sequential transaxle for GT40

FOX1 · Feb 11, 2012

I am producing T906S, used by Apollo Gumpert, Tramontana and GTA motor.
It is a manual sequential with or without synchros.
For more info, because I cannot advertise, send me a private E-mail.
Regards
Wanni

ingvar · Feb 12, 2012

This might be something, using a "cheap" audi 01e gearbox and a sequential shifter
Link to manufacturer website:
SQS Racing | SQS-G Audi Quattro 01E

soulcoaxer · Apr 24, 2012

superflyte said:
I have an 6sp sequential Elite Racing Transmissions TXL300 in my RF. Major mods to make it fit, but a totally custom build anyway, so no worries

ranger jim · May 3, 2012

Hi Robert from Yorba Linda. Thanks for your research on sequential's for our GT40's. Haven't contacted EMCO Transmissions as yet, but there is some great promise on their website. Emco is based in Indianapolis. Their sequentials are used presently in many Lemans cars with great success. Yes, I do realize sequentials clunky and whiney, but when performance is paramount, I'll tollerate a little extra noise. Also, with the GT40's tranny hanging in the rear of the car, noise will be minimized vs a front engine car. I will be following up the Emco lead. Thanks, ranger jim

soulcoaxer · May 3, 2012

ranger jim said:
Hi Robert from Yorba Linda. Thanks for your research on sequential's for our GT40's. Haven't contacted EMCO Transmissions as yet, but there is some great promise on their website. Emco is based in Indianapolis. Their sequentials are used presently in many Lemans cars with great success. Yes, I do realize sequentials clunky and whiney, but when performance is paramount, I'll tollerate a little extra noise. Also, with the GT40's tranny hanging in the rear of the car, noise will be minimized vs a front engine car. I will be following up the Emco lead. Thanks, ranger jim

Thank you sir, and I'll check out that product site. I've learned more since my last post, but it's not yet clear enough to attempt to communicate. My anxiety about a sequential purchase over the most typical ZF, came about recently as I discussed the use of such in a car designed for shows and street use, much more than tracking. I will share that, the moment more pieces to the puzzle appear. And, when I can explain more precisely what clunky may really mean. For me, I conjure the image of an old clunker, being a noisy, old rattling car that, well, clunks along. But, I'm fairly confident it has a different meaning when applied to sequentials.

Also, thanks for the correction from Klunky to clunky. I knew you'd come in handy :thumbsup: :laugh:

Cheers, and thanks for your note. Robert

superflyte · May 3, 2012

You've got to be very forceful when changing gears in a dog-ringed / straight cut transmission. You can't just toddle off down the street, hit 3000rpm, push the clutch in, let the revs drop, change gears, etc, etc. The difference in rotational speed of the meshing parts (the dog rings) will wear prematurely.

Many sequential race cars use a strain gauge on the gear change cable, which links to the ecu giving the signal to cut ignition momentarily.

Also, when comparing systems (particularly bike oriented systems), many will only control up-shifting, while others will also allow 'stacking' of shifts on the down shift. I believe Geartronics in the UK to be one of the better systems available, the only downside is the on-board air compressor. Albins also offer a similar, closed loop arrangement with their AGB Transmissions. They could be easily adapted to a different gearbox.

Also, just for info, here is my TXL300 mated to an LS2 (using an Albins Bellhousing / Billet adapter plate) with 8 Stack injection.

soulcoaxer · May 4, 2012

superflyte said:
You've got to be very forceful when changing gears in a dog-ringed / straight cut transmission. You can't just toddle off down the street, hit 3000rpm, push the clutch in, let the revs drop, change gears, etc, etc. The difference in rotational speed of the meshing parts (the dog rings) will wear prematurely.

Thanks for the info, picts, and for your efforts!

I read what you said above, but I must be slow or inept in this area. Okay, I'm trying very hard here. Taking two examples: 1) Use clutch, and toe off gas pedal=slower engine RPM. 2) Use an auto signal to cut fuel and/or spark to engine=slower engine RPM. Other than slower engine RPM, how is it possible to slam into a gear in circumstance 2), whereas it is detrimental to the gears in circumstance 1). I've thus far been unable to reconcile those characteristics, and have never felt dumber for it.

Taking the above scenario to the extreme, how can using an auto system that senses a shift at 7,000 rpm while at WOT, and cuts fuel or spark, enable one to make a 10ms shift without wearing the gears? Because that is what Geartornics and others desire to sell me for upwards of $7k. Once again, I envision reaching 7,000 rpm, taking foot off gas, stepping on clutch pedal, shift upwards, releasing clutch and return to WOT.

BTW, I did contact Geartronics two weeks ago, gave them the link to the sequential transaxle maker, and requested a price for a system. He sent me about three eMails saying he was busy, but still, no other information - no adverse reflection on you, of course.

Is your vehicle operational yet, the one with the sequential? If so, do you have a shifting system with ECU? If not, how to you negotiate your shifting?

Thanks again for you participation in helping to solve this riddle.

Robert

Dave Deerson · May 4, 2012

It's not so much the RPM at which the shift is made, but the tempo...
Dog rings do not like a slow shift tempo, either shift or don't......You can't be indecisive about a shift or you will hurt the dogs. Sometimes I would bauk a shift on a cool down lap or entry to the pits due to me being "off pace" and making a shift too slowly. I too, would not suggest a dog-ring trans for the street. I have one in my track car and would not like it for even a fun street toy.

Dave D.

soulcoaxer · May 4, 2012

Dave Deerson said:
It's not so much the RPM at which the shift is made, but the tempo...
Dog rings do not like a slow shift tempo, either shift or don't......You can't be indecisive about a shift or you will hurt the dogs. Sometimes I would bauk a shift on a cool down lap or entry to the pits due to me being "off pace" and making a shift too slowly. I too, would not suggest a dog-ring trans for the street. I have one in my track car and would not like it for even a fun street toy.

Dave D.

Great info. Thanks Dave. I will reply in more detail! I'm hoping that Troy responds again and answeres some of my questions about his sequential.

Thanks so much, Robert

soulcoaxer · May 5, 2012

Dave,

I'm back.

Thanks for that recent info you posted. You are not the only one that has recommended against having a sequential for a street car rather than for strip or track car, and provided a mix of reasons.

Some have mentioned the noise. I would not probably like the noise if it were in a car I was going to make a lengthy trip in, or use as a daily driver, or such similar circumstances. But with a GT40 that will be used for shows and only some recreational drives, cruises, or short trips to places of interest, I would enjoy the sound, as I will the loud obnoxious engine and exhaust notes. I have heard the sequential trans sound on newer luxury performance cars, though the distinct whine was more muted on those factory cars than it would be on the HD sequential transaxles typically used on GT40s.

As for the shift tempo phrase you coined, which I thought was very appropriate, I have yet another question and some comments. First, I shall attempt to ensure we have a common agreed definition of shift tempo. I garnered from your note that shift tempo likely includes speed of shift and the forcefulness of the shift (Indicating no hesitation). So shift tempo is a term that describes the two characteristics that are important to sequential transmission shifting: speed and forcefulness.

If we agree on that, then I would like to suggest the term ideal tempo shift. That term would simply indicate that a shift was made with the appropriate speed and forcefulness, with no hesitation. As compared with a shift that was attempted or made when one or both characteristics were not optimum.

Now for the question relating to your car, your sequential trans, and your manual shifting experiences. If you had an expensive, elaborate control system that blipped the throttle for down-shifting, and cut the fuel and/or spark for up-shifting, and the equipment to make affirmative, ideal tempo shifts under ECU control, theorehtically then, there would never be a lazy shift, all shifts would be ideal tempo shifts. If at all speeds, up and down shifting was always ideal, would that change your mind about having a sequential for a GT40, if such GT40 was only used in the limited manner I described above?

Thanks again. I know others will appreciate your help in understanding this as much as I will. At least, I would hope so. Please Dave, you or others feel free to change or correct anything that improves the explanations.

Cheers, Robert

IanAnderson · May 5, 2012

Robert

I am not sure you have the terminology correct.

Sequential denotes that you go up and down in a sequence 1-2-3-4-5 and bac down 5-4-3-2-1

Stop when in 3rd and you cannot engage 1st without first having to select 2nd then 1st before taking off.

Some of the original GT40 cars had this mechanism on their selector system so that going up means moving the selector back a nd forward with a right side pressure and coming down the gears the same but with a left wards pressure.

Tou appear to be thinking sequential means you have to have straight cut gears that whine more than a stock gearbox

Ian

soulcoaxer · May 5, 2012

IanAnderson said:
Robert

I am not sure you have the terminology correct.

Sequential denotes that you go up and down in a sequence 1-2-3-4-5 and bac down 5-4-3-2-1

Stop when in 3rd and you cannot engage 1st without first having to select 2nd then 1st before taking off.

