Just as the title states. I need direction on upgrading the drivetrain on our '79 Mariah Racing widebody with a turbocharged (TO4B), streetported 13B, liquid intercooler, 48 IDF throttle body, 3" full exhaust, 15x8 in the front and 15x9 in the back, etc. (just to give you guys a very brief idea of the car. Typically runs anywhere from 10-18 lbs. of boost or more when the drivetrain gets modified. Last time it was dynoed at 350 at the wheels. Currently, it has a 2nd gen non turbo tranny, stock first gen driveshaft, and an 81-83 limited slip differential with rear drum brakes. We've already gone through 1 tranny because half of the teeth on one of the gears inside sheared off, and with the current tranny, the wear inside of it is accelerating rapidly as well as the noise coming from it. The rear axle is also getting noisy.
So guys, what can be done within reason?

 

pick up a t2 tranny.... that should solve the tranny issues, as how they're known to stand up to 500 hp plus. As for the rear end the only real option is pretty expensive... but it'l last. Ford 9", lots of ratio options to cose from and built to take a beating... Granny's Speed Shop sells modifed Ford 9" for 1st gens... but they aint cheap... looks like they're going for about $750 with axles... here's a link to their site.

http://www.grannysspeedshop.com/

 

What I was REALLY wanting and hoping to do was to use the TII tranny like you said, but use the larger rear axle that was in production for the 1st gens, and somehow find a driveshaft to fit, but have no idea where to find one or how to get one that would work/fit. The one problem is that I have to retain to stock 4x110 bolt pattern because of the rare SSR wheels being used. (Look very similar to Epsilon wheels but better). This is the dilemma. Also, my brother has spent more than enough money on the car, so persuading him to spend alot on the drivetrain, and then somehow doing something with the wheels will be hard. Here's the thing, we really like the wheels, but if the bolt pattern had to be changed, then we would need the front changed as well to the same pattern. This would most likely result in needing a new front hub and brake assembly from a 2nd gen 4 piston setup which would up the cost. So as you can see, that would be VERY expensive. I know that it would be the "smart" and "correct" thing to do, but the expense of it all just would justify it to him. He would rather keep breaking trannies and diffs. The thing is that he has already invested wayy too much money into it as it is. Any other "possible" options?

 

Use a 84/85 GSL (4 x 110) or GSLSE (4 x 114.3) rear end, disc brakes, bigger bearings and they are running on cars with a lot more power than yours with no real issues.

You can easily swap the GSL-SE front struts also to match the pattern

 

i have a mazdaspeed billet LSD (4.7 ratio) which is tight as and incredibly strong, S5 13BT box and the S2 disc rear end.

i've heard of people using the 5sp supra box wit a custom bellhousing and i KNOW that those are incredibly strong boxes.

 

My friend had an 11sec 1/4 mile RX-2 , and swore by the supra 5 speed , and ford 9" combo......after blowing many previous

 

TII boxes are tough,but not indestructable.....mine is starting to make a bit of noise,so its time for a rebuild with about 100K miles on it.They are known to be tougher than the FD 5-speed and the TII is definately the strongest tranny that is a simple bolt-on to a rotary engine.

The 84-85 rearend does have larger axles and bearings,but I dont think it will be enough on its own,especially if you are going to drag race or street race a lot with those HP numbers.If you upgrade to 1st gen Moser axles,then it might hold up a bit better.But youll shift the weak link to the 3rd member,which can be costly and frustrating when it fails. Axles are easier to fix and relatively cheap.

As an alternative to the big,heavy Ford 9",why dont you consider the Ford 8.8"?Plenty of people have done it,its plenty strong enough for the job,its plentiful and its smaller.Even with 400HP,a 2 rotor doenst make a lot of off-idle,axle snapping torque.The 9" is legendary for its strength behind big-block V-8s and a 400HP 13B isnt going to be making anywhere near that much torque.

