Club Cobra - New Tremec transmission

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Quote:

Originally Posted by eschaider (Post 1486502)

All my teasing and Patrick's collaboration not withstanding something we all should probably take to heart is a comment Shelby made in the interview he did for the British documentary The Snake and The Stallion (if I remember correctly).

Shelby was being interviewed about the origins and reasons for what would later become known as the Daytona Coupe. In his typically Shelby response he likened the roadster to a street brawler and suggested (in so many words) that the roadster could hold its own against any car in the world, at that time, on the shorter tracks. Their problem, as Shlby described it, was vehicle aerodynamics actually the lack there of, at the longer faster tracks like Spa. The roadster was a challenge to control as the car approached 160.

If I remember correctly his association of a street brawler with the roadster contrasted with his example of a gazelle or some similar animal with the coupe. His reference was specifically to the coupe's better aerodynamics which translated into much better handling at speed and stunning top speeds on the long straights, speeds that nobody else could match.

One of the drivers, I think it was Bondurant commented on an early head to head confrontation with a Ferrari that starts around 160 mph the general end point for the roadsters. The Ferrari's were capable of just shy of 180 mph or so. Bondurant (if it was him) says he played footsie with the Ferrari until about 175 mph and then decided to end the game by pulling away in a very convincing manner. I want to say middle 190mph speeds but I can't recall with certainty.

I do remember the joy he took in recounting the event for the interview. It was the first time the Cobra's literally owned every portion of the track with no if's, and's, but's or maybe's. Very entertaining interview, great insights into where each car excelled.

Ed

It's too bad the Coupe didn't get more time, but by that time the GT40 and its aerodynamics were ahead in the game.

In virtually every "business" I've ever been involved with and that is that your job is to replace your with newer better faster

Quote:

Originally Posted by twobjshelbys (Post 1486503)

It's too bad the Coupe didn't get more time, but by that time the GT40 and its aerodynamics were ahead in the game.

Actually Pete Brock stated that the super coupe had better aerodynamics than the gt40, and would have been faster, but way too much money and time was spent on making the gt40 a winner , and the super coupe was never going to be given a chance to be a winner

Quote:

Originally Posted by eschaider (Post 1486464)

I am sure that would not be good for the transmission but I got the impression from Hauss's commentary that he was power shifting 5th gear from 4th gear, when these failures occurred.

Ed

Not sure why you guys are going off the rails but let me try to clarify what is going on. 1st off to me power shifting means no clutch this is not the case.Heavy throttle in 4th using clutch to shift to 5th and rail breaks around 5500 rpm. new rail will eliminate roll pin adding more material to shaft {no 2nd hole drilled for roll pin.} making it stronger. same design on the new TKX holding the finger to the shaft.the new rail will share features but will not be the same as the TKX so there will be no patent violations. Tremec or silversport or liberty gears should have already done this!

Hauss, power shifting is disengaging the clutch, changing gears, and reengaging the clutch as rapidly as possibly but not re-engaging the clutch prior to completing the gear change. The power shifting definition you are embracing is not powershifting it is mechanical abuse that in short order results in broken transmission parts.

Liberty Gears were the originator of the clutchless transmission for drag racing and nobody other than Liberty offers it, which might be because of expense, market size or intellectual property protections. Not sure which or perhaps something entirely different but Liberty is the only source.

This is a picture of the insides of a Liberty Clutchless transmission;

http://www.clubcobra.com/photopost/d...Dog_Clutch.jpg

Aside from the dual countershafts to reduce the torque and shock loads the countershaft is required to handle, in a race environment, the significant design issue here is the shape of the dog teeth on the individual sliders and gears.

Normally a manual transmission will have a single synchronizer sleeve to engage and disengage adjacent gears (first to second, third to fourth) gear changes. Liberty made two significant changes to their racing transmissions to allow clutches operation without abusing the transmission internals.

The first change was to split the slider into two independent sliders that operated independently of each other. The second was the use of ramped dog teeth on the sliders and gears for engagement, see the larger pic below;

http://www.clubcobra.com/photopost/d...g_Clutch_1.jpg

When a gear change is executed the slider for the current gear is not moved by the shifter, only the slider for the next gear is moved. The large dog teeth allow quick and easy engagement. As soon as the next gear is engaged the lower gear speeds up. As the gear speeds up the ramp that has been built into the gear and the slider, kick the slider for the previous lower gear out disengaging the lower gear (see pic and arrows above).

