henyaman

iTrader: (1)

Just curious what people tend to run for a PP13b. Given the RPM range is so high (9-10k), I wasn't sure if the TII transmission was up to the task. HP wise it would be, but I figured I should ask what people run with them. I am trying to lay a budget out for this project and need to decide what I will run.
Thanks!

peejay

I have just a regular ol' smoothcase and I run past 10k.

If I need to shift I tend to shift at 8k or so. This is fine for me as 1st gear is mostly useless anyway, and I don't hardly ever need 3rd. When I kill transmissions it is mostly because of the center bearing failing, which is a high power on rough terrain issue and not really an RPM issue. It manifests as a hellacious vibration in 5th gear (but not 4th) and/or the shifter moving a lot when going on and off throttle.

Probably a Miata gearset would be best gearing-wise, but every time I buy a Miata trans it gets stolen from my garage/car, so I have a kind of supersitious fear of buying Miata parts now.

henyaman

iTrader: (1)

So that would be a standard NA transmission right? I have an 88 NA, so this gives me hope I can run the same trans I already have, at least for a little while. Have you done anything on yours for the power or it runs fine as long as you arent bouncing around?

peejay

Bouncing around is kind of what I do with my car. The rougher it is the faster I am because everyone else slows down.

FC transmissions seem to last the longest. I've gotten as much as an entire season out of FC units. FB transmissions usually die in one or two events.

With great power comes great drivetrain stress.

I don't really "do" anything to the trans, although if I have to have the tailhousing off for any reason, I will remove the center bearing retainer bolts and Loctite them. I had a failure that I traced to one of those bolts backing out and getting lodged in the gears. This is the phase of motorsport wrenching where strange prejudices and quirks are developed, like, say, always running a thread chaser over new spark plugs because of the ONE TIME he got a plug that had a munged thread and it damaged a cylinder head.

henyaman

iTrader: (1)

Ok, thank you very much for your info. This helps me plan things out, so I know I can at least start with the FC trans and concentrate on the motor build.
What made you stay with the smoothcase over the TII? I've head the TII takes more power to run, is it weight and gearing, or just whats available?

peejay

I have an FB... putting a Turbo trans is expensive to swap.

henyaman

iTrader: (1)

Got it. Thank you for all the info!

rotatrix

I've been running a Toyota Altezza 6 speed behind a 13bpp with Tilton twin plate clutch in a circuit car for years now, I originally purchased this before rx8 6 speeds became readily available( the rx8 and altezza boxs are supposed to be the same, both made by aisin(?) i believe) This has done a hell of alot of work now but it doesn't seem to mind shifting at 9k+,and the ratios through 3rd,4th,5th really suit the pp with about a 2000-2500 rpm drop, the car is a FC and runs 245/17s slicks so not the lightest of cars.If you can get a cheap rx8 6speed could be worth a go!

henyaman

iTrader: (1)

That was my first instinct because the RX8 units are all over right now, and cheap.
I think I'll start with the FC trans just so I can concentrate on the motor and then do the RX8 unit when I come across one.
Thank you for the input!

peejay

Kevin up in MI swapped an RX-8 trans into his FC and he says it shifts like butter at any RPM. He did start from having a Turbo II trans so that probably made it easy since IIRC the RX-8 uses a Turbo II sized flywheel and input/output shafts.

j9fd3s

iTrader: (3)

there is an old old old thread where a guy dynoed his PP in the car and at the engine, and he found that the T2 junk takes 83hp to spin(!), so his 320hp at the flywheel P port was only making 235rwhp... my other friend has a PP with a t2 drivetrain and it does similar wheel hp, although he's never just dynoed the engine.

my friends car destroys T2 transmissions, they do fine behind a low revving turbo engine, but the PP just literally shreds them.

and B the T2 gearing is ok for a low revving torquey engine, like a ranger pickup, but its pretty useless behind a PP engine.

so buy an Rx8 trans, its the competition gearing with a granny 1st

Kenku

I'm working on a mutant transmission... I think it should be possible to hybridize the 8 and Toyobaru transmission for the better 4th. My specific intent is to, in an ideal-but-not-ideal-enough-for-a-dogbox world, end up with the M-Factory 1st and 2nd (roughly 3:1 and 2:1) and 8th (0.86:1) on an otherwise Toyobaru gear stack, with a 5.38 final drive.

But, all of that idea is worth what you paid for it so far. I mean it should work but I haven't bought the parts yet either.

peejay

I remember someone (j9fd3s?) looked at the parts listings for the Miata and RX-8 versions of the Aisin box and found that pretty much the only things they had in common were the dealer network that sold the cars. Bearings and shafts all different diameters so you couldn't easily, say, pop an RX-8 bell on a Miata trans.

I'm not sayin' don't look into it, mind you. Sounds like an interesting idea.

j9fd3s

iTrader: (3)

at some point i have had both apart, and its surprising how different the Miata and Rx8 transmissions are, even though they are both Aisin A6somethings. the Rx8 has much beefier shafts, bigger than a T2/FD. the Miata trans is sized like, well a Miata.

the Lexus IS and S2k also have transmissions in this family.

so lots of parts to choose from, but not sure what is compatible with what, outside Mazda

73rx313b

iTrader: (40)

For what its worth, I have a 2005 rx8 trans in my rx3 with a big street port 13b and a 4:44 rear gear. I love it!! I have great power just about anywhere on the tach. Even at DGRR on the dragon, I was always in my power band. I dont know why more people arent using this transmission.

peejay

1-2 is a bit of a big drop, though, worse than the common RX-7 transmissions IIRC. 2-6 is nice but to make 2nd a useful 1st gear you would need a rather low final drive, and one thing the RX-8 trans doesn't have is a tall overdrive.

