You could get a Guru tranny: http://www.xtremerotaries.com/main2/guru/gearbox.htm but then you'd have to learn to shift a dogbox and they cost a lot.

-Andy

 

Hey Greg

I did a little research about this, and this is what I came up with.

- Prob the optimal gearset to get would be the T56 Z06 gearset
- You can't use the Z06 tranny housing, however (if you see pics of it, you'll know why )
- The Mustang case is practically a spot-on match dimension-wise to the FD's case (minus the secondary access plate in the front), so that's prob what I'd see if you can retrofit the Z06 gearset into. I don't have any info on how this can be done, so maybe someone else can chime in on this. This also means little to no modification to the PPF and driveshaft would be necessary
- Powerwise, I've seen videos of a 1800+ Viper running the stock T56 (or so it's claimed).
- Richmond trannies will be a waste of money in your case. The Doug Nash design was purchased by Richmond gear, and as per my conversation w/ them, they rate their tranny at 450 ft lbs of torque. They also have one currently in the test phase that supposedly will be good for 500 ft lbs of torque. So that's prob. not the way you wanna go if you think you'll ever be increasing your power level

Dunno about that, but I can tell you that from what I've heard, the T56 feels like you're shifting a truck. It's far from crisp shifting.

They're called Quaife. And I've been pressing them (over the last few days) for an exact torque rating. I'll have one for ya soon Even then, however, you face a completely different problem. The gears may be strong enough to hold the power, but a) are the input/output shafts upgraded as well? Because those are the weakest points in the stock tranny and b) even with the upgraded shafts, the stock casing is aluminum and is thus prone to flexing where the shaft enters/exists the case. As such, you risk shearing the gears. I don't know if it's possible to reliably reinforce the stock casing around the entry/exit points of the shafts?

Andy, learning to shift via a dogbox is hardly difficult. The real problem lies in remembering that Reverse lies in place of 1st gear, and 1st in the place of 2nd gear, and so on and so forth in the Guru box (the new version). That would be a DISASTER should you be in the middle of a downshift and forget the revised shift pattern...

~Ramy

 

Oh, I seem to have remembered reading that it was more difficult, maybe this is what they meant In anycase wouldn't the dogbox be the best option? It's supposedly made for the FD thus requiring no modification and I thought dogboxes are higher performance (shift faster, something..) than synchromesh and that one seems to handle a good bit of power.

-Andy

 

Yes a dogbox is prob what you'll need once you hit the higher powerlevels - beyond what a synchromesh is good for. But even the new Guru box isn't rated for more than 500 or so ft lbs of torque. They're 100% confident of the internals, but beyond that, they do NOT recommend the box due to the flexing issue I mentioned above of the stock casing. So you're back to square one

~Ramy

 

Eh.. I am never going to go past 10's so I think the stock trans will do fine for me so why bother looking into it...

 

A few points worth noting:

- torque ratings vary considerably w.r.t. conservatism. Since these guys sell to very hard use end-users, I would think they are alittle more conservative when assigning ratings. If you pressed Mazda for a rating on the stock tranny, I assure you it would be far lower than the 300-400ft-lb that many FD owners consider to be a reasonable limit. So you would probably find an aftermarket dogbox will probably hold much more than 500ft-lb before breaking down.

- the housing flex no doubt will affect bearing life and gear strength. However, the teeth on a dogbox are much larger, so it's my theory that they will be less sensitive to housing flex. So while the problem doesn't go away, it steps back a bit when going to a spur-gear setup.

- spur gears have much lower frictional losses and thrust loads compared to stock helical gears. This results in somewhat lower loads applied to the housing given the same torque level.

My understanding of dogboxes used on the street is this: they are much, much louder, much less smooth to ride around in, and more sensitive to proper rev-matching. It's not that they are hard to drive, it's that they are hard to drive comfortably.

Dave

 

A stock T56 will self destruct if you try to throw 1800hp through it. They begin to fail around 600 RWT. A Z06 tranny can be used but you have to change out the input shaft etc to change it from a torque tune config to a bellhousing config. A built T56, Tremek TKO or dog box are good options, but I would look at forged gears first.

What transmission is Ernie T using for his 700+RWHP FD?

 

Indeed, dog boxes are much less smooth to drive for the very reason of not having synchro rings. That means that your gears will crash unless you're very highly skilled in matching gear speeds. Thus, in some circles they are called "crash boxes". They are built to be shifted without the use of the clutch both up and down. Yet, even with the use of the clutch they will grind and crash. In race applications, (for which they were designed for) the rev differences between gears tend to be far closer (close ratio) than street gear ratios. For that reason you can crash the race car shifter into the next gear without clutching with minimal damage. Still most serious racers will take apart their tranny after each road race weekend to check/change the worn dog rings.

