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Tim240Z · 03-23-2005, 08:21 PM

OK...everything I've read in my searches on this board says that my 'corporate diff' should be 4.10:1 or lower (up to 5.x by some accounts).
I need to send my PCM for the 99 suburban engine for reprogramming so I checked the diff for accurate ratio.
Here is what I got:
For every one revolution of the wheels, I get about 3.4 revolutions at the driveshaft. Wouldn't that give a 3.x :1 diff ratio?

Anyone have any ideas? I want my PCM to get as accurate a speed signal as possible.
Thanks,
Tim

03-23-2005, 08:21 PM	#1
Tim240Z Senior Member Join Date: Jan 2005 Location: LAX area, So Cal Posts: 499	Diff ratio help (again!)..very confused!!! OK...everything I've read in my searches on this board says that my 'corporate diff' should be 4.10:1 or lower (up to 5.x by some accounts). I need to send my PCM for the 99 suburban engine for reprogramming so I checked the diff for accurate ratio. Here is what I got: For every one revolution of the wheels, I get about 3.4 revolutions at the driveshaft. Wouldn't that give a 3.x :1 diff ratio? Anyone have any ideas? I want my PCM to get as accurate a speed signal as possible. Thanks, Tim __________________ 1972 Suburban C20 454/TH700R4, eaton-corporate 4.10 (looking for 3.7) Sold: 71 Cheyenne 20 Installed a 99 5.7L L31/4L60E from Suburban 1500 (2005)