Turk82

iTrader: (17)

So on my way to get an "inspection" today I had some clunking from the rear while turning. I knew it wasnt the bushings because they have been replaced. It got worse and worse as I went on and then my foot slipped off the clutch and things it almost felt like the diff fell out of the car. Got it on the lift at the shop and popped the cover. The teeth on torsion gears were pretty much gone.

My question is where to go from here as far as what parts to put in. I know the rx8 gears fit in just fine but I dont need the 4.33. I have also read the S4 T2 rear fits and is stronger than the FD rear. I am just looking for some guidance as to what to go with and where to get it. I would like to keep this as cheap as possible while still doing it right so aftermarket gears and swaps are out of the question.

I have no experience with diffs so I will just be gathering the parts and taking them to a shop.

Thanks,
Ryan

DaleClark

iTrader: (55)

Just get a good used pumpkin and swap it in. Doing the RX-8 gear swap just swaps the ring and pinion and it looks like the diff itself is broken.

That's an easy bolt-in to swap the pumpkin and you'll be back on the road.

Dale

Turk82

iTrader: (17)

Thanks Dale. My real concern is that this will just happen again in the future. The car is planned to put down about 400hp. I know diff and trans bracing can help prevent this but how much can it really help. They were on the menu for this winter but I didnt even make it that far.

I am not even boosting right now because I am in break in period so if this broke it I am scared of what real power can do. Chances are good that it was broken when I got the car but I will never really know.

Thanks,
Ryan

cptpain

iTrader: (1)

bracing can help alot.

The main issue is the LSD itself..... people have blew their rear ends in stock form.... yes, even stock power levels.

you can change the LSD itself to a TII clutch type LSD( i believe) which holds a lot more power. and it wont break.... it'll just get worn to the point where you are essentially running on an open diff.

Or you can upgrade to a Kazz or Cusco or some other performance LSD

HppRX7

iTrader: (2)

Whatever replacement you select, when you get to 400HP you may want to consider the HPP 2in1 Diff cradle/brace to protect your diff housing and reduce wheel hop....it costs $375 shipped in Red or Black powder coat......here's the link:

https://www.rx7club.com/group-buy-ce...brace-1002000/

MADDSLOW

iTrader: (11)

I blew my diff in August at Rotorfest on the track, and it was a very unpleasant and unexpected situation. Rather than risk putting myself in that same situation in the future, I decided to go all-out and COMPLETELY upgrade the entire setup: 4.44 RX-8 ring and pinion, new bearings, KAAZ 1.5 way differential, solid diff mounts, and a Greddy diff cover with the HPP 2in1 diff/cradle brace that HppRX7 linked above.

While I understand that you're looking to spend as little as possible, consider the extra security you would have if you put a stronger unit in and didn't have to worry(as much) about this happening in the future at an unexpected and inconvenient time.

If the ring and pinion is damaged, PM me and I can try to find an RX-8 4.44 or 4.77 ring and pinion. After upgrading to the 4.44, my car feels like a completely new animal, to the point that I wish I had gone with the more aggressive 4.77. A lot of people swear by the T2 diff, and(based upon research into reviews and opinions) I would strongly recommend that unit over the FD's torsen unit. And while you have the cover off, you can swap it with the RX-8 diff cover, which DaleClark showed to have larger fins and possibly more efficient cooling. And new bearings would be a good idea since the unit is already apart.

If you REALLY want to throw an OEM pumpkin back on, I know someone that has one that he may sell to you for a reasonable price.

I wouldn't recommend the KAAZ unit for your situation. I have it on 100% lock(which I plan to reduce to 66% or 33% in the near future), and it sounds like the rear-end is DESTROYED when I go around turns at a low speed. It doesn't bother me, but I can see why most people steer clear of this option.

Banzai-Racing

iTrader: (11)

The S4 TII LSD will swap in but it still need to be set up correctly. There are several hundred in installation components, bearing, crush sleeves, seals, shims etc. It still needs to have the preload and backlash set correctly. You should also rebuild the LSD unit prior to install since they are all 25 years old.

The Carbonetics Carbon is the best LSD unit that I have found, I am running it in my 20B, it is completely silent and holds all the power & torque. I bring this up because it makes sense to do it right the fist time. The Carbonetics metal LSD is a little noisier but less expensive. Carbonetics LSD (93+ RX-7)

There is no way you broke the torsen while breaking in your engine, it was damaged prior. If you are looking for the cheapest solution to get you back on the road buy a used FD third member and swap it in, then when you have the extra cash set up your blown one the way that you want it.

Install one of our Banzai Diff braces, I have well over 600whp/500ftlb with our brace. The money you save can be spent on a better LSD unit Banzai Diff Brace (93+ RX-7)

RENESISFD

iTrader: (13)

I want to just say I have the carbonetic carbon LSD as well and it is silent, I would go that route if you decide to go aftermarket.

David Hayes

iTrader: (6)

+3 for the Carbonetic Carbon Diff. I too have it installed in my 20B, along with the Banzai diff brace. Super smooth, no noise at all, and great at holding almost any power level. Frankly, nothing better than this on the market.