I used them plenty on my race cars but, would not be interested using them on my street FD.

Also, if subjected to extended periods of high speed driving (racing) they will require an oil cooler of their own as the straight cut gears develop huge amounts of heat during ***** (even with clutching). I had seen my tranny oil temps over 340F when the oil cooler pump failed.

Albert

 

A little more research would have turned up this...

MN6 (LS1) T56 - 2.66:1, 1.78:1, 1.30:1, 1.00:1, 0.74:1, 0.50:1
MN6 (GTO) T56 - 2.97:1, 2.07:1, 1.43:1, 1.00:1, 0.84:1, 0.56:1
M29 ('93 LT1) T56 - 2.97:1, 2.07:1, 1.43:1, 1.00:1, 0.80:1, 0.62:1

In other words, the MN6 from the GTO has the same gear ratios as the Z06 Corvette, and the M29 has an even better 5th and 6th gear combination, both in a front-mount case.

Two more tidbits; the Tremec (formerly Borg Warner) T56s are rated for 24 hours continuous duty at the torque levels listed, and the torque load of a transmission (and all drivetrain components, for that matter) varies greatly on whether you're launching from a dead stop on sticky tires (drag racing) or applying that level of torque while in motion. When in motion, torque capacity is significantly higher.

There are quite a few Vipers pushing 1,000 rwhp and torque with the stock transmission.

You may shear the output shaft if you're drag racing or abusing the car, but they can be easily replaced with a 300M part. Same goes for the input shaft. Add steel shift forks and a couple other mods, and you've got as bulletproof a manual transmission as you're likely to find. Far stronger than anything Mazda's ever built, that's for damn sure.

 

To add to this, the torque ratings on these trannies are subject to several factors, including vehicle weight, load placement (dragracing vs roadracing for example), etc. This varies the impact the tranny will be taking. Most of these dogboxes are made for much heavier domestics, and as such, the same exact tranny will have a higher torque rating/capacity on an FD. If you have a short discussion w/ Jerico or G-Force, for example, they'll ask you your vehicle's weight and your racing application PRIOR to quoting you a torque rating

Loud, yes. Kind of like driving in reverse. But the handful of guys I know that have them have yet to complain about 'em

I think Jim already addressed this point

Rob, have you seen the rear of the Z06 tranny? There's NO WAY you're gonna fit that in an FD.

PPG dog gearset. 2nd is in place of 1st, and 1st is in place of 2nd, and so on and so forth.

Albert, is this the case w/ even newer dogboxes? On that note, however, Holinger recommends rebuilding their trannies every 3K - 5K kms haha

Interesting...I didn't know that.

I actually had heard that the GTO may have the same gear ratios as the Z06, but I hadn't had the have a chance to verify this as of yet. Now I know

What I still don't know yet is, does the GTO use essentially the same case as the Mustang tranny? B/c if so, then that would be a PERFECT swap into the FD. Very very minor modification would be necessary, given the dimensions would be very close.

The only thing left for the 20B guys would be to see if an additional access plate could be welded on to the front of the tranny (as in the FD's tranny), so those who push the motor back would still be able to retain the shifter in the stock location.

To add to this, if you're still worried about the torque rating on the T-56, G-Force makes a Street 6-Speed upgrade kit for the T-56 with "the ability to handle approximately 900* horsepower and 800 ft-lb. of torque depending on the application." http://www.g-forcetransmissions.com/tran_gt-56.asp

Very interesting. Care to elaborate on what the "couple other mods" are?

~Ramy

 

I discussed this with Ramy a few weeks back. My original plan was to use a T56 transaxle in the 20b project. However, after spending 2 years to get the front sub frame and firewall work right I decided to wait on that. Since most of this information has been pushed pretty far out of my mind, don’t take anything below as an absolute truth without verifying the facts.

Based on the measurements I took I think it is possible to use the transaxle (really a transmission bolted to a dif), but it would take some serious cutting to the back of the chassis. The major limiting factor that I saw was the width of the tunnel. The gearbox with the torque tube connection installed would extend up to or just past the seatbacks. If it goes beyond them (and this depends on how far back you sit) the tunnel would have to be spread out to accommodate it. The clearance then gets tight between the seats and the console.

The best gearset option I came up with was the M12 -which is found in the Z06 case with a 4.1 rear gear. The M6 (non Z06) would also work with shorter 5/6th gears as the same final drive.

G-Force felt that it was important to use a gearset with triple and double syncros given the rpm range of the motor. My understanding is that all the gearboxes for the F-body cars and mustangs do not have this. The Corvette boxes and the unit used in the GTO and the CTS-V do. I believe the unit used in the CTS-V has the same basic gearset as in the Z06 in a front mounted case.

