OK, this is kind of a two-question thread...

1. My Current Setup (its confusing):

Ok first of all... Ive been under a false impression for a long time that my car had gears when i bought it. You can probably even find old posts of mine where i thought I had a 3.73 or 4.10. I got under it and turn tested it, low and behold its got a 3.42.

Something must not be right in my car because it even seems to drive like it has a bigger gear. Seems like i finish the 1/4 on the upper half of the 5k range as it is. This was the best shot of the gauge cluster i could get at speed, this is in 4th gear just after letting off from a WOT run.



first of all, if anyone knows whats going on with that id like to know, its stumped a lot of people. Only thing I can think of is that the car had a different gear at one time and never got recalibrated back to stock, however that doesnt explain the RPM i finish the 1/4 at. The car was purchased pretty much original everthing down to the clutch which i pulled at 83k and still looked good. The rear has been solid, makes little if any noise and has handled the abuse of my spec 3 clutch.


Thinking about going bigger:

I want to know if anyone here is running 4.56 and what the impressions are. Would a 4.56 be more likely to break than a 3.42? (stock 10 bolt) I know it would put more stress on the axles, but im talking the gears themselves. I plan on camming the car later (mild, 224/230). would it hold up? I will use strictly street tires. Im alot more concerned about it holding together on the shifts than on the launch actually. I have a spec stage 3 as mentioned previously and it bites on the shifts.

How I use the car:
fun summer car. I do race my car, but track times arent my biggest concern. I would need to shift to 5th to finish the quarter even stock. As far as traction goes.... I really dont care I like being able to blast the tires off in first and second when i want to, but I understand bigger gears also make hooking a little easier too. I want something thats gonna put me back in the seat and i know that gear would.

Lastly, is a gear swap something I could potentially do on my own? Ive read a couple write-ups briefly... I have most all basic tools but nothing fancy like a bearing puller. Ive done headers and a clutch so far no problems. No real experience but i take my time. good idea/bad idea?

 

It doesn't seem like anything is "wrong" with your car (RPM wise or anything). When you say you finish the 1/4 mile in the high ~5000's RPM, are you still in 3rd gear, or do you shift to 4th? Running ~104 mph, it's border-line for 3rd/4th (probably just into 4th). But that should put your RPM's around ~4600 - 4800 .

Check out this link: http://www.f-body.org/gears

Use that to compare the speeds/RPM's that your gauges read. Maybe someone did / un-did some work to the car before?

As for going to 4.56's, I haven't heard of too many people running them in a 4th-gen, let alone in the stock 10-bolt, BUT that's not to say that you can't. As long as you're only running street tires, you shouldn't run any more "risk" than the next guy running 4.10's as far as breaking the gears ... you're always chancing it when you thrash on a 10-bolt with a 6-speed .

You will probably find that 1st gear is almost useless ... probably do a lot of 2nd gear starts while just driving around! But when you get on it, it's going to pull, no doubt. Just think, they put 4.56's into some of the GMMG built "ZL1's" in 2002! And that was behind a 600 HP LSx engine!!

Doing the gears yourself isn't impossible, but for a "first timer" could prove to be a little tedious / frustrating. The important "tools" are a micrometer to measure the thickness of the shims to know how much / which ones to use to get the spacing correct, and a dial indicator to measure the back-lash. If you need to change a bearing on the carrier, yeah, you'll need a bearing puller too. For the pinion, it might be best just to install a new bearing (save having to pull the old pinion bearing).

Not impossible for a "do-it-yourselfer", but there are some steps that are probably easier to "show how" than "explain how".

 

Looking at the fuzzy photo, it looks like the speedo is reading 82 MPH and the tach is around 4,000 RPM. With stock tire diameter and 3.42 gears, in 4th gear, 82 MPH would produce about 3,675 RPM. Allowing for the typical stock tach reading 100-200 RPM higher than actual engine RPM, it looks like you are close to where you are supposed to be.

Rather than take a picture of the dash, why not just post the RPM and MPH? Include your tire size or diameter, to make is more accurate to check.

 

I would go out and do that but my car is put away for the season, cant get her out now

You just cleared something up for me though, I always thought the tach was inaccurate BELOW the actual reading instead of above, that makes more sense then.

CaptainPete, that RPM calculator is what i was using all along.

Injuneer can you confirm or deny that 4.56s are any more dangerous (to the ring itself) than a 4.11?

 

From my experience with (broken) 4.10's, it was the pinion that lost 2 teeth.

Consider this. The ratios 2.73, 3.42, 3.73, 4.10, and 4.56 all have 41 teeth on the ring gear. The pinions are what differ (15,12, 11, 10, and 9 teeth, respectively). IMO, there are equal odds of breaking a tooth off the ring for any ratio. I think the pinions are probably where the odds increase the lower you go??

Now a TRUE "4.11" ratio has 39:9 teeth, ring/pinion. IMO, the ring gear should be stronger, but again, the 9 tooth pinion may not be??

 

the less teeth the stronger it will be, the tooth is bigger and more material and support.
I would not try a 4.56 in a 10 bolt...you need a split cross pin and a 4.10 will work just fine for what you want....do some calculating on what you want to go thru the traps atm.p.h the see if you want a 4.10....4.56 is going to be too much for what you want to do