Rob...hold up...I'm searching for the pOwNeD picture... (You know I love ya man )

~Ramy

PS: It wasn't a fair fight; I spoke to BOTH shops on the phone extensively, so I actually knew what I was talking about Ok ok, I'll stop haha

 

jdm made it sound like G-force custom built this thing on the spot, but I guess it's a matter of picking up the phone and seeing what is out there, which I obviously didn't do because I already have a t56 bolted to my engine ;o). A good man can admit when he's right and when he's wrong. I plan to do neither ;o) Relocating the starter, shifter position AND fabricating a tranny mount can still be classified as more than "little to no" fabrication work. It's a matter or perspective ;oP. hehe

 

"the only custom part would be the driveshaft" - Ramy < reaaallly?

"It's not like *anything* has different dimensions." - Ramy < ummm, wrong. If the parts can be bought off the shelf then slap my *** and call me Susan cause that's great!, BUT dimensions ARE changing externally. ;P

"I personally think it's a stretch to think it wouldn't be much more stout than any OEM parts-based setup." - Ramy The Cobra Differential is OEM ;o) You're replacing OEM Mazda with OEM Ford.

Try again buddy :o) Neither of us is exclusively right, or wrong.

Back to the Cobra diff.
In the pictures above it does not look significantly thicker than the Mazda diff casing and regardless, we're trying to compare apples and oranges. Iron is a ****-ton stronger than aluminum, so a comparison based on visual observations of thickness alone is pretty meaningless.

The Cobra diffs are grenading for essentially the same reason, and they are getting blown apart. Until I see proof proving otherwise I am going to have to say that there is little evidence currently in place on this thread that support the conjecture that the cobra diff case is any stronger than its FD counterpart. The fact that people are incorporating special braces and bandages just to make it work for high-output applications doesn't really support the strong casing hypothesis. However, it does seem, based on my non-existent knowledge of Mustangs, that the axles do hold up better than ours, but even this I would need to look into further. So the Cobra conversion makes sense in that respect, and of course the gear options that it offers. Again, I'm not trying to bust your ***** Jim, just making evaluations as an objective third party. I think it's a good offering, but perhaps a more robust starting point would have been a better option. IOW, why start with the Cobra diff over available GM options? I'm assuming weight was the prime concern? Just wondering...

Also, the 3.9 - 4.1 gear seems to be a pretty natural fit based on feedback from the V8 FD crowd and if you do some reading on the LS1/Corvette forums, as I'm sure you do, you will see that the 4.1 rear gear is a popular upgrade. More options would be nice, but for most are probably not extremely necessary. Regardless, it is nice to have options.

Lastly, am I the only one that notices that the hard-core rotor heads are slowly slipping over to "the Dark Side?" hehe First the rear, then the tranny, then you know what.... (sinister laugh) hahahaaa.....

 

You're comparing the rear cover of the Cobra diff to the front of the housing of the RX-7 diff... BIG difference in function and required strength.

Yes, but not for the reason you're about to mention.

When an FD differential comes apart at the snout, the pinion gear and the ring gear tend to chew eachother up somewhat, so you can pretty much plan on replacing the entire case. The driveline and PPF are also no longer attached to the differential, so if you're traveling at any serious rate of speed, you have vastly increased potential for further damage to the car. The only "good" thing is that the transmission tunnel braces should hold the PPF and driveshaft up off the pavement.

When the rear cover on a Cobra diff breaks, you get fluid all over your exhaust. It will probably smell. Then you get a new rear cover and some more differential fluid and clean up your exhaust.

Especially when you're comparing the wrong parts.

Find me one person who has broken the snout on an 8.8" IRS differential and fragged the internals. Just one.

No, they crack open. The Mazda differentials are the ones that blow apart.

I can't respond to that without saying something derogatory about your intelligence or eyesight, so we'll just have to agree that you need more proof than I plan to provide.

And people don't apply extra braces and bandages to the RX-7?? Are you serious?!? You've got differential braces, transmission braces, transmission tunnel braces, engine braces, upgraded powerplant frames... I suppose next you'll tell me that adding a Kaaz differential and 300M axles to an RX-7 aren't bandaids for drag racing either.

It's not the fault of the Cobra IRS that it was compromised by the OEM mounting configuration, and one simple and cheap brace eliminates most of the problem in about 30 minutes.

Well, at least we agree on something.

Educate yourself.

