soontobeLS1

I am contimplating going to 410's in my 10 bolt. I know it will mess the speedo, but I can live with that until I get a re-tune for a blower or something.

But for now, I think this may be my next mod.

Where does the odometer measure from, is is the front tires?? This would make sense anyways. I am just worried about my car racking up more miles than I drive.

If that aint a problem, then I am gonna do it.

Can a shop with an LS1 Edit tuner do my car and adjust it for the gear ratio...I already have an LS1 Edit tune.

Thx for the help.

Tally TransAm

iTrader: (17)

it will rack up more miles as it will throw you speedo off

and yes you can just get a shop to change the gear ratio in the pcm

staringback05

iTrader: (8)

i put in 3.73s over my 2.73s...and it threw the speedo off by about 20mph...the tranny shifted different also because of the tune....and the miles did go faster...

if you know someone with efi live...itll take all of 5 minutes to change the ratios in the pcm

MannyZ28

iTrader: (1)

When you say the tranny shifts different....is that detrimental to the driveability of the car? My friend has 2.73s in her car now but will get the 3.42s out of my car, how exactly does that affect the shifting?

sixvi6-camaro

iTrader: (9)

the shift tables reference the vehicle speed and TPS position to know when to shift at part throttle and WOT so with the spedo off it will shift at odd times and the car will put miles on the odometer quickly.

when I went from 2.73's to 3.73's without changing the tune the car shifted hard as hell in traffic and held the shifts much longer than they did but I have an FLT tranny and 3600 stall. I only drove like that a few days though until I had time to fix the tune.

Travis99LS1

iTrader: (2)

i just went from 2.73's to 3.42's..and my shift points are normal, but your right..it does seem to shift harder now..if i get on it, it will bark second hard, i'm not sure if its from the actual change in gear ratio, or if its from the PCM increasing line pressure..also when im coming to a stop i can feel the trans downshifting as i slow to a stop. Im still debating on whether or not to get it tuned tho...i mean..the speedo being off really doesent bother me that much, its just my odometer reading more miles than i'm actually covering is what bothers me.

MannyZ28

iTrader: (1)

Any guesstimate by how much it is actually off?...the odometer that is. How does the car feel in comparison to when you had the stock 2.73s in there...does it feel quicker?

RZRSEDGE

iTrader: (21)

I went from 2.73s to 3.73s and could'nt feel alot of difference in acceleration, but there was some. Say goodbye to running 70 @ 1800-1900 rpms. I went to 60 @ 2000 rpms. Both were with the stock size tires. If you run different tires at the track, you'll have to change the ratios in the tune or it will throw your shift points off. Little nit picky stuff but it all plays a part in the whole picture.

WolfgangX

iTrader: (3)

410s + 10 bolt + blower.... good luck keeping it in one piece

MannyZ28

iTrader: (1)

Ok as far as the odometer goes...I reset my trip odometer after getting gas after the gear install, and usually I get 230 miles out of one tank...we'll see if I will get "exceptionally" good mileage out of this tank One preliminary measurement was going over our local bridge which was, using crude ways of measurement with my odometer, 1.2 miles long. After the gears it was 1.4 miles.

So we'll see what she racks up.

sixvi6-camaro

iTrader: (9)

I'd take the time and get a tune because the change from 2.73 to 3.42 is about a 20% difference so the odometer and spedo wil be off by that much. Your bridge test sounds right if you don't get it tuned for every 100 actual miles you drive your odometer will have an extra 20 or for every 10K actual miles your odometer will tag on an extra 2K.

I have a spreadsheet that I made when I did my gear change before I corrected my tune. Its attached just put your old ratio in the yellow cell and the new one in the blue and it will spit out the aproximate speed the car is actualy going. My buddy and a few other found it handy when they changed their gears and still drove the car so they would know how fast they are going at a glance.

MannyZ28

iTrader: (1)

Yeah it was kinda funny last night. My friend was driving next to me in her car, which is the car that now has my old 3.42 gears in it since I replaced mine with 4.10s, and her speedo was showing 65 mph while mine was showing 60, but according to my rpms at the time I was doing 45.

I ran almost an entire tank of fuel through my car this weekend, and so far I am off by about 25 miles. I am just waiting for the new tuner in town to get his computer set up so her and I can both get our speedos adjusted.