Rx8 Transmission PHAIL!!!

chickenwafer · Postby **chickenwafer** » Thu Sep 03, 2009 9:14

I knew these POS Aisin transmissions weren't that strong, but damn I guess it can't handle 325+ ft-lbs of torque....

I was setting up my boost controller and finally making some headway...doing a pull in 3rd gear at 14psi probably pushing over 350-rwhp....shifter just popped out of gear and the transmission started grinding. I tried to grab 4th gear but it wouldn't budge, I was stuck in neutral.

I was able to coast into a parking lot and after a few frustrating minuets I got it into 1st by just forcing it in LOL. Once the clutch was out it started grinding like a mother and I couldn't shift to any other gear. I was about to call a tow truck when it finally started cooperating and I could drive.

I was able to drive all the way back home, about 6-7 miles, without any major issues really. I trolled around my neighborhood and it was actually shifting nicely. So I'm not sure what happened. I think I bent a shift fork, I know 3rd and 4th gear is almost impossible to get into. Either that or I spun some bearing or the countershaft.

So now I'm at a crossroad; buy a used RX-8 transmission, which is a ticking time bomb since we all know it's weksos, OR I could man-up and just do what I really should do and get an RX-7 FD 5-speed. The trans is cheaper, it's stronger, and it bolts up to the bellhousing. Only catch is I need a custom driveshaft since it's roughly 2.5" longer, a new center console since the shifter will be relocated, and the most expensive part, custom transmission mounts which could even evolve into a custom powerplant frame which is uber $$.

Ugh

Colombia28 · Postby **Colombia28** » Thu Sep 03, 2009 9:14

Aw i'm sorry to hear that. I would cry if my trany went out... the sounds are like from a horror film.

Postby **RX-7 Chris** » Thu Sep 03, 2009 9:14

why not look into other tranny options? maybe see if you can get an adapter for a T56 out of a Ford or Chevy V8.

chickenwafer · Postby **chickenwafer** » Thu Sep 03, 2009 9:14

Because that's even MORE work than an FD 5-speed. Honestly I can pick up an FD trans for about 1/3 of the cost of an RX-8 6-speed and it's stronger and shouldn't require too much work to get it shoehorned in there.

A T56 would require a custom CNC bellhousing ($$$$) and the transmission itself is easily over $1k.

AIM WO4 · Postby **AIM WO4** » Thu Sep 03, 2009 9:14

Sorry to hear the news...

But you could call this a "chickenbone" for future reference. :eek:

tbot · Postby **tbot** » Fri Sep 04, 2009 9:14

nvm in the other thread...that sucks bro, sorry to hear

*DarthRX8* · Postby ***DarthRX8*** » Fri Sep 04, 2009 9:14

"F"! That is horrible. If you can afford it I say go with the FD 5spd.

If you put another 8 tranny on its only a matter of time before you do the same thing. Your tq is too much for it.

Plus once you get that 5sp on, your 8 is going to be JIZZ IN YOUR PANTS mo better!

Eclipse · Postby **Eclipse** » Fri Sep 04, 2009 9:14

bummer deal man, that sucks... do it the right way now, that way you arent piddling with this crap later on

bmwzoom · Postby **bmwzoom** » Fri Sep 04, 2009 9:14

Awww.... sorry to hear Dave!!! An RX-7 FD would be awesome to watch you build/mod!!! Can't wait to see what you come up with!

TheNewBlack · Postby **TheNewBlack** » Fri Sep 04, 2009 9:14

Damn sorry to hear this, good luck with everything, keep us all posted.

