Today my mechanic told me that my 02 camaro ss automatic should run at 1800 rpms when going 110km/hr. But my car runs more like 2100rpms at this speed. He is saying maybe it isnt shifting into overdrive or something. Now is he wrong or right? Now he has me worried that something is wrong with my car, or maybe the rear end had something done to it. As far as i know the car should have the stock rear end. Let me know what you guys think.

 

thats about 68-69 mph, and 2100 sounds about right to me for an automatic.

 

110 kph is 68 mph. What rear gears are in it? You can check the RPO codes. Also how tall of a tire do you have? That will effect rpms. Assuming you have 3.73s with a 26 in tall tire, you'd run at almost 2300 rpms. It's possible you don't have OD any more, but unlikely. With a 28 in tall tire, and 2.73 rear gears at 68 mph would result in over 2600 rpm speed. I know the SS's didn't have 2.73s.

Feel for four shifts when you go out on the road.

 

the automatic came with 3.23s iirc. my Z28 a4 was at about 2200-2300 at 70 with 3.23s on a stock tire.

 

2.73 was standard, 3.23 was optioned last I recall. 3.23 may have come standard on the z28 and SS though, best check your RPO codes to find out for sure

 

The standard 3.23 gears, original height (25.7") 245/50Zr16 tires, at 68 mph, puts the rpm's at 2,010. Are your tires worn at all? Even 1/8" less tread (1/4" overall height) would bump the rpm's to 2030. Is your tach that deadly accurate? Do you have slightly lower profile tires? I'd say what you're getting is right on the money.

 

i am at about 2k at 59mph with 373 in mine when it was stock 323 i think i was at 68 mph at 2k. auto trans.

 

If you are using the speedo to measure speed (as opposed to a GPS or something else), then tire size and tire wear wouldn't change how it matches the rpm, unless the speedo math has been changed. This is because the speedo gets its reading from the output shaft on the trans. This is why it needs to be corrected when swapping rear end gears.

My '94 A4 Z28 only touches 2,000rpm is OD when going around 62 mph. At 70 I'm closer to 2,500 rpm. It'll cruise near 3,000 when I'm at around 85 mph.

Kinda higher than I originally expected but the power is THERE so I don't mind it at all. I enjoy the V8 drone at 2,750 rpm.

 

My tires are 275/40R17s. I guess the backs are slightly worn. Where do I find the RPO code and how do I use it to find out what rear end I have for sure. Thanks!

 

RPO code is useless, since it will only tell you what gears GM put in there, not what somebody else may have swapped in.
Jack both tires off the ground, put trans in neutral, turn one tire one full revolution while noting how many times the driveshaft turns. Say the driveshaft turns about 3.25 times, then you have 3.23 gears.