2000LS1Z28

I've asked this question so many times before on LS1.com but got no answer.

Right now my automatic 2000 Z28 with the 3.23 gears(and stock converter) downshifts HARD into 1st gear anywhere from a 15-29 mph punch. The car then becomes a total DOG anywhere from 30-40 mph with no downshift at all. 40-45 mph ain't much better. However, from 50-59 mph my car has a KILLER downshift into 2nd gear(55 is AWESOME) but then quickly becomes a total DOG again from 60 mph on up. There is one sweet spot way up top but I don't remeber exactly where.

Now that you know exactly how my 3.23 car works, where exactly would my sweep spots be(exactly) with 3.73 gears? And as a reference, where would the dead spots be with the 3.73's?

Whats weird is that I've heard others say that their 3.23 A4's downshifted differently than my 3.23 A4 does and ironically, my old 2000 3.8 Liter automatic Camaro had 3.42 gears and had exactly the SAME downshift points that my current 5.7 Liter 3.23 car has now. Whats with that?

Anyways, I'd appreciate it if I could get some answers and the facts on this.

Thanks for your time,

Mike

Ragtop 99

iTrader: (7)

The sweet spots are going be exactly 14% lower. 3.23/3.73 = ~ 86%

Thus your car will be a dog with 3.73s in the 26 - 34 mph range, although not as bad due to the extra torque multiplication from the 3.73 gearing. You can calulate any speed with 3.73s by multiplying your current speed by .86

Now the problem with changing gears is that sometimes the car will not downshift at as high an rpm as it use to. sometimes HPP3 works perfectly, sometimes that's a quirky by-product of a gear swap.

The real way to cure those dead spots is with a torque converter, not gears. Go look at Yank's website www.converter.cc click on "dyno shop" and then click on "SuperYank 3500".

Look at the SY 3500's torque curve (purple line) between 3000 - 3500 rpm (which corresponds to your 30 - 40 mph deadspot in 2nd). Now look at the blue line which is stock. Notice the HUGE increase in torque from the SY's torque multiplication. <img src="gr_eek2.gif" border="0"> That's how you eliminate the dead spot. <img src="gr_grin.gif" border="0"> Gears are just the icing on the cake if you decide later you want them. You can see the percent gains from the converter by clicking on the overlay of torque gains.

2000LS1Z28

Ragtop99,

I actually already had a Vigilante 2800 in my car with a Trans Go shift kit but had to have both of them removed due to multiple problems that they were causing with my transmission(weren't installed right) so I'm currently 100% back to stock thanks to the dealership. Basically, I know what a converter is capable of but the Vig 2800 actually did not cure my dead spots at all with the 3.23's

And if I ever do put in another aftermarket torque converter if will definitely be the SY 3500(done my homework on this) but right now I am more concerned as to where my powerband spots would be with 3.73's as compared to 3.23's. You said 26-34 is a weak spot, but where else will the car be weak and strong? I'm not real good with the gear multiplying thing.

Thank You,

Mike

2000LS1Z28

TTT

Ragtop 99

iTrader: (7)

I don't have any dead spots with my set-up because my converter eliminates them. <img src="gr_images/icons/wink.gif" border="0">

I'm not sure I understand why you have a dead spot at 60 mph in 2nd. With 3.23s you should be around 4300 - 4500 rpm which is right around maximum torque. Your car should leap if you punch it from there. If it doesn't downshift at 60 mph and you stay in third, that would make your car a dog, but there's something wrong if your car won't downshift at 60 to 2nd.

2000LS1Z28

[quote]Originally posted by Ragtop 99:
<strong>I don't have any dead spots with my set-up because my converter eliminates them. <img src="gr_images/icons/wink.gif" border="0">

I'm not sure I understand why you have a dead spot at 60 mph in 2nd. With 3.23s you should be around 4300 - 4500 rpm which is right around maximum torque. Your car should leap if you punch it from there. If it doesn't downshift at 60 mph and you stay in third, that would make your car a dog, but there's something wrong if your car won't downshift at 60 to 2nd.</strong><hr></blockquote>

My bad, maybe it does exactly at 60 mph but anything above that and it will not downshift(rpm's stay low). Sorry for the confusion.

Mike

Ragtop 99

iTrader: (7)

That's odd your car should downshift at 65 mph probably even as high as 70 mph. 65 - 75 mph will be a bit of dead spot with 3.73s because it won't downshift that point and you'll be low in the rpms, assuming a stock converter.

hope you get your tranny issues taken care of; that's a lot of your problem right there.

RPM WS6

iTrader: (3)

Just as a point of reference, my old ’99 Z28 with stock 3.23s and a stock ‘verter would do the following:
29mph and under: down to first
65mph and under: down to second
66mph and above: down to third

Now, my current ’00 WS6 with 3.23s and both the stock stall and the SY3500 does this:
29 and under: down to first (same for both)
70 and under: down to second (different)
71 and above: down to third

So, from car to car the downshift points do seem to change a little. I can see how your car would feel very weak downshifting to third at 60mph with 3.23s. That’s just not going to give you enough rpm. 3rd gear is a 1:1 trans ratio too, so that’s not going to make it feel any better. I would say to try a ST3500 or SY3500 and keep your 3.23s for now and see if that helps your dead spots any. It won’t make it downshift any higher, but it sure will make the car pull a lot harder in the “dead spots”.

Supertrapped

Manually shift it yourself and you won't have those "deadspots" <img src="gr_stretch.gif" border="0">

2000LS1Z28

In order to be exactly sure, I'm going to take my car out tomorrow(if it is not snowing) and do a couple of WOT runs in the 60-70 mph range and find out what is really going on. I guess I could be wrong but it always seems like my car becomes a dog above 60 with the 3.23's.

Thanks for everyone's help and I'll post my results tomorrow or sometime soon.

Mike

Ragtop 99

iTrader: (7)

Tested my today and the car wouldn't downshift until I dropped to 55 and then it upshift almost right away, probably due to traction.

99BlueZ28

What exactly happened when you mentioned a bad install? Was the transgo install fugged up? Even though I have the 273, i've had no problems with downshifting after the PP3 adjustments. I wouldn't give up on the converter just yet. Give us a little more info on what went wrong and maybe we can found out what happened to your car.

Whats great about the 273 is that I can mash the gas up to 43 mph and still get a downshift to 1st. <img src="gr_stretch.gif" border="0"> <img src="gr_eek2.gif" border="0">