the factory gear ratio of an FB is 3.90. But with the added weight I would have to think that a lower ratio would be better? I'm going to run 165/50r15 tires. Does anyone have any feedback with experience on this? The lowest gear I could get for the Datsun would be a 4.10. But I have to wonder what it's street manners would be like with that low of a gear?? |
4.1 is fine and pretty much the go to for fb's. 5thgear 60mph im guessing 3100rpm?
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Originally Posted by WANKfactor
(Post 12231742)
4.1 is fine and pretty much the go to for fb's. 5thgear 60mph im guessing 3100rpm?
I want a decent top speed, and hiway revs. But don' want it to be a total turd in normal traffic. 3100 at 60 wouldn't be to bad though. |
I think I’d stick with the stock flywheel though.
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Originally Posted by Sgtblue
(Post 12231863)
I think I’d stick with the stock flywheel though.
Why do you say that. From the added driveline stress?? |
If I understood you correctly, you have concern that the Datsun final drive might be too high. Adding a lightened FW might make it less friendly for street ‘stop-n-go’ driving and accelerate clutch wear.
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Originally Posted by Sgtblue
(Post 12232459)
If I understood you correctly, you have concern that the Datsun final drive might be too high. Adding a lightened FW might make it less friendly for street ‘stop-n-go’ driving and accelerate clutch wear.
The 3.30 gears are way to steep for a car that size with a 12a, I know that much. If anything I'm going to drop to a 3.90 gear. I was more curious about the street manners of a 4.10 gear behind a 12a?? cause I can run that gear. But if that's to low, I don't want to waste my time on it. |
Both 3.9 and 4.1 will be good. Manners on the 4.1 will be better unless you want to shave 1-200rpm off your cruising speed. Tyre size and weight you mention are close enough to an fb to go off what other fb drivers say on the matter.
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Both 3.9 and 4.1 will be good. Manners on the 4.1 will be better unless you want to shave 1-200rpm off your cruising speed. Tyre size and weight you mention are close enough to an fb to go off what other fb drivers say on the matter.
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Cool.
Thanx bud! I thought there would be a bigger rpm gap. But it's not that big of a jump I guess.. lol |
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