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Rear End: Gear Ratios, brands, noise levels
#112454 December 06th 2006 11:22 am
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FroOch Offline OP
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OK guys and gals, this is something I know very little about so I ask of your assistance.

With my new van, I've been going over and updating a bunch of little odds and end things but I'm looking bigger now.

I'm thinking about changing my gear ratio and adding a posi rear to boot.

Two questions I have that maybe you can help with is which brand of posi should I go with. I see SummitRacing has two, Eaton and Strange. They both are simarly priced but and I see no major difference from their descriptions.

Also which gear ratio to go with. People are telling me 3.42's are a good all around gearing but I prefer the number of 3.73 in my head.

I'm not too concerned about gas mileage, more about giving the van some snot off the line. The motor is a tuned 305 with nothing crazy special but a couple of nice pieces to give it its extra get up and go... now I gotta get that power to the wheels.

Another thing I see is Clutch Operated and Cone Style... I'm assuming Cone is sronger but noisy??? I'm not looking to do massive burnouts but I would like something that is strong versus just an OE replacement.

Any help is appreciated... thanks

Last edited by FroOch; December 06th 2006 11:23 am.
Re: Rear End: Gear Ratios, brands, noise levels
FroOch #112459 December 06th 2006 12:27 pm
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Madman!
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Both brands are very good. I've always used strange, mainly because back when I bought this type of thing they were the best. I believe Eaton product are just as good now tho.

The 3:42 gears would be a better choice if you plan on going to truckins (I hope so). The 3:73 will give you a bit more umph off the line, but will buzz the motor more on the highway. The height of the rear tires will make a difference as well. The taller the tire, the less the ratio will be. Also with a taller gear 3:73's you need to make sure you have enough rubber on the pavement as to not sit-n-spin.

As far as the clutch or cone settup. I'm assuming the cone is more of a "lockup" type unit. The clutch is like a limited slip posi. The new ones are both quiet. The biggest thing to remember is to use the right gear oil. I prefer the lock up type, but it will wear your rear tires faster than a limited slip type.



Ken Schwarz
Tricky Truckers, N.J.
Van Clan Plus One, Canada
Manse Vans, Finland
Rebel Vanners, N.J. "USA"
Toopa Sinner Tribe, N.C.

www.showvans.com

http://www.cardomain.com/ride/360991

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"Coolness ALWAYS trumps comfort"
Re: Rear End: Gear Ratios, brands, noise levels
Superbeast #112470 December 06th 2006 1:25 pm
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FroOch Offline OP
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Thanks for the Info Ken, shoulda IMed you directly like the norm.

And yes I do plan to come this year with my new ride that I'm planning out now. Thats part of the reason, I'd like to keep up in the runs, the gearing I have now is for the birds. Its great on gas but living where I live the hills are killing me.

I guess its going to be the 3:42's then, I just dont want them to be wimpy on me.

Now looking on Summits site, its seems I can piece together a Posi unit from either make and get the Gears seperately. Both say they'll fit my Application. Is this true though? I know I can get a whole new rear end complete from the wrecker but I'd prefer new if the cost doesnt kill me. Ideally I'd like to keep what I have and just plug in the new parts in the existing pumpkin. Do I need new axles and bearings as well. I dont know what the gear spline they're referring two when looking at the Posi. They say 28/30, is this what I have already or anyone know how I can find out.

I exhaust myself too... sorry bout that. ;)

Re: Rear End: Gear Ratios, brands, noise levels
FroOch #112476 December 06th 2006 2:27 pm
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First it is best to find out what you have. There is no sense in ordering gears if they are the same as what you have. Like I said above, your tire height will make a difference too.

To find out what you have, if the previous owners can't tell you is to pull the rear cover. Spint the rear till you find the numbers stamped on the ring gear. This will tell you all you need to know. If you can't find the numbers, count the number of teeth on the ring gear and we can come close to what ratio they are. The 28/30 is the number of teeth (spline) on the axles. Sorry, not a Chevy Guy, but I'm assuming the 28/30 means you can have 28 spline or 30 spline.


