New Tremec transmission

[RockBit]

Originally Posted by Gaz64

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.

Really nice video.

My TKO600 shifts well, but I don't do a lot of speed shifting. One thing I noticed in the video is there is a reverse lockout for shifting out of 5th gear. My unit does not seem to have this feature. I have to be careful when downshifting from 5th to 4th to not go into reverse. Does anyone else have this issue?

[eschaider]

That makes more sense, Gary. Until you raised the one part two pieces after breaking alternative, I was viewing the picture as an image of two parts, one good shaft and one broken shaft. The length of the misidentified 'good part' and location of the dowel pin hole was leading me to believe it was the reverse idler gear shaft.

When you look at it as a broken fifth and reverse shift rail that fractured at the selector link pin hole, then Hauss's early pic and the method of failure makes sense. Thanks for the wake up call.


Ed

[Anthony]

Originally Posted by Gaz64

The photo above of Hauss's broken 5th/rev rail shows 2 pieces at the fracture point. