12 bolt r & p setup
 

I'm halfway through setting up my first ring & pinion for my stocker, and thought I'd better stop and ask a few questions before buttoning it up...don't want to have to do it all over. First, the manuals I've been using are all aimed at the typical rebuild, not a race application. The pinion bearing preload specs are calling for 20-25 in./lbs. for new bearings...is it unwise to lower that number for less rolling resistance? Same goes for carrier bearing preload...they say "as tight as you can without damaging the shims during installation"; that seems kind of vague to me, but I don't see any way to measure it. One more: I am assuming backlash is not really a place to gain or lose rolling resistance - specs call for .006-.008 for a pro gear...does that sound right? Thanks in advance!
BTW, the gearset is used - just a few passes, but looks fine and has a good pattern.

Re: 12 bolt r & p setup
 

Paul,

I will give you my opinion, it makes sense to me and I have used this method successfully for many years. You touched on part of the setup that is important to me, low rotation resistance.

I use a solid pinion spacer [I do not use the factory crush sleeve] Then experiment with shims to have a VERY slight pinion bearing pre-load. Basically just taking the slack out minus a few thousands. It will require taking the pinion in and out a number of times to sneak up on the correct shim pack. As a final step, once you are completely satisfied with the set up, put blue lock-tite on the pinion nut threads.

For side bearing pre-load, again, not much. I use a small, light weight hammer and just tap, tap, tap the side shims in. If I encounter much resistance, take off .002 - .003 thickness and try again. Also, it is important to be rotating the spool/ring gear assemble as the shims are being tapped in. This helps the side bearings become centered in the bearing races.

This link is for Precision Gear http://www.precisiongear.com/setupkits.htm The specific page shows "set-up bearings" the bearings are honed for a slip fit on the pinion, thus, experimenting with shims is easy. On other pages you will find a solid pinion sleeve kit with shins. These are very helpful tools.

About the pinion depth shim, you will find somewhere between .029 - .033 will give a good pattern with .031 - .032 being a common final shim.

I suggest back lash closer than you mentioned, .005 - .006 range is fine. Rarely do I use more than .006.

Pattern marking grease will help you finalize the set-up. Your manuals may show some acceptable patterns, use those as guide lines.

Re: 12 bolt r & p setup
 

I forgot to mention, the car will roll very freely with the above mentioned set-up.

Re: 12 bolt r & p setup
 

Larry -
Thanks for the info...that's exactly what I was looking for. I'm already using the solid pinion spacer w/ shims, and got it set to 22 in.-lbs. after about 8 tries. Time for a do-over! Also was not aware of turning the carrier while shimming, that makes sense. I have another question, too: I bought another pinion bearing to use for a checker...took out a little with a die grinder, just enough so it would go on and off by hand. Got the pinion depth set, and put the pinion in the press to put the good bearing on....it barely put up a fight, and when it was fully seated against the shim, it would move by hand. I can't really see this as being a problem, but then again, I've never done this! What do you think?
Thanks

Re: 12 bolt r & p setup
 

Paul,

something is not right with that pinion bearing press fit. I would feel better finding out what is wrong. I have never seen a loose fit like you describe. Do you have another pinion and rear bearing that can be measured for comparison? I suggest finding the reason for a loose fit and correcting it.

Re: 12 bolt r & p setup
 

Made a call to the guy I got the gears from to ask about the pinion bearing fit - he talked to the guy that sets up his rears, and was told he does that to all his pinions to make it easier to set them up. My guy's been racing S/SS for a couple of decades, so I'm gonna give it a shot. You guys will be the first to know if it comes apart! :D
Thanks again for the help.

Re: 12 bolt r & p setup
 

now that we know why the fit is loose, I am fine with the deal. It simply did not make sense without knowing about the modification.