Some of the original GT40 cars had this mechanism on their selector system so that going up means moving the selector back a nd forward with a right side pressure and coming down the gears the same but with a left wards pressure.

You appear to be thinking sequential means you have to have straight cut gears that whine more than a stock gearbox Ian

Thanks Ian, I appreciate you watching my back. I do know that sequential means you must proceed up and down the gears sequentially, as is the case with most motor cycles.

My interest is to explore the feasibility and pros and cons of installing a sequential into a GT40, when one is not track racing most of the time.

Thanks again friend!! :thumbsup:

soulcoaxer · May 9, 2012

I finally heard back from a company - perhaps a major player - concerning controls for a sequential transaxle for a GT40, or other vehicle.

First, for those not up to speed, here's an overview. Sequential transmissions/transaxles are typically available with a torque converter (Auto trans, no clutch pedal), or with clutch pedal. Sequential transmissions are typically used for high horse-powered off-road vehicles, and for track racecars. The off-road sequential users typically shift with the common shifter supplied by the trans company or a third party vendor, and typically do not employ supplemental electronic or mechanical shifting equipment.

The true high-speed race vehicles typically do employ supplemental electronic and mechanical shifting equipment capable of making gearshifts in milliseconds and at wide-open throttle (WOT). For the brainiacs only: 1 second (s) = 1,000 milliseconds (103 ms) und 0.001 second (s) = 1 millisecond (ms). 1 millisecond (ms) = 1000 microseconds (µs) und 1 second (s) = 1,000,000 microseconds (106 µs) 1 microsecond (µs) = 0.000001 second (10-6 s) = 0.001 millisecond (10-3 ms).

Mechanical and electronic assisted shifts can be made somewhere between 45ms and 245ms depending on the system installed. Some vendors claim you can down shift through 5 gears in less than a second – though I can’t think of a time when that might be necessary.

The supplemental shifting equipment consists of two major categories:

The first category includes electronic sensors and processors. Their purpose is to vary the engine RPMs to the proper speed at the proper time preceding a shift, to reduce wear on the gears. For up shifting, the controls typically either cut the EFI fuel supply, and/or, cut the spark to the engine. Such action results in a drop of engine RPM to more closely match what that RPM should be when an up-shift is made. To make that crystal clear: if one starts out in first from a still vehicle, and winds out to redline @ 6800, then the RPM should be dropped to 4000 when the shift to 2<sup>nd</sup> gear is made. These numbers will vary depending on gear ratios and redline maximum. For downshifting, the controls attempt to raise the RPM to more closely match what the optimum RPM should be when a downshift is made.

The other purpose these electronic modules can serve is to signal the second category of mechanical shifting equipment to make the shift, thus eliminating the need for the driver to do anything more than actuate a shift by: pressing a button, moving a sick shifter very slightly, lifting up or pressing down on a steering wheel paddle shifting mechanisms, or a lever connected to the steering column.

The second category of shifting equipment includes mechanical devices that makes the up or down shift when a signal is received from the electronic equipment to do so. The mechanical shifting equipment can consist of the use of: pneumatic actuators (Compressed air), electric solenoid actuators, and hydraulic actuators. Each product manufacturer usually only employs one of those three choices, and simultaneously touts their choice as the best, while enumerating the cons of the other types. This is but one major reason for the mass confusion that would-be-buyers, especially those not involved with NASCAR, would be subjected to when contemplating a sequential for their GT40 or other performance type vehicle.

Below is a copy of one text exchange between a vendor and me. The vendor’s name was redacted.

Thanks (deleted). For your email. NOTE, (deleted) is the Operation’s Manager for Roush Engines, and not for FAST. But, (deleted) will know which FAST ECU they will employ. I will attempt to send you a photo, and maybe the size of the very traditional GT40 steering wheel, so we can decide what look we desire for the shifting method.

I do have additional questions.  
1. Apparently, the circumstances of sequential transmissions are rather an enigma, to me anyway. The transmission makers say that if you tip your tow on the gas pedal to remove the torque, then you can shift up or down without a problem or any other controls. Granted, for racecars, where the driver would rather run at wide-open throttle during shifting, an electronic control would be the answer. Others, including you, have non closed-loop systems for a fraction of the cost. So, I continue to ponder the circumstances, since this car will not be raced.

