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Discussion Starter #1
I have an 01 GMC Z71 that has been lifted. I am running 35s and next week I am getting 4.56s installed. My calculations put me with the speedo reading high after the gear install. (compared to 265/75/16s with 3.73s) What is the cheapest way to access the computer and make these changes? I really don't want to spend 300 bucks on a hand held tuner just to do this. I didn't realize at first that some of these tuners are VIN locked so once you use it you own it.
 

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GMFS slowest truck :read:
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It may not be the cheapest, but get a nelson tune...he can do all that stuff plus a lot more for around 300$$...i think you could also go to the dealership and they might be able to do it for like $50 or so.
 

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RedneckDude said:
It may not be the cheapest, but get a nelson tune...he can do all that stuff plus a lot more for around 300$$...
His 2001 would be 425 bucks before any group purchase ect.... superlift makes a calibrator and so does granitelli(sp) or you could just use a hypertech on there if you dont wanna pay for the tune
 

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Discussion Starter #4
RedneckDude said:
It may not be the cheapest, but get a nelson tune...he can do all that stuff plus a lot more for around 300$$...i think you could also go to the dealership and they might be able to do it for like $50 or so.
Dealership can't do it. They don't have the ability to input for a 35 inch tire. Or at least that's what I am told. If I have to spend the 300 bucks I am probably going to go to a local dyno shop that uses ls1edit. I'll have to buy a piggyback license but I will always be able to go there and use it. I plan on putting in a radix sometime in the next year and really want to dyno tune it.
 

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The bigger thing than the speedo in this case would be shift points IMO.

With the 4:56 the truck will shift funny plus the speedo will be off.

I would say Nelson or Hypertech but you said you didnt want to go what way.
Taking it to a speed shop like you have already brought up is about the only way I can think of w/o putting up the cash for a nelson or hypertech.
 

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Discussion Starter #7
BDZ71 said:
The bigger thing than the speedo in this case would be shift points IMO.

With the 4:56 the truck will shift funny plus the speedo will be off.

I would say Nelson or Hypertech but you said you didnt want to go what way.
Taking it to a speed shop like you have already brought up is about the only way I can think of w/o putting up the cash for a nelson or hypertech.
So Brandon, have you corrected for your tires yet? What did you use? I didn't know if there was a cheap way to just get the correction done. I guess going to the dyno shop is what I am going to do. I was wondering about the shift points myself. Are they based solely on RMP measurements? or does the torque load factor into it? It would seem that adding the gear change is a corrective action at this point since the new tire circumference has it all out of whack.
 

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RedneckDude said:
It may not be the cheapest, but get a nelson tune...he can do all that stuff plus a lot more for around 300$$...i think you could also go to the dealership and they might be able to do it for like $50 or so.

not 300, try 495-500+.00
 

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I'm just gonna buy a hypertech :imo its not as good as a nelson tune but it might be easier for me and they can now read DTC's
 

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Yes, I am using the Hypertech. I have had it before the lift. It will work with up to (down) 4:56 gears and 34" tires. Yea I know you have 35's but at 60MPH its only off by a couple so it basically fixes it IMO.
If I ever had some extra money I would sale this thing and get a Nelson tune because you will get more performance gains from that over the HPPIII

Grant said:
Superlift TrueSpeed recalibrators go for about $150-$200.

Grant, does truespeed fix aftermarket Gear ratios or just tire size?
 
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