I realize this is largely speculative, and without pulling the diff out I won't have any real idea, but maybe someone that has sat/owned/ridden in cars with different differential types can put in their two cents.

Pretty positive (no pun intended) that my car has an upgraded diff. During normal driving, its fine. No noise, issues etc. Issue comes when turning. Good god does it happen when turning. Pulling into a parking space, backing out of one, making a turn (u turns included), you name it, it literally sounds like one tire is skipping and vibrates the whole car in short but intense waves (like..one tire trying to spin as fast as the other, basically symptomatic of an upgraded diff.) This only happens when the clutch is mostly/fully out, clutch pushed in, nothing.

What I'm curious about is, assuming this is an upgraded diff, would one think this is a 1.5 way or 2.0 way? I haven't noticed or felt like any lock on decel (haven't noticed, I figure with a 2.0 way LSD it would be pretty unmistakable.) Downshifting, accel off, etc, nothing. But everything else mentioned above, yikes. Definitely needing a factory diff. Was curious as to everyones input on what type of diff they might think it is.

 

it’s probably the LSD type; what specifically (brand/model) did you upgrade to?

 

I didn't upgrade it at all, it must have been done in Japan by the previous owner. All I have to go on (aside from pulling it) are the symptoms I have described. Definitely going to change it out for a factory type LSD, though. I can't imagine this would be useful for anything aside from drifting or circuit use.

 

Don't need to totally remove....although it may be the way to go if you're certain you're going to put a stocker in place and the workshop is doing the work. Rear cover off and looking at the cam in the centre should give clues of 1, 1.5 or 2 way.

Strictly speaking the torsen isn't a LSD either

 

This sounds like my kaaz 1.5

 

some of those want special oil, if you just have regular stuff in there its worth changing the oil and doing a few figure 8's and see if it gets better

 

apology for not having read through the first post clearly enough, also reminded me of a Kaaz LSD from a long time ago is why I asked about what brand and model.

 

Aftermarket diffs are best for track use, they SUCK for street driving. On the street stock is the best.

There may be a way to identify what you have if you pull the diff cover. But if it's using special funky diff oil you'll have to find more of that before you can drive the car again.

Stock diffs don't do what you are saying it's doing so something is definitely up there.

By far the easiest way to solve this would be getting a whole manual trans diff from someone and bolting it in. Swapping the innards of the diff out is tricky. It may be hard to find a diff, high horsepower/drag racing can bust stock diffs so they can be in demand.

You can probably find a buyer for the current diff if you can identify it. somehow.

Dale

 

I'd start with a fluid change; a stock diff can do similar things to what you are describing if it has broken spider gear teeth. If no metal chunks come out in the fluid I'd rest assured that it is an aftermarket unit, as others have mentioned some use an additive and others just use a heavier duty gear oil without additive.

Take a peek at the rear cover, most aftermarket LSD units come with a sticker that is intended to be placed on the cover.

 

Stock is best for the street as long as you dont have too much torque for the stock Torsen bias ratio to work. I loved my FD torsen at 300ftlbs torque.

Once I had 420ftlbs torque in that car it was dangerous. Just spin one tire super fast and hook the car to that side like an open diff. Not fun on the freeway.

I now have an OS Giken SuperLock and the only driveability issue it has is backing up the inside tire does bind/stutter a bit.

Havent noticed any driveability issues at all driving forward- but, yeah you pay for it... its a premium diff.

I dont have any torque yet in the car with the OS Giken, but it does always hook you forward. So much confidence.

 

If you are going to replace the oil as an interim step as some suggested, you might as well remove the diff cover and have a look at what's in there. Then try to determine what diff is in there and what oil is specified for that diff.
Also try to see if it's welded like the drifty bois like to do

 

I don't think I'll ever understand the reasoning behind welding a diff.I just couldn't justify doing things like that to my car. Couldn't be a mad tyte drifter, not my crowd.

 

This right here is what I am thinking. I know upgraded diffs can make a bunch of racket but this description sounds excessive.

 

Wouldn't it still lock though when the clutch is pushed in around turns, etc if it was welded? When I push the clutch in it goes silent.

 

If it were welded, I'd think there'd be no noise from the diff, since it would not be doing anything. You could have some weird wheel hop or something as the L vs R wheels would be trying to go at different speeds making one or both slip. You'd also notice that you'd have understeer under almost all conditions on the street due to the locked diff.

