[XSPSI]

I'm new here and came across some helpful tech info while researching gear installs. In my case, I'm setting up a new set of Ford Racing 3.31 gears (face-hobbed) along with a Strange spool and new bearings/cups.

My question is with the pattern difference between the drive and coast sides. My understanding is that if the patterns are on opposite sides of each other, this indicates the pinion depth needs to be increased to bring the pinion closer to the ring gear.

I didn't have the original pinion shim as a reference, so I used a 0.030 shim as a start with 0.008 backlash. I'm using a mockup pinion bearing (new) that I honed out to allow for easy removal/install when adjusting pinion depth.

This is the pattern I got with a 0.030 shim and 0.008 backlash:

DRIVE

COAST

The hard parting line across the top of the drive side makes me think I need to go deeper (maybe a .032 shim), but the opposing patterns between the drive and coast confuses me.

I then tried a 0.033 shim with 0.009 backlash and got this...

DRIVE

COAST

Meh, not any better. So, then I tried a 0.040 shim with 0.006 backlash to see what the gear pattern would be. Sure enough, it moved it deeper but the pattern looked a bit more "balanced" with the 0.006 backlash.

DRIVE

COAST

Went with 0.036 shim and 0.006 backlash and the pattern got better with the drive and coast patterns.

Should I try a 0.037 shim with the same backlash, or am I going in the wrong direction?

Thanks in advance!

 

[big gear head]

That's too much backlash with that gear. The pinion is too deep. Go back to about .032 and set the backlash to about .005.

 

[XSPSI]

That's too much backlash with that gear. The pinion is too deep. Go back to about .032 and set the backlash to about .005.

Here's what I got using a .032 shim with .005 backlash.

 

[XSPSI]

BTW, I'll be using a solid spacer vs a crush sleeve and have not set pinion preload while setting pinion depth. What I do is, install the pinion gear along outer bearing and pinion nut, but leave out the oil slinger and seal. Then I snug the pinion nut down to eliminate any play and tighten just tight enough to have a slight drag as I turn the pinion yoke. Is this the correct procedure?

 

[lmsport]

drive is better.
go to 0.028 shim and reset BL

 

[big gear head]

You need to get the p[inion bearing preload pretty close to correct each time you check the pattern. Otherwise you are doing it right. Go to the .028 shim and see how it looks.

 

[XSPSI]

Here's with a 0.028 shim with about 0.0055 backlash...

 

[lmsport]

coast is still favoring the root.
try a 0.024

 

[big gear head]

Yeah, keep going. Still too much shim.

 

[XSPSI]

Will do, but unfortunately for me I ran out of time to work on it. I'm going on vacation for a few days, but I'll work on it as soon as I get back.

I really appreciate the help and looking forward to getting this done. Thanks again!

 

[alwill923]

A vacation is getting in the way of working on your car? Working on the car is the vacation!

 

[XSPSI]

A vacation is getting in the way of working on your car? Working on the car is the vacation!

Actually, I got the opportunity to change the shims and backlash this morning before heading out.

This is what I got with a 0.024 shim and 0.005 backlash.

Drive and Coast Side-by-Side

 

[alwill923]

I was just joking on the vacation.
The best pattern is the first one. You have to get the coast and drive patterns opposite each other. This is what the pinion depth mainly does. once that is done the backlash will affect the shape of the pattern. The last pattern was the worst. Do a you tube search for "adjusting differential gear pattern". Below is one of the best. I noticed that you are not keeping the backlash the same for all your patterns. The backlash should be the same each time, approximately in the middle range until you get the pinion depth sorted out. 0.005 is to tight for pattern checking. Copy and put this link in your search bar.

adjusting differential gear pattern - Yahoo Video Search Results

The search engine that helps you find exactly what you're looking for. Find the most relevant information, video, images, and answers from all across the Web.

video.search.yahoo.com

 

[big gear head]

I went back and looked at your other patterns and the pattern with .040 looks like it might have some potential. I don't know why it's all the way at the root, but as far as heel to toe it looks the best. Try it again and try more and less backlash and see what it looks like. The current path isn't going anywhere.

 

[lmsport]

the 0.036 pattern has the longest patch on the drive side but the coast looks buried in the root. these pics may be hard to read, I have been taking pics of the gears I install and find the angle of the camera and the local lighting can really alter how they look in person.
I would try .036 again andf add some BL to see if the coast will move toward the middle of the tooth

 

[ericnova72]

When you do the pattern check, stick an axle in and use it to rotate the gears through a dozen revolutions or more forward and backwards....and a little less marking compound so ir flares out better without being too gloppy and thick.

 

[XSPSI]

Back from the mini-vacation, I jumped back on getting the gear pattern right. Now with a clearer head, I remembered that a while back I had purchased a Ratech Pinion Setting Tool. I left it sitting in the toolbox bottom drawer in its original box, essentially out of sight and out of mind.

Using the provided instructions I calculated needing a 0.034 pinion shim.

With the 0.034 shim I set the backlash at 0.008, which in my opinion appears to be a sweet spot.

These are pics from different angles and lighting in an attempt to show the patterns.

 

[alwill923]

Looks very good, no not perfect. I think the backlash at 0.008 helped get a better pattern. The video I attached explains which way to go but only in very small increments, 0.002. Pressure on the gears will help the pattern. If you turn the pinion, wedge a piece of wood on the ring gear and create some drag or leather glove on your hand.

 

[big gear head]

Still not right. Go back to the .040 shim and try different backlash settings and see how it looks. I see that you are using a spool with this. Stick an axle in it and use the axle to turn it several complete turns in both directions. If you have the pinion bearing preload set correctly this will give nice clear patern.

 

[lmsport]

drive side looks good.
If this is a race piece, then the drive side is what matters.