2001 Cobra axle vs. FD axle. Note the difference in diameter in the axle shafts.



2003 Cobra axle vs. 2001 Cobra axle. Note the difference in beef here.



Now consider that we're replacing the center shaft on the 2003 axle with a 300M replacement. The Driveshaft Shop rates the completed axle for 900+ horsepower. I know for a fact from talking extensively with Ari Yallon that the OEM axles won't hold anywhere near that kind of power, even with 300M center shafts.

Is that what you're doing?

Like what? A custom 9" IRS center unit that wouldn't fit in the car and would cost more than a completed 8.8" conversion? I may be accused of a lot of things, but not completing my homework isn't one of them.

The C4 IRS is much weaker than the Ford 8.8 and uses axles that adapt well to FCs, but not FDs.

A C5/C6 differential would require extensive work to be mounted in the car (it has no front mounting provisions) and to cap the front of the differential (which normally bolts to a transmission). Then a pinion flange would have to be fabricated, because the Corvette has none. After that, you'd have to figure out how to adapt the inner stub of the Corvette axles to the outer joints of the RX-7. The Cobra uses axles that are easily adapted to the RX-7 outer hardware, which is one of the reasons I made the decision to use it. The C5/C6 doesn't.

After all that, you'd still be stuck with an 8.25" ring gear (C5) vs. 8.8" ring gear (Cobra). I shouldn't have to tell you that the larger the ring gear (the FD's is a puny 8.0"), the more mass and strength it has. Supposedly the C6 differential has a 9.0" ring and pinion, but you'd still have all the other fabrication problems to deal with, and at the time I made the decision to use the Cobra 8.8" IRS, obviously the C6 differential wasn't available yet.

Most of whom are typically so broke and/or cheap that they'd live with 5.33s if that's what the car came with.

The 4.10s and 3.90s work just fine with stock or nearly stock engines, although they aren't exactly conducive to improved gas mileage. However, 4.10s and even 3.90s make 1st and 2nd gear basically useless for a V8 car with 400+ RWHP wearing street tires. I also think you'll find that anyone building a turbo car would benefit from the availability a much lower (numerically) gear ratio also, since boost is load dependent.

The goal of the 8.8" IRS project was to provide access to a wide range of gear ratios for various applications. The fringe benefits were that the assembly is much stronger than the Mazda OEM parts (whether you want to believe that or not), and it doesn't add any weight to the car. I don't see how you can argue with that.

For those with stock or mildly modified engines (and little cash), they make an immediate improvement in acceleration, at the expense of gas mileage and speed. It's a fairly cheap way to get more performance out of your car if you're willing to live with the tradeoffs.

No one said it was necessary, and it was never forced on anyone, yet 34 people now have that option, and others seem to be very interested because my kits resell very quickly and I've sent many people to Alex Hagedorn (TT_Rex_7), who now has my welding jig, templates, and blessing to produce more of them.

 

A broken diff is a broken diff, regardless of where it breaks.

Yes I agree that the PPF setup is crap and I know how it breaks.

Ford owners are not switching rear ends because of broken covers.

No, apparently I was comparing the wrong section of a part which as a whole is still broken.

a little bit from an online magazine:

With that kind of power and torque readily available, the Cobra's independent rear suspen-sion, a feature unique to '99-and-later SVT Cobras, has been criticized for not holding up when the power is put down. Wheelhop in the first iteration of the Cobra IRS was rather noticeable, so in 2001 Ford added better bushings to solve the problem. Obviously, the whopping increase in power for the 2003 models required further development of the IRS, and this resulted in even stiffer bushings, as well as thicker axle shafts.

IRS failures usually occur at the dragstrip where traction is plentiful. Having witnessed numerous abbreviations in IRS life expectancies at events all over the country, we can tell you there are two main causes. The first problem comes from inexperienced pilots who believe they can drive through wheelhop. Keeping the pedal down once the car has started bouncing will, nine times out of ten, end in breakage and a call to AAA.

The other main cause for failure is a combination of shock load from a clutch drop and/or the differential housing moving around in its carrier. When the diff moves, it dissipates torque throughout the aluminum case-rather than the ring-and-pinion gears, which are designed to handle that sort of pressure-and it can blow apart. This won't be an issue with the Shelby.

Terminator owners who frequent the dragstrip have been known to swap out the IRS for a solid axle. It's a fairly easy job. We've seen quite a few solid-axle Cobras and thought the swap was pretty common, but as we found out, that's not the case. After surveying some shops and a generous amount of Cobra owners, we learned that most enjoy the IRS and plan to keep it.

http://www.musclemustangfastfords.co...xle_value.html

Hmm, that's funny, I thought I read somewhere that they blow apart. Ohh yeah ^

I appreciate your tact. And as I said before, the proof is in the testing. I don't expect you to prove anything in this thread, but don't expect rational consumers to just assume that your word is gospel. You know your **** Jim, but you of all people should appreciate my skepticism. At the end of the day I lean towards saying that your IRS will work. But it HAS NOT been proven and no rebuttal that you provide will change that fact.

Show me where I said that

Serious drag racers are using OEM shafts on their Fords? You know I agree with you 100% about the axles being superior to those on the FD.

I hope you are not suggesting that a cover brace fixes the problem that is inherent to its mounting configuration.

That **** is unnecessary.

I've already pointed the axles out as superior to the mazdas

Yes, and apparently you don't deal well with people challenging your ideas, just as you do to others. This doesn't need to turn this into a pissing contest. You know that I respect your hard work, but that doesn’t mean I should be ready to buy your product simply because you say it’s the new sliced bread.

I wouldn't have commended you if I thought that was the case. Hopefully it should be clear to you at this point that I am inquiring about your design because I find it interesting and because I am not a mind reader. Do not assume that any question about your design is inherently negative. How is one to learn subjective information if he never asks questions? Also, are you trying to keep prices low to meet market demand or build a stout-*** rear end? I think you’ve tried to hit the happy medium, which makes sense. I think we both know the 9” rear could fit (on a custom rear sub-frame if need be), it just wouldn’t be cheap or easy. You state this below….

A lot of good information. Here's the thing. You speak about this 8.8 IRS as if it were the end-all solution, but then you reverse yourself by acknowledging that it was selected because it required less extensive fabrication and fit within budget constraints. This decision process makes complete sense and is quite sound, but I think ruling out other options as impossible means confusing budget compatibility with mechanical feasibility. With that being said, if it holds the power, it holds the power, just depends on how much power we are talking about.

At the end of the day this will likely prove to be an affordable and effective solution for the FD.

That is a matter of opinion and a lot of people with well sorted V8 FDs would disagree. Again we can't speak for everyone; certainly there are plenty of FD owners who would live a lower rear end ratio.

Sounds good to me, and we'll see about the casing.

But you also realize that your reputation is such that people will buy a chrome plated turd if you tell them that it will make their car faster. The reputation of your IRS is based off of word of mouth and theory primarily. This is not your fault, but it is what it is. I tend to believe that this Cobra IRS of yours will deliver as promised, but I am not going to sit here and powder your *** like 80% of the people on the forum just because you believe in your own design. I will give you a very big pat on the back once people get off of their lazy asses and prove the design. Again, no rebuttal will change this fact. Until then, I think it is beneficial for ***-holes like me to grill you about this design so that people can learn the decision process that went into it, and make informed decisions based on more than your word alone.



Has anyone broken an OEM diff with nylon/delrin bushings to your knowledge?

 

Hyperion is running Jim's cradle on the track, maybe you can ask him how it is holding up and if it was a benifit to him (he's in your group buy)

 

No, it isn't. Not in terms of potential damage.

No, they're switching because a live axle can be built much stronger and is far more predictable for drag racing. The key to competitive drag racing is consistency.

Sure, whatever.

You highlighted the wrong section.

I'm not selling a product nor do I care if you install a Cobra IRS in your car, so obviously that's not my objection to your "challenging questions". Challenging and intelligent questions I can handle; an obvious inability to understand the answers provided, I can't.

The only conclusion I can draw is that you don't possess the background or experience to understand some basic fundamentals that would make most of them unnecessary, so this discussion is at an end as far as I'm concerned. I'll be more than happy to answer questions from anyone else, but I don't respect your knowledge on the subject or ability to comprehend my answers enough to waste any more of my time on you.

 

Right Jim, that's the only reason people are switching differentials....

I find it amusing that you are so singularly focused on the outward forces created by the climbing ring gear that that breakage caused by this force has become your only cause and definition of differential failure. Welcome to the real world: If your diff cover cracks you are not driving home. I understand your point, now understand mine. If your diff breaks you are assed out. PERIOD.