The vendor replied:
Well, the obvious benefits of paddleshift is the ability to keep both hands on the wheel and safely change gears anywhere including mid corner ! On a street vehicle it brings a whole level of safety to not torque pitching the car with so much power and having an incident on street.

The Easyshift is very good for upshifts, but the problem with downshifts is that you need some method to physically open the throttle. With the paddleshift, we already have the air supply to drive the pneumatic blipper, but that's not an option with the easyshift. The downshift function of the easyshift was mainly added for those who want to experiment with their own hardware (solenoids, blipping devices, Drive by wire setups).

There's also another problem with downshifts, and that's the timing of the blip. With the paddleshift system, we fire the blip ahead of the shift to try to get the engine to respond at the correct time.

2. My engine will have a FAST ECU, and it will be programmed to limit the RPMs of the engine - will cut fuel and spark - if engine is over revved, so missing a shift should not be a problem even if we have no transmission controller. Is this correct?

The vendor replied:
It will only be limiting RPMS on driving the engine up the rpm.. when you downshift and drop the car into gear our system will not allow a downshift if the engine under drive circumstances would indeed go past and exceed a safe engine rpm value in our system. Your fast ecu cannot safeguard this scenario.

3. I am also interested in the circumstance when the driver is in the car, the engine is running, the car is in neutral, and the driver reaches over and accidentally hits the shifter, and the car engages into 1st gear. Is this true, or is there some safety aspect that you must do to eliminate the car from entering neutral by accident?

The vendor replied:
There most definitely is a safety mechanism built in. Let’s say you had buttons on the steering wheel for shifting as well as your stock shifter with micro switches in place. If you were in neutral you could hit any and all of the buttons / lever and no shift would occur until you push a button (usually put on the dash) and pull the lever for an up shift or the up shift on the steering wheel.. this is the safety mechanism for not accidentally going into gear when in neutral.

end

soulcoaxer · May 11, 2012

One Company's Shift Control Package

Vendor wrote:

Hello Robert,

Thank you for your time today outlining your paddle shift requirements.

Please find attached manual for a typical system and also some drawings for the fitment of the actuator to various ___ gearboxes (I believe you mentioned ___ as the gearbox supplier but I might have misheard you).

From your description of the system, the most suitable system we can offer will be similar to the units supplied to the Grand-Am series. I am not familiar with the Fast engine management system but we can look into interfacing with it if you can forward any technical details?

As I mentioned earlier, our system is Pneumatic and is supplied with an efficient and reliable air pump, accumulator and aerospace quality solenoid actuating valves. The system comes complete with the Gearbox Control Unit (GCU), Paddle Switches, Throttle Blipper (that fits in line with the engines throttle cable), Actuator and compressor.
The system is very efficient and uses an average current of around 3A.

Costs
For a typical system, parts work out at 22,350 USD
To complete an installation requires fitting pipe work and harness that’s not normally supplied in the kit (as all cars have different dimensions). I expect we can provide local assistance for your project and I will investigate this in more detail if you decide to order.

If you’re in the area (I know California is a huge place), we have a car running in the ALMS in Monterey this week and one of our guys will be pleased to show you the Paddle Shift System if that’s of any interest (LMP1 Lola Mazda AER of Dyson Racing).

I look forward to hearing from you.

Best regards,

Reply to vendor:

Thanks Mike,

I'll study the info. What would the guess be for the additional harness wiring?

Also, does anyone ever have a stick shift actuator placed in position, with cable to trans, to enable using both the automated shifting system, and the more manual system?

Can you even guess what the approximate install labor would be for the equipment, paddle shifter, plumbing, wiring harness, etc.?

By the way, the heavy duty, American made, 5-speed sequential transaxle with stick shifter and LED gauge for gear identity, is all around $18k USD.

Thanks, Robert

darrinps · May 13, 2012

As a reference point, I have a 7 speed auto Nissan 370Z with paddle shifters. The option was only a couple thousand dollars and does rev matching on down shifts. Now, why is it that Nissan can do this so inexpensively? Is it because it's an automatic (FWIW, the automatic 370's are a few tenths faster in the quarter mile than the manuals) instead of a manual perhaps?

I was thinking lsat night while driving the Z how much I would love to have that transmission in the GT40...along with anti-lock brakes.

fastdruid · May 13, 2012

Nissan can do it because all the modern 'auto' boxes are computer controlled and once you have a computer controlling both gearbox and engine it's easy (and so cheap) to add such extra functions. It's also done in the mass market rather than an add-on.

