transmission help for 20B
 

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let me start w the caution that while the rotary is simple the $s start adding up as you add more air and fuel.

my transmission solution is not inexpensive but it is stout, and provides significant gearing advantages. while i will offer for sale the adapter plate, the other items will need to be acquired independently and there is a modest amount of machine shop time.

so why go through all the effort and expense?

the FD arrived on the showroom floor producing 184 SAE foot pounds of torque.

500 SAE rwhp FDs produce 400 foot pounds and lots of stripped 3rd gear teeth and twisted mainshafts. if you really crank up the boost and are drag racing you will be replacing trans as often as changing your oil.

then there's the gearing

yikes!

a 3.483 first gear? great for pulling stumps. not great for doing anything but getting into second. and second? what's w a 42% drop in revs?, third a 31% drop and then the really long drop to 5th which is pretty much an economy run gear.

plainly stated the gearing sucks.

practical alternative trans options do not abound. there are all the racing trans options but they do not have syncros and after living w that type of box in my real racecar for 6 seasons, trust me, you don't want to be anywhere near one for the street. they are also really expensive. and you will eat up interior pieces and get to know the nice people at the trans shop far too well.

there is the fairly high dollar Toyota box. Getrag. nice gear spacing, nice syncros, stout but generally available around 4K++ just for the box.

i zeroed in on the Tremec T56. modern engineering, available at a junk yard near you for between $800-$2000. (there is the totally redone new T56 called the Magnum which sells new for less than 3K which is a bargain).

the T56 is often found in F body Camaros and later in the GTO. lots around. the Camaro has better ratios and the GTO has better syncros. i have a 99 F body Camaro trans that i am purposely installing to see how the syncros actually work at 8000. and for the ratios.

i am indebted to Jered Olson (IronMdnx) for alot of the engineering on the project. the T56 is just a touch too wide to clear the starter so he figured by using the auto bell housing the starter would point forward and clear the trans. one smart solution from a very very smart guy. WTG Jered.

so i had the benefit of his initial install which he kindly shared.

so here's how i did mine...

auto rear iron. necessary (i think) to mount the starter.. maybe you could do some mod work on the standard rear iron if you were creative.

auto rear bellhousing. machine .25 of an inch off the rear face to move the input shaft further into the stock pilot bearing. machine a small opening on the driver's side for the 2 dash 3 hydraulic clutch actuating lines.


bolt on my adapter plate ($375)

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find an auto trans flex plate for your flywheel (and an auto starter).

call QuarterMaster. talk w Geoff Tickes (847-540-8999 ext 250) tell him Howard suggested you call.

you will need a button flywheel(less than $200), the 8.5 double disc(less than $900) , a driveshaft (around $3-400) and a small button to flywheel adapter and the Tri Lite clutch release bearing (around $300). i am uncertain on exact pricing. that's between you and QM, i am just trying to be of help.

here's the clutch release bearing. custom setup for proper clearance w the pressure plate. adapter plate is drilled/tapped for it...

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the clutch is neat. clutch spring pressure is your call between 1800 pounds and 3000. it depends on your app. i don't drag race but needed a clutch to hold 600 rw so i am running, initially 2250 spring pressure which is the same as my wonderful Exedy cerametallic that wouldn't work in this app. unlike the racing apps my clutch has thicker friction material... the "rally" option. the clutch has 18% more frictional surface than my old Exedy. more surface, less spring pressure. win win.