The power delivery effect at the tire is indistinguishable from a gear change in an automatic transmission or a Lenco. This is a transmission that does not require a clutch disengagement to change gears. So why don't we all use these for our street driven toys?

The answer while intuitive is not immediately obvious. East time you let off the gas it is the equivalent of changing gears for the gear you are currently in. Once the vehicle momentum begins to drive the transmission gears through the tail shaft it kicks the current gear dog clutch into a disengaged neutral condition. This would be a nuisance factor in a street driven car. Same thing is true for a road race car. The driver is on and off the gas so frequently he would be hard pressed to keep the transmission engaged in the gear he was already in before letting off the gas.

So the urban legend / story of macho man just ramming the shifter from one gear to another without clutching, while a romantic rendition of power shifting, is just more urban legend. Ask anyone who has tried it, how difficult it is and also how damaging it was to their transmission.

Speed shifting (power shifting for the uninformed macho crowd) requires rapid clutch disengagement, rapid gear changing, and rapid clutch re-engagement. The hand / foot / eye (assumes you look at your tach) coordination requires a manual dexterity level that is a variable from driver to driver. Physically able drivers can do very well. Not so physically able — well not so well.

Contrast that to the Liberty clutchless design where the power transmission to the tire is never interrupted even on a gear change — no matter your physical dexterity because it is a mechanical process executed entirely within the transmission.

BTW, check out the Second Strike Gearing Calculator <= clickable, to get a sense of where you vehicle is speed wise at 5500 rpm for your "Power Shift" into overdrive.

If you use a 295 x 55 x 15 rear tire and a 3.55 R&P you will be North of 120 mph at your 5500 rpm gear change into overdrive (check the calculator).

A couple of observations are worthwhile here;

If you haven't won your contest by 120 mph you're not going to!
Racing these cars at or above 120 mph on the street is irresponsible,
Racing these cars at or above 120 mph without appropriate prep and safety equipment is irresponsible,
Overdrive transmissions were designed for fuel economy not racing,
"Power shifting" overdrive wil virtually always over stress your transmission.

The use and operation of a TKO as you describe is what I would classify as abusive and I tend to use that terminology conservatively. Just surrender the contest if you have not won by the top of fourth gear. — because you are not going to!

Enjoy the car for all the fun it is capable of providing. Don't abuse it and it won't abuse your wallet not to mention it will reduce the number of times you need to endure TKO removal, repair and re-installation — and, big bonus, it will be less likely to kill you or some innocent bystander.

Ed

I have watched every video that Paul has done. Very impressive. I was a little dismayed during one of his videos where he stated he will work on them but he doesn't like or sell Tremecs.

Fred

Quote:

Originally Posted by Gaz64 (Post 1486379)

Here is a video:

https://www.youtube.com/watch?v=8YBeFZzv83Y&t=1815s

At 20:21 is where Paul is removing the 5th/rev shaft.

5500 was a guess but actual speed was way below 120mph closer to 65+ Hwy 5 average speed is 80 drive 70 in stockton and you will get shot for driving to slow I see you live in the bay area were 25mph is hauling a$$ I was getting on the freeway when it happened the 3rd time. I will admit I am no angel but I am no fool either. Now lets get back to the rail problem. You seem like a inteligente guy how about you make them and Ill buy one from you.

Quote:

Originally Posted by eschaider (Post 1486534)

Hauss, power shifting is disengaging the clutch, changing gears, and reengaging the clutch as rapidly as possibly but not re-engaging the clutch prior to completing the gear change. The power shifting definition you are embracing is not powershifting it is mechanical abuse that in short order results in broken transmission parts.

Liberty Gears were the originator of the clutchless transmission for drag racing and nobody other than Liberty offers it, which might be because of expense, market size or intellectual property protections. Not sure which or perhaps something entirely different but Liberty is the only source.

This is a picture of the insides of a Liberty Clutchless transmission;

http://www.clubcobra.com/photopost/d...Dog_Clutch.jpg

Aside from the dual countershafts to reduce the torque and shock loads the countershaft is required to handle, in a race environment, the significant design issue here is the shape of the dog teeth on the individual sliders and gears.

Normally a manual transmission will have a single synchronizer sleeve to engage and disengage adjacent gears (first to second, third to fourth) gear changes. Liberty made two significant changes to their racing transmissions to allow clutches operation without abusing the transmission internals.

