Gear pattern
Thread Starter
Heel & Toe
Joined: Apr 2012
Posts: 17
Likes: 0
From: Bergen
Gear pattern
Hi folks,
I'm new at these forums and in the task I've started, rebuilding my differential for my 79 Corvette. 4.11 US gears.
This is my current pattern after 2 tries, but I'm not sure if this is a runner or not. The pinion shim used is 0.0155 (0.015?) and BL ranges between .0063" and .0079" Any opinions from you experts out there?
Don't mind the date :P
Thanks
I'm new at these forums and in the task I've started, rebuilding my differential for my 79 Corvette. 4.11 US gears.
This is my current pattern after 2 tries, but I'm not sure if this is a runner or not. The pinion shim used is 0.0155 (0.015?) and BL ranges between .0063" and .0079" Any opinions from you experts out there?
Don't mind the date :P
Thanks
Last edited by Bullseye83; Apr 10, 2012 at 05:56 PM.
Burning Brakes
Joined: Mar 2005
Posts: 1,231
Likes: 34
From: Ontario
Looks OK to me, you should be able to look up pictures of correct gear patterns in old manuels or on the net .
Your pattern looks like it has good contact and not running off the ctr too far. I would check the pattern on the oppisite side of the crown gear for good measure .
Bill
Your pattern looks like it has good contact and not running off the ctr too far. I would check the pattern on the oppisite side of the crown gear for good measure .
Bill
Thread Starter
Heel & Toe
Joined: Apr 2012
Posts: 17
Likes: 0
From: Bergen
As for the bearings, these came with the rebuild kit from Nitro Gear and axle
(MK GMVET-C1). Everything is new, including the carrier.
Last edited by Bullseye83; Apr 10, 2012 at 06:15 PM.
Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
Without knowing the exact brand it's hard to say. Going by your patterns you are shallow. I would go .002 or .003 like Bill said on the pinion shim. Be sure the rear pinion race is fully seated. If these were Yukon gears then .017 shim would be about right. Open your backlash up a little, average .008. Add a few drops of gear lube to your marking compound to get a cleaner pattern.
Mike
Mike
Thread Starter
Heel & Toe
Joined: Apr 2012
Posts: 17
Likes: 0
From: Bergen
Without knowing the exact brand it's hard to say. Going by your patterns you are shallow. I would go .002 or .003 like Bill said on the pinion shim. Be sure the rear pinion race is fully seated. If these were Yukon gears then .017 shim would be about right. Open your backlash up a little, average .008. Add a few drops of gear lube to your marking compound to get a cleaner pattern.
Mike
Mike
The ring and pinion is by U.S Gear, this set:
http://shop.cruiserparts.net/index.p...a586353b9b71f5
So I should try running a 0.018 shim instead? *sigh* It was a real pita getting the pinion bearing off without breaking it, not using a setup bearing
. By shallow you mean the drive pattern should be more towards the toe? Wouldn't this cause the pinion to start engage off the very edge of the toe? As is now it starts to engage slightly within the tooth face..? Thanks
Thread Starter
Heel & Toe
Joined: Apr 2012
Posts: 17
Likes: 0
From: Bergen
Without knowing the exact brand it's hard to say. Going by your patterns you are shallow. I would go .002 or .003 like Bill said on the pinion shim. Be sure the rear pinion race is fully seated. If these were Yukon gears then .017 shim would be about right. Open your backlash up a little, average .008. Add a few drops of gear lube to your marking compound to get a cleaner pattern.
Mike
Mike
How come it's too shallow? There aint much face left towards the toe for a deeper pinion the way I see it ? If adding a thicker shim, wouldn't that result in the pinion engaging the very edge of the tooth?
Appreciate your feedback, thanks.
Raymond
Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
Changing the pinion shim will move the pattern slightly to the toe. Your pattern is too far away from the root. The best drive pattern is on the teeth in the center of the pic is where you'll have your lowest backlash reading. All the other teeth have the pattern going shallow as the backlash increases. The deformation of the coast pattern is showing too little backlash. The pinion needs to go deeper towards the root to average out the drive pattern and then open up the backlash to clean up the coast pattern. As you open up the backlash the drive pattern will move towards the heal but the coast pattern will only move slightly.
The pattern you have now will work and will probably be quiet. What you can't see is the pattern on the pinion gear which will be high on the teeth.
Mike
The pattern you have now will work and will probably be quiet. What you can't see is the pattern on the pinion gear which will be high on the teeth.
Mike
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Thread Starter
Heel & Toe
Joined: Apr 2012
Posts: 17
Likes: 0
From: Bergen
Changing the pinion shim will move the pattern slightly to the toe. Your pattern is too far away from the root. The best drive pattern is on the teeth in the center of the pic is where you'll have your lowest backlash reading. All the other teeth have the pattern going shallow as the backlash increases. The deformation of the coast pattern is showing too little backlash. The pinion needs to go deeper towards the root to average out the drive pattern and then open up the backlash to clean up the coast pattern. As you open up the backlash the drive pattern will move towards the heal but the coast pattern will only move slightly.
The pattern you have now will work and will probably be quiet. What you can't see is the pattern on the pinion gear which will be high on the teeth.
