Todd157k

iTrader: (5)

So I'm as happy as a pig in sht. I got my 3.42s in and took it home to program. Go through my hypertech (until I get a 'real' program) and the only options are 2.73 and 3.15 gear ratios (C5, A4). I've read through the few posts and found out that's the only option I get... HOWEVER.. I'm thinking that I can adjust the wheel diameter.
See if this sounds right..
I've set the program to 3.15s and calculated the wheel diameter should be 24.4 dia. to make up the difference (although not sure this will work)
3.15 / 3.45 = 1.086
26.5" tire diameter / 1.086 = 24.4" tire diameter to log into hypertech.
According to my pee brain, that should make the correction factor.
Did I miss something?

2001NBMZ28

Don't know if this helps but thought I'd post anyway. I have one of the first Predator tuners that came out and it wouldn't change my speedo for 2.73 to 3.42 gear swap and had to use this tire size change from a chart that used to be on RWTD's site:

2.73 to 3.42 - Factory tire size 275/40-17 to Actual tire size 275/30-14

Worked fine for me, checked it against one of the gear/rpm calculators.

Todd157k

iTrader: (5)

I'll try and search out a calculator for it. I tried setting the wheel size now. Seems to work but have to get someone next to me to see how accurate my calculations are. So far, no codes.

2001NBMZ28

To check mine this is the one I used - you can change final drive ratio, tire size, gears, etc. to your application and recalculate even though it's for F-bodies. www.f-body.org/gears/

koolaid_kid

iTrader: (21)

When I went from a 2.73 to a 3.42, I contacted Hypertech because the transmission was confused as to when to shift. They had me send my PCM to them, and they changed it there (for free). It took a little while to get it back, but the speedo and the shift points were correct.

Todd157k

iTrader: (5)

Thanks. I'll check that out too. If they can't / won't do it, I'll have to spring for a HPtuner setup a little sooner than planned.

Todd157k

iTrader: (5)

UPDATE:

Finally threw codes last night and shifted with the delicacy of a sledge hammer.
Ordered the HPtuner this morning and put the Hypertech on CF for sale. Dang that HPtuner program is intimidating. Oh well, one step at a time... right? LOL.

Beer99C5

iTrader: (21)

Looks like you will be ready for the 28's , just out of curiousity, can you log the IDC on the 26's on spray before ya swap?

Beer

Todd157k

iTrader: (5)

If I can figure it out, I'll run a log. From the garble I'm reading on HPtuner forums.. looks like