The first change was to split the slider into two independent sliders that operated independently of each other. The second was the use of ramped dog teeth on the sliders and gears for engagement, see the larger pic below;

http://www.clubcobra.com/photopost/d...g_Clutch_1.jpg

When a gear change is executed the slider for the current gear is not moved by the shifter, only the slider for the next gear is moved. The large dog teeth allow quick and easy engagement. As soon as the next gear is engaged the lower gear speeds up. As the gear speeds up the ramp that has been built into the gear and the slider, kick the slider for the previous lower gear out disengaging the lower gear (see pic and arrows above).

The power delivery effect at the tire is indistinguishable from a gear change in an automatic transmission or a Lenco. This is a transmission that does not require a clutch disengagement to change gears. So why don't we all use these for our street driven toys?

The answer while intuitive is not immediately obvious. East time you let off the gas it is the equivalent of changing gears for the gear you are currently in. Once the vehicle momentum begins the drive the transmission gears through the tail shaft it kicks the current gear dog clutch into a disengaged neutral condition. This would be a nuisance factor in a street driven car. Same thing is true for a road race car. The driver is on and off the gas so frequently he would be hard pressed to keep the transmission engaged in the gear he was already in before letting off the gas.

So the urban legend / story of macho man just ramming the shifter from one gear to another without clutching, while a romantic rendition of power shifting, is just more urban legend. Ask anyone who has tried it, how difficult it is and also how damaging it was to their transmission.

Speed shifting (power shifting for the uninformed macho crowd) requires rapid clutch disengagement, rapid gear changing, and rapid clutch re-engagement. The manual hand / foot / eye (assumes you look at your tach) coordination requires a manual dexterity level that is a variable from driver to driver. Physically able drivers can do very well. Not so physically able — well not so well.

Contrast that to the Liberty clutchless design where the power transmission to the tire is never interrupted even on a gear change — no matter your physical dexterity because it is a mechanical process executed entirely within the transmission.

BTW, check out the Second Strike Gearing Calculator <= clickable, to get a sense of where you vehicle is speed wise at 5500 rpm for your "Power Shift" into overdrive.

If you use a 295 x 55 x 15 rear tire and a 3.55 R&P you will be North of 120 mph at your 5500 rpm gear change into overdrive (check the calculator).

A couple of observations are worthwhile here;

If you haven't won your contest by 120 mph you're not going to!
Racing these cars at or above 120 mph on the street is irresponsible,
Racing these cars at or above 120 mph without appropriate prep and safety equipment is irresponsible,
Overdrive transmissions were designed for fuel economy not racing,
"Power shifting" overdrive wil virtually always over stress your transmission.

The use and operation of a TKO as you describe is what I would classify as abusive and I tend to use that terminology conservatively. Just surrender the contest if you have not won by the to of fourth gear. — because you are not going to!

Enjoy the car for all the fun it is capable of providing. Don't abuse it and it won't abuse your wallet not to mention it will reduce the number of times you need to endure TKO removal, repair and re-installation — and, big bonus, it will be less likely to kill you or some innocent bystander.

Ed

5500 rpms was a guess more like 65+ mph. I see you live in the south bay Where 25 mph is hauling a$$ .Up here on hwy 5 people drive 80 mph do 70 in stockton and you will get shot for driving to slow! I was getting on the freeway when it broke the 3rd time. You seem like a intelligent man why don"t you build the rails and I will purchase one from you.

Thank you for the kind words but with all due respect I don't think there is a sufficient market available to recoup the development costs for a venture like this which is possibly why manufacturers have not offered a replacement part. Other than yourself it appears you can count the number of potential customers by counting fingers on one hand.

You should be able to hit 70 mph in third gear by 4000 rpm or so and nearly 100 in fourth by 4500 rpm. The car's acceleration will always be greater in either third or fourth gear at these speeds than it is in overdrive. This again begs the question why are we power shifting into a slower accelerating gear at a point in time when we are attempting to increase vehicle speed to match traffic?

I think your breakage problem would disappear if you used the overdrive feature of the transmission as an overdrive to minimize engine speed at highway speeds. If you continue to use 5th gear overdrive to accelerate the vehicle to traffic speeds rather than using third or fourth gear, you are going to continue to experience component failures.