Mike
The pattern you have now will work and will probably be quiet. What you can't see is the pattern on the pinion gear which will be high on the teeth.
Mike
Thanks Mike.
Thread Starter
Heel & Toe
Joined: Apr 2012
Posts: 17
Likes: 0
From: Bergen
Changing the pinion shim will move the pattern slightly to the toe. Your pattern is too far away from the root. The best drive pattern is on the teeth in the center of the pic is where you'll have your lowest backlash reading. All the other teeth have the pattern going shallow as the backlash increases. The deformation of the coast pattern is showing too little backlash. The pinion needs to go deeper towards the root to average out the drive pattern and then open up the backlash to clean up the coast pattern. As you open up the backlash the drive pattern will move towards the heal but the coast pattern will only move slightly.
The pattern you have now will work and will probably be quiet. What you can't see is the pattern on the pinion gear which will be high on the teeth.
Mike
The pattern you have now will work and will probably be quiet. What you can't see is the pattern on the pinion gear which will be high on the teeth.
Mike
It definately has moved towards the toe.... (The shim kit didn't have anything inbetween 0.020" and 0.025")
What do you think Mike? Somehow I liked the other better though :P
Last edited by Bullseye83; Apr 13, 2012 at 04:05 AM.
Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
These are much better patterns. Now I believe that they are US Gears. You will not get the pattern you are hoping for because of the honing done on the gears which creates a slightly diagonal contact patch.
This pattern is almost perfect. You are slightly deep. An .023 shim and .001 less backlash would make it better. Put some gear lube on your brush and lightly recoat the teeth. Rotate the gears 10 times in both directions to get your average contact pattern. Yellow marking compound is hard to work with. Thinning it with lube will give you better results.
Mike
This pattern is almost perfect. You are slightly deep. An .023 shim and .001 less backlash would make it better. Put some gear lube on your brush and lightly recoat the teeth. Rotate the gears 10 times in both directions to get your average contact pattern. Yellow marking compound is hard to work with. Thinning it with lube will give you better results.
Mike
Thread Starter
Heel & Toe
Joined: Apr 2012
Posts: 17
Likes: 0
From: Bergen
These are much better patterns. Now I believe that they are US Gears. You will not get the pattern you are hoping for because of the honing done on the gears which creates a slightly diagonal contact patch.
This pattern is almost perfect. You are slightly deep. An .023 shim and .001 less backlash would make it better. Put some gear lube on your brush and lightly recoat the teeth. Rotate the gears 10 times in both directions to get your average contact pattern. Yellow marking compound is hard to work with. Thinning it with lube will give you better results.
Mike
This pattern is almost perfect. You are slightly deep. An .023 shim and .001 less backlash would make it better. Put some gear lube on your brush and lightly recoat the teeth. Rotate the gears 10 times in both directions to get your average contact pattern. Yellow marking compound is hard to work with. Thinning it with lube will give you better results.
Mike
Instructor
Joined: Sep 2009
Posts: 190
Likes: 0
From: Hiawatha Iowa
One more suggestion under the assumption with running 4.11 gears you will be running it hard so the suggestion is while you are at it .... polish the carrier. Smooth all the edges in the openings and round them plus then polish the edges and exterior. Also if you feel like taking the spider gears out it is worth it because then you have access to the casting lines that should be knocked down on the inside. A polished carrier reduces the risk of having the rough casting areas from cracking. Something you should really consider if you are running 4.11 gears because you are going to be doing hard launches.
Thread Starter
Heel & Toe
Joined: Apr 2012
Posts: 17
Likes: 0
From: Bergen
Ok, I did not make any changes to BL. Here are the pictures with 10ish complete turns in both directions. Voidhead1, the car won't see the strip, it's for street use only. Should I consider polishing anyway? I've never heard\read anything about that before though. Thanks.
It's time to get those wheels back on the road
Instructor
Joined: Sep 2009
Posts: 190
Likes: 0
From: Hiawatha Iowa
On this forum was a great write up by Jeremy Smith: http://forums.corvetteforum.com/c3-t...ild-paper.html
Talks about polishing the carrier and much much much more.
Talks about polishing the carrier and much much much more.
Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
I'm very familiar with Jeremy's set-up since I walked him all the way thru it. However, that was on an eaton posi. This auburn will see no benefit to polishing and any radiusing will weaken the case. The eaton is a disc style unit while the auburn is a cone style.
Mike
Mike
Instructor
Joined: Sep 2009
Posts: 190
Likes: 0
From: Hiawatha Iowa
tracdogg2, is that because the cone style is a better design and distributes the stress better and the machined holes for the pin to the window has more metal?
I certainly don't want to take over this post and first to stand corrected about the recommendation to polish and radius the hard edges of the auburn carrier. My bad, just was under the understanding all stress point metal parts can benefit with cutting down hard edges that could turn into stress cracks. Eaton posi carriers are very famous for that and that is what I put in my rebuild after I polished and radius the edges.
I certainly don't want to take over this post and first to stand corrected about the recommendation to polish and radius the hard edges of the auburn carrier. My bad, just was under the understanding all stress point metal parts can benefit with cutting down hard edges that could turn into stress cracks. Eaton posi carriers are very famous for that and that is what I put in my rebuild after I polished and radius the edges.
