Wow, I'm really surprised to hear these opinions on the KAAZ unit. My diff is shot (wheel hop) and I was going to go with the KAAZ. Forget the noise for a second, throw out some performance reviews if you have it and have time, i'd appreciate it.
In order I use my car mostly on the street, then strip, then autox, and hopefully road racing eventually.

(btw mazdatrix price for a new torsen is like $1100, $820 for KAAZ from rx7store)

 

Wow, I'm really surprised to hear these opinions on the KAAZ unit. My diff is shot (wheel hop) and I was going to go with the KAAZ. Forget the noise for a second, throw out some performance reviews if you have it and have time, i'd appreciate it.
In order I use my car mostly on the street, then strip, then autox, and hopefully road racing eventually.

(btw mazdatrix price for a new torsen is like $1100, $820 for KAAZ from rx7store)

 

Then explain how the single turbo cars bust them with 340rwtq yet someone else can make pass after pass after pass after pass for over a year with almost 50% more tq launching at lower rpms. Course it did snap when be bumped it up to 6000rpms like it does where everyone starts to launch high like that.

In addition why are people are MORE prone to busting the diff when launching from high rpms (like 7,000rpms versus 4000rpms), eventhough at 7000rpms they are making LESS TORQUE than they were at say 4000-4500.

You can say what you want but everything I've seen points toward the rpms you launch at, not the amount of tq your making. Especially the part about rotaries making less tq at the higher rpms where they are more prone to breaking the diff

STEPHEN

 

What you're actually describing Stephen is torque, the difference is during a launch it's stored in the flywheel and all other rotating mass of the engine etc. So if you raise the RPM of launch your increasing the stored torque (it's ability to produce instantaneous twisting force) in the rotating mass because it's spinning at a higher speed.

Something that has just as much effect as the launch RPM is the clutch and what technique the person is using to launch. The clutch, your skill in using your leg and the ability of your rear tires sidewalls to absorb some of the initial driveline shock will make the difference between pulling a good time and being the clown sitting at the stagging lights with a puddle of diff oil and ring gears below the car. Simply revving to 7000 RPM and sidestepping the clutch deserves a broken diff.

People badmouth the stock diff far too much. Unless you really think you're going to run a 9 or very low 10 you should be perfectly fine with the stock diff. I made literally hundreds and hundreds of passes on the stock diff. The only time I ever broke one was when I was an idiot and let the car constantly wheel hop after about a year of owning it back in 94 when it had almost no mods other than exhaust.

If Drag Radials don't have enough flex in the sidewalls then throw them away, they're junk. An M&H DOT racemaster on stock rims will get you high 1.5 or low 1.6 60' times and save your differential.

Instead of assuming the fault it with a part being too weak consider that maybe the user is screwing up or is using the wrong parts in conjuction. Enough preaching sorry.

Kevin T. Wyum

 

Thats sounds like your describing the momentum and inertia thats created by the weight of the flywheel and the rpms its tuning. Not the tq of the engine. At idle and the very part of the launch a rotary makes very little tq, which is why a light flywheel hurt it off the line. They need the momentum of the heavy flywheel to help get it going.

I never said it wasnt caused by drivetrain momnetum from high rpms. I didnt really get into why high rpms hurts anything, I just said the rpms in general.

Still though what you described doesnt sounds like the tq created from the engine but rather the momentum and inertia built up from the rotating assymbally at high rpms......if thats what your saying then I would very much agree with you.

STEPHEN

 

Because I'm not talking about engine torque, you dope. Rev the average economy 4-banger high enough and dump the clutch and you stand a good chance of breaking something even though it probably produces less than 200 lb-ft. of torque at peak.

As Kevin said, the kinetic energy stored in the rotating assembly and flywheel of an engine increases as rpm increases. The faster it spins, the harder it is to stop, and that's precisely what happens when you dump the clutch from a standing start. The rest of the drivetrain resists the rotating force of the flywheel and one or the other has to give. Since it's very difficult (if not impossible) to stop the flywheel dead, either the tires spin, or if they hold, the car moves or something breaks. Sometimes both.

Consider an average ceiling fan. Would you put your hand into the blades on the slowest speed and try to stop the fan? Maybe. Before you learned the lesson that putting your hand into a moving fan is a stupid thing to do, anyway. Would you put your hand into the blades on the highest speed? Probably not. What changed? The amount of energy stored in the rotating mass of the fan. Just as your hand would get hit with a greater amount of force if the fan were spinning more quickly, the drivetrain and differential get shocked with more force as rpm increases because of the increased energy stored in the mass of the rotating assembly and flywheel.

Apply that energy instantaneously to the drivetrain of a car not in motion, and you're just asking to wad something up or snap something off unless the rest of the drivetrain was purpose-built to withstand the load.

 

Hows the stock LSD for track alone and 400 hp and less SOFT launches?

 

I totally understand the momentum and inertia stored in the flywheel, and totally agree that it kills the drivetrain, including the diff. The momentum and inertia is increased with rpm.... Therefore as you increase the rpms your run a higher chance of busting the diff.

My main point was just that its not the engine tq (to a point) that kills the diff. Jim, when you were saying tq I thought you were refering to the engine tq.

WOW, look at that, everyone agree's and it didnt even take 7 pages.....This must be a record or something haha

STEPHEN

 

Zerobanger wasn't involved.

 

F = ma

 

My KAAZ keeps grabbing on the highway. Scary!

 

I don't know much about gear ratios but I think the transmission and and ls motor would effect all of the rotation.