Rear gear change vs changes to PCM?
06-05-2014, 10:48 AM
#1
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Rear gear change vs changes to PCM? Hey guys,
I've been fine tuning my 54 Ford LS swap and I've got a major gear whine in my 9" Ford rear end cuz of a set of used 3.70 gears I installed & its loud enough on acceration @ 70mph its deafening so I want to get a new set and thought of going to a 3.50 gear in my LQ4/4L80e setup as well as lower the rpms a bit on the highway since with my 27.1" tire its at 2408rpms @ 70 now and according to a website it should be 2278rpms with a 3.50. Only bad thing is it'll hurt my 60' at the dragstrip
My only issue is my PCM is setup for a 3.70, I'm not worried about the speedo since it uses a programmable Autometer style (not tied into the PCM) but, will it affect the shift points, lock up etc?
Anything I will need to change?
I've been fine tuning my 54 Ford LS swap and I've got a major gear whine in my 9" Ford rear end cuz of a set of used 3.70 gears I installed & its loud enough on acceration @ 70mph its deafening so I want to get a new set and thought of going to a 3.50 gear in my LQ4/4L80e setup as well as lower the rpms a bit on the highway since with my 27.1" tire its at 2408rpms @ 70 now and according to a website it should be 2278rpms with a 3.50. Only bad thing is it'll hurt my 60' at the dragstrip
My only issue is my PCM is setup for a 3.70, I'm not worried about the speedo since it uses a programmable Autometer style (not tied into the PCM) but, will it affect the shift points, lock up etc?
Anything I will need to change?
06-05-2014, 12:08 PM
#2
You don't HAVE to change it, but the closer to accurate the speed sensor's data is, the closer to right your shift points and TC lockup will be. If it is driven a lot, this could make a difference in economy and / or frustration when navigating hills or passing.