The overdrive feature on any of the currently available transmissions is meant solely to reduce engine rpm at highway speeds for better fuel economy or reduced engine noise. Using it to provide acceleration rather than a lower gear will always produce a reduction in life for one or more of the overdrive components.

The overdrive components in the transmission can not provide the mechanical advantage to the engine a lower gear ratio can. More importantly the difference in under drive to over drive gear ratios strains parts of the transmission that were not engineered for that kind of loading when used for acceleration.

I think you will find relief from the parts breakage if you change your driving style. Of course you don't have to but a continued use of 5th gear overdrive will likely produce a continued trail of broken parts. Even if the modifications you are contemplating for the current parts failure succeed (which I suspect they would) you would just begin breaking the next most vulnerable part in the overdrive section of the transmission.

Perhaps most significantly your desire to merge with existing vehicles at the speed they are traveling would be much easier to achieve using third and fourth gears as you enter the highway. Once up to traffic speed you can always normally shift into overdrive to reduce engine speed and noise at that vehicle speed.

Ed

What? This is happening in a on-ramp at 65 mph?

I have never EVER been in 5th gear in an on-ramp.

On-ramps are part of my acceleration tests, generally 2nd into 3rd.

Once merged and cruising, select 5th in the normal manner.

I have only selected 5th at above 135mph once.

Ed,

Your comment about trying to get power in 5th gear and how it i not defined for that clicked a memory trace for me. My father never had a lot of excess money and always for his trucks bought the most stripped down model that he could find. Fuel economy was also prominent in his mind and he would boast of how he could exceed the estimated fuel economy of his vehicles. He had a late 1980's Chevy S10 pickup that he would use to drive around town when he needed to haul small loads; it did not see a lot of highway miles. It had a 5 spd in it and he would shift into 5th gear at around 35-40 mph. You could feel the truck bucking and my brothers and I would tell him that he shouldn't be shifting into overdrive at such a low speed, bu he would state that it was the best gear for fuel economy. In an effort to make a long story short, the transmission blew at 22,000 miles.

Overdrive gears are not meant for power, they are designed for economy.

Hauss, you might want to use save 5th gear until you are up to cruising speed and then use it for what it was intended for, saving you some fuel at the pump, wear and tear on the engine, and a little easier on your ears at highway speeds.

Good luck.

Jim

So, what you are saying is you do not wish to purchase my new rail . I have tried to show you folks the light but you just keep going off the rails! I almost feel like I am talking to a bunch of Tremec share holders.

Hauss, you just see things differently than the rest of us.

In the end it is your car, your driving style, your decisions, your parts and your money! If you wish to operate your car that way and enjoy all the associated peripheral events like parts failure, transmission repairs, removal and reinstallation, then who are we to deny you these simple pleasures by suggesting otherwise?

I think you should continue to march, just as you have been. This will probably provide the greatest satisfaction, not to mention sense of accomplishment, for you.

Ed

For Pete's sake just buy something else. The tremec 5ths aren't power gears. The Ford gt 6th was and the difference was so huge you knew that you shouldn't try it on a tko

Quote:

Originally Posted by twobjshelbys (Post 1486575)

For Pete's sake just buy something else. The tremec 5ths aren't power gears. The Ford gt 6th was and the difference was so huge you knew that you shouldn't try it on a tko

so the new tkx ? Does it drop in same as the tko? Some say yes some say no witch is it?

Here is a video on the TKX, with some comparison to TKO:

https://www.youtube.com/watch?v=NUDDYWDi7yY

Ok looks like it will drop in. Fyi the rail breaks somewhere between 4th and 5th never made it to 5th until slowing down fiddling with the gears and clutch then it gets stuck in 5th .

One more thing just came to mind, if not using your clutch to shift is abusing your transmission, then I guess their are a lot of big rig drivers abusing their transmissions .

If not using your clutch makes your day, then by all means you should stop using your clutch.

Ed

Informative thread on a range of related topics, but I'm looking forward to hearing from someone who has actually installed a TKX and driven it around some...anyone?

Hello I’m new to the forum and currently have a BDR4B GT in the build process. It has the Iconic 427S in it and currently a T5 transmission. I have the option to upgrade to the TKX for $3500. Is it worth it? I see much if the discussion here is TKO, T-56 to TKX, so interested in what others who are more knowledgeable than me on this think? Thanks!