Howard Coleman

iTrader: (6)

i believe there will be two major 07 stories.

1. the emergence on a broad basis of 100s of Fds running around on the street w the boost set at 20 plus psi. running pump gas and AI and making 500 rwhp.

2. the widespread destruction of most anything relating to the FD drivetrain.

let's talk number 2.

i have previously started a thread re clutches in the AI section... (same theme)

so, let's move on to the next AI victim, the poor old transmission. bad things start happening beyond 450 hp. third gear strips the teeth etc. for it's physical dimensions the trans does a great job. above 450 it will be reduced to a bunch of broken parts. there are no fundamental fixes. Ari Yellen must run an OEM trans in his drag car. he has been all over the place trying to keep it in one piece. he has run brand new transmissions, microteched etc etc. they are good for around one day. granted that's at 700+ hp. so maybe your 14 year old trans will hang in there for a couple of months at 500.

the trans needs to be gone.

then there's the rear end. if you run 500 hp w the stock rear end there are a few problems. and fortunately a few solutions.

the PPF bolts to the nose of the trans and laterally off center. it acts like a big torque wrench. many differentials have had the nose ripped right off the rest of the casting.

here we get in to theories and there has been mucho written. some believe that the diff case is strong enough if it is properly supported. others just replace it w the mustang cobra 03 IRS unit.

i believe either works. Jim Labreck did the cobra swap. (https://www.rx7club.com/showthread.p...t=cobra+cradle)

Paul_3rdgen engineered a really slick FD rear diff support. (https://www.rx7club.com/v-8-powered-rx-7s-299/rear-subframe-take-look-601934/)

in both cases you junk the PPF. it is certainly partially culpable as to rear end failures.

if you are drag racing and making 500 hp w sticky tires you measure your OEM axles in runs. they twist. they break.

if you elect to retain the OEM rear you can get turnkey axles that won't twist or break. the Driveshaft Shop (http://www.driveshaftshop.com/item135656.ctlg) not only makes the axles but is making the CV joints too. if you do the cobra rear you use most of the cobra axle and mate it w the outboard portion of the fd axle.

axle bounce is a primary factor w regard to broken drivetrain components. it must be avoided. period.

primary contributors to axle bounce are the rotten big rubber bushings that suspend the OEM diff. they need to go away and be replaced by nylon.

the other culprit is the big rubber bushing at the front of the lower longitudinal link. nylon or a rod end a necessity.

so that is a brief summary of the components necessary to have fun w a 500-600 hp rx7. if you are running a 60 pound per minute turbo and AI this power level is yours on pump gas w a properly tuned setup.

i will be going thru my FD's drivetrain and will post my journey in detail within this thread.

at this moment i am planning to run a Tremec T56 GTO 6 speed transmission, i am leaning to retaining the FD diff w bracing and a T2 LSD along w upgraded axles.

any and all comments are welcome within this thread. i consider the subject to be a bonafide AI concern as without AI i wouldn't have a need for such stuff and therefore it will stay within our section.

it is a slippery slope so save your money

a great deal more to come.

howard coleman

calculon

iTrader: (29)

Thanks for the additional attention to this VERY important topic. I for one will also be going the T56 route. I've been following the thread

T56

and am very much in support of it. I already have Jimlab's diff setup, not installed yet, but definitely intend to use it when I really start exploring my power potential.

Please keep everyone posted here as to the development of this integral part of the big power setup. I'll do my best to do the same.

Once again, thanks for the initiative.
ryan

RotaryEvolution

iTrader: (30)

i just picked up my new turbo so my FC should be at 500 in the near future though i don't expect to see quite as many issues with the FC since there is no torque brace at the differential and has a CPD vs torsen but it will need to have a solid mount put in to reduce wheel hop.

i think the trannies will be more resilient at that HP level than you think and mainly depends on driving habits, if the tranny is used at the strip only then sure it may not last a long while but daily driven with abuse thrown in here and there i think it will be able to handle it.

slo

iTrader: (1)

Two words, pinion snubber, I Have no where near 500 HP, but with upgraded suspension and the mazdacomp front diff mount and delrin rears was getting big wheelhop, Pinion snubber fixed that for less than 20 dollars and 1 hour. Using the install pics, on torque central I drilled from the the top down and it was perfect. A solid front mount will have the tendancy to break subframes.

blitzboy

have ran 450 at the wheels for the last year, I use a Mazdaspeed PPF, diff brace and Petit racing Launch kit and a Kazz 1.5 way diff, no failures yet with numerous launches

Howard Coleman

iTrader: (6)

T56

did some additional measuring today which leads me to some interesting conclusions:

the input shaft may work w almost no modding.

it is one inch ( all measurements here are close, not guaranteed) longer than the fd input shaft. the pilot bearing diameter of my input shaft is .593. the T56 i measured was .599. that's real close.

the center of the splines from the end of the input shaft on the fd is 2.06. the T56 is 2.22. the t56 spline length is an inch longer. looking good.

what this all means to me is i space the t56 rearward one inch using the adapter plate i will make. use a chevy, or whatever the t56 clutch disc is and there is no need to slice and dice the t56 input shaft. other than maybe to turn the pilot bearing diameter a tad.

