zrsnopro97

iTrader: (1)

I swapped the rear end in my camaro this weekend; went from the origional 2.73 to a stock 3.42 rear that came out of a WS6 6-speed.
I was expecting the speedo to be way off, but apparently its still accurate?

To check the speeds I downloaded a GPS speedometer app to my iphone.
30 on the speedo was 30 on the GPS
50 on the speedo was 50 on the GPS
70 on the speedo was 70 on the GPS...
(give or take 1-2 mph)


This doesnt make any sense to me...
No tire size change, no tune
Try a different speedo app???

Oldsmobility85

iTrader: (1)

Maybe your just that good??? LOL.

FirstYrLS1Z

iTrader: (4)

2.73s' to 3.42s' should be giving you a 25% higher indication in MPH,60 mph before should be showing 75 mph now.

zrsnopro97

iTrader: (1)

LOL I have no idea but it's not off at all..weird.

Dr Tran

iTrader: (10)

So was it off before???

justin hover

are you running the same rpm as before?

deelong4002

iTrader: (8)

You sure the rear you bought is a 3.42? You realize this isnt physically possible right?

96lt1m6

iTrader: (31)

When I swapped to 4.10s from 3.42s I showed 12 mph off at 60....
When I destroyed the 4.10s I only had a 3.23 rear available my speedometer would NOT go past 45 while GPS showed 65-75-85-110 and 140.

Your situation is just strange you should see a difference between the gears unless you actually installed the same as you had.

dubga

iTrader: (8)

Zrsnopro97, it looks like you and I were doing the exact same thing this weekend. I just made the exact same swap as you this weekend. Even without a gps, I could tell as soon as I drove it that the speedo was off. Speedo said I was doing 60 but I could tell I wasn't close. I used my Jet DST to set the new gear ratio and it recalculated all my shift points and speedo changes, loaded the new program, and all is back to normal.

If I were you, I would check the rear to make sure it is a 3.42. Jack the rear wheels off the ground, put the car in neutral (front wheels chocked), make a mark on the driveshaft that is easy to spot. Spin the tire one complete revolution and count how many times the driveshaft spins. If you really have a 3.42 rear, then the driveshaft will spin about 3.5 times. But if your speed really didn't change, my guess is that your driveshaft is going to spin about 2.75 times.

I really hope you didn't do all that work for nothing. I'm still sore from my ordeal.

Randy WS6

iTrader: (69)

Get a friend in there car to drive 55mph and follow them, and see what you have. But like what dubga said, thats a good way also.

Oldsmobility85

iTrader: (1)

Im going with magic. Lol

chief455

iTrader: (21)

I'm going with same ratio went in that came out = math.

_JB_

iTrader: (33)

Maybe the car already had 3.42s, and the speedo was adjusted? Or you got screwed over and got another 2.73