OBVIOUSLY it is less expensive to replace the cover. It's unacceptable to have to replace anything.

No you're just a selective reader. That is the only explanation I can muster Your inability to realize that the reputation of the Cobra IRS is rooted beyond cracked rear covers. I suggest you do a little more reading and "educate yourself," some more as you say.

Very classy Jim. You are a software person in engineers clothing parading around as if you are in any way qualified to engineer automotive suspension systems. Furthermore, you chose to sell these systems to buyers without so much as one beta test. Let me ask you something. Why have so many people who purchased your expertly engineered bushings since removed them? Of course this has nothing to do with the design, it’s certainly not your fault. I am willing to admit than I am not an expert at everything, are you? No of course not. You know everything about everything, including suspension geometry and especially scrub radius, which Damon made painfully obvious that we both knew little about. How proficient would you be if you didn't have Google to bail you out every time a challenging question came up? Don't sit here and insult my intelligence, because you know damn well that you are off base. You are my elder and a longer-time member of this forum, so I will yield you your due respect, but if you think I'm going to sit here and be insulted intellectually you are out of your freaking mind. Now enough with the disrespect.



I too am done with this conversation.

 

from a prior post in this thread it appears to me that i am after a T56 w the following ratios:

2.97, 2.07, 1.43, 1, .80, .62

apparently these were/are in the '93 LT1? no other applications? i realize the gto/c6 are close.

if you know, any ford boxes w the above ratios?

any tips as to getting a good condition used box?

i plan to try to use the FD bellhousing and probably make an input shaft so i can use a regular exedy double disc.

BTW, i did check w someone who at one point told me mazda was going to have 10 T56 adapter bellhousings made... they decided not to go ahead as the planned mazda racecar was nixxed by the sanctioning body.

hc

 

Take off the lower cover or anything that gives you a good view of the gears. Look for sharp points on the gear dog teeth and synchro teeth. Also look at the oil and collector magnet - any visible metallic material is not a good sign. The gear teeth should have wear marks near the middle of the tooth faces, and any wear should leave a polished look to the teeth - nothing grey or the slightest bit pitted. The condition of the bearings is also important, but 9x/10 the oil is going to be your best clue.

Dave

 

I've been researching a T-56 swap for a while now. The FD manual bell housing happens to be the correct dept for a LS1/LS2 t-56 with the MCLeod adaptor plate.
The problem is the transmission is too big in girth. Your starter and clutch hydrolics will not fit on the bellhousing.

The automatic bellhousing from the 20b manual tranny is 6.5" same as the classic gm muscle trannys. But then input shaft for the ls1 t-56 will be .5" short. I also found out the input shaft for the aftermarket GM will not work with the tripple cone synchros of the GTO tranny.

 

Howard, the above mentioned ratios are readily available: http://ddperformance.com/t56__6_spee...nsmissions.htm. Having said that, anything above the 500 ft lbs of torque mark will require to use the alternate gearset: 2.66/1.78/1.30/1.00/.74/.50. It's simply stronger (650 ft lbs or more).

Having said that, call D&D. They can essentially make a custom box for ya w/ whatever gear ratios you desire, for only slightly more than the standard price. And with the standard trannies running for only $2499 - $3199, I'm not sure why you'd consider getting a used box. It's simply not worth the risk, when the NEW T-56s are so cheap anyway. But if you insist, you can always send the tranny to D&D and they'll inspect and repair it as necessary.

I'd take that up w/ them and see what they say. I don't particularly care for what shaft I use as I'll be going w/ a Tilton clutch, custom made for whatever spline pattern I need.

D&D makes their own input shafts, and I believe an upgraded 300M input shaft is also available. So I don't think it would be a major issue to have a custom one made 0.5" longer if that'll solve the problem.

So am I correct in understanding you that other than needing a longer input shaft, you can use the 20B bellhousing w/o any problems? Do you need an adapter plate? Or will it bolt right on? Any other modifications necessary?

Thanks!
~Ramy

 

You can use the McLeod 8-207 ($228 from summit) adaptor plate and have it redrilled for other bell housings. The advantage of the auto bellhousing is the starter is mounter to the motor / front of the bell housing vs. the rear like the FD manual bellhousing. The disadvantage is no slave cylinder & throwout bearing provisions. I am using a Tilton clutch and it uses a over the shaft hydrolic t/o bearing like the stock GM LS1 setup.

