Technical Help with gear pattern

I’m in dire need of help. I’m currently doing a gear swap in a truck 12 bolt rearend. The current set up on pinion is 20 thou with 8 thou back lash. Can some one explain what this pattern is telling me and what I need to do?. Thanks

 

I think drive it

 

Looks perfectly serviceable to me

 

2-cut or 5-cut gear??

Two Cut vs. Five Cut Ring & Pinion Gears - West Coast Differentials

I don't like that sharp cut-off to the pattern at the root on both drive and coast sides. Straight lines defining a pattern are always bad, you want the pattern to be a soft fade along every edge, just like the look when bodyworking a paint chip.

I think it needs more pinion shim.

Do you have the original pinion shim the factory put in that housing with the original ge****t??

 

Agreed with Ericnova. To add to that when you add that shim make notes as you go along. To keep from getting lost on shims and patterns

 

Don’t you all think the pinion is already too deep as it is running off the toe on the drive side? That would mean less shim.

 

I’m almost positive the gear set is a 5 cut. Here the pinion at 24 thou, with 8 backlash. Yes I have the factory shim

 

My opinion that looks better!

 

24 & 8 looks better to me, did you load the ring while turning the pinion? Are these new gears?

 

yes I added resistance on the ring gear. Yes new gear

 

I think your coast side is ideal, but you want to set up for the drive side pattern. I think drive would look closer with more shim added, not too far off, but some.

 

The pattern looks very fine to me. FYI if it were for a drag car I would locate the drive side pattern down closer to the inside of the ring gear, to account for the extreme deflection encountered on hard drag strip launches, which drive the contact patch outward up the outer edge of the ring gear.
But for the street - I'd drive it.

 

I would run either bit the second pictures you posted look better, send it!

 

So I was standing around in the shop going over some things. Grab the pinion and started inspecting it and notice I seen daylight, between the pinion bearing and shim. Decided to grab my filler gauge, started at 10 thou and went right in. Stuck the pinion back in the press and heard a “pop”. Grab my filler gauge and couldn’t get nothing between the shim, and bearing.

!!!!Set up is 20 thou at 8 back lash!!!!.

the 24 thou was from the other day

 

Won’t get much better than that!

 

So you would run it?

 

NOW looks great.
Gear pattern is kinda an art. Many times you can run it “as is” and have no problems, sometimes you will. Like-I check my dwell after I gap my points, but some guys won’t.

 

I agree. Gear interpretation can be a pain in the ****. But it seems like the drive is favoring the heel, and the coast seem like it favors the toe, but in the same breath it looks great.

I’m about to pull it apart, clean, install the crush sleeve, and send it but I want to verify before I do?

 

I would be thrilled with that pattern, I would absolutely run it.

 

I think taking into account drive and coast side, you have split the difference, and if anything the drive looks a hair better. I would run it. I don’t think you could get it more optimal, period.

 

Alright I’m about to dis***emble, clean up, and install the crush sleeve. Thanks. I will report back on test drive

 

Agree, looks good where you ended up now. Run it

Looks like second attempt which had the air gap was too much shim effectively, pattern shifted over and went past best fit....the final pressing fit cleared that up.

Good thing you caught that air gap....that would have quickly turned into destruction

 

Agreed, the pattern now looks great. Good job.

 

Kinda late to the thread, but I think the later pattern is good! Sometimes guys get a little to carried away with patterns. But gears can be funny! I have seen gears way out of “ pattern” run silent! I have seen some real close make some noise!
I did my wife’s ot truck a few years back and found no shims anywhere, just piput new bearing in and ran it! lol Made a little noise, but out lasted the engine!





Bones

 

Thanks guys for your time. I will be taking it off the stands tomorrow. I done had what I can take today lol.


I’m so glad I decided to inspect and go over things. Sometimes we attend to over look things and some times walking way does the trick. Again I really “appreciate” everyone that has chimed in .

I will keep y’all updated tomorrow.

 

I wish I can send a video to y’all, but I took to the end of the street she smooth and quiet.