New Tremec transmission

[patrickt]

Originally Posted by Gaz64

This sounds like the cause.

Any more info about how this happens Hauss?

In 15 years of driving hard, soft and everything in between, I have never missed a 2-3 shift and hit 5th. Never. Ever.

[eschaider]

Originally Posted by patrickt

In 15 years of driving hard, soft and everything in between, I have never missed a 2-3 shift and hit 5th. Never. Ever.

Nor have I. When you look at the shift gate in the transmission, I guess it might be possible but it would be a rarity if it were possible at all.

Ed

[eschaider]

It is possible to deliberately execute a 2nd to 5th shift but when you miss third the interlock system and the shift gate mechanism makes it feel like you hit a wall and there is no penetrating that wall no matter how hard you push on the shift lever, the mechanism just locks. This is the reason no one responded to Patrick's call for second to fifth miss-shifts. I'll bet that we never see anyone respond, who has miss-shifted 2nd to 5th on a power shift — it is all but mechanically impossible.

The breakage that Hauss has experienced, if I am not mistaken, was previously identified by him as occurring after a power shift into 5th OD from 4th gear. Considering how fast these cars are in fourth gear at the top of the engine's safe operating rpm range it brings us back to the why do this question.

If you have not won the speed contest by the top of fourth gear, fifth gear Is not going to do the deed for you! Additionally, you are at least 50 mph over the maximum safe scary speed that people with poor critical thinking skills and worse judgement operate these cars at and you are power shifting 5th overdrive?

It simply does not make sense. Fourth gear in most of these cars and with adequate horsepower is capable of bringing you to just shy of 200 mph. The rest of the car is just not ready for this level of performance. In a Cobra replica this is not just scary, it is suicidal and all but impossible.

Attempting closed course race car speeds in a replica that has not been prepped for that sort of performance is beyond foolish. Don't forget the fear factor at those speeds and the car's predisposition to fly without the proper ground effects to keep it marginally glued to the ground. Of course you also have to stop this missile from 200 mph and that takes some skill and lots of space.

The power shift that is breaking the transmission is not occurring anywhere near 200 mph. In fact I would bet it is occurring at or (most likely) well below 100 mph where it begs the question, why do we need to power shift 5th gear at this speed??? If we are still attempting to win a speed contest (which at that point is foolish) there are far more effective gears to be shifting into than 5th overdrive!!


Ed

p.s. Here's an interesting little side observation, how many of you have tires on your car (fresh or otherwise) that are speed rated for 200 mph?

[patrickt]

I know the speed of my car when winding out 4th gear at 6200RPM, which is my basic shift point for all my gears. That speed is just under 140mph. I would not think of power shifting in to 5th at 140MPH. Now, it is on my bucket list to take my car up to its absolute top speed, which I would guess, but do not know, to be somewhere in the 160's. My 5th gear ratio is .64, my rear is 3.54 and my tire height is just over 26 inches. On paper at least, I could go well over 200MPH before hitting my red line. Of course, we all know that ain't happening in real life on the salt flats. Somebody at ERA told me though that with an anteater nose, my build had a good shot at going past 170. I don't know if that's true or not, and I've never even seen an anteater nose except in pictures.

[eschaider]

Your car will usually begin to discuss these kind of matters with you in an intimate sort of car to driver communication, advising you of places you probably don't want to go. Sometimes cars are smarter than we are ...

Of course there is always the self preservation instinct that can play positively in the experience — as long as we listen.


Ed

[patrickt]

Originally Posted by eschaider

Your car will usually begin to discuss these kind of matters with you in an intimate sort of car to driver communication, advising you of places you probably don't want to go. Sometimes cars are smarter than we are ...

Of course there is always the self preservation instinct that can play positively in the experience — as long as we listen.


Ed

I could always just hire Morris to do it for me. The car would probably run faster for him anyway.

[eschaider]

Touché!

I suspect that Morris prefers race prepped cars for those sorts of adventures however ...


Ed

[patrickt]

Originally Posted by eschaider

I suspect that Morris prefers race prepped cars for those sorts of adventures however ...

If Morris is craving a thrill, then finding out what my ol' girl can hit at WOT in 5th, on her old Yoko tires, will definitely scratch that itch. And no point wearing a helmet. If something happens, it wouldn't help.

[eschaider]

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

[twobjshelbys]

Originally Posted by eschaider

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 <children> with newer better faster <children>

[Anthony]

Originally Posted by twobjshelbys

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

[eschaider]

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;



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;



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

[hauss]

Originally Posted by eschaider

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;



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;



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.

[hauss]

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.

[eschaider]

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

[Gaz64]

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.

[1795]

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

[hauss]

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.

[eschaider]

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

[twobjshelbys]

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