I also was looking at D&D's tranny's a GM afermarket/ electric spedo, but have them install the LS1 tailhousing to move the shifter back as far as possible. The issue is the single cone sychros are not as good for high rpm shifting.

A couple of pics of the interferance of the adaptor plate on a FD manual bellhousing.

 

NICE. So I'm guessing Tilton provided you w/ those parts? That's all ya had to do?

You're absolutely right. What you saw is the "basic" tranny setup. There are upgrades available (http://ddperformance.com/t56_partsupgrades.htm) including the double (or was it triple? I forget) synchros such as the Z06 ones, CF blocker rings, upgraded input shaft, and a steel shift fork. So they would prob. bring the price up to the $4k mark for a BULLETPROOF tranny when all was said and done.

~Ramy

 

Wow, didnt know my thread would still be going. Ramy, keep me updated on the 99 tails and your T56 venture.

There is a solution to the Mazda stock rear diff case breaking. The craddle that Peter Farrell, Ray wilson, Adam Saruwatari, Ari Yallon, and Dan S. that they fabricated and used/uses. Like I had stated in another thread, each is a little different in design, but do essentially the same thing.
When you wheel hop or come under Hard load, the pinion wants to push back and up...well since the connecting point is the nose of the case where the PPF attaches, its just breaks the case there or near there as it wants to push up.
Adding one of those general diff braces that everyone sells adds to the breaking factor as it gives less deflection for the diff to move.
The craddle encases the whole diff and the PPF frame attaches to the outer part of the craddle and transfers all the torque/load from the front to rear and essentially lifting the whole entire diff up instead of it trying to lift it up at the front where the PPF attaches and cracking the diff case in the middle. Now the weak link would be the PPF breaking, but if you could fit the general style diff brace in addition to the craddle then essentially you are eliminating all of the weak points that move. I would rather break a PPF frame then have to go through and replace the diff case, ring and pinion and have to go through and set everything up again.
Peter would cut 1.3xx 60 ft times with the stock rear diff case and had no issues.

 

Any pictures of Peter's brace available Greg? Out of curiosity, what were Peter, Ari and the rest using for diff bushings?

I am going to make one last attempt to explain why an OEM IRS setup makes sense (assuming that the current axle weaknesses will be resolved, or that the current axles are suitable for the power goals of the majority of FD users).

My intuition tells me that the diff becomes significantly more susceptible to breakage when it is in a flexed state. Flick a relaxed sheet of aluminum foil and it will not break. Flick a stretched piece of foil and it will. Same concept

There are those who think that simply mounting solid bushings on the rear end of the diff has the same effect as frontal bracing, but this is gross oversimplification and ignorance and is fundamentally wrong. By supporting the front end of the differential you are eliminating the flexing by transmitting the rotational forces to the chassis. Furthermore, there is no longer a PPF or TA to transmit such forces from the power plant to the rear end, and you are creating a steel wall that the pinion must push against to escape.
Solid bushings will decrease wheel-hop, certainly, but at a cost. When used in conjunction with a PPF they will increase the amount of strain experienced at the front center of the differential as they will no longer act as shock absorbers for the differential as the PPF attempt to role the differential over. Visualize the rear end of the diff is held completely still by its carrier while the free-hanging front end is twisted by the PPF. Again, this is not enough to break the diff casing on its own, but I have a hunch that this is creating enough strain on the diff to make it susceptible to the leverage which is caused by the pinion which is attempting to escape.
The incorporation of solid or high durometer bushings alone, results in a trade-off between wheel hop and torsional casing flex. Yes, you will decrease wheelhop, but you are now requiring the diff casing to absorb more torsional strain and leverage than before because these damaging forces are no longer partially absorbed by the diff carrier bushings.
The pinion is already trying hard enough to escape without the casing in a stressed state. It is a mistake to solely focus on the pinion and ring gear and ignore the casing.
The incorporation of a front mount on the diff also absorbs upward, rearward and sideways forces from the pinion, and thus decreases the likelihood of a breakage occurring at the front end of the diff. Paul's IRS (shown below), for example, incorporates a steel mounting plate bolted directly over the nose of the diff which is machined flat to accommodate this. When the pinion try to climb it is climbing directly against this brace and is therefore climbing directly against the chassis via two moderately stiff bushings. Take a careful look and see that this setup is fundamentally different than the stock setup. The forces that were once being applied directly to the front and center of the differential casing are now being transmitted almost directly to the chassis.






