Official A4 to M6 (T-56) Thread!
04-02-2010, 05:01 PM
#731
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DAMN! that looks **** as hell! i was wondering how that would work cuz i got a RC with a 5-spd and was def plannin on putting a t-56 in it..this will help tons!..thx
04-26-2010, 02:12 PM
#733
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Ive had my t-56 for the last 3 months, its been great.
the only thing thats bugging me, is that my cruise does not work.
when i first had the swap done, the cruise worked, but the speedo was waaay off.
so i got a blackbear tune and had him give me the manual tune, after that my cruise has stopped working.
im curious what wires the cruise looks for to turn on/off, because im thinking the 5-speed wiring is different than the auto. btw i only have the wires hooked up for reverse lights,speedo, and the start wire hooked up to my brake
btw, its an 03 ext cab 4.8
the only thing thats bugging me, is that my cruise does not work.
when i first had the swap done, the cruise worked, but the speedo was waaay off.
so i got a blackbear tune and had him give me the manual tune, after that my cruise has stopped working.
im curious what wires the cruise looks for to turn on/off, because im thinking the 5-speed wiring is different than the auto. btw i only have the wires hooked up for reverse lights,speedo, and the start wire hooked up to my brake
btw, its an 03 ext cab 4.8
That's something I was never really able to figure out. I'm not sure how the 5spd trucks work in regards to the cruise control. It shouldn't really care what trans is behind the engine, since the VSS is the same. That's the only feedback on the control system, so I'm thinking something got turned off in the tune, or somewhere in the tune it thinks the truck is in neutral/park and not drive.
04-26-2010, 02:33 PM
#734
That's something I was never really able to figure out. I'm not sure how the 5spd trucks work in regards to the cruise control. It shouldn't really care what trans is behind the engine, since the VSS is the same. That's the only feedback on the control system, so I'm thinking something got turned off in the tune, or somewhere in the tune it thinks the truck is in neutral/park and not drive.
I am waiting for HPtuners to send me a beta program that will have the gear ratio tables opened up. I remember back from my LS1Edit days that this table exists and my guess would be that IF I set 4th gear in the 4L60 table to 0.5:1, then the cruise should work. However I won't be able to confirm this till I actually do the swap in June.
Another thing to look at:
I compared the Speedo information between my 4L60 silverado and my T56 camaro. The trans revolutions/mile settings are considerably different even when the same tire and rearend ratios are used.
ex: 4.56 gears and 26" tires on both
Camaro = 803.2 rev/mile
Silverado = 3488.4 rev/mile
now...why on earth would the same tire and gear combo give a different rev/mile of output shaft? This number is entirely separate from speedo reluctor ring count and instead is 100% related to a physical/mechanical connection.
IF someone wants to try it, I can run your tire size and gear ratio through the F-body tune and give you the pulses/mile and the rev/mile that it outputs. Then manually enter the numbers into your truck file and give it a try.
For my setup (4.56 gear and 31.2" tires) with the T56 17tooth reluctor, it shows:
VVS pulses/mile = 50113
Rev - Trans = 17
Ratio = 4.56
Trans Revolutions/mile = 858.226
feel free to PM me...
04-26-2010, 09:32 PM
#735
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well, in regards to that...
when i had the auto tune with the t-56 the cruise worked..
i just had to get the speedo over 25mph which was like 60 according to my gps.
when i had the auto tune with the t-56 the cruise worked..
i just had to get the speedo over 25mph which was like 60 according to my gps.
04-27-2010, 04:31 AM
#736
So even if you have the correct tooth count speedo gear the cruise may not work? I am in process getting a six speed built. And requested he make it a 40 count tooth to match our trucks. Unfortunately the cruise hasnt worked in so long for me because of my swap and the throttlebody I am using at the moment, But I was hoping to fix all that.
Mine was a v6 5 speed truck, I also have noticed the cruise module is different between v8 and v6.
Mine was a v6 5 speed truck, I also have noticed the cruise module is different between v8 and v6.
!
04-27-2010, 08:19 AM
#738
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i think it has something to do with the manual tune..
there are a couple wires on the ecu that may need to be addressed to get cruise, although im not sure which exactly and if they need power or ground
im thinking either 18 or 35
not sure though
pin 33 on a auto truck goes to the brake pedal, so that should be fine...
there are a couple wires on the ecu that may need to be addressed to get cruise, although im not sure which exactly and if they need power or ground
im thinking either 18 or 35
not sure though
pin 33 on a auto truck goes to the brake pedal, so that should be fine...
05-01-2010, 01:00 PM
#739
Then last night as I was about to fall asleep, I was mulling this over when it hit me.
A t56 has a 17tooth speedo gear, while a 4l60 has a 40tooth gear. This results in the output shaft RPM being under reported by 60%. (which is why your speedo said 24mph at 60..... 60*.4=24)
ex: on my setup, the difference would be:
17 tooth count = 49454 pulses/mile
40 tooth count = 116362 pulses/mile
Therefore, the engine is turning a much higher RPM in comparison to what the computer THINKS the output shaft is doing. So even though you are IN 6th (t56), the computer was perfectly happy to assume you were in 3rd of 4th (al60), which seems to work just fine.
The issue only seems to come up when the engine rpm is LOWER than the computer thinks is possible. My guess is this is the result of a fail safe against a faulty vehicle speed sensors. GM does not want people engaging their cruise control with a bad VSS (remember all the issues Toyota is having with their cars driving themselves to 100+MPH uncontrollably).
Knowing all this still doesn't negate the need to adjust the OD tranny gear ratio to 0.5:1 in order to solve the no-cruise problem, but it at least I believe it shows where the problem is coming from.
I have attached 2 files (excel files... download and unzip them).
One is a shift point excel file (thanks to another PerformanceTruck member) that I have converted to show 4l60 and t56 RPM-vs-MPH in 1st-4th.
The other is an excel file I made up to show shaft RPMs, VSS pulse, Engine RPM, etc. with different tire sizes, gear ratios, VSS pulse counts, etc... It's very handy for getting speedos dialed in.
Between these two, you can see what I'm getting at about the VSS reported input-vs-output shaft issue.
Last edited by 2001CamaroGuy; 05-01-2010 at 01:30 PM.
05-01-2010, 01:26 PM
#740
Also thought to pull two, bone stock F-body files from HPTuners repository. The attached screen shots show the speedo calibration section.
Note the Trans revolutions/mile on each (805 for manual vs 2615 for auto).
If you read the "note" about Trans Rev/mile, it says:
"This value is used to calculate the speed that is used for shift and TCC calculations."
Which may be why the F-body table is just pushed so far off. Since the manual cars obviously don't care about shift or TCC lockup, putting the output shaft RPM low might solve the problem.
I'm not sure if this will solve anything or not as I can't actually TRY my solution yet (tranny goes in 1st of June after classes are out). Perhaps someone else could take 5 mins and give these numbers a shot?
Note the Trans revolutions/mile on each (805 for manual vs 2615 for auto).
If you read the "note" about Trans Rev/mile, it says:
"This value is used to calculate the speed that is used for shift and TCC calculations."
Which may be why the F-body table is just pushed so far off. Since the manual cars obviously don't care about shift or TCC lockup, putting the output shaft RPM low might solve the problem.
I'm not sure if this will solve anything or not as I can't actually TRY my solution yet (tranny goes in 1st of June after classes are out). Perhaps someone else could take 5 mins and give these numbers a shot?