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Are "thick" gears noisy?

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Old 11-12-2005, 05:46 AM
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Default Are "thick" gears noisy?

I want a 3.42 ratio on a series 2 carrier (stock rear end) so I called a sponsor and asked the price for a set of "thick" gears. Price is not an isue, they just have to be easy to adjust and not noisy. Just the best quality.

They answered that there are no "thick" gears available that do not whine, as they always make noise
Best solution is to buy a new carrier and install a stock 3.42 ratio.

Is it true? What is your experience with "thick" gears?

Thank you - Stefano
Old 11-12-2005, 02:13 PM
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Thick or thin gear sets make no more or less noise than the rest of them..... if set up incorrectly.

When set up correctly, any gear set, of any manufacturer will run quiet.
Old 11-12-2005, 04:45 PM
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Thank you!
Old 11-12-2005, 05:01 PM
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Originally Posted by chicane
Thick or thin gear sets make no more or less noise than the rest of them..... if set up incorrectly.

When set up correctly, any gear set, of any manufacturer will run quiet.
Boy, if this is true I really need your help. I've got a set of 4.30's in an 8.8 that have a slight drive whine at 45-65. I've got .010 of preload on the diff bearings, 25 in lbs of preload on the pinion with a solid pinion spacer, .008 lash, and a pattern that is centered. I would LOVE to get rid of the whine, but the consensus of everyone I ask is that I must have crappy gears and they are just going to whine a little.

I can send pics of the pattern if you are an expert and can take a look at them I would very appreciative
Old 11-12-2005, 06:20 PM
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Originally Posted by TRex
........ if you are an expert and can take a look at them I would very appreciative.
.......A self proclaimed expert, no. I have however, built somewhere around 1500-1750 8.8's in the last 15+ years though. I will help if I am able......

What I would like to know is what gear manufacturer, ratio and type of oil you are using to start off with...... and then any pictures from there.
Old 11-12-2005, 08:22 PM
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The gears are Ford Motorsport, 4.30 ratio. I broke them in with Pennzoil 75w90, then changed to Mobil 1. I broke them in with two 20 min. sessions on the stands, then a few easy driving session. Took the cover off and re-checked the lash, still at .008.

Here are the pics











Thanks in advance for your help !
Old 11-13-2005, 04:04 AM
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Well........ the gears are not crappy and the pattern is not centered.

Just from the pictures alone, I say the gear set is still set up too short (as it is shown slightly crossed up), and lash is too tight. Meaning, that it still needs about 0.002 to 0.003" more in depth (maybe even 0.004 to 0.005", but it depends on a few other things) and then I would throw 0.010" lash at it to see what it yields.

As for the carrier bearing preload, it normally takes a good 6 to 8 hard swings to seat the carrier (I use my Snappy 56oz dead blow). 0.010" is really a wag for a number..... Id think it takes somewhere in the 0.015 to 0.020" to get it close enough.

Pinion pre-load, when new should yield 35 rolling inch pounds of resistance. Used bearings, about 15.

As for lubricant (and also one reason for running 0.010" gear lash), I would use a straight 140 wt oil for any performance build. The lash needs to be open enough to let the higher viscosity oil in to provide the film thickness that is associated greater film pressure strength.

You are really looking for something like the pictures below, dont expect to. The first one would be what I consider a text book set up and the second is how I would set up a drag chassis that had some decent vehicle weight, launched hard and hook up well. Either way you look at it, the 'coast' side should be centered for both drive patterns shown.
Attached Thumbnails Are "thick" gears noisy?-contacta-wince-.gif   Are "thick" gears noisy?-contactb-wince-.gif  
Old 11-13-2005, 07:29 AM
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Is adjusting a Strange 3.42 ratio also so difficult?
This would be in a stock LS1 rear end.

Would you use a solid spacer for the pinion bearing preload or stick with the crush sleeve?
Old 11-13-2005, 08:21 AM
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Originally Posted by chicane
Well........ the gears are not crappy and the pattern is not centered.

Just from the pictures alone, I say the gear set is still set up too short (as it is shown slightly crossed up), and lash is too tight. Meaning, that it still needs about 0.002 to 0.003" more in depth (maybe even 0.004 to 0.005", but it depends on a few other things) and then I would throw 0.010" lash at it to see what it yields.

As for the carrier bearing preload, it normally takes a good 6 to 8 hard swings to seat the carrier (I use my Snappy 56oz dead blow). 0.010" is really a wag for a number..... Id think it takes somewhere in the 0.015 to 0.020" to get it close enough.

