I am soon to have my car running with the LT4 hotcam and ported heads with .200 intake valves, shorty headers, and no cats. On the highway at 70 with 3.42s it turns almost 1600 rpm, which is probably too low, even maybe lugging a little. With the extra duration on the cam, what would be a good rpm for highway usage? I think with 3.73s it calculates out to be around 1700, and 4.11s it is like 1850. What would be ideal for gas mileage, also which would be less stressful on my engine???

Another question - for those of you with 4.10s or 4.11s, do the gears make 1st gear practically useless for street driving? I don't want to have to shift out of first almost immediately after I start moving. How fast are you moving when you need to shift to second on the street??? Thanks,
Will

 

I really like the 4.10's in my car. First gear is still usable but my rev limit is set to 6800, so depending on how high the LT4 hot cam pulls it may be usable or it may not be. If you plan on spraying the car you will most likely want the 3.73's.

 

I am doing all this to my WS6, it doesn't have juice, just the beater Trans am . So I won't be spraying at all or racing it much at the track, probably just a few times to get an idea of how fast it is. I thought the 3.73 would be good but don't want to lug it on the highway in 6th, the pilot bearing was already destroyed thanks to whoever owned the car before me lugging it. There aren't too many hills here in the TX panhandle, but I wouldn'twant to have to downshift when I go up one because I am undergeared.

 

4:10s all the way. Just got them for my T/A and I can't wait to get them put in come spring time!

 

i have a 94z28 with a 6speed-
i when to the 3.73's at first and did not like them. not a big change from the 3.42's
then i when to 4.10's and loved them!! they are good on the high way and for the street.

THEN i broke some teeth off the the 4.10's and had some 4.56's laying around and put them in........... VERY Fun gears but i think too much.. i have not taken my car to the track with them but i think i would be in 5th at the end of the track.
and they are not too good on the high way!!


4.10s all of the way!!

 

4.10's!!!

I've done plenty of installs in M6 cars of 3.73's where the customer didn't listen to me and 90% of them came back soon after to swap out for 4.10's. Make sure you get a genuine GM gear though to make sure they don't whine. Any install questions just ask, I'll give you some tips.

 

i'd say 4.11s
37/9 teeth since they are stronger
the only company that makes them are motive

 

I had 3.73s in a cammed M6. I seem to be one of veeery few people who were happy with 3.73s. Yes i've driven both stock and modded cars with 4.10s, they are a little too low on the highway IMO. I went with 3.89s when i got my ford 9" and wouldn't go any lower than that. In fact i'd if someone made 3.90s for a 10 bolt i'd recommend them. I'd rather stick with the 3.73s and not run out of gear in the 1/4 or run 2300+ rpms on the highway. Just my two cents though.

-brent

 

I have 3.73's as well, and I'm pretty happy with them. I ran some quick math, and 1st gear tops out about 4 mph lower at 6k (6 mph in 2nd - 25.5 inch tall tires) with the 4.10's - so your shifting really won't change a great deal.

Running the 1/4 could become an issue, if you trap over 110 mph - you may have to shift into 5th, depending on your shift point. The 3.73's are good to about 120 mph in 4th gear.

I think that they are probably close enough, that either would work. 94formulabz hit the nail on the head - 3.90's would be the schnitz.

 

check out my sig.... best choise i made for my car so far.. other than the hood =-)

they are a VERY reliable gear... NO WHINE at all, i had a shop install them and it took just over 3 hours. i LOVE the 4.10's would only recomend them... the M6's should have been 4.10 from the factory....

 

I'm very happy with 3.73 and wouldn't consider 4.10. I use mine for lapping and solo2 and find tha thte gearing is just about perfect.

 

I have 3.73's in my car, with a built 396, cam has 240* + duration on the intake, and I will be ordering 4.10's soon. I shift around 6600 RPM, and Im barely at 6000 RPM when I go through the traps. I will see what other ratios are available from Strange for my 12 bolt, as I might even go steeper. By the way, where are those gear ratio calculators?



Nick

 

3.73s are a little stronger and a little quieter than 4.10s, if neither of those matter go with the 4.10s, more bang or SOP fun than 3.73s.

 

the only 4.10's that are noisey 99.9% of the time are richmonds... mine only whine when the car is cold... SOMETIMES... most if the time i dont hear a thing..

 

i have an m6 car and im wondering how many rpms at 70 will the motor be turning in 6th gear? also ive heard horror stories about guys with aftermarket gears in stock 10bolts but my gm mechanic today said if installed properly they shouldnt be a problem