Now examine the photograph below and notice where the breakage is occurring. The differential is not breaking at its nose is breaking at its center where the casing is the most thin and where the differential is stressed internally by the lever that pinion/front of the diff, and externally by the rotational forces exerted by the PPF. And there is your aluminum foil. I have yet to see one photo of diff cracked at the actual nose end; this is undoubtedly due to the thick casting at this portion of the diff.
Now closely look at the photos above and follow with your mind the path that the forces are following. The pinion is pushing against a wall which is the front brace, and the front and rear ends of the diff are necessarily held in sync. It should be clear that this setup is not the OEM crap-box PPF setup. It is fundamentally different. It is almost equilaterally supported and reinforced by the rear sub-frame so that the rear sub-frame becomes its brace. Also considering that no torsional forces are coming from the tail end of the trans because there is no longer a PPF.





I'll leave it up to you all to make up your own minds. I have stated my piece.

good day.

 

Just FYI.

300M inner and out CV stub assemblies are currently in the works at DS Shop and will be available in about 2 months, give or take ;o)

300M CV joint GB interest list HERE.

cheers

 

Good News.
Here's the deal. I've made some calls and worked something out for you rotor heads. First I talked to someone at one of the largest trans shops in the country, Keisler, to discuss transmissions. They attest that the T56 is only rated for 450ft/lbs of torque and that (in the words of Nick the head tech guy at Keisler) there is no way in hell that a 900hp Viper was using a stock trans. He stated that the T56 High HP cars that you see running around are using G-force, Tranzilla and the like. The 2 and 3 piece countershafts make it impossible for them to consistently hold big power, not to say there aren't fluke occurrences. And just FYI, there are over 40 T56 varieties, the most stout of those being the new Viper version.

A built G-force trans will cost somewhere in the neighborhood of $5,500 without a bell housing or adapter plate. This by no means outrageous, but it means you've spent 6500 by the time you bolt this to your car. Perhaps D&D can do it for less. I like the T56 but there is another logical option in addition to it.

Another transmission option is the Tremec TKO600 5-speed with overdrive. The tranny is rated at 600ft/lbs continuous and is commonly used on blown big block Hemis and other muscle cars making somewhere in the neighborhood of 700-1200rwhp. Keisler is the largest seller of this transmission and have only seen one break, (due to a broken gear). Another very attractive feature about this trans is the fact that the tail shaft can be custom machined to order both front/back and side/side. What this means for us is that we can have a transmission built specifically for our cars so that the shifter lines up perfectly with the stock shifter location. It is also slimmer than the T56 allowing more room for the exhaust.





Keisler delivers TKO-500 and TKO-600 transmissions from TREMEC in a range of options, from unmodified, "as-is" transmission units to complete, fully customized kits for easiest bolt-in fit and perfect stock appearance!

All TKO-500 and TKO-600 units feature:

• Super duty all Chromoly steel construction gear set
• Ultimate strength 1-piece countershaft
• Improved shifter with user-adjustable spring bias centering
• Dual mechanical and electronic speedometer outputs

In addition, the TKO-600 unit provides:

• Close ratio 2.87 1st gear for less 1-2 RPM drops
• TALL 64 overdrive for lower cruising RPMs and longer engine life (.82 option still available)

CUSTOM BELLHOUSING
I have been making some calls and now have the ability to make a custom bell housing for the FD. For this to happen it would require me to sell 10 units at $650 to break even. If I had less buyers the price would need to go up.

YOUR INPUT PLEASE
What I need to know from the 3rd gen community is what you are looking for and for which transmission? Ofcourse the dimensions of the TKO will need to be verified, but Nick seemed confident that this would fit given the fact that these are used on older Vettes where the T56 is too wide to work. My thoughts at this point are that a custom-tailored bell housing that retains the stock starter positioning as well as the stock clutch assembly, slave, and hydraulics, would be the best bet. Basically the equivalent of the stock FD bell housing only modified to fit the selected transmission (TKO or T56). If the t56 is selected the bell housing could potentially be made long enough to provide for OEM shifter placement. We'll have to see how it all measures out.

PRICING
A custom-tailored TKO setup would run $2200 without the bell housing and custom input shaft. I have already confirmed that I can get a discount if several of these are ordered. Again, I would sell the bell housing for around $650 each, perhaps even offer a custom trans brace to match.