Again best to find out what you already have first.


Ken Schwarz
Tricky Truckers, N.J.
Van Clan Plus One, Canada
Manse Vans, Finland
Rebel Vanners, N.J. "USA"
Toopa Sinner Tribe, N.C.

www.showvans.com

http://www.cardomain.com/ride/360991

[Linked Image]

"Coolness ALWAYS trumps comfort"
Re: Rear End: Gear Ratios, brands, noise levels
#112545 December 06th 2006 8:36 pm
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old hand
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If your using a OD trans 700R4 or a 4L60 your rpm with 373's at 70 MPH will be about 2300 thats not to bad I say about because tire diameter comes into play.

There are a lot of RPM calculators online I had one but didn't keep it in the favorites. I think the final gear ratio of the OD box is .076


Take Care, Billy

Have Van Will Travel

Re: Rear End: Gear Ratios, brands, noise levels
Billvill #112567 December 06th 2006 10:44 pm
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FroOch Offline OP
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As far as my wheels go they should be stock rolling diameter or close to it. I'm a big fan of running that way, I know anything can be adjusted but still. I'll be running 17's when i get my summer wheels but overall they'll be the same diameter as the 15's I run now with their stock tires.

I havent a clue what kind of tranny i'm running though I believe it doesnt have an OD.

We already have the backlash tool and according to my friend anything else we'd need. Seemingly I'm at the point that I can go ahead an order other than not knowing the spline size whether 28 or 30. I wanted to know that before I ordered to keep the rig on the road as long as possible with as little down time as possible but that might be unavoidable. frown

Re: Rear End: Gear Ratios, brands, noise levels
#112602 December 07th 2006 9:00 am
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Madman!
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Originally Posted by Casey

There may be a tag held on by one of the diff. cover bolts that states what the gear ratio is, and the FSM will probably list the spline count, too, so that may preclude the need to remove the cover and count


aS LONG AS IT WAS NEVER messed with. I would still recommend pulling the cover. You can do it in less than an hour. Will save agrivation in the long run. If you order the wrong one you will have to send it back and wait for the new one. If you clean the housing well, you can save the old gear oil to put back in till you do the swap and you can just use some silicoln on the cover for a week or so without any leaks.


Ken Schwarz
Tricky Truckers, N.J.
Van Clan Plus One, Canada
Manse Vans, Finland
Rebel Vanners, N.J. "USA"
Toopa Sinner Tribe, N.C.

www.showvans.com

http://www.cardomain.com/ride/360991

[Linked Image]

"Coolness ALWAYS trumps comfort"
Re: Rear End: Gear Ratios, brands, noise levels
Superbeast #112618 December 07th 2006 10:57 am
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FroOch Offline OP
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There has been alot of updates done to this van in the past so I have no confidence in what the tagging would say.

Sounds like we'll be pulling the cover, checking and counting.

I'm weighing my options to see Wrecker vs Rebuilt, Performance vs OEM etc.

Thanks everyone, I'll let you know how it works out. I'd like to do it all before the summer the only down side is my snowtires. I'd hate to eat them up laying rubber down at the traffic lights with all the little Civic kids. ;)

Re: Rear End: Gear Ratios, brands, noise levels
FroOch #112838 December 08th 2006 2:37 pm
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I called Summit and asked a few techs at work and they all say that a GM van is 28 spline no matter what. I told them they owe me cash if they're wrong.

Checking Summits site I cant find a 3:55 gear setup to fit my application. Only 3:73's and 42's. With no OD tranny again, I think 3:42's it is then.

Thanks for all the help, I'm hoping to have this all done in the next few months. I'll be taking massive pics since I dont know what the hell I'm doing it should be funny. ;)

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