I have 4.11 gears right now and I had adjusted a few parameters with tunercat this afternoon and reflashed the computer..For some reason my speedo seems to read a lot lower when driving now so Im not sure what happend It was fine before I reflashed it..

What should my calibration table look like with 4.11 gears?

Thanks

Cody

 

Put 4.11 where it says rear end ratio and enter your tire info.

 

Well when I got my tune from PCM4less he knew I had 4.11's and it didnt have that as the gear ration or the tire size and my speedo was correct..Did he adjust something else I dont know about?

Cody

 

I e-mailed Bryan about this once. He told me that he uses LT1 Edit for the gear ratio stuff because it seems to be more accurate than TunerCat.
His thinking was that LT1 Edit uses different formulas/equations and that they are "more" correct.

 

Atually both are accurate. The main thing at Edit does that TC doesn't do is to automatically change the transmission shift points in all three shift tables.

There is a problem when changing from say 3.07 gears to 4.11 gears. Because of the new gear ratio the trans often may not shift properly at WOT and will often hit the rev limiter.

If you are having problems I have edit as well, you can email me your BIN and I can make the changes for you as well. All I need is your tire size to make the change seeing how we already know what gear ratio you have.

 

If you have both TC and Edit, then you can check this for me.
Set a file up with a certain gear ratio in Edit, then open the file in Tunercat and set that same file up for the same gear.....
Does it change anything as far as the speedo calibration?

 

I also have tunercat and my settings for speedo dont match
what my car actually has. Speedo is dead on with my GPS
though.
Brian changed it for me when I went from 273s to 342s. But it was when I first got the car. Now Im going with 373s and Im doing my own tuning with tunercat.
I can manually change the shift points If i have to but what I need is either a .bin set up for 373s or some help getting the right settings.
Thanks
Rasta

 

I am about to try to use tunercat for the first time. I want to reprogramm a few things, including from 3.42 to 4.11s for an M6 car. I have tunercat. So, are you guys saying IF the programming was done with LT1edit, it'll be different with tunercat, or just that tunercat does not work properly when trying to change the gear ratios. I was also considering getting Brian to do my initial programm, then me to try to play with it later on with tunercat. HOWEVER, if you are having gear ratio problems and such, I will likely too. What do you guys think.

 

OK, I tested both TC and Edit using the same identical files with the same identical inputs into the speedo calibration.

First off when using Edit or TC, one has to remember to make sure that you pick the car type and transmission ie;

F-body manual transmission

Next be sure that you either input the correct tire size or its known revoulutions per mile. For the most part tire size is accuarate as well. To be the most accurate you can take a circumference measurement and calculate revolutions per mile. The easieast way to do that is to mark your tire and the pavement, roll the car forward and mark the pavement again when the mark on the tire comes around. Measure the distance between the marks and do the math.

For instance a 26" diameter tire has a circumference of 6.8 feet to find revs per mile divide 5280 feet by 6.8 feet which would equate to 776.4 revs/mile

OK I ran the two files and did the gear ratio change here is what I found:

TC:
Speedo Scaler: 14
speedo Scaler Fraction: .998
speedo Scaler Scantool: 55.487
Time between pulses for Stop: 63.614
Pulses per drivershaft rev: 17

LT1 Edit:
Speedo Scaler: 14
speedo Scaler Fraction: 1.012
speedo Scaler Scantool: 54.966
Time between pulses for Stop: 64.27
Pulses per drivershaft rev: 17

As you can see there is very little difference. The only values that matter as far as actual speedo readout accuracy are the three speedo scalers. Now if you mess up on picking the correct body and transmissions then nothing is going to work right. For instance a F body M6 is different than a Y body M6. A F body M6 has 17 pulse per driveline revolution while a A4 has 40 pulse and then the Y body M6 has 2! See the what a difference in choosing the correct transmission can make!

Yes, there is a slight difference in what TC and Edit calculates, but its so close that one should not see any difference between the two.

Another thing to remember when doing this, and that is to always start with a fresh unaltered BIN. Especially if you are working with Edit. One reason is that Edit makes automatic changes in the transmission shift tables. It will correct all three shift tables when you make the gear ratio change. TC does not do this so its not nearly as important to use a fresh BIN.

I have used both programs, and I haven't had any problems to date with accuracy.

 

Cool. Thanks for doing that. When I fiddled with it I came out with slightly different numbers too. And after Bryan Herter told me that he thought the LT1 Edit stuff was more accurate, I just left it for him to do.