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auto flywheel counterweight 4.02 pounds
auto flywheel 4.8 pounds

ACT lightweight FW 9 pounds plus CW = 13.02

QM pressure plate w button 18.8 pounds.
Exedy single cerametallic 27.6 pounds

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you will need to buy a short clutch master cylinder. .75 piston. Willwood, Tilton AP take your pick. about $100.

whether you use an F body or GTO box you will need to get the GTO linkage assembly. it situates the shifter rearward 2.5 inches and locates it exactly in the center of the Mazda rectangular shifter hole.



you will need a rear trans mount. i spent some time on this as i didn't like anything i saw. i wanted nothing sticking down underneath my car. so all trans mounts that bolted across the tunnel were out. secondly i wanted no interference w my exhaust. i ended up w a very short (9 inches or so) mount that sits high under the tailshaft. it angles higher on the pass side to clear the exhaust. i will have a 4 inch by 4 inch stainless steel plate on the interior of my car which will be the sandwhich plate. i could have ripped out the carpet and mounted it under the carpet but that was too much work for me. i have no problem w a tidy stainless plate in the car. you may feel otherwise. feel free to have at it.

the FD driveshaft has always been a source of irritation. no option to replace worn U joints? are you kidding me? the new (aluminum) driveshaft has replaceable joints and is good for 1000 hp. it weighs 12.6 pounds V 15.

rebuildable...

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then there is the PPF and what to do. i am extremely happy w my solution. after looking at all kinds of torque arms etc i decided i wanted none of them. bulky, heavy and stressing things i didn't want further stressed... trans tailshaft and trans mount. i called Justin Samberg and he had exactly what i wanted. he delivered his usual masterpiece on time and on quote. around $500. it solved all my problems and installed in 30 minutes. i also hear from the FDV8 guys that the Samberg subframe hooks up (launch not love) significantly better than the torque arm options. PPF weighs 4 pounds more than the Samberg subframe.

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that's pretty much it from a hardware aspect. i just have to reassemble my motor and bolt everything in.

one of the more challenging items was the adapter plate. the quick summary is that it took almost 2 months and a grand to get it exactly right. it is so centered that the input shaft has about a thou clearance to the FD bearing and you can turn the crank without turning the input shaft. this will all make contact once up and running of course but it is dead nuts. to promote deeper penetration of the input shaft into the pilot bearing the adapter plate is 3/8.

you will want to grind a couple of tabs off the trans. (you can see this in the pics.)

a Dakota Digital convertor box will zero in the speedo. ($75)


back to gearing:

let's assume we shift at 7800:

we reach

............................................FD.... .......................T56 F body

second gear at..................4512.......................... 5219

third gear..........................5384................ ...........5696

fourth gear.........................5607................. ........6000

fifth gear.............................5608............. .............5772

who do you think wins the race?

FWIW, i have designed my ports so i make 400 SAE rwhp at 5500. the rotary makes great power up top but if when you shift you could be driving a Yugo you have a problem. the F Body T56, with it's closer ratios helps the rotary given it's narrower torque band.

horsepower under the curve wins races. the T56 gearing puts the curve better into the narrow powerband of the rotary.

finally, that's how i did it. feel free to do it differently, maybe better.:)



that's it for now. road reports when we actually get it going soon.

howard

I have a customer interested in the trans crossmember and the Bell housing adapter.

If you are offering these 2 parts for sale, please let me know..

I am sure I could build them myself, but time is of issue....

Please advise..

i have a exedy twin plate for the fd trans could i just swap pressure plates and the center peice for the t56 input shaft or should i just sell it and start over? this for the 20b dont know if that will matter.

is there going to be a kit for sale in the future?

will the factory counterweight not work for the swap?

Yes the 20b factory counterweight will work.....

so I picked up an fbody t56 transmission and I would like to do a rebuild just for peace of mind. i have been told that the gto sycnhros cant go in without changing all the guts so I called gforce transmissions and didnt have the best of luck. the guy who answered the phone said there was no way that a t56 transmission or any transmission other than a straight cut gear race transmission could handle shiftiting at 8500 rpms. I didnt want to be rude to him but i know i took my factory tranny that high many times. So i need to get the synchros from a gto in my fbody t56 but i want to keep the fbody gearing anyone have any suggestions?

Get a C5 Vette 2.66 core tranny. It has the better synchro's.

Thanks Iron I may do that but what do you thing about the Magnum T56 i found a good deal on the new magnum transmission but im not sure if the shifter would be in the right place or if could even fix the position if it is off.