 

I haven't noticed any understeer, but the turning at low speeds I definitely hear the noise I described above which I believe is a result of the inner tire skipping/etc because the diff is locking up. I guess the degree of severity could be subjective to each person, but it definitely makes the car vibrate as it happens in waves, I think its beyond uncomfortable. I'm going to be changing the transmission fluid this week (unrelated, I know) and while it's on the lift I think I'll ask to have the cover looked at, since I can't do any work on my car where I live currently.

 

From your symptoms, I don't think its welded. Your "bang, bang, bang" description sounds to me metallic, not like a tire slipping. However, no matter what it is, you still need to get rid of it and go back to OE.

 

Yeah, it's most definitely not a diff meant for daily driving.

 

it’s 99.9% Kaaz or similar aftermarket type, the popping and banging is quite normal for them just as is being described

The OS Giken is the streetable solution that’s just as happy or happier at the track or strip, but it’s the premium option for sure. People balk at the price, but once you use one and understand the difference then that’s just what it costs if you want that level of performance. Like anything else I suppose.

The RX8 factory LSD is a direct bolt-in on the FD as well, but might not be the best option for an increased power level. Though I’m not aware of anyone running it up in the 400 - 500 whp turbo applications reporting any issues with it. If you can find one it’d probably be cheap. I had one, but gave it away to someone else in need.

I can ask around though, lmk.
.

 

How much HP were you pushing in your S1? Ideally I'd like to just swap in an entire stock diff/case to minimize the trouble, but finding a known good condition one might prove difficult.

 

I’m not aware that the entire assembly can be swapped, just that the LSD is interchangeable.

There are a few Renesis Turbos running 400 - 450 whp, and REW turbo swaps exceeding 500 whp.
.

 

What setup were you using in your S1? I'm assuming the OS Giken?

I figured the RX8 diff assembly wasn't interchangeable, but hopefully I'll find a known good condition whole FD assembly. If not, its good knowing I can retrofit an RX-8 one if need be.

 

God, don't put a rx8 centre in the thing. That spring loaded piece of crap isn't worth pissing on - wear out looking at them.

First, I'd still place priority on identifying what you have. If by some chance it's a Cusco, that's one where you can adjust the lock up characteristics on the cam, it might be acceptable after reassembly at a less aggressive ramp in that case. A welded diff is pretty evident pushing the car.

 

Sounds similar to symptoms I have from my car from Japan which came with a cusco 1.5 diff with an absolutely absurd diff ramp. It'll lock up and make nice metallic THONK noises followed by tire chirping at 10-20 mph turns in the city.
The Japanese enjoy their drifting culture so they set these 1.5 way diffs with absurd diff ramps so that they'll lock up and break traction early while still being able to roll through parking lots and make U turns (tight streets in japan)
At least that's my working theory.
I was told by someone much more versed with building drivetrains than I that diff ramps can be changed fairly easily to be less aggressive and thus much less painful for street driving. I have yet to try this myself but you might consider it as an option.

 

well I’ve been in the game a bit and haven’t heard of many failures, the few of which I know of were really high mileage. Including the one I donated mine for a replacement.

pretty sure the springs mentioned are only for preload to keep a wheel from spinning excessively if it comes off the ground like a Torsen will, though they offered several variations on those in later years to specifically address that sort of thing

It’s not clutch pack based, but is a cone-contact type and wouldn’t be my first choice for heavy duty, competition, or high power use. That’s why I own multiple OSG lsd diffs, but for street use with low to mid-ish power it seems like a cheap alternative if you can locate a low mileage one. I gave mine away for free, but that might be an exception. I recall that the last several LSDs I had installed ran around $300 each plus parts with me taking the diff in/out and dropping it all off at the drivetrain shop. Been a few years though.

So I looked around and couldn’t find anything to really support that other than it sounding more like forum lore and the most likely answer is to instead look at all the RX8s running turbos over the years. Because I’ve rarely heard of them either swapping out the stock one or having a failure/issue. That said, comparatively it’s likely a smaller pool of vehicles to judge from and they’re not all on the forum documenting their experience, I suppose you could know better about the situation than anyone else.

but honestly, compared to an OSG they all pretty much fall into that overall description imo, including a Torsen which I’d never specifically choose to use myself. Thirty years ago though, it was all the talk and now most people recognize there was some hype and forum lore going on then too. And let’s be honest, most people buy a diff/lsd new off the shelf or used and just toss it in rather than have it adjusted or tuned accordingly. Only the hard core competition crowd is likely to do that.

anyway, it’s the the same lsd in the FC T2, FD3, and RX8/SE3P so those are your options if you change your mind about swapping a whole diff or just the LSD.