DESIGN
I am not going to be designing or engineering anything. What I am going to do is supply the experts with every tool and resource and info needed to make these parts safe and custom tailored to our application.

I'll probably be PMing or emailing some of you 20B owners to get more specifics so that we can line up something that works for all rotary power plants. Measurements will be needed and I'll be needing sample parts such as bell housings, clutch mechanisms etc as well as some good advice.

This is by no means a comprehensive post, but I igured I'd touch on these developments here and I will follow up later with a comprehensive thread in the GB section.

cheers
Your thoughts please....

 

interesting...

while i am literally years behind the primary posters on this thread i concluded 2 days ago that i would go w the TKO. it is 20-30 pounds lighter than the t56. it is a 5 speed which is fine w me. it has nice ratios.... i currently run a .82 5th gear and wouldn't trade it for anything. some t56s have good ratios too.

i am interested in a bell housing as long as it would retains the stock postion starter and stock clutch engagement pieces.

now all we would need is a custom input shaft w mazda's 23 spline 26.4 mm clutch drive. i am not going w anything but an exedy hyper double disc.

howard coleman

 

another option would be to take an FD belhousing, machine the rear flat, add an aluminum plate, machine the plate to accept the TKO trans. maybe that's what you are planning?

i did this w a datsun competition 5 speed and mated it to a ford bellhousing...

also, i did see someone selling new TKOs for around $1850.

hc

 

Why doesn't something sound right to me? (looking up info before I open my mouth even further)

 

I will get some pics up soon, I have been sooo busy at work and havent had a chance to stop over at the shop to take some pics, and he is going to be making these to the public soon.

 

I went down that path before looking into the T-56 transaxle. Tell them it's for an engine that redlines at 8,000rpms and makes peak power around 7,000 and see what they say. When I brought that up G-force said there is no way the standard syncros will work. They can face the gears, but it's terrible for street driving.

 

Just FYI, D&D lists the torque ratings for the trannies THEY build here: http://ddperformance.com/t56__6_spee...nsmissions.htm. Indeed, the Viper version (2.66/1.78/1.30/1.00/.74/.50 ratio set that I mentioned to Howard ealier in this thread) is the stronger torque set, rated for 650 ft lbs. Keep in mind there are several upgrades he makes to these trannies; it's not a stocker unit. The only reason to go w/ the G-force unit is if you're putting down significantly more torque than that. I don't think *any* rotary will have that problem. So G-Force related costs are out.

Also, D&D is THE LARGEST seller of T-56s in the nation And keep in mind that I'm sure Keisler knows of D&D, and is one of their largest competitors, so take everything both sides say w/ a grain of salt (underrating the competition's tranny, etc).

So far, I LOVE it. Minus one HUGE thing...it's a 5 speed. That basically says w/ a GOOD close gearset, you're looking at a top speed between 140 - 150 mph if I'm not mistaken. If the 5th is taller, you're losing in the acceleration side...so it's an absolute no-win situation. You MUST give up one to gain the other. A six speed, however, gives you the best of both worlds...(even though I've been anti-6-speed for sooo long).

Yummy
Where do I sign up? And I'm still stuck on the T-56...

1) THANKS! I really appreciate all the legwork 2) The major prob w/ the TKO is the rpm rating. As CMonakar mentioned, it's not built to handle higher rpms. I'd def. call 'em back and ask 'em about that. These old Vettes redlined at what...6K rpm? hehe

~Ramy

PS: Rob, I PMed ya a while back w/ the pic of the bushings...never heard back from you?

 

i just did the math on top speed.... yuch.

i haven't run brainerd since i switched to my short 5th. as mentioned brainerd is a daytona like track in that you can easily go thru turn one at 170. w my current 5th and 5% tire slip it looks like 7000 is 149. that works great on the street and at road america mid-ohio etc but does not work at brainerd.

also i am planning to run the Silver State Classic in nevada and 150 won't do it. so it looks like for me i will want the T56 w the 2.97-2.07-1.43-1-.80-.62.

BTW, i have a friend who has a nicely built FC w an LS1 in it w a T56. he drives it lots and hammers, i mean hammers on it all the time. he has a bit hotter cam so it does rev to about 7000. i have driven the car thru the gears and there are no issues w shifting. admittedly he only has around 380-390 rwhp but he does beat it bad.

h c