12 Bolt Backlash

impstocker · 02-02-2014, 06:40 PM

Hello, going through my rear for the Impala, 12 Bolt w/ spool and 4:88 Pro Gears- what amount of backlash should I be looking for?

Thanks!
Will Lamprecht 65 Impala 396-325 I/SA in progress

HandOverFist · 02-02-2014, 06:44 PM

I look for .006 - .008 in our car.

Mark Yacavone · 02-02-2014, 08:23 PM

.005-.009 with automatic...tighter with stick

Greg Reimer 7376 · 02-03-2014, 10:03 AM

In all the 12 bolts I did, I tried to get .008" back lash,on a street application, as much as .010' is OK due to the fact that any heat soak can cause this spec to tighten up. I'm also assuming room temperature gears at the time of set up. Sometimes, the pro gears take different shims to arrive at the same spec as the street gears.

02-02-2014, 06:40 PM	#1
impstocker Member Join Date: Dec 2008 Location: Wingdale, NY Posts: 302 Likes: 27 Liked 53 Times in 16 Posts	12 Bolt Backlash Hello, going through my rear for the Impala, 12 Bolt w/ spool and 4:88 Pro Gears- what amount of backlash should I be looking for? Thanks! Will Lamprecht 65 Impala 396-325 I/SA in progress

02-02-2014, 06:44 PM	#2
HandOverFist VIP Member Join Date: Oct 2013 Location: Gulf Breeze, FL Posts: 1,651 Likes: 8 Liked 33 Times in 16 Posts	Re: 12 Bolt Backlash I look for .006 - .008 in our car. __________________ Rich Taylor I/SA - 321

02-02-2014, 08:23 PM	#3
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,815 Likes: 2,903 Liked 5,120 Times in 1,951 Posts	Re: 12 Bolt Backlash .005-.009 with automatic...tighter with stick __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers

02-03-2014, 10:03 AM	#4
Greg Reimer 7376 VIP Member Join Date: Nov 2008 Location: Glendora,Calif. Posts: 1,135 Likes: 172 Liked 705 Times in 219 Posts	Re: 12 Bolt Backlash In all the 12 bolts I did, I tried to get .008" back lash,on a street application, as much as .010' is OK due to the fact that any heat soak can cause this spec to tighten up. I'm also assuming room temperature gears at the time of set up. Sometimes, the pro gears take different shims to arrive at the same spec as the street gears.