The driveline will just have to be made from scratch.Not a big deal,just bring in the front of a TII driveshaft and the rearend drive yoke so the shop will know what size flanges/yokes/splines they need at each end.Mine cost about 175 bucks,uses factory parts at each end,so its nothing terribly custom and its greasable/rebuildable.The u-joints are roughly Mustang sized (1310's) and its held for years and years with about 300HP.

Youve got a fair amount of power there....nothing earth shattering,but definately more than your current drivetrain is cut out to handle.Your current tranny and rearend are the weakest/lowest rated units availble for the RX-7.Some upgrades within the realm of stock rotary drivetrains should have a big impact on reliabilty,but whether or not it will be reliable over the long run will depend on how you drive/race the car and how you juggle your clutch type,tires and gearing selection.

 

As usual - Extremely well said.

 

Steve wasn't kidding; you do have the weakest parts. A slightly stronger tranny is the '81-'83 which has large tooth gears, and is a direct bolt-in. My friend has been running one on a supercharged 13B and it takes all the abuse he throws at at it. I'll run one of those until I break it. I wonder how long it'll live with 250-300 HP?

 

these guys are all right on point... especially steve.... if he says it, take it as the bible, when it comes to T2 FB's

 

The 81-83 tranny won't last in his horsepower range... I ran one on a PP and blew the **** outta it in about three months... go with the supra they are not only tough but they shift smooth as **** even if you just drop it... They really take a beating

 

BTW 81WideMariah what color is your car I've seen a Mariah RX a couple times while cruising town

 

Don't try and save money and use the 1st gen rear end. Get a ford rear and you will never have a issue.. That's the only option in my book..

 

was black.... right now it's primered... getting ready for paint!!!

 

It gets done a lot over here in Aus. So have a look for a Toyota hilux diff setup. There is one model that the width is almost spot on, all you need to do is cut the mounts off your diff and reweld them onto the hilux. Get the hilux hubs drilled to your stud pattern and put some wheel studs in them.

Hilux are drum rear ends (big drums, just fit behind my 15" simmons, but you can do disc brake conversions pretty easily.

Also there is a wide range of ratios available, you can get air lockers etc, and also there is a rumour that the old Toyota Supra TORSION LSD will fit straight in with only a small mod to the bearing carriers or something.

These diffs are a lot stronger than the mazda units, axle diameter is huge compared to a 79-84 rx. They can and do hold well into the 400RWHP.

Then match it with a series 5 Turbo gearbox, and a custom 3" tailshaft and you'll have one mean setup that can handle the big numbers.

Hope on www.ausrotary.com for some more information on the hilux setups

-James

 

From what I've heard the 84-85 isn't HORRIBLE if not dumped repeatedly at 7 grand from a dead stop. Of course if the 8.8 is an option for you jump on it! Plus like they always say it depends on your tires too. If you can't get traction, you aren't going to break the rear end!

 

Thanks alot guys for all the useful info! There are definitely more options out there than I originally thought. I'll be debating as to which setup to go with. If anyone else has any more info, please post!
Brian

 

just kinda an out of the box question, but what do you have to do to fit a supra tranny (t56 i believe its called) onto an rx? how do people get the clutch/ input shaft/ other **** to mount up to the flywheel? someone explain this to me because i have no clue what in the hell it takes to do something like that. oh yeah, also the bell housing to the motor? i know there are adapter kits or something like that.

 

Anyone know WHERE I can find a Toyota hilux rear end? Do we have a similar truck over here, but badged with a different name that I can source it from? Either way, anyone know what year or model as well? I just figured I'd ask while I'm searching.
Thanks

 

Well, we definitely didn't get them over here. I don't recall any Toyota trucks in the U.S. ever being this unbreakable:
http://video.yahoo.com/watch/100875
But, was the rear end used in other models as well that were sold over here?

More info:
http://en.wikipedia.org/wiki/Toyota_Hilux

 

http://www.rx7.org/jes/axles.html

Hope the link works. This might work for the rear.
chuck

 

Thank you!!

 

good god thats a tuff truck lol