The only thing you need to watch with the magnums is the shifter locations. By default they sit even farther forward than the camaros. Just do your homework.

i thought they probably did. I saw some pics and I was afraid of that. Im going to see if the guy that i talked to can just replace the internals of my f body t56 with the gto internals or vette internals whichever you think is better for a street/track setup and go with that. i think i have probably been making it too complicated. the magnum would be nice but i would need to move the shifter darn near 8 or so inches back and that probably isnt do able without a lot of fabrication work. Either way thanks for the info and support Iron!

Howard are you going to have the adapter plate for sale? or did you not make copies? also where can we get one of those ppf's

i am getting closer to getting down on the ground. i do plan to sell the adapter after i know it absolutely works.

the rear subframe comes from samberg rod and custom in ca. justin samberg. he is a vendor on the v8rxy forums and does A+ work.

there are tons of T56 shops. call Tick performance or Texas Motorsports. it is not difficult to upgrade syncros etc... and not particulary expensive.

as far as whether they shift at 8000+.... i don't know for sure but i see lots of small blocks running 9000 w their T56s. we will see.

hc

thanks howard. do you know if the i can use the gto synchros with the camaro gearing? or do i need diffferent input and output shafts.

The the gears, input shaft, output shaft, and synchros are all different. You can't use GTO & Vette syncros on a F-body, Viper, or Mustang gears.

The few people I've talked to all went faceplated gears when they started having problems above 7k. A faceplated setup is like dog engaged transmission no synchros. They will shift at rpms like no tomorrow, but are a pain on the street.

Before I did my swap I talked to alot of people. Pluss the few local guys I know that run big HP with the t-56's.

does anyone know if the fd manual transmission flywheel is the same diameter as the fd automatic flex plate? I want to make sure that the automatic transmission starter will engage the fly wheel or if I need a special unit made.

After leaving 4 messages with Geoff I finally was able to get him to answer the phone. Clutch is $12xx, flywheel is $2xx, and the release bearing is $3xx for a total over $1800. He said you have to send in your flex plate in order for them to make the clutch.

I wonder if we can get the price down??? I suggest working with someone other than Geoff. He doesnt call people back.

I wanted to add Justin Samberg's phone number for those that are looking for his differential mount. 925 484 5800

does anyone know of a way to convert the t56 to a pull type clutch. I have the ability to get custom input shafts with the same spline as the fd transmission. if i can convert the t56 to pull type then we could use ANY fd clutch and fly wheel setup. in theory which should greatly simplify picking out parts and open up a large selection for clutch and flywheel setups.

The LT1 T56 used a pull type clutch, at least on F-body applications if thats of any help.

The only way it will work is make the input shaft about 4" longer. You need the clearence for the stock slave cylinder and starter. Then you need a custom spacer & adaptor. Even then there is a chance the t-56 will not fit moved that far back in the tunnel.

Another option that I thought about back in the day was to have a new t-56 front plate cast or cnc'd that would match up to the FD manual bellhousing. It could be shaped to clear the starter & slave cylinder. The cost involved would not be worth the investment.

this is getting ridiculous. Im having to have my 3rd flywheel made because apparently no one makes a rx7 fly wheel for an that can hold a quarter master 8.5 clutch. so I'm having aasco make one but they say that im going to need an adjustable throwout bearing because the pressure plate may not sit in the stock position. Im so dang tired of this im about to just throw the 20b in the garbage and go 2jz

Guys any advise for us here in london UK......i want to know what shall I do with my FD3S Transmission as I am running 20B now and don't know what i shall do with it as I know it can break on me very easily.....plz advise with the proper links and if possible with the proper emails so that I can contact the relevant people and buy the goods of them before my standard transmission breaks on me....

Regards

Does anyone have any 1st hand experience shifting the magnum at 8-9000rpm?

Application is a 20B making 600-700rwhp street/strip. At this stage the options appear to be a T56 magnum, or a shift modified TKO500 from Liberty's.