In my ongoing learning process of 20B / 3rotor powered cars, i came up with 3 new questions for everyone.

Since the Turbo 2 tranny cant handle a single turboed 20B, what does eveyone use? Do you just adapt to a t-5 tranny like out of a mustang or something? What can handle that kinda power?

Are any of these trannys shorter than a T2 tranny?

With all this power being put down, what kinda wheel and tire setup do people run on these things? Would the tendancy to understeer from a staggard tire setup be counteracted by the enormous power/torque of a 20B? I see that the roush mustangs and other high power V8's run 275 - 295's for rear tires, are those wide enough for a 20b car?

Hopefully this can be another good thread for people to search on!

 

Since I'm still getting by on the stock turbos and a T-II gearbox, I can't answer the first question.

For the question about wheels and tires, though, nothing that you can get under the stock fenders will be adequate. Jim, at Mariah Motorsports had some custom-offset wheels that allowed him to put 255-wide tires, but he said they weren't really enough rubber.

With fender flares, I have 275 x 40 x 17 on the rear and 235 x 45 x 17 on the front. On the track and on the street these are wonderful. If you want to do autocrossing, though, you need the same width in the front as in the rear.

 

You can fit ~265 or 275 wide tires in the rear of an FC if the offset is perfect. But that still probably won't be enough

Drag radials could be used.

 

As far as wheels and tires go I am planning on running 265's front and 295's rear on my 3rd Gen

 

One popular OEM transmission is the T56 unit. There are a few variants, but the best one is the stock unit found in Dodge Vipers, or F-Body cars which have an LS1 engine. This unit is also used in some Cobras, but I am not sure about which. The rating is 450 ft-lbs of torque, but it easily handles much more (just ask any viper owners).
A popular rear end for both drag racers and street cars is the Ford 9", Ford 8.8", and Chevy 12 bolt. All can be found in junkyards easily for cheap, or new for a good price, and have dozens of gear ratios available. You won't make enough power to break one well maybe, but draggers have been using them for dozens of years.

Then you can get into all the racing transmissions, sequential, dog box, all that jam, which are AMAZING but, you get what you pay for

If you can afford a 20B swap, it won't be too much of an expense to get the tires to fit (properly offset rims, and slightly flared fenders is a pretty easy solution). If you want to go all out, you can always tub the rear, even backhalf the car, throw in some slicks.... hehe

 

awesome replies, keep em coming....

Well, its not for and FC. Most likely a tubbed Datsun 510 with a jaguar rear end (like used on cobra kit cars, its like a ford 9 inch, but better geometery). If not a 510, then something else that is pre 1974. I really like 510's though......

The parts wont be too big a deal, i have some connections and this will be something done "over time" bit by bit. I know i want 17's on the car so i was thinking maybe 295's in the back or something. This is a weekend only car, so practicality isnt much of an issue. Yes im aware how light a 510 is and that i can get plenty of power with a 2 rotor, the point is that i want to try a 3 rotor. Do i have hands on experience with a 3 rotor ? Yes i do :-)

I like to do alot of planning with any project i do, so thank you for the ongoing information!!!

 

By the way, thanks for the info on the T56 tranny, ill be looking into that. Another great thing about those that i just thought about.....6 speeds!.....

 

The Turbo II/FD tranny is way stronger than a T5. There's a reason why Ford uses a variant of it in its trucks, and left the T5 to passenger car use.

 

A person I will NOT name... who used to run a 20B in his FC.. ran it with the stock rearend and a stock NON-Turbo tranny.... IIRC.

He had no problems with longevity or rearend problems at all. He also DID NOT DRAG RACE... He road raced..

He would roll into the throttle in 3rd gear or 4th gear on the track coming out of a corner.. and it would just light the tires for the majority of the streight....

Had a guy I talked to from a vendor out west who did track events with the other guy owning the 3 rotor car and he would catch him in his Porsche 911 Turbo with a TON of mods.. and just follow him for a couple laps to watch the black marks get laid down.

Lots of fun.. N/A with a after market ECU..

But tranny and rearend life was fine.. he went for 2-3 years I believe without problems.. Not sure on tire size..

But it comes down to this.. If you cant put the power to the ground.. you wont break parts..

 

I'm not very schooled on this type of info. I wasn't raised around hot rods, my dad hates that I'm into cars. How can these trany's from the f-body cars match up with the 20B or 13B engine? I understand that there isn't much involved with hooking up a beefier rear end but the trany?