Why not bite the bullet now and solve the problem?

Turk82

iTrader: (17)

The ring and Pinion is still in good shape, as far as I can tell when I had it up on the lift. That may be different when I get out of the car to inspect. I am unsure if I would like the lower ratio from the rx8 because I have truthefully only driven my car a handful of times and was never really able to push it hard.

Maddslow and Banzai have stated that the best option for now would be to put in a whole used FD pumpkin for the time being. I agree with this to a point because it will get the car on the road the fastest and give me a diff to build in the meantime. The only thing here is that the car is most likely down for the winter at this point so getting it on the road fast isnt really a concern.

Does anyone have an estimated cost of the S4 T2 swap? this would include buying the t2 rear, needed parts, and labor?

Thanks,
Ryan

DaleClark

iTrader: (55)

Yeah, swap in a stock pumpkin to get you back on the road and breaking in the motor, then you'll have your old pumpkin to build up and get ready for the future. That way you can buy parts bit by bit as money comes along instead of putting it all together in a rush. Swap it in, then you'll have a stock pumpkin for a spare or to sell to recoup some costs.

Not sure on the costs myself, my stock diff with my '99 twins is doing fine . 4.44 gears is a good thing to think about if you're single turbo, that will get you up in boost much quicker and really help with acceleration. You can also get the RX-8 4.44 ring and pinion VERY inexpensively.

I want to say the new parts from Mazda for just doing the R&P swap weren't bad, you basically need the front pinion seal and side seals, lock nut, and crush washer. Swapping in a TII diff depends on how cheaply you get the diff and whether or not you rebuild it, I think it is costly for the clutch packs for the diff. I'd search on this, I'm sure it's been covered. I'd also have a shop set up the ring and pinion and assemble for you, it's a complicated procedure that requires some special tools, I had my RX-8 ring and pinion installed for about $100, it was WELL worth it.

Dale

Turk82

iTrader: (17)

I definately wouldnt be doing the work myself. I will only be pulling and reinstalling the pumpkin when done. How does the rx8 ring and pinion effect the speedo calibration? I know I saw you had a thread on that but I havent had a chance to really read through it.

I see there is a lot of research ahead of me.

Turk82

iTrader: (17)

Half the car dissasembled, a possible broken finger, 3.5 hours and the diff is out. Inspected the ring & pinion for about 10 min and couldnt find a thing wrong with it but all but one spider gears are missing nearly every tooth. So I still have a good 4.1 if I want to go that route.

Speed 1 has an t2 diff for 100 bucks but I am still waiting on confirmation it is and s4 clutch type and what condition it is in. Depending on mileage and a check with some local shops on pricing I may go that route.

The rx7 ring and pinion is an option I am seriously considering as well. I can probably find one of those at a local yard for pretty cheap.

Thanks,
Ryan

MADDSLOW

iTrader: (11)

Again, I HIGHLY recommend the 4.44 while you have it apart, really made my car feel fast again. You can always resell the 4.10.

IRPerformance

iTrader: (41)

Putting in another stock torsen is usually a waste of time as they don't hold up at increased power levels or for drag racing. Most cost effective option is to swap in a series 4 turbo ll diff. You can't just slap it in there. It may work for a while but will eventually make noise and fail. Give me a call at the shop or pm me. Be happy to set it up for you.

phdofski

iTrader: (4)

I would fix it right the first time and put it back together once and be done. All the time and nickle & dime stuff you need to do it twice isn't worth it. I had mine out twice in 3 months last year. I have a spare stock 4:10 diff in Stroudsburg. Was brand new Torsen diff has 1000 miles on it. Let me know if your interested. I Changed to a 3:90 rear.

papsmagu

iTrader: (19)

$100 for an S4 LSD doesn't sound right? Usually they go for $200-$300. Make sure its not an S5 or NA unit.

Reno_NVFD

iTrader: (2)

My diff also went out as well recently and I was wondering what route you ended up choosing and why.

thewird

iTrader: (8)

OS Giken LSD is better then Carbonetic imo. I've tuned a car with a Carbonetic and the clunking going around low speed corners is ridiculous. The OS Giken doesn't have that issue.

thewird

justturbo2

iTrader: (4)

i like the kaaz diff. i would also recomend the pfs diff girdle. works great.
gl in what ever you do

jkstill

iTrader: (11)

Agreed about the clunking. My car is autox only, but it makes a *lot* of noise on slow speed corners, such as 1st driving to/from grid and such.

The 2 posters that mentioned the Carbonetics is silent, I am curious why theirs are so quiet.

Not that it matters much.

David Hayes

iTrader: (6)

^ It's the "carbon" ones that are silent, not the metal ones. My carbon unit makes zero noise and is whisper quiet.

Carbenetic no longer sells the LSDs as Banzai Racing points out they were actually ATS units. So check out the ATS options now at Banzai.

jkstill

iTrader: (11)

I have he carbon one.

Positive it is carbon, I have looked at it and installed it.

Perhaps there were some refinements.

IRPerformance

iTrader: (41)

Kaaz super q is pretty nice as well