3.42 gears or 3.73 or 4.10 - Third Generation F-Body Message Boards

redirocz28 · 08-04-2009, 09:38 PM

I have a 1986 Iroc that I pulled out a 305 and went 350. I kept the t-5 and its geared well with the stock 3.42 gear. The car would run like a raped ape, but spun too bad. I recently put in a posi chunk and had to get new gears because the chunk I got needed thick gears so I got 4.10. I am just wondering if anyone knows if I would get better performance from a different gear. The 4.10 seems to go through the gears quickly (45 mph in 4th gear). I would like to know if Im wasting power by having this gear. And what gear should I have. Thanks

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net_coma · 08-04-2009, 10:18 PM

I prefer the 3.42, worked well with my 700r4.
I think the ones behind the t56 in the other car are 2.73 or close to that. Even with that the t56 first gear feels much lower than a t5 with similar gears. Forgot what the first gear ratio is on the t56.

4.10 just demands to many rpm for me.

Air_Adam · 08-05-2009, 12:04 AM

Whats the engine combo? 4.10 is too much gear for most small blocks out there, especially anything stock or close to stock. 3.42 is generally considered the best all-around gear for a street car with a near-stock small block.

88fastgta · 08-05-2009, 12:17 AM

i think the 3.27 gears are excellent for a built tpi and a built 700r4... i think the 3.42 are a tad high for my setup....

studdmstr · 08-05-2009, 12:19 AM

That 4.10 would be perfect if you were running a T56 but with a T5 I would go 3.42.

redirocz28 · 08-05-2009, 04:42 PM

Thanks for the advise Ill probably go back to 3.42 it seems to give me the best bang.

antman89iroc · 08-06-2009, 03:35 PM

I've run 2.77, 3.27 and 3.70's in my 9 bolt. I really liked the 3.27's for auto and then T5. I recently went with a 3.70 since they are about the only new gear set available for my rear. I must say that the 3.70 was the best so far. My engine is well built but still redlines at 6k. The 3.70 (or 3.73 for your 10 bolt) is a good all around set to me. Actually I wanted the 3.42 but couldn't find a new set without ordering it from Australia. I thought the 3.70 would be a little low but it's not that different from the 3.27 for everyday driving. But, the 3.70 is much better at the track. Worth around 3 tenths a second in the 1/8 mi for me. I think the lower rear is easier to get off the line with a stick shift. On the street is a different story as 1st gear has to be pedaled quite a bit to avoid massive tire spin! I don't think I hit full throttle on the street til about 5 grand in 1st.