RMCosta

Hello All, I have a quick question just wondering if others have done it with any type of gains. I was thinking about changing my rear end gear from the stock 3.23 to a 3.73. Its an automatic car, stock 4L60E and nothing to speak of performance upgrades. I'm looking to add headers and perhaps an intake swap, since its bone stock.

Thanks for any advice
Ryan

pdxmotorhead

You'll notice the increase in jump when you launch, not extreme but you'll notice..

FirstYrLS1Z

iTrader: (4)

This should've been posted in the gears and axles forum as it's a similar question that has been asked over the years.
Yes it'll give you a slight performance gain, maybe 1-2 tenths in the 1/4. A good aftermarket convertor alone could give 5 tenths+ gain.
Look thru the threads in the 'gears and axles' forum and the 'auto transmission' forum, your answers are there.

RMCosta

Yes the car seemed kinda I guess soft until you get the rpm up. I might do it for the heck of it

RMCosta

Thanks for the heads up on where to look. I still want to keep the car street-able, I see you have changed your converter do you still street drive regularly?

jlangley

iTrader: (8)

I would do a converter before gears. Likely end up being cheaper too.

Just don't get a low budget converter. Yank Circl d fti.

RPM WS6

iTrader: (3)

Excellent advice.

With that gear ratio, I wouldn't even think of touching the gears until after a converter swap. 3.23 is an ideal balance for street application, IMO, and would pair nicely with a *quality* ~3500 stall speed for regular driving (or 4,000+ for track use).

The actual gain (ET reduction) from 3.23 to 3.73 is very limited. Not worth the cost (including a retune for shift points/speedo) unless you can do the work yourself, or you need a whole new rear end anyway, or you have already installed a converter and want to tighten the part throttle feel a bit (not usually a concern for a quality converter).

Kjduvall

Yep, go with a quality 3600 to 4000 converter and wait till that rear end goes to ****, then upgrade to a strange S 60 or 9in in a 3:73 or 4:11 . don't spend 600+$ on the rear you have just to be disappointed.

440_Stroker

2.73 to 3.73 and no other changes netted me over .5 and 4 mph at the same track and very similar conditions. Tires were even the same just more worn. Mileage dropped on long trips by about 2 but normal driving was barely a 1 mph drop.

If yours stock then the rear might be ok for a while but I wouldn't spend money on it if you plan to mod your engine tranny with sticky tires.

RPM WS6

iTrader: (3)

The ET improvement is much less dramatic for a 3.23 to 3.73 swap, and then doubly less (barely even noticeable) once a ~3500 stall speed is in place. Even a 2.73 to 3.73 swap isn't going to be worth more than a tenth or two once you have a 3500+ stall speed. With that said, typical gains from a quality ~3500 stall would be more like 0.7-1.0 seconds with a 2.73-3.23 gear and proper tires.

FirstYrLS1Z

iTrader: (4)

My Z in the horsepower department is stock as I do much travelling with it and I want the reliability of a stock engine, I'm currently at 190,000 miles.
I used to participate in the local group's test'n'tunes at the local strip. Consistently 13.90s/13.80s' with the 3.23s'. Threw in (2006) a TCI 'breakaway' 2800 and that changed to consistent 13.80s'/13.70s'. It was a very 'loose' convertor and no change in trap speed. In 2007 I built and threw in a 4.56 geared rear end. The consistent 13.80s'/13.70s' changed to consistent 13.30s'/13.20s' with only a 1 mph gain in trap speed. On the street in light-to-light streetfighting, 1st and 2nd gear were vicious. In 2011, the TCI came out and a Yank SS3600 went in. The top end looseness of the TCI was gone and pulling strong in the top end (as with the stock convertor) was back. Have not taken it to the strip with the Yank and 4.56s' but the comparison feel should be somewhere in the 12s'. On the street with the Yank and 4.56s' (with Nitto 315 drag radials and relo backets), 1st and 2nd gear became 'dangerous' from wild 'fishtailing' when the 3600 hooked up. Hopefully this spring the 3.23 rear end (or build a 3.73 rear end) is going in. I build the little 7.5/7.625 rear ends and have a couple extra housings, many gear sets, carriers, and axle shafts.

RMCosta

Looks like a converter change might be in the card rather than a rear end gear change.Seems like its something I could do on my own, after the converter change would it be suggested to get someone to do a tune on the car?

FirstYrLS1Z

iTrader: (4)

If ^^^ that's true, don't 'cheap out' on a convertor. Any convertor that's sitting on the shelf somewhere ready to purchase is not the one to buy. Those $300-500 convertors are tempting but why buy disappointment. And don't be afraid of an advertised high stall rpm, it doesn't take that kind of rpm to get the car moving. My Yank SS3600 drives normal in city traffic.

RMCosta

No I don't intend to go cheap, going cheap always comes back to bite you. I am a little concerned about the advertised rpm and how it actually works on the street. I want to keep it for the most part on the street, just want a little added performance. Thanks for the advise

jlangley

iTrader: (8)

I have the SS 3600 as well. If you are driving around normally your passengers would likely never think you had a high stall converter.
I did converter, headers & ory, mail order tune. Took a full second off my et and gained 6 mph in the 1/4.
If I was doing it again I might try the 4000 instead. Driving around the only time slipping is definitely noticeable is reversing up a hill.

440_Stroker

My Z28 was .1 and .15 behind two friends stock WS6 cars (one was a convertible) that as you know have 3.23 gears. Same track, same day, even swapping drivers. One of them went with a Monster (not my choice) transmission, 3500 stall and a 3.73 12 bolt. Only power mods were long tubes and tune. He went 12.2-4 the same day I went 12.9. he had exhaust, wheels and tires and a converter vs my gears and torque management adjusted. Our MPH was almost spot on to one another. Just my experience.

Spot on with a stall. Many folks feel the need to do gears and a stall when it's not needed for the extra revs and crappy gas mileage. At least in my opinion.

RedXray

Swapping out the converter is a lot easier than gears... at least for me. Pulling the carrier back out half a dozen + plus times moving shims for backlash and pinion preload, crushing the crush sleeve, making setup bearings, pressing on carrier bearings etc. is not easy work unless you've done it often. I'd much rather R&R an engine than do gears lol

Roarin_8

iTrader: (5)

For your case with the 3.23s, I wouldn't do a gear swap at all. Just focus on the converter, cooler and tires. Unless the rear is on it's way out get a rear from a manual, which I did or get an aftermarket 12 bolt with the gears of your choosing.

RMCosta

The rear end is good to my knowledge, so it will stay for the time being. So you are suggesting a trans cooler, when you mentioned cooler in your post?

RMCosta

Interesting, so your car had zero mods and wasn't that much slower et wise. What gears do you have?