So as j9fd3s said, it's a Competition box with a granny low.

I do have this V8 T5 sitting here, which has decent-ish ratios and a nice .67 overdrive to make the low final drive needed for the 3.35 first gear to work out, but they shift like garbage over 4500 or so. No idea what the friction losses are like, but given that it was designed got max fuel efficiency behind 4 cylinder engines in compact cars, it's probably okayish.

Kenku

Well, I'm doing this into a Miata, so there's FD options. Including, thanks to some people importing them, up to 5.38:1 ones now. 5.38:1 in a Miata with the RX-8 box works out to 135mph in 6th at 9k RPM, or with the Toyobaru box with an aftermarket 6th, 133mph. 2nd redlines at 50mph for the 8 box or 56mph for the Toyobaru one with an aftermarket 2nd (a 3:1ish 1st comes with it but who cares, granny gear) so it's damn close to the PBS box normal ratios with a 4.77 rear. If I were building another E-Production car, I'd lathe turn 1st gear off and call it a dogleg 5-speed for the non-dogbox weight break.

For parts interchange, the Miata tailshaft housing fits on the RX-8 box but I'm probably going to have to machine it for the RX-8 size bearing. I 100% know this, it's test fit up in my barn - the Miata end ends a little shorter than the RX-8 one (such that the RX-8 output is slightly recessed) but nothing I can't fix with material removal. The Toyobaru vs RX-8 I don't know yet - the castings look like they have the same boltpattern to bolt to the middle section but I haven't put an effort into getting one yet to confirm or not. The splines are obviously going to be Subaru and the shafts may be the wrong length, but screw it, I have a lathe, and am using a little dinky racing clutch and a custom driveshaft anyway. Nissan S15 6-speeds and IS200 Altezza 6-speeds are also the same family but I figure why bother when the Toyobaru version is junkyardable.

The S2000 box may be sourced from Aisin, and that may mean gears interchange, but I'd be surprised. If it is the same family, Honda changed it, to the extent that the gear order is different and there's no direct drive gears.

fidelity101

iTrader: (11)

I had the SA gearbox on the FC tailshaft then ditched it for the t2 then ditched it for the rx8 gearbox because I got a new trans for cheap.

if you run an NA rear diff its easy, just get an auto trans driveshaft and it bolts up otherwise you need to shorten it about 3/4" use the turbo flywheel/clutch or rx8 flywheel clutch (same thing) and the rx8 starter. You do need to fabricate a transmission mount which is pretty easy. if you have a turbo rear end I would assume you need a turbo auto driveshaft but I'm not sure if the turbo cars came auto... or they are certainly more rare.

the slave cylinder I want to revisit, I tend to grind second if i'm not careful when shifting at 8700 or so if I grab it too quickly. You can't use an rx7 or an rx8 slave cylinder because of the location, rx7 doesn't bolt up and the rx8 slave cylinder is too long so it hits the oil filter pedestal. I have a write up on what you need in my build thread under the 2nd gen section with more details.

Shainiac

iTrader: (7)

I interned for an World Challenge team for a bit in college that campaigned an RX8. They would blow through S1 RX8 gear boxes. IIRC, they'd bring a trans for qualifying, practice, and race day because just 1 wouldn't make it through the weekend. When the S2 RX8 gearbox hit the market, one box would make it most of a season. The S2 trans is a complete departure from the S1 RX8/Miata/S2000 Aisin. It's a top loader trans with much more ribbing and is just better all around. They aren't exactly cheap, but they're a big improvement over the S1 RX8 gearbox, if you're given the choice.

fidelity101

iTrader: (11)

sooo, speedsource? thats a pretty sweet intern job!

Shainiac

iTrader: (7)

No, actually. It was a small independent in TC. Owner/driver car that campaigned for 3(?) years and very competitive.
I was only there a couple months, but it was very cool.

Kenku

Yeah, I keep hearing that. I figure if I go through more than one or two of the Aisin boxes it's time to pony up for a real transmission.

peejay

I have a rotary to Jerico bellhousing that I might sell for the right price

Kenku

We're all weird parts hoarders, aren't we. I mean, good lord, I'm in the middle of figuring out how to put RX-8 ABS into a 1st gen Miata because it'll probably handle Hoosiers better than the early Miata ABS and flatspotted race tires are expensive.

I'm actually working on designing a big enough 3d printer so I can do patterns for casting a bellhousing in one shot... my stupid idea of the moment is to redrill an automatic counterweight to the LS1 bolt pattern and adapt a Tilton small diameter reverse mount setup. Something about an off-the-shelf 8.6" flywheel. If I had any sense I'd take you up on the Jerico adapter. But if I had any sense I would do a Duratec build instead of shooting for a big power streetport 13B.

Anyway.

The problem with the S2 RX-8 box from my point of view is that there's no options to fix the annoying 4th gear ratio like there is with the Aisin box. I've gone inside the MX-5 version of the same family and I like it, but good lord is it a pain in the *** to get ratios into it. If I had my druthers and even less common sense (ha!) I'd be looking at cramming Hewland FT gears into the toploader case, but I'm friends with Ron at Barrington Performance and I've seen what he's gone through to try to get smoothcase based dogboxes working.

j9fd3s

iTrader: (3)

the S2 box is a Mazda unit. from the parts side it seems to be derived from the P type 5 speed found in the 90's ranger/B trucks.

fun fact, rarest Mazda is a 2010 US market B truck, there were only 6.