ABS is easy, if not cheap. Google Bosch ABS M4

soulcoaxer · May 14, 2012

Another exchange across the big pond with a company that manufactures a complete system for sequentials: both the electronics, and the automated shifting actuators.

Hi Robert,
We supply the harness but you (or team) need to tell us where the various parts fit in the chassis so that we make the wire lengths correct. Jason English will send you our electrical layout template so you can see what we mean.

The mechanical gear lever was sometimes left in place so that it could be connected quickly if desired. The fact is, these systems are normally very reliable and few ever reconnect the old linkage. It isn’t practical to have both mechanisms connected simultaneously as the extra mass and drag of the mechanical linkage will slow the system significantly (as well as thrashing about in the car which can be disconcerting to the driver).
I would imagine for most new cars there is a couple of days of work for a skilled fabricator to get all of the parts fitted and in suitable places. The USA has some excellent shops for this sort of work.

I agree, the cost of some of these US transaxles if very reasonable. The fact is they are manufacturing a lot of parts for a lot of vehicles whereas the paddle shift system is manufactured on a small scale and often individually using aerospace parts.
Best regards, Mike
————————————————————————————————————
THANK you Mike,

I spoke to a FAST ECU programming instructor late Friday afternoon. I inquired whether or not the FAST system provided an input means to blip the throttle to raise the RPMs for a down shift. He said that the air conditioning input that is normally used to raise the RPMs slightly could be used for the need I mentioned, but he said it would have to be a fixed raise in RPM, not an adjustable RPM variance. The other question I continue to have, though I think you answered it earlier, has to do with downshifts. Common sense tells me that depending on the rate of speed of the wheels and transmission at any given time, the need to raise the RPMs can vary significantly. At a high rate of speed in fourth gear, if one initiates a downshift, then the RPMs may need to be raised by 2,000 RPM, whereas, if the vehicle was traveling at a much lower speed, then a downshift from fourth to third would require less of an increase in RPMs. Is that true, or not? And, if true, how would we accomplish that since the FAST ECU is not equipped for that task?

I ponder in my simple mind whether two separate ECUs could be employed simultaneously on one engine, one like the FAST for all the typical engine EFI controls and such, and one to control RPM when the transmission shifting circuit required such. I have no basis, but my conclusion was that the two would conflict, rather than work harmoniously. What are your thoughts? I also noted that your company makes and/or markets a separate engine ECU. Is that ECU more robust in its capability, i.e., more inputs, more controls for transmissions, etc? What is its cost, and what is the learning curve, and are their programmers here in the states?

I understood your comments on the shifter stick and auto shifting controls, and how leaving the shifter stick connected would compromise the auto shifting controls. I liked your thought that the shifter stick could be installed, but left unconnected, and utilized at a future time if desired.

I examined the CAD drawing you sent, I came to realize that your shifting components/actuators appear to mount onto the transaxle, as compared with all other systems I looked in to. The question begs, how to discern whether there are existing threaded bold holes in the trans case that could be used for mounting, or that there is safe areas that could be drilled and tapped for that purpose?

Thank you, Robert

soulcoaxer · May 14, 2012

Continued . . . from above

Hi Robert,

It does sound like your ECU is quite limited in functionality. You are correct in assuming a reasonable range is required to control downshift speeds. Downshifting is controlled using either our throttle ‘blipping’ valve that connects in line with the throttle cable if fitted (included in the kit) or by opening the throttle electronically if the engine is Drive-By-Wire (DBW). The ECU has to control a DBW throttle directly and it therefore has to have an adequate strategy to do this (using an air conditioner input isn’t good enough in my view).

Our ECUs are all capable of running the engine AND the transmission (in fact, our gearbox controller is an ECU with the engine functionality turned off). Therefore, if you use one of our ECUs for the engine the paddle shift kit price is reduced as you will already have the ECU that simply needs the gearbox control option selected.

As a suggestion, why not consider using our agent in California to get the engine and paddle shift fixed up properly? That way, he could take care of the entire installation and all relatively locally. The company is ——— Performance based in Lake Elsinore. The owner is Chris Muzio who is over here in the UK until next week. I am seeing him next Monday and I could ask his opinion if that helps?

In terms of the transmission, can you send some photo’s of the area with the gear lever link? That way we could see what’s involved. So far, we have not found a gearbox that can’t be accommodated.

Best regards,

Mike

sequential transaxle for GT40

wanni

Ingvar Öhlund

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