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Discussion Starter #1
I started this to help out Paul, rather then add pictures to his post I'll just put them here until he's done. I'm doing a '65 diff now with new 336 gears as well, everything is the same as Pauls except these old units require more grinding to set up the pattern. The shims are thinner then the 69-79's and require grinding each set for every pattern change!:thud:

After playing around for a starting point with this unit I got to the following.

.031 pinion shim
068 LH shim
.080 RH shim
6-8 BL This is looser then I like but this is the first setup.

Here is what I have:








The pattern is deep in the root of the teeth. I will drop the pinion shim down to about .025-.026 and set the BL to 5-6 then recheck- re grind and pattern.

Takes some time to do this.
 

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Damn...wish mine had hit that close the first time!

I noticed that my 3.36 drive is more towards the heel and my coast is more towards the toe. The ones you are doing are just the opposite.

Are those US gears?
 

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Discussion Starter #3
Yes, Toms US Gears. I had to stop today to help a buddy with his 68 diff. This one is also going into a 68, maybe I should play that number! :laughing:

I have the shim changed to a .024 and have to grind the shims to get the backlash to 5-6, then I'll post a pattern. I had to make a new wrench up to use with the ARP bolts as well.
 

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so when you get the ring gear moved towards the right, the pinion will mesh tighter with the ring gear and the backlash will decrease. You measure that by how much the ring gear will move without moving the pinion?

once the backlash is smaller i assume the patterns on the drive and coast side will be more symetrical?
 

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Discussion Starter #5
1st have to get the pinion centered on the RG, that is with pinion shim. BL will affect pattern but you don't want to compensate for the wrong pin shim with BL.
 

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Here I dropped the Pin shim to .024 and dialed in the backlash to 5-7.

You can see it's too high now with the .024 shim. Have to break it down and reshim.





 

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so when you get the ring gear moved towards the right, the pinion will mesh tighter with the ring gear and the backlash will decrease. You measure that by how much the ring gear will move without moving the pinion?

once the backlash is smaller i assume the patterns on the drive and coast side will be more symetrical?
On the first question...I sure hope so cause that is how I've been measuring with my dial indicator.

On the second point, I was wondering that myself. Here is a picture of what West Coast Differentials call acceptable patterns:

 

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I may be wrong here, but the ONLY acceptable pattern I see on that diagram is the top one in the right column. the others are going to make some noise.

And you got it on the backlash- how much the ring gear moves without the pinion moving. If you move it by hand and hold the pinion, you can feel a tiny "clunk" going from one to the other. That's what the .003-.005 (or whatever you're looking for) is.


If I'm incorrect on the pattern, apology in advance please. It's been about 15 years since I did a rear axle....

:cheers:
 

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I may be wrong here, but the ONLY acceptable pattern I see on that diagram is the top one in the right column. the others are going to make some noise.

And you got it on the backlash- how much the ring gear moves without the pinion moving. If you move it by hand and hold the pinion, you can feel a tiny "clunk" going from one to the other. That's what the .003-.005 (or whatever you're looking for) is.


If I'm incorrect on the pattern, apology in advance please. It's been about 15 years since I did a rear axle....

:cheers:
I've seen a lot of posts from Gary which resembembles more the bottom on the left column.

Here is what US Gear has as an acceptable pattern in their installation instructions:



http://i141.photobucket.com/albums/r54/beachbeanerman/diff build 2/USGEAR.gif

Not sure how the pic will come out...click on the link for a better pick.
 

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Gary,

Went back through your diff post on that other forum. Snatched this pic of your final pattern of the 336 you were doing. Hope you don't mind. Although it is a little difficult to see, it looks as if my 336 pattern is getting close to it.

Paul

 

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Discussion Starter #11
That was a 69 336 I built for a BB car. It needed a case too and the garage I did the work for didn't want to go for a blueprinted case, (Big mistake), I used the new Eaton as it came out of the box ( big mistake #2). It's on the road and quiet but that posi is going to hammer and slip in time. That Eaton is only good for the case but the guy didn't want to listen.:huh:

Those patterns are fine, that page is used by Randy's and I think everyone copied his manual. It's online as well. I have had few that lined up back to back. The one I'm doing now is drive/Toe and Coast Heel. The important thing is to get the face and flank equal. My 336's had a faint whine in them, you may get some in performance cut gears. I pick it up but others who ride or drive it don't pick it up.
 

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Discussion Starter #12
I worked on this all day today, grinding shims for the case and pinion. The pattern is going to be like the LH middle on the above chart. This is the pattern I found with the 336's, the 373 setup like my avitar. I'm taking a break at this point too much yellow paste for today!:crazy:









 

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out of the patterns that smokin posted which is optimal and why?

