742 gear pattern.

[wagonman]

Howdy All, I am setting up a 742 with all new everything from Dr Diff. I have pinion preload @ 15 in lbs. Installed the ring and carrier, set B/L to 10 and ran a pattern. looking at the pics can you advise what shim I should start with under the Pinion. I started with a 0.060 I have a new bearing I honed for ease of set up. Coast is barely on the toe and the drive is almost non existant

 

[zyzzyx]

Your pinion is too high. WOW! The first thing you need to do is set the pinion depth from the Center Line
of the ring gear. The pinion will have markings on the end of it. It will tell you if it's +, _, and how much.
Gears are ground so close nowadays that it won't be off by much. You've really got the yellow goo slathered
on heavy! Take it easy and use Dykem HiSpot Blue, not Permatex. Permatex has the consistency of ink
mixed with petroleum jelly. Dykem is nice, dark, and applies easily. Use a piece of felt pad to apply the
Red Lead and Dykem (or whatever that yellow stuff is). The last thing to do is get your gear clearance set.
Probably around 0.004 to 0.007???

 

[silversedan]

the factory shims for 742 case were around .090.

 

[steve340]

The factory service manual has some pretty decent illustrations of which way to go.

 

[khryslerkid]

Thicker pinion shim.

 

[dvw]

Needs way more pinion shim.
Doug

 

[wagonman]

Thanks looks like I will star with a 90 and go from there. Should be able to get a new pattern tomorrow will post some pics. Gotta Love This Place.

 

[66Satellite47]

Use less marking compound, a thin coat is all you need. Aftermarket gears typically have the pinion depth scribed on them, not like factory +/- markings. So you need to get a pinion depth micrometer setup to measure the actual depth. 8 3/4's were difficult for me to get a factory looking pattern with Richmond gears. For some reason didn't have so much trouble with Dana 60's.

 

[wagonman]

This is with a 90 shim and decreased BL to 8. Looks like I need to go with more shim to bring it in a bit more, Maybe 5 thou. Yes i did water down the marking compound with some PB.

 

[zyzzyx]

Now that really looks nice! You got it Maynard!

 

[steve340]

Most of the patterns I see these days are a bit "all over the place"
I pay more attention to the drive side than the coast side. The diffs work out to be "acceptably quiet" but if you are really fussy and have good hearing most gears sets have a bit of noise somewhere.
If they are set up really close to perfect a bit of use settles them down.

 

[Runcharger]

Wow: Tons better. I'll let some of the smarter guys than me comment if it's perfect though.

 

[khryslerkid]

Pinion might be ok. Looks like maybe the backlash is off.

Are you placing some resistance on the center section when turning the pinion? Something like a screwdriver against it while turning it both ways.

Preload the center section bearings using a spanner wrench. As much pressure as you can apply with just the wrench.

 

[wagonman]

Went with a 5 thou thicker shim package and see no diff in the pattern. Think I will go back to the 90 and give it a whirl. Yes I put pressure on the pinion when doing the pattern check. Now it is time to tear it all down clean, put the seal and press the bearing on and retest. Wish me luck.

 

[dvw]

Top pic looks close but slightly shallow on the pinion depth. The next pic looks like the pinion is even further away. Maybe its the angle. Get a pic from this angle. You ideally want a football shape with the end points halfway between the face and the root.
Doug


View attachment 1193696[/QUOTE]

 

[wagonman]

Here it is with the 5 thou thicker pack

 

[steve340]

I see the pattern is different on some of those drive side markings. Camera angle perhaps?
Also the drive and coast markings are in different places on the tooth. That is a bit odd.
But they are both high on the tooth. See that "line" in the marking compound generally that ends up about 20 thousands from the root of the tooth. I use that line to work out how much pinion shim to add. I would take the 5 out and put 15 to 20 in.
Sometimes going to far and then coming back is OK. Makes you appreciate the design of the Ford 9 inch when you need to do this.
Have you checked the ring gear run-out?
I also check the carrier prior to installing the ring gear.
IMO opinion that marking might be noisy. Unfortunately there is really only one way to be sure.
I would be trying to get the main mark lower towards the root/flank of the tooth were the gear is stronger and less likely to vibrate or resonate.
If the carrier is spot on it may be you would need to reject those gears if possible.

 

[wagonman]

I see the pattern is different on some of those drive side markings. Camera angle perhaps?
Also the drive and coast markings are in different places on the tooth. That is a bit odd.
But they are both high on the tooth. See that "line" in the marking compound generally that ends up about 20 thousands from the root of the tooth. I use that line to work out how much pinion shim to add. I would take the 5 out and put 15 to 20 in.
Sometimes going to far and then coming back is OK. Makes you appreciate the design of the Ford 9 inch when you need to do this.
Have you checked the ring gear run-out?
I also check the carrier prior to installing the ring gear.
IMO opinion that marking might be noisy. Unfortunately there is really only one way to be sure.
I would be trying to get the main mark lower towards the root/flank of the tooth were the gear is stronger and less likely to vibrate or resonate.
If the carrier is spot on it may be you would need to reject those gears if possible.

That is why I added 5 to the pack trying to get the pattern closer to the root. I will pull the 5 out and add 15 to the mix and see what happens. And yes the 9in is easier to shim. More to come

 

[66Satellite47]

Maybe a stupid question, did you check the flange runout of the carrier? My first Dana 60 carrier was used, I got from a local SS/A Hemi '68 Cuda. Turned out the carrier had a fair amount of runout. IIRC about .006" I decided that explained the variability of the gear pattern. Decided it was close enough. Worked great for 2 years till I went to a spool. Drag car, didn't care about gear noise, just the gears will last.

 

[wagonman]

Maybe a stupid question, did you check the flange runout of the carrier? My first Dana 60 carrier was used, I got from a local SS/A Hemi '68 Cuda. Turned out the carrier had a fair amount of runout. IIRC about .006" I decided that explained the variability of the gear pattern. Decided it was close enough. Worked great for 2 years till I went to a spool. Drag car, didn't care about gear noise, just the gears will last.

Brand new unit from Dr Diff but yes I checked 0.002 and I wet stoned the carrier and gear, take nothing for granted.