new differential

[Austin90]

hey guys I'm finally putting in the posi unit I got to replace the stock limited slip unit. The new unit is a eaton differential. I had put a 410 ring and pinion on the old limited slip differential and wanted to put it on the new one, but now the ring gear on the new unit is to much toward the passenger side of the housing. My machinist told me for new eaton differential I would have to change the ring gear but the gear shop where I bought the new unit said I didnt.

[Mike 57]

Did you get a 3 or 4 series carrier? If it is a too far away from the pinion it sounds like you bought a 3 series carrier they usually work with 3,08 to 3.73 gear sets. If it is too close to the pinion you might have a 4.10 gear set that is made for a 3 series carrier and your new carrier is a 4 series.

[72MC]

Too many unknown variables here to figure out the problem. First, limited slip and posi are the same thing.

Mike's statement above is probaly the problem but lets walk through some things.

 

What series carrier is the original unit?

 

What was your original gear before the 4.10's?

 

Is the 4.10 gear you're using now made for a series 4 or a series 3 carrier? There are a few 4 series gears built to install on series 3 gear carriers (ie. I have a series 3 Eaton carrier with Richmond 4.10's made for series 3 carriers. The gear is very thick and thus stronger than standard 4 series 4.10 gears).

 

What is the carrier series of the new Eaton carrier?

 

What was wrong with the old carrier? Was the old carrier a GM unit? Was the old carrier cracked or was just the spider gears, side gears, or clutches bad? If the carrier is a 68-72 GM limited slip carrier, it is interchangeable with Eaton's Posi/Limited slip internals.

 

Sorry if this is confusing but there is no "Silver Bullet" answer without knowing all the variables. I have an idea of what the problem is but will wait to hear more info.

 

 

[Austin90]

I ran the numbers on the top of the unit it is a series 4. So I'm going to have to get a series 4 ring and pinion. There was nothing wrong with the old unit I just dont like the full limited slip. The ring gear I was trying to use was a 410 for the stock unit that came with the car.

[Heckeng]

Hey Austin, it sounds like you have things figured out. As a piece of advice for when you are talking about the differential with the shop guys, or on the forum for that matter, if there are no clutches or "posi" type of device in your differential, it is called an "open" differential. Posi is GM's term for a limited slip differential, just like Traction Loc is Ford's, and Sure Grip is Mopar's. They're all the same thing basically. All of the manufacturers also have open differentials as their base units which means that nothing tries to get both wheels locked together.

 

Are you staying with the 4.10 gears? Do you do a lot of highway driving? If so, you might get a little higher gear and that could make it much more fun to drive. If you are dragging the car or constantly stoplight to stoplight, you might like the 4.10's better than higher (numerically lower) gears!

 

Give us some updates when you get that posi installed! You'll love it!

[Austin90]

I want my car to be a street strip car, I hated the stock 256 gears, I wanted to go with the 373s cause I heard they are perfect for the street and track once in a while. But when I was in boot camp my dad put the 410s in. I'm about to order the 410 series 4 ring and pinion off of jegs now ill let you guys know how it goes when I put them in.