wow

at the moment the Quartermaster clutch setup makes this happen. they have a rotary flywheel that bolts up to their 7.25 inch double disc clutchpak.

overall length of the fd trans is 28.5 v 26.5 for the late model camaro t56 i measured. (this is ex bellhousing).

shifter location is 26.75 from the front (x-BH) on the fd and 23.75 on the t56.

width of the gearcases is fd 6.75 and 13.5 t56.

height from the centerline of the main shaft is 3.7 fd and 6 t56. i am going to check for vertical tunnel clearance tomorrow. the wifey's fd has the motor in it...

overall looking prospective.

i meet w a fab guy re the bellhousing adapter plate and clutch monday afternoon.

howard coleman

slo

iTrader: (1)

[/QUOTE]i meet w a fab guy re the bellhousing adapter plate and clutch monday afternoon.
[QUOTE]

I thought there was allready a T56 belhousing adapter on the market.

crispeed

i meet w a fab guy re the bellhousing adapter plate and clutch monday afternoon.
G-Force transmission has it.

Howard Coleman

iTrader: (6)

"my present plan (always subject to change) is to acquire an auto trans starter and starter bracket and adapt it to the manual trans."


since i posted "always subject to change".... here's how it is actually going to get done.

use stock FD manual bellhousing
make spacer plate approx 4 inches plus a hair. this spaces the trans back and allows the use of the stock starter and of course stock clutch package.

moving the trans back a bit allows clearance for my twin 3 inch downpipes. i plan to angle mill the pass side of the adapter for max exhaust clearance.

the key in doing it this way is you have to add approx 3. something inches to the T56 input shaft. (call Liberty, send them an FD and T56 inputshaft and $350)

i am going to use an input shaft of the approx dia of the T56... lots stronger and i plan to use a Quartermaster double disc clutch package, QM flywheel and a QM internal throw out bearing actuator. i plan to visit QM in Illinois tomorrow.

G Force sells a similar adapter plate for $550.

on another note i checked gear ratios and here's what i want:

2.66-1.78-1.3-1-.80-.62. shifting at 7000 here's what you get:

2nd 4684-3rd 5112-4th 5384-5th 5600-6th 5245.

stock fd is:

2nd-4063-3rd-4816-4th-5035-5th-5740... (that's my .82 5th not your stock 5th)

the ZO6/GTO is

2nd-4878-3rd-4835-4th-4895-5th-5600-6th 5425 not good.
back at you,

howard coleman

crispeed

Howard.
You should speak to Craig from Liberity about the magic he can do to a stock fd tranny. I've heard about a T56 input and main shaft with dog syncros in the stock FD case and also a complete straight cut/clutchless Liberity gear set for the stock tranny.

paul_3rdgen

iTrader: (6)

Not to bash your idea but that makes the Tranny pretty much good for Drag racing only, very hard to match on down shifting and alot of gear noises when shifting. Have you ever driven with a dog box? I have driven an FD with an HKS tranny and it sucks!(stronger, yes) Good for a track car only.

Howard Coleman

iTrader: (6)

one interesting item:

T56 Rebuilds is, as i write, disassembling a 2007 C6 ZO6 trans. it failed w 1200 miles on the dyno making around 1000+ rwhp at the time.

there's lots of talk about new stuff inside... for instance higher rpm capability. the owner is shifting at 8200 rpm w no problem until he twisted off something.

T56 Rebuilds hopes it will find uprated components in the box it can adapt. i will know tomorrow.

stay tuned.

Howard Coleman

iTrader: (6)

comparative speed at 7500 rpm. 25.85 inch tire. no slip. top speeds of course only theoretical

-------FD-----supra------t56 C5------t56 ZO6/GTO-----supra w 3.13 rear gears

1-----40------36-------------52---------47------------------47

2-----69------59-------------78---------67------------------77

3----100------82------------107--------97-----------------107

4----140------107----------140--------140----------------140

5----194------139----------188--------174----------------181

6---------------176----------278--------224----------------230



observations: supra too short w stock rear gears but looks v good w 3.13.
i am going w the C5 T 56 w 07 shifting guts.

howard coleman

Terrh

iTrader: (7)

A word on driving technique.

An important thing to mention is that with big power the Mazda (FC/FD) trannies is 5th gear is weaksauce. Be gentle to it. Buy it a coffee. Make it your best friend. Don't do crazy highway pulls in 5th. DO NOT powershift into it, unless you want it to break in half. Don't even shift hard into it. Let off the gas, shift the gear, roll into the throttle. Alot of the v8 guys I know say to NEVER put power down in 5th period, unfortunatly my car has short gearing so that isn't possible, but be nice to your 5th gear.

it is much nicer to your transmission to spin out of the hole than deadhook (faster too, if your car bogs when it hooks) but don't let it wheelhop, you'll find out how quickly things break

The stock output shafts on the TII diffs (especially S4) seem to be the weak point, luckily they're cheap, replacements come with a warranty, and the S5 parts swap in and are stronger.

I'm not sure how much help fluid is or isn't, but I've been running about 3L (overfilled 0.5L) of Royal purple in my S4 TII tranny (after I broke the first one) - and it seems to be holding up well - also shifts great, doesn't do the usual 1-2 grind at super high RPM. Was shifting 1-2 at the track at ~8500 and then 2-3 and 3-4 at 7500.