Pinion pre-load, when new should yield 35 rolling inch pounds of resistance. Used bearings, about 15.

As for lubricant (and also one reason for running 0.010" gear lash), I would use a straight 140 wt oil for any performance build. The lash needs to be open enough to let the higher viscosity oil in to provide the film thickness that is associated greater film pressure strength.

You are really looking for something like the pictures below, dont expect to. The first one would be what I consider a text book set up and the second is how I would set up a drag chassis that had some decent vehicle weight, launched hard and hook up well. Either way you look at it, the 'coast' side should be centered for both drive patterns shown.
Thanks for the reply, I will try that !

Also, by more in depth, do you mean add pinion shim ? Just want to clarify the direction to move it.

Thanks
Old 11-13-2005, 03:39 PM
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Originally Posted by tici
Is adjusting a Strange 3.42 ratio also so difficult?
This would be in a stock LS1 rear end.

Would you use a solid spacer for the pinion bearing preload or stick with the crush sleeve?
No.... all gear sets require the same attention to their set up and the Strange units (in this or any ratio from them or any other manufacturer) are no different in this application.

Any rear loaded gear set will be pretty much the same, with the exception of the GM Corp 10.5", as it has a removeable pinion support and is adjusted there.

....and I would opt for the solid spacer, if I had the differential apart far enough for its assembly.
Old 11-13-2005, 03:47 PM
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Originally Posted by TRex
Thanks for the reply, I will try that !

Also, by more in depth, do you mean add pinion shim ? Just want to clarify the direction to move it.
Yes, by more depth I do mean for you to add thickness to the pinion shim itself. This will move the pinion gear head closer to the ring gear in mesh and I think it will center it up and then you will use the lash adjustment to place the drive pattern in slightly toe, with coast centered.

Also, if and when you make adjustments with pinion shims, try and use only one shim..... if you can not, install the thinnest shim toward the pinion head first and the thicker one towards the bearing. Sometimes the thinner ones (dependant on actual thickness) can come apart when loaded in contact with the inner pinion race...... which if this were to happen, it would drastically change your pin depth and cause you all kinds of headaches if and when it acme apart.
Old 11-13-2005, 06:32 PM
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OK, thanks. I really appreciate your thoughts. No one else seemed to have any ideas, seemed like they thought the pattern was about as good as it could get, and I admit I was concerned about going deeper and getting too close to the root of the tooth.

At this point the car may be going into storage next weekend, so I might not get to fix it this season, may have to wait until spring. Would you mind if I contacted you back at that time if I have any questions, or just to say thanks, that did it !
Old 11-14-2005, 12:04 AM
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Ask away.... any time.
Old 11-14-2005, 12:37 AM
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I have a GM manual for setting up differential cases. It was given to me from a GM garage and it's what they use to teach their mechanics. So I guess it's correct.
They don't make any difference between the 5 or 2 cut gears, they just show different patterns and how make the corrections.

On another place I saw that the old 5 cut design needs a different contact pattern than the 2 cut.

So now... what is what? I think the late (LT1 - LS1) gear design is a 2 cut. Does it make a difference?

I think the 5 cut needs a straight centered line from heel to toe. The 2 cut design needs a diagonal line from bottom toe to top land.
(I know... it sounds complicated...)
Old 11-18-2005, 07:17 PM
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Originally Posted by chicane
Thick or thin gear sets make no more or less noise than the rest of them..... if set up incorrectly.

When set up correctly, any gear set, of any manufacturer will run quiet.
AMEN!

For gear setup help check these:
http://www.fullsizechevy.com/fscu/axletech/
http://www.keliente.com/gears.htm

If you are unsure about doing it yourself, go to a reputable 4x4 shop. They do gears more than any other performance shop, from what I've seen anyway.
Old 11-19-2005, 12:14 PM
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The actual problem is to find a seller.

It's cheaper if I organize the shipping from here. I can send DHL to pick up the parts, I only need weight and dimansion of the box to have a shipping quote.
I already asked a couple of vendors and nobody is able to give me those informations.
At the same time they can figure out a price if they ship it themselves...
$85 USPS and $200 for UPS. THis for ring + pinion + install kit (!)

It costed me $800 for a 370 lbs crate from South Carolina to Zurich. This was with DHL. So I guess someone is trying to make some additional cash...!



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