GR-8 · Postby **GR-8** » Fri Sep 04, 2009 9:14

Wow that sucks. Only seems right though when the tranny can't even handle the N/A TQ. What's that again like 120 Ft. Lbs. ? I'm looking for a new tranny. I am not having this one rebuilt again. I feel your pain.... Kinda.

roninsoldier83 · Postby **roninsoldier83** » Fri Sep 04, 2009 9:14

Damn torque! Always breaking things! Sorry to hear about that bro

Hope you get her back on her feet and stronger than ever ASAP

chickenwafer · Postby **chickenwafer** » Fri Sep 04, 2009 9:14

Thanks guys

I am still strongly considering teh FD 5-speed trans swap...FD transmissions are readily available and dirty cheap. So even if I do the swap and the transmission breaks I can pick up another one for about 66% LESS than an RX-8 transmission.

Plus you get rebuild kits for the FD 5-speed and they are crazy expensive for the RX-8. Might as well just buy a used trans.

Plus the gear ratios are much better in the FD 5-speed gearbox for a turbo motor. 1st gear is basically useless in my car and just results in wheelspin. Even 2nd gear is stupid. These Aisin transmissions are basically just modified Miata gearboxes and not designed for the Renesis' 9,000rpm and our torque, let alone turbo'ed. Koni Challenge cars are swapping them out left and right.

I'm still weighting options out there...I want to do the FD trans swap but the biggest hurdle is mounting it (requires modifing the PPF possibly) and the clutch actuation. The stock 8 uses a push type clutch and the FD trans uses a pull type clutch, so it will require some work. Luckily the bellhousing bolts up. That's about it. The shifter is 2.5 inches further back, the transmission is longer so a custom driveshaft is required, and the mounting locations don'g line up.

chickenwafer · Postby **chickenwafer** » Thu Sep 17, 2009 9:14

So some updates:

Apparently my car fixes itself, LOL. I had to move my car out of the garage to put up some new shop lights so I was nervous about moving it. Car fired right up no problem there, once warmed up I pushed the clutch in and put her in reverse and no grinding. It actually went right in and the shifter moved freely. Huh.

So it backed out of the garage just fine, zero issues. I was then able to get it into 1st gear and pull it back into the garage no problem, either. So I decided to flush my transmission fluid and I swapped in some Redline Lightweight Shockproof trany fluid over the current Redlien MT90 I was running.

I took the car for a spin and amazing! I still have to granny shift it but the car is driveable! I still think I am going to do the RX-7 trans swap tho. I can't rip the car through the gears like I should which makes the car feel slow, haha.

This is what I have learned about the swap thus far:
-Clutch actuation is no issue since I am swapping transmissions. I just need to use the RX-7 clutch slave cylinder
-Instead of the FD transmission I am going to use the FC T2 S5 transmission 89-92. This turbo gearbox is virtually identical to the FD trans except it's cheaper (generally) and has an external gear linkage so I can cut down the linkage to move the shifter forward so it lines up with the hole in the RX-8 trans tunnel. This is the biggest plus. The only real difference is the external shifter linkage and 5th gear overdrive is a little taller in the FC gearbox. 1st thru 4th are the same ratio, the case is the same
-Bellhousing bolts right up to the block
-Turbo trans takes the same 240mm flywheel and clutch combo as the RX-8 so I can keep my Fidanza billet lightweight flywheel and ACT Stage 2 clutch
-I will need a custom driveshaft roughly 12 1/2" longer than the FD driveshaft and a new rear u-joint so I can install the RX-8 rear driveshaft yoke that hooks up to the differential
-I will need to fabricate custom transmission mounts so I can keep the original PPF
-I will also need the RX-7 turbo or automatic transmission starter motor

I am buying a TIG welder next week so I can hopefully start on some of this and pratice TIG welding.

sookiespeed · Postby **sookiespeed** » Thu Sep 17, 2009 9:14

try driveline service here in the springs if you dont have a good driveshaft builder up there.

They built me a custom cv style rear driveshaft for my jeep when it was lifted. The stock one bound up and ripped the front u-joint off the shaft...ill see if i can find the number

719-634-2548

Rx8 Transmission PHAIL!!!

Rx8 Transmission PHAIL!!!

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