As far as shifter position is concerned, there are a bunch of options depending on how far back you move the motor and how long the bell housing adaptor plate is. One thing that I thought was interesting about the CTS gearset is that it has what looks like a remote shifter mount. It might not feel very precise though.

 

The Z06 T56 is configured to be a torque tube transaxle, but it can be converted to a regular bellhousing style T56 (like the one that is bolted to my car as we speak) with the same dimensions because the same tremec housing is used.

 

http://www.quaife.co.uk/Mazada-RX7-t...gement-gearkit

 

No, but D&D performance does offer a Mustang T56 with the same gear ratios as the M29 (2.97, 2.07, 1.43, 1.00, 0.80, 0.62). PN BA4.



There is a forward access plate that can serve as an alternate mounting point for the shifter (see schematic above), but it is likely too far foward.

However, the LS1/GTO T56, even with an adapter plate, would probably end up with the shifter in just about the right spot since the shifter of an M29 LT1 T56 with the bellhousing (about 0.6" shorter than an LS1's) even with the firewall is perfectly centered in the stock opening.

D&D Performance - T56 Upgrades

 

If an M12 from a Z06 can be converted to a "front-mount" configuration, it is definitely not as easy as just turning it around and bolting a bellhousing on it or more people would be scavenging them to get the better gear ratios.

 

That's the same as the Trust unit.
What about the HKS?

 

It's not quite that easy.

The same gear ratios can be found in the M12 GTO T56, that's why people aren't converting. The Z06 T56 can be converted, but it is not as simple as turning it around, like I said earlier it involves swapping coupling components.

 

Which might be why I said it wasn't that easy...

No, they're not converting because most people try to get a T56 along with the LSx donor engine because it's cheaper, and with 3.90s or 4.10s in the back, the deep overdrive of the LS1 T56 isn't that bad.

Right. Replace the output shaft, add a tail housing, add a driveshaft flange, replace the intput shaft, replace the front plate, add a bellhousing, shake twice...

 

Good so we all agree

Most people, or most RX-7 owners? A GTO low mileage T56 is not prohibitively expensive. If people are not purchasing them it is (A) because they are unaware that it has the Z06 gear set, or (B), they don't see the benefits of the conversion to be worth the associated costs (time/money/hassle etc).

If someone is dead set on getting the Z06 gearing, he/she can either spend a few hundred $ extra and buy the GTO trans, or spend $2600 for parts + labor to transplant Z06 gears into an F-Body t56.

---from c4c5specialist

"The cost is for the following, 1,2,3,5,6 gears, both the drive and the driven.
Input shaft and seal
Inner and outer cones for all gears, except reverse, because reverse does not have them.
All driven support bearings.
Reverse syncronizer
1/2 syncro
3/4 syncro
5/6 syncro
output shaft inner and outer seals
All these parts are needed for this build, and amount to about 2600 list for them."

I hear ya. You can also swap all of the Z06 T56 internals directly into an F-body with the addition of a GTO input shaft. Both of these options are possible, yet make no financial sense.

 

Wow...that's perfect. Didn't know that!

Forgive me, as I'm obviously missing it. Where is the forward access plate in that schematic?

Is that taking into consideration whatever bellhousing/adapter plate would be necessary to mate the tranny up w/ a 20B? Because that's obviously going to push everything back some.

Its been a while since I've said this (lol) but thanks Jim!

~Ramy

 

nm

 

The yellow cad-plated cover right above the sensor on the far right in the picture below...



The rotary engine sits farther forward in the car allowing plenty of space for an adapter plate...





The longer LS1 bellhousing and tail housing is probably ideal, because using the shorter aftermarket bellhousing shown above, the shifter ends up too far forward.



No problem.

 

I've wondered if anyone has done a sequential setup in an FD. Is that your car?

BTW, that "shock drifting" image in your sig is funny as hell! Love the hubcap flying off in the background.

 

No, my car is blue and rotary-less.

That was DamonB's idea.

 

I believe there's a guy on the forum who has the HKS sequential setup in his FC. I can't recall his name ATM. But mind you, a sequential setup doesn't exactly shift as fast as most ppl think. The lightening fast shifts you see on videos like the BMW M3 GTR and such have multi-million dollar R&Ded ECUs controlling the transmission & shifting, enabling it to be so fast and crisp. So don't be fooled into think that a sequential dogbox (which is much more expensive than a traditional dogbox mind you) is an easy option/alternative. You'd be looking at about $12K+ easy for a real sequential system that can handle the power.