It seems Gary likes to shoot for the shallow pattern on the drive side.

It seems to me the drive side is important with the coast being much less so.


Am i right?

if the gears are machined correctly shouldn't you be able to get them somewhat symetrical?

if a gear makes noise is that necessarily a bad thing? I actually like my car to make some of these sounds. I don't mind hearing lifters, i don't mind some popping or whining coming from the diff. Gives the car personality.
 

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Discussion Starter #14
To follow up on this. I did a lot of shim grinding because this is an early housing. The Final patterns are below. I fit a solid sleeve(more grinding) and set the preload to 18 -19 in/lbs with new seal installed this is up to 20 in/lbs.
This is about as high as I set this even though the GM books calls for 20-25 in/lb. This is the typical pattern I have with Tom's 336 gears. The pinion shim is one I ground to .025" .024 too high and .026 was close but I like this one the best. I kept the backlash at 5-7 as this will open up about .001 as the gear break in. The pinion preload will also drop once the bearings seat.

There is no way I know of to get these back to back unless the backlash is set way out of range, There is no option to the pinion shim either as the gear need to be centered.

This job would have been done except for a bad set of new yokes. They had .020 endplay. I have 1 rebuilt yoke and that was .002 when checked.











Here is the Face of the pattern. you can see both sides lined up






Here is the job less yokes. New case bluepritned and polished, new cap screws, ARP RG bolts, radiused edges, drain plug, solid sleeve.



 

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Discussion Starter #15
out of the patterns that smokin posted which is optimal and why?

It seems Gary likes to shoot for the shallow pattern on the drive side.

It seems to me the drive side is important with the coast being much less so.


Am i right?

if the gears are machined correctly shouldn't you be able to get them somewhat symetrical?

if a gear makes noise is that necessarily a bad thing? I actually like my car to make some of these sounds. I don't mind hearing lifters, i don't mind some popping or whining coming from the diff. Gives the car personality.
Pattern must be equal in the face and flank of the tooth while maintaining the proper backlash. That is why they will not usually be like the text book patterns. The chart shows the various patterns that will work.

You will get gear noise, just what level this is will be determined by setup , gear cut, and oil used. In my 72 with new 336's I can hear some noise but most people do not.
Popping is from the clutches and the way they are setup. If too tight and abused, those snowflakes will break.
 

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Discussion Starter #16 (Edited)
To close out this post, here is the final assembly with all the goodies, ARP bolts, HD yokes,tuned posi,336's, solid sleeve, socket heads, only thing not used in this one is the steel cap.




Yoke endplay .005 LH .008 RH

 

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Great Post....at least for me:D

One more question I keep forgeting to ask. In your paper and in this post, you elimnate the hex bolts for the socket head cap screws. The one you use here are ARP.

All all of these rated the same? I can get them at the local hareware store, but I passed on them not knowing how they are rated. Do they have the shoulder on the head?
 

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How many other addicts are in the garage today....

instead of out at Fourth of July celebrations? Jeez I blew off 2 good parties just to try to set up my ring & pinion......:crazy: (or should that be :partyon: ?)

Anyway, the problem I'm fighting now is equal face/flank on my drive/coast. I've been able to move my patterns around as needed for other specs, but no matter what I do, my coast is higher (to face) and drive lower (to flank). When I get one centered nicely, the other is off too far. All I can think of is my pinion is offcenter to the ring axis.....Jeesh I hope not.
As it sits right now, backlash is .0063"; coast nicely centered heel-toe; drive 1/3 from toe, 2/3 from heel; but coast pattern is a 'D' flat side toward face and drive is a 'D' flat side to flank. (Vertical as typed here) centerline of 'D' about center of face/flank for both. Both 'D's are about equal size, 1/4" by 7/8" +-.

I'm here looking at photos & posts to try to get an idea...
I think the best idea is to close the garage door and go to a party. Come back later with a fresh mind.....;)

Happy Holiday, all! :buhbye:

John
 

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Discussion Starter #19
Well taking a break and having a hot dog was a smart thing to do, working on the 4th of July!:surprised ( I tuned a 68 posi myself:crazy: )

Something doesn't sound right there John. Pictures would be the way for me to help, if you can't get them posted here email them to me.

Get the backlash to 5-7, 6-8 is ok but I like 5-7. What do you have for varience with the BL? I don't think you have a bad gear set just need to dial it in.
 

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Gary,
E-mail sent. Never occured to me to check the BL in several places till late last night. I'll do that when I get home.
John
 
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