installing a posi and gears in a 74 nova 8.5" rear end for my 69 nova. heres a picture of my pattern with .009-.010 baclash. the richmond gears call for .008. any help would be apreciated. i think i need to go a little thinner on pinion shim and tighten up back lash. gonna mess with it a little more tomorrow if i get some extra time
The pinion depth looks pretty good. I would reset the backlash first and then maybe take .001 or .002 out of the pinion shim. If correcting the backlash improves the pattern then leave the pinion depth alone. You are very close to being right on.
Thanks big gear head! I moved my thinnest shim from right side of carrier to left and ended up with .003_.004 back lash, but the pattern was a little different I though I took a picture of that pattern but can't find it.
I think your right about taking a little out of the pinion and tightening back lash up. I will try that and report back.
Thanks again
Don't take anything out of the pinion until you get the backlash set within spec and take more pictures. I think the pinion depth is probably close enough to leave it alone.
Here's with .007 back lash. Only way I could get that back lash had to set up shims to where carrier had to be lightly tapped in. When I had .010 it would drop in pretty easy by hand. How's the pattern now. Didn't change too much
Also I used honed out low mile bearings to set up pinion with old crush sleeve tightened till there was light drag on the pinion. Will the new bearings change depth at all
Yes, the new bearing will probably change the depth a little. Be sure to check everything again after you change the bearing. You need to set the pinion bearing preload correctly each time you do a trial assembly so that your readings will be consistent. Your differential bearings should be tight enough that you can not pull the differential out by hand. You should put the shims in the left side along with the differential and then tap the shims in the right side.
I would run it like this if the pattern doesn't change with the new bearing. This pattern looks real good. What brand of gear is this?
There the cheaper richmond excel. And when shinning the carrier I put the shims in housing then dropped in carrier took some light tapping to get it seated.
I am afraid to damage the shims tapping in. Is the straight edge on the pattern at the root of the gear ok? All I have is the single stock shim on pinion not sure of the thickness my caliper is kind of jumpy.
How much bearing preload should I have?
Also should I install with old crush sleeve and new bearings to check pattern before setting preload with new sleeve?
No need to use the old crush spacer. You can set the bearing preload for trial assemblies without using the spacer. You need about 19 to 21 inch pounds of preload with new pinion bearings.
alright looks like I'll try a little less shim on the pinion. The funny thing is the first shim was .041 then when I put new bearings I I went a couple thousandth thinner
got a new crush sleeve and seal. this time i'll make sure it's right with the new bearings. i'll never use set up bearings like everyone else advised. thanks again big gear head. how much should i take out of pinion shim? .002?
Ok here's is pattern with .003 removed. Is it normal to hear a little back lash rattle while turning with axle. I'm sorry for all the questions. Just want it to be right. Paid a pro to do my jeep once and they messed it up
Pattern looks very good.
Sometimes they rattle a little even when everything is normal, I think it has to do with speeding up and slowing down as you turn it.
I did a late model Mustang yesterday with a Ford gear, The best pattern looked odd due to how the gear is lapped, and it rattled a little which made me nervous, but it was noise free on the test drive
Ok I got it all buttoned up. Preload at 20 back lash .007_.008. No noise when I turn slow by pinion. Only get a little rattle when turning fast by axle in reverse probably just inconsistent rotation is kinda hard to turn
Yes, you may have to take about 1 inch out of the drive shaft. The 8.5 has a slightly longer pinion shaft.
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