Bones Z28

iTrader: (8)

I was debating rather put this question in the drivetrain section or here. I think the LT1 section is more suitable because the question pertains to LT1 cars. Ls1 guys are just not going to be able to answer me here (unless they were LT1 guys).

Ok I'm going to be getting gears this spring. I was thinking 3.90's instead of 4.10s because a friend told me it will kill the top end. Given LT1's are not top end cars when you compare it to the LS1. But why make matters worse? That's my question. If I got 4.10's am I going to completely lose my *** from a 40 roll to 100mph or so? So I was wondering if 3.90's would be a good compromise.

What do you guys think? Is this a good idea? Or is this theory my friend has told me bogus, and I should get a set of 4.10s. Also I cruise the car more than race it. Idk if that matters but I figure I'd throw that in there. Let me know what you guys think. Thanks.

JoeliusZ28

iTrader: (2)

Ive also been looking at a gear swap recently and was thinking the same thing you are.

www.f-body.org/gears

Quarter mile may not be important to you, but look at the calculations there. I wouldnt want 4.10s because of the RPM i would be turning crossing the line. I say 3.73s or 3.90s are the best option unless youve got a built bottom end with 4 bolt mains, because 4th gear is where you are holding the RPM longest.... and beyond the finish line.

White 96LT1

iTrader: (4)

i have 4.10s in my 96 LT1 M6 and i love them

JoeliusZ28

iTrader: (2)

are you still finishing the quarter in 4th?

Id be afraid of needing to shift to 5th in the quarter mile with 4.10s after i do my cam swap.

ecniv

iTrader: (1)

4.10s and a taller tire.

the_merv

iTrader: (88)

How high are you spinning your Engine too?
I was crossing the line with 27" Tires at 110mph with 3.73's, my Rev Limit on that Engine(LT1 at the time) was 6500rpm's and it was probably at 6200rpm's. That was 3rd in the A4 which is the same as 4th in the M6, still 1:1 Ratio.

I would go with 4.10's with a 28" Tire, with any smaller of a Tire you may be hitting 5th.

BOLO

iTrader: (40)

You have an M6, it'll be awesome w/a 4.10 gear and you still have od for cruising in the hwy.
I love my 4.10 gear on my A4.

Ray@Nitrous Outlet

I ran 4.10's and a 26" tire with my H/C/Nitrous setup...was trapping 120 in 4th gear

the first pass is the T56 H/C pass
http://www.youtube.com/watch?v=b62TDtb7tok

SincalT/A

iTrader: (16)

By the time you get enough power to run out of gear in the 1/4 mile with 4.10's.You will need a whole different rear end.

FASTFATBOY

iTrader: (23)

It does not say if you have a 12 bolt or not, If you still have the stock 10 bolt the 4.10 will most likely break because the pinion is so small.

If you have a 12 bolt, go ahead.


David

Bones Z28

iTrader: (8)

no, that's one thing I do know, they make 4.10's for 3 series carriers. So the car won't brake. Maybe what your thinking of is that they like to shift out of place over time? That can be solved by buying a girdle for the car, which I plan to do. FLP is most likely going to be doing my gears. Those guys know there ****. I've emailed them and he came back as well to tell me that 4.10s are the way to go for my situation. I was just questioning the top end. Really appreciate the feedback guys, gotta love these forums, I always like to here everyones opinions and experiences before I get myself into something.

JoeliusZ28

iTrader: (2)

actually no thats wrong. a 4.10 gear for a 10 bolt has a larger number of teeth, meaning each tooth is smaller... the result is a weaker gear, and yes you will break a 4.10 before you break a 3.42. I believe the 4.11 gear has less teeth and is stronger than the 4.10. A girdle is not a solution for anything, it is merely an ineffective insurance.

SincalT/A

iTrader: (16)

What makes you think the girdle is ineffective insurance?

Revelation Z28

iTrader: (10)

i have a girdle.

its meant to keep the carrier from deflecting and push towards the rear when torque hits the gears, and doesnt push the bearing caps out. its supposed to keep the carrier "there". but so far so good for me.

95N20FORMULA

iTrader: (3)

I have 4.10s and i shift at 6k in my Bolt on/tuned lt1 and as per my speedo which is like 2mph of says the drag strip, i shift into 5th at 105ish, and then it completely falls on its face really, ive raced 4 stockish ls1s 3 m6s and one a4, all from 10 rolls, and each of the m6s i would jump a full car and thed slowly catch up until around 100 and then as soon as i shifted to fifth theyd pass and slowly walk....now the a4 with 3.23 gears, i jumped 2 cars and held all the way

JoeliusZ28

iTrader: (2)

because the following is the best it can do. the inferior size of the ring gear is still the weak point of the axle girdle or not. a girdle might make it hold up longer, but if youre abusing it, its gonna break either way IMO. I should have said marginally effective instead of ineffective. worth having, but definitely dont think youve got a stronger axle because of it.

CALL911

iTrader: (17)

Back to the original question; I believe it depends on 1; what mods are going to be done to the car when it is finished, and 2; what you want to use it for.

If all you are ever going to do is leave it with bolt ons, or even keep it N/A with maybe a few motor mods, I say go 4.10's. You have a M6, and back in the day a buddy of mine topped out his car with me in it in 6th gear with 4.10's and it was still well over 150 MPH, and it will get there faster than 3.90's and a LOT faster than the stock 3.42's.

To be honest, there won't be much of a difference between 3.90's and 4.10's all together though as they are not really that far apart gear ratio wise. If you do a lot of 1/4 mile stuff, you may want to consider what speed you will be trapping, and 4.10's may be too steep as you don't want to be shifting into 5th before the end of the 1/4 mile.

Also, as posted above, the higher gear ratio you go, the weaker the rear will be, or the more prone it will be to breaking. As long as you aren't putting sticky tires on the back, its not going to break anything even with 4.10's especially just with bolt ons. However if you plan on running drag radials or especially slicks, you may want to know that your chances of breaking the rear end will drasticly increase with 4.10's (or 3.90's for that matter).

T/A girtle will help, but the only way to have 4.10's and run slicks and not expect to break will be with a new 12 bolt rear end.

Just all food for thought. Good luck with your decision.

Mighty Whitey

I'm running in to this problem with my car right now.

I've got 4.10's and running 275/40/17's. the car traps 114mph in the 1/4 at around 6400rpm in 4th.

I'm out of the power range of my motor and I think the gear cold possibly be hurting performance due to turning to many revs.

if you plan on running the mph like I am, I'd try a 3.90. that's what i'll do if I buy another gear, I think the car will pick up another mph or so because of it.

just my $.02

phantomLT1

iTrader: (2)

I'd get a taller tire if I were you.


To the OP Call911 is right you need to base your decision on what your plans are for the car.. Quit wasting your time with 10 bolt I broke mine twice with 4.10s get you a 12 bolt or 9 inch. Now I got 3.90's with a 28' tire on my 12 bolt it feels like 3.42's it was a bad idea with a nitrous car but I will be going procharger soon as I get the funds. I think 4.11's would have been perfect but not for forced induction I think 3.90's might have been lil high but we will see. If you want a nitrous wheel lifting car I would get lower gears 4.11 or even 4.56's since you have a 6 speed. If you want a forced induction dyno pulling like a freight train get higher gears 3.73's.

Bones Z28

iTrader: (8)

Yeah sure of course, I mean that's why they make girdles for the cars, it's all ineffective, and just scams.

Anyways it doesn't matter because I'm going with 4.11's from Strange Engineering, and I'm having a professional shop set them up. Also another thing to remember is that it's only a bolt on car. I'm not building on the LT1.