 

so everybody that drivers their's on the street in here uses a Fd or tII tranny?

 

Spin...


Very interesting info, thank you. So between the T2 tranny and the FD tranny, what advantages does each have (if any) ??

I was thinking maybe run Redline heavy shockproof oil in the tranny and transmission to help it last longer (i have run the lightweight version in my t2 for years with great results).

An evil grin came about when you said he was chasing a porsche with mods.....

 

Well... the power increase from N/A to TII to FD IIRC is like 50 or so effectively from the N/A to the TII. I believe if I am not mistaken hat the FD and TII are the same basic box.
Best bet if going with a stock tranny would be either of the stronger boxes... I would DEFINATELY use the heavy shockproof. You will loose a few HP to the wheels but you will gain a ton in life of the tranny.. I know a certain race team based in Atlanta uses the heavy exclusively in a particular car they use... and they have real long life from the transaxles.

Personally... FD vs TII.... Stick with the tranny already in the car... That way it is one less thing to convert.. they have differing clutch styles.. pull and push.
As far as availability... the TII trannies are being used up in FLorida and I have RARELY seen one for sale.. The drag racers scoop em up and cut every other cog on the gears so they can slam through without using the clutch. Sooo they get used up fast.
So I would think there would be more of the FD available.
BUT.... ANother option I have seen quite a few people use.. is the N/A tranny. There are a Zillion of em out there.. and they are cheap to re-build. ALso parts (Clutch and flywheel) is the same as it has been since the early 70s.. (CHEAP and proven)
You can buy one OUTRIGHT for around 600 I believe from ISC Racing in Winterhaven Florida.. Sooooo As this is modified for hard use.. it becomes a consumable at that price. Figure it lasts Say a year.. with NON-Drag use on a 20B... The TIRES will last less than that.. so it isnt soo bad...
As I said though.. I would not worry too much about the tranny till the car is running.. IF you are making MAD HP... the Flywheel comes apart with RPM.. 20B's arent gonna be over 8 grand unless very modified.. soo No blanket really needed.. The only concern you MIGHT have would be in the gear area.. MAYBE if you were really worried you could put a blanket OVER the tranny in that area... but other than a driveshaft loop.. I wouldnt sweat failure.
When it starts to go you will hear it... the tranny will start making noise.. it will start shifting hard.. and whining.. that would be your tip to get it fixed or replaced.

(yes its 7:40 AM and I have been working all night.. 15 hours.. he he sorry for rambling LOL)

 

Almost any RWD engine and transmission can be mated together with the use of an adaptor. Even better is a custom bellhousing. Some companies specialise in this, otherwise you have to have a machine shop do it for you. It's not too complicated/expensive.

 

The T2/FD tranny is based on the old "Ribcase" transmission as used in the RX-3/4/5/REPU. Stout unit.

The "smoothcase" tranny used in the N/A RX-7s (and the 1st-gen Turbo) is completely different. Common to fail, either breaking 3rd gear or snapping the output shaft (tiny shaft). Usually only has problems when sticky tires and/or a strong clutch are used.

I have access to milling machines, a decent welder, and piles of tranny parts to take measurements from. I plan on making my own scattershield which has a standard GM transmission bolt pattern and reference bore, so I can use a T-10 fourspeed. (Which also is the basis of 90% of the race trannies produced in the US) The only thing I don't have access to is spare time.

 

this was recommended to me so...
Why not go with the Mustang T-5 trans conversion? There is a company that makes an adapter plate for the T-5's. It is stronger than the TII trans and you could even get the tremec 3550 which uses the same bolt pattern as the T-5.
the 3550 will use the stock mustang T-5 bell housing. Here's a link to the compsny that makes the T-5 to rotary adapter plate: http://www.kennedyeng.com/other.htm The T-5 is halfway down the page. I think they are gong for $1200-$1400


here's the mfg website:
http://www.ttcautomotive.com/English...ts/TR-3550.asp

let me know what you think cause i dont know much about it yet.

 

Read peejays post up on this page.
The TII/FD transmission is stronger than a T5.

 

sorry but its based on the t5. its a tremec 3550 not the Mustang tranny. did you veiw the link? and the mustang trannies dont like high RPM shift as an added note.