Ring and pinion set up question

Dana Fitzpatrick · 02-21-2015, 06:47 PM

I'm setting up a new set of Motive pro gears in my 12 bolt,the pattern is out towards the heal of the gear. Do I need a thicker pinion shim or thinner to move in towards the toe? Right now it has a .016. Thank you.

Greg Hill · 02-21-2015, 07:18 PM

Quote:

Originally Posted by Dana Fitzpatrick

I'm setting up a new set of Motive pro gears in my 12 bolt,the pattern is out towards the heal of the gear. Do I need a thicker pinion shim or thinner to move in towards the toe? Right now it has a .016. Thank you.

Try a .030-.035. That was where the Richmond pro gears usually were.

Dragsinger · 02-21-2015, 08:19 PM

Dana,

What ratio are you installing?

As posted above, a pinion shim of .032 - .033 will almost always be good with a 12 bolt.

Dana Fitzpatrick · 02-21-2015, 08:41 PM

They are 4.56's. It's a Strange housing,could that make a difference?
Looking at an old Richmond gear instruction book I have, the pattern looks like one they show as having "low tooth contact,heavy in the root of the drive gear.Move the pinion out of the gear mesh,i.e. increase the pinion cone setting.Translation, please, Lol.
My present pattern doesn't look quite as low on the toe side as their drawing,though.

pbp1 · 02-21-2015, 09:05 PM

Moving the pinion in or out will not change the contact pattern from heel to toe, it will only move the pattern deeper into the root of the teeth or out toward the top edge of the tooth. Heel to toe is mostly affected by the cut of the gear and the alignment of the pinion bore machining to the carrier bearing bore. What you are looking for is the pattern to be centered between the root of the tooth and the edge of the tooth with a rounded edge on the pattern and not a pointed edge on the pattern.

Dana Fitzpatrick · 02-21-2015, 09:30 PM

Quote:

Originally Posted by pbp1

Moving the pinion in or out will not change the contact pattern from heel to toe, it will only move the pattern deeper into the root of the teeth or out toward the top edge of the tooth. Heel to toe is mostly affected by the cut of the gear and the alignment of the pinion bore machining to the carrier bearing bore. What you are looking for is the pattern to be centered between the root of the tooth and the edge of the tooth with a rounded edge on the pattern and not a pointed edge on the pattern.

The pattern does come to a point at the root side of the tooth. Not at all bullet shaped. I did increase the pinion shim to .022. It was .018, not .016. How do I get rid of the sharp point? Back lash is set at .008-.010. The ring gear is marked .008 from Motive.

Greg Reimer 7376 · 02-22-2015, 07:45 PM

Back in the bad old days,I was a line mechanic at a few Chevy dealers. There were still quite a few 12 bolt equipped cars running around out there then, and it seemed that the lower the gear, the thicker the pinion shim needed to be for a good set up. OEM stock gear ratios, 2.73-3.73's seemed to like a .030"-.031" shim, 4.10-4.88's all seemed to like an .032" shim,5.38's and 5.57's seemed to need an.032-.033", and insane ratios like 6.14's might want an .034-.035. .008-.011 on the backlash seemed to be optimal,as well.You are right in the center of the infield with the dimensions you mentioned, but you didn't state what gear ratio you are using. This info should get you started.

02-21-2015, 06:47 PM	#1
Dana Fitzpatrick Member Join Date: May 2009 Posts: 148 Likes: 4 Liked 10 Times in 6 Posts	Ring and pinion set up question I'm setting up a new set of Motive pro gears in my 12 bolt,the pattern is out towards the heal of the gear. Do I need a thicker pinion shim or thinner to move in towards the toe? Right now it has a .016. Thank you.

02-21-2015, 08:19 PM	#3
Dragsinger VIP Member Join Date: Jul 2008 Location: Liberty City [East Texas] Posts: 1,759 Likes: 5 Liked 99 Times in 60 Posts	Re: Ring and pinion set up question Dana, What ratio are you installing? As posted above, a pinion shim of .032 - .033 will almost always be good with a 12 bolt. __________________ Larry Woodfin 471W

02-21-2015, 08:41 PM	#4
Dana Fitzpatrick Member Join Date: May 2009 Posts: 148 Likes: 4 Liked 10 Times in 6 Posts	Re: Ring and pinion set up question They are 4.56's. It's a Strange housing,could that make a difference? Looking at an old Richmond gear instruction book I have, the pattern looks like one they show as having "low tooth contact,heavy in the root of the drive gear.Move the pinion out of the gear mesh,i.e. increase the pinion cone setting.Translation, please, Lol. My present pattern doesn't look quite as low on the toe side as their drawing,though.

02-21-2015, 09:05 PM	#5
pbp1 Junior Member Join Date: Mar 2013 Posts: 78 Likes: 11 Liked 18 Times in 5 Posts	Re: Ring and pinion set up question Moving the pinion in or out will not change the contact pattern from heel to toe, it will only move the pattern deeper into the root of the teeth or out toward the top edge of the tooth. Heel to toe is mostly affected by the cut of the gear and the alignment of the pinion bore machining to the carrier bearing bore. What you are looking for is the pattern to be centered between the root of the tooth and the edge of the tooth with a rounded edge on the pattern and not a pointed edge on the pattern.

02-22-2015, 07:45 PM	#7
Greg Reimer 7376 VIP Member Join Date: Nov 2008 Location: Glendora,Calif. Posts: 1,111 Likes: 164 Liked 649 Times in 208 Posts	Re: Ring and pinion set up question Back in the bad old days,I was a line mechanic at a few Chevy dealers. There were still quite a few 12 bolt equipped cars running around out there then, and it seemed that the lower the gear, the thicker the pinion shim needed to be for a good set up. OEM stock gear ratios, 2.73-3.73's seemed to like a .030"-.031" shim, 4.10-4.88's all seemed to like an .032" shim,5.38's and 5.57's seemed to need an.032-.033", and insane ratios like 6.14's might want an .034-.035. .008-.011 on the backlash seemed to be optimal,as well.You are right in the center of the infield with the dimensions you mentioned, but you didn't state what gear ratio you are using. This info should get you started.