01-09-2008, 12:38 AM
I have a 2000 camaro z28 and i know a bit about cars but someone told me that i have a spool under the rearend of this car and not spider gears???

i know i have some type of lsd and i was just looking for an explination of whats behind the diff covor. i was thinking about pulling it off to look at it but if theres no gears i dont think id know what i was looking at. and i know it has to have a ring and pinion.

01-09-2008, 08:13 AM
A spool is just that. Like one from your mom's sewing machine... Solid, and no "differential action". They are generally for drag racing ONLY, although some circle track classes and tracks allow them. If your car "chirps" the outside tire on tight corners at lower speeds, you have a spool. If not, but you can leave two stripes when you burn the tires, you have a limited slip differential, which in a Chevy is known as "PosiTraction". If you leave one stripe, it's an "open" rear.

Based on your comments about gears and covers, I advise you get a book at the library that describes differentials and how they work, BEFORE you remove any parts. I would also advise taking anythig your buds (the ones that suggested you have a spool) say with a grain of salt... (:-


01-09-2008, 08:47 AM
A spool is just that. Like one from your mom's sewing machine... Solid, and no "differential action". They are generally for drag racing ONLY,

Wouldn't that also be referred as a "locking" rear end. :2cents:

01-09-2008, 01:14 PM

No, actually. A "locker" is a ratchet-type differential. Rather than using clutches and limiting the "slip", it uses a ratchet system that applies the power to slowest wheel (where an open rear will put the power to the wheel turning faster). Detroit Machine Company is famous for the "Detroit Locker". It was available in some high performance Ford products (9") from the factory. They also produce a unit for the GM 12-bolt, Chrysler 8 3/4 and Dana 60, and probably other popular axles. The locker is easily distinguished by the "clicking" sound it makes while making a corner. The action is a tad "harsh", making many people uncomfortable with it. Good for road racing or drag racing, too. BULLETPROOF!

A spool offers no differentiation at all. It literally locks the axles together.


01-09-2008, 01:24 PM
Gotcha :thumbsup:

01-14-2008, 04:03 PM
ok that cleared alot of things up for me, ive rebuilt rearends in fords, im just not used to cheverolet and wasnt sure what it was.

01-15-2008, 07:53 AM
That'll be $1.50... (:-


02-01-2008, 11:58 AM
Your car has a Zexel-Torsen rear end. Chevy started using them after '98 I believe. Zexel-Torsen (torsen = torque sensing) perform the exact same function as any limited slip rear with clutches, the only difference is there are no clutches that will wear out. The Torsen uses all gearing to accomplish the limited slip action.

When you step on the gas (apply torque) a spring slides a gear sideways so that it engages the wheel on the other side. As you go around a corner negative torque is applied to one wheel, and that spring moves back allowing the wheel to move at a different rate.

The Zexel-Torsen is not an on-off system. It can engage at variable levels. You friend probably told you that you have a spool because it looks nothing like spider gears or a typical limited slip. It looks like one solid case. But its not, there are gears on the inside.

I put one of these in my Third-Gen because they are great for street performance and straight-line racing (without having to use a locker) and much tougher than a typical LSD.

I have a pic of mine that I'll post.

02-01-2008, 12:34 PM

Good info. I'm trying to update myself for the late models. Where can I read up on this thing? Your description makes it sound a bit like a combination of the "locker" and the old cone-type.

NOTE: Cone-types were not discussed in this thread before, because they're both weak AND obsolete, but they DID use them in GM cars until '68. Two cones in a tapered housing, using centrifugal force to move them into the "locking" position. A good running '65 GTO would blow them out toot-sweet!


02-01-2008, 05:53 PM

if it was spun so that you didnt see the slit and the gears inside, you might think it was a big spool... but no.

It's actually nothing like a spool or locker, nor combination of the two. The internals more closely resemble a transmission with spiral gears.


Here are a couple of links I'd had bookmarked.

This is a really good general description/explanation.


02-01-2008, 06:01 PM
oh yea, i forgot to mention, that if one wheel (the left wheel, i believe) is off the ground or just not getting traction (on ice), the car will go nowhere. This is because the road resistance provides the preloading action for the spring. If you find yourself in that situation (going nowhere on ice), all you have to do is hold the brake slightly while on the gas. This will provide enough resistance to get the necessary load on the spring. The racing version of the Torsen cost an extra $200 bucks, but it has built-in preload... for track racing situations where one rear wheel might momentarily come off the ground around a hard corner. This way you dont loose acceleration.

02-02-2008, 10:13 AM
Okay, I see it. Interesting apporach. It's like a mixture of a planetary gearset and the clutch-type. The planets hold the force outward, and the clutches allow it to have the differential action. I like it!



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