I tried looking around, but I'm still confused.

Alright, essentially, I want to pop the LSD from a manual into my '09 auto, but I need to know which year diff to look for and if it'll even work without a catastrophic drop in my acceleration or gas mileage. A lot of people are parting out RX8's, so it seems like a good time to pop an LSD in, since I hate my open diff with a passion.

Thanks.

 

you sure yours is open?

 

I was under the impression that all automatics came with an open rear diff. It sure as hell doesn't feel like a LSD. I feel like even 160 lb-ft should be enough to break the rear loose with an LSD, and my car struggles with it.

 

I wondered that also but the specs seem to indicate that a SPORT AT didn't come with it.

The Torque sensing Limited Slip Differential first shows up on a Touring or higher AT

 

well autos are hard to brake the tires lose.
autos do only have open diffs according to Mazda's website

 

i use to drive a muscle car, and it would break traction no problem with an auto. then again, muscle cars generally run on autos and launch from torque converters.

at any rate, this is why i ask which diff would work in my auto with the gearing it has.

 

Someone has to know which year LSD will work in my car. Please help me out!

 

I believe this still applies to our cars, I'll have to check it myself, since mine has the LSD.. But, try jacking both back wheels up and turn one of them, with the transmission in neutral, and the parking brake not set obviously. Chock the front wheels to make sure she won't roll anywhere on you, as well.

If they turn in opposite directions, you have an open diff, if they turn in the same direction, it's an LSD.

But why I wonder, I don't honestly know what style LSD we have. I've never looked into it, but the style with clutches that grab as they start to slip, and the fluid heats up from them slipping, I could see them rotating in different directions until they heated up. I've honestly never checked an LSD of that style this way, so that's why I'm not 100%. I'll try to check that either later today or tomorrow and get back to you.

I also don't know this for certain, but the yoke could be different as well, so you might have to get a custom driveshaft. Just thinking back to say, FC's, where the turbo diff was different than the NA, and you'd have to get a hybrid driveshaft. A driveshaft shop could do that for you, then you just bolt her up.

If your's really is an open diff, I'd recommend just sticking with an S2 rear end, vs an S1, simply for the factor of trying to keep everything the same year. I have to head out here in a moment, I'll try and find the gearing for the different years when I get back, if no one else has found it by then.

Have you tried looking in FSM's? Or you could try calling a dealership, and ask them, they SHOULD be able to tell you that, unless the guy that picks up the phone is lazy as hell.

But, if you don't mind me asking... Why are you sticking with an auto?

And, since I've honestly never looked into it, can't auto'd be reflashed to have the 9,000rpm redline? If so, have you?

 

According to the "bible", aka. "RX8" by Jack Yamaguchi, the "Super LSD" in the manual 8's is a preloaded Torsen with a reduced torque bias ratio. (It's not the fluidic type which requires motion to have any effect, it's purely mechanical.) The Series I has a 4.44:1 ratio for both auto and manual. The Series II has a 4.77:1 final drive ratio. 4th gear in the 4 speed auto is 0.694 vs. 6th gear in the manual of 0.843; I don't have the info for the 6 speed auto handy. I think finding a used Series II LSD will be nearly impossible because of both rarity and demand from the racer crowd.

 

^Damn, thanks for having it handy. Do you have the link for that by Jack Yamaguchi?

 

From all my reading on the differences, the auto and manual diffs will bolt right in place of each other, even across the different years. The gearing will be lower if you get a Series I diff, which will give you better gas mileage on highway runs.

Looking at car-part, they have several Series I rear axles listed, and several of those are from manual cars. That's the way I would go if I was in your shoes.

BC.

 

If the numbers are higher as in 4.77, its a low ratio diff, if the ratio is 4.44, its a higher ratio.

 

RX-8's have the third type, Torsen:

http://www.fc3spro.com/TECH/MODS/DT/lsd.htm

 

Mazda says it's an open diff, and I don't have any reason to question them on that. I know all the diffs will bolt up, but my main concern is gearing. Which diff will give me about the same MPG and acceleration? I'm pretty sure the S2s have different diffs between auto and manual, where the S1s are the same for both. If an S1 diff will behavior similarly, then I'll go for it. Otherwise I need to know if an S2 manual diff will work well.

And I stick with the auto because I live in the horribly disorganized city of Richmond, Virginia. I don't feel like clutching every light when I'm out and about. The few times I go out for spirited country sprints, the auto suits me fine.

 

Lets see:

According to Mazda, the S2 cars have 4.78:1 rear axle ratio for manuals, and 4.30:1 ratio for automatics.

S2 cars came with 4.44:1 rear axle ratio for both autos and manuals.

Now you have to as yourself:

Which is closer to 4.30:1?
4.78:1 or 4.44:1?

Once you can answer that question, then you can decide which axle ratio is the better one to put in your car.

BC.

 

Think you mean S1 came with 4.44:1. But anyway, thanks! This made it seem really simple. Since 4.44:1 isn't quite 4:30:1, what will change? Higher MPG or higher accel?

 

Does anyone know where can i find the rear axles for a 2004 rx8?? my rear axles are making a noise and its really bothering me. i need to buy another ones because the guy that sold me my rx8 damage the axles because of racing. please someone help me

 

I would suggest further verification of that, as the drive shafts are different.
A friend of mind just converted a RX-7 automatic to a manual, and the drive shaft was not compatible with the differential. Just FYI...

 

That's more than likely because the drive shaft is a different length, not because of the diff. Manual and auto trannies have different lengths, requiring different length drive shafts.

All of the RX-8 diffs should swap right in.