Regearing and tuning
02-16-2016, 08:46 PM
#1
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Regearing and tuning I have the 2.73s in my car now and going to a 4.10 dont drive on the highway and building the car for the 1/8 question is i was told i have to tune as soon as i regearing or the trans wont shift and run weird. Is this true?
02-17-2016, 08:53 AM
#5
A regear wouldn't impact your tachometer reading...if you have an A4 your shifting will still be whack. If you have an M6 your speedo will be wrong, but it won't stop you from driving the car. As for tuning you can always just do a cheapo tuner from amazon and fix for the gears if you don't have the coin for a real tuner.
02-19-2016, 07:58 AM
#6
Regearing and tuning I don't get why it would cause problems? Some one explain this to me..
As I understand it (lets say for ease of explanation) if with 2.73s shift at 5500 rpm and 50 mph nothing has changed by changing gears as far as the pcm can tell.
Even though at with the new gears the values will be different the pcm sees them the same no? 50mph will still be occurring at 5500 rpm as far as the pcm knows. The odometer will be off, as will the speedo, but even though at 50mph you're actually only going 40mph it would still meet the 50mph 5500rpm criteria wouldn't it?
As I understand it (lets say for ease of explanation) if with 2.73s shift at 5500 rpm and 50 mph nothing has changed by changing gears as far as the pcm can tell.
Even though at with the new gears the values will be different the pcm sees them the same no? 50mph will still be occurring at 5500 rpm as far as the pcm knows. The odometer will be off, as will the speedo, but even though at 50mph you're actually only going 40mph it would still meet the 50mph 5500rpm criteria wouldn't it?
02-19-2016, 08:41 AM
#7
I don't get why it would cause problems? Some one explain this to me..
As I understand it (lets say for ease of explanation) if with 2.73s shift at 5500 rpm and 50 mph nothing has changed by changing gears as far as the pcm can tell.
Even though at with the new gears the values will be different the pcm sees them the same no? 50mph will still be occurring at 5500 rpm as far as the pcm knows. The odometer will be off, as will the speedo, but even though at 50mph you're actually only going 40mph it would still meet the 50mph 5500rpm criteria wouldn't it?
As I understand it (lets say for ease of explanation) if with 2.73s shift at 5500 rpm and 50 mph nothing has changed by changing gears as far as the pcm can tell.
Even though at with the new gears the values will be different the pcm sees them the same no? 50mph will still be occurring at 5500 rpm as far as the pcm knows. The odometer will be off, as will the speedo, but even though at 50mph you're actually only going 40mph it would still meet the 50mph 5500rpm criteria wouldn't it?
This older thread has some good info: https://ls1tech.com/forums/automatic...ift-point.html
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02-19-2016, 11:44 AM
#8
MPHs' @ 5500
1st-2.73=50 4.10=33
2nd-2.73=95 4.10=63
3rd-2.73=154 4.10=102
4th-2.73=220 4.10=146
Installed a TCI 2800 'off the shelf' convertor.
Couple years later,I went from OEM 3.23s' to 4.56s',used a Hypertech to reprogram for the gears. Hypertech is worthless except for reprogamming gears. That was the only 'tuning' I did. Everything was fine,shift points were an automatic function of the Hypertech gear programming,shifts occurred just as 3.23 OEM.
Installed a Yank SS3600 and didn't touch anything in the tuning. Everything was fine again.
Rebuilt the 3.23 rearend and put that back in and used the Hypertech to return to the 3.23 gear setting,everything was fine again.
Never had a problem,without 'tuning',on the street or strip. Maybe I was lucky.
1st-2.73=50 4.10=33
2nd-2.73=95 4.10=63
3rd-2.73=154 4.10=102
4th-2.73=220 4.10=146
Installed a TCI 2800 'off the shelf' convertor.
Couple years later,I went from OEM 3.23s' to 4.56s',used a Hypertech to reprogram for the gears. Hypertech is worthless except for reprogamming gears. That was the only 'tuning' I did. Everything was fine,shift points were an automatic function of the Hypertech gear programming,shifts occurred just as 3.23 OEM.
Installed a Yank SS3600 and didn't touch anything in the tuning. Everything was fine again.
Rebuilt the 3.23 rearend and put that back in and used the Hypertech to return to the 3.23 gear setting,everything was fine again.
Never had a problem,without 'tuning',on the street or strip. Maybe I was lucky.
02-19-2016, 11:16 PM
#9
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Part throttle shifts won't change very much, what will though is WOT shifts. These are based on a preprogrammed speed and RPM range, so if you put say 4.10's in and didn't program it you would bang the rev limiter if you held the pedal to the floor. Also your speedo is way off then. Reprogramming the shift points basically scales everything accordingly so say a 4.10 ratio is roughly 50% deeper then 2.73's all your shifts points mph will change by that ratio to get a baseline. Sometimes you need to manually change the mph or rpm slightly afterward depending on the health of your transmission so you don't bounce off the rev limiter.
02-20-2016, 10:00 AM
#10
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I don't get why it would cause problems? Some one explain this to me..
As I understand it (lets say for ease of explanation) if with 2.73s shift at 5500 rpm and 50 mph nothing has changed by changing gears as far as the pcm can tell.
Even though at with the new gears the values will be different the pcm sees them the same no? 50mph will still be occurring at 5500 rpm as far as the pcm knows. The odometer will be off, as will the speedo, but even though at 50mph you're actually only going 40mph it would still meet the 50mph 5500rpm criteria wouldn't it?
As I understand it (lets say for ease of explanation) if with 2.73s shift at 5500 rpm and 50 mph nothing has changed by changing gears as far as the pcm can tell.
Even though at with the new gears the values will be different the pcm sees them the same no? 50mph will still be occurring at 5500 rpm as far as the pcm knows. The odometer will be off, as will the speedo, but even though at 50mph you're actually only going 40mph it would still meet the 50mph 5500rpm criteria wouldn't it?