Cascade Crew

mrpopo573 · Posted: Sun Oct 30, 2005 10:22 am Post subject: I have gears????

So, it has come to my attention, after consulting with a fellow third gen buddy, that I am running way higher rpms than him at the same speed.

So...I did the calculations on thirdgen and they said I have somewhere around 3.42s

At 60 with 16inch tires I am doing 2000 rpms if not a tiny bit more.

Does that sound like 3.42s? I can't believe I didn't even notice this.

Any performance gain???

I feel like a Newbie

Twilightoptics · Posted: Sun Oct 30, 2005 10:27 am Post subject:

Um... 16" tires? You mean 16" wheels? What is the tire diameter? Which gear are you in, I assume OD?

Measure the tire DIA and check it in your 1-1 gear. (3rd Auto, 4th manual)

Doesn't sound all that high to me. But then again I run 3200rpm at 60mph, so everything seems lower! Laughing

If you still have the RPO code list in your center console, you can look up the codes, I believe the G codes show your type of rear and gear.

Dewey316 · Posted: Sun Oct 30, 2005 10:34 am Post subject:

Thirdgen- tachs are also knowing for being VERY inaccurate. Do you have an aftermarket tach? If not when we eventualy do some datalogging, we will see the actualy RPM's.

mrpopo573 · Posted: Sun Oct 30, 2005 12:36 pm Post subject:

I know the tach isnt a VDO like accurate one, but I've run this car side by side with an exact same setup and I am turning more rpms. My torque convertor is locking up so that isn't it.

My bad, yes 16 inch wheels. I will go around and drive the thing in D and see what I turn out.

It feels more like my GTA did than my friends camaro with 273's

Oh, well, thanks for the input guys...I'll do some more intelligent checking and get back to yah

Cool

mrpopo573 · Posted: Sun Oct 30, 2005 4:30 pm Post subject:

Ok, so I couldn't get on it around town, BUT...at 30 mph I am turning 1750 RPMS in 3rd. (Drive)

What more info should I get guys?

Thanks again for your help

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2320

Asuming a 13" tire radius this would give you 4.51 gears.

Kinda doubt that. If your gears have been changed then your speedo may be off to. Between the speedo maybe being off and the unreliability of these stock tachs everything your doing here is a guess. Pulling the cover and looking for the numbers stamped in the ring gear may be your only option to know for sure.

mrpopo573 · Posted: Mon Oct 31, 2005 7:02 am Post subject:

Ok, thanks guys. I'll just pretend I have gears for now so that my signature can be longer.

Surprised

Thanks again Wink

Fastspec2 · New Member Joined: 24 Oct 2005 Posts: 3

Jack up the back of the car. In neutral mark the driveshaft in 1 place. starting with the mark at the bottom, mark 1 tire at the botton. rotate the driveshaft and count how many times it turns to get the tire mark back to were you started at the bottom having made 1 full rotation. this is the gear ratio. so 3 full turns and almost another half is 3.42. This will only work on cars with a posi.

Twilightoptics · Posted: Mon Oct 31, 2005 7:52 am Post subject:

Fastspec2 · New Member Joined: 24 Oct 2005 Posts: 3

To get the ratio right you need to know the ratio of the side to spider gears, in witch case you would probably know the gear ratio already.

mrpopo573 · Posted: Tue Nov 01, 2005 10:32 am Post subject:

I will just wait until I swap my motor and put in the eaton posi diff and then I'll inspect.

From what i can tell, this car does not feel like 2.73s.

But thats just gut and butt dyno guessing.

I appreciate all the expertise guys. Very Happy

iansane · Posted: Tue Nov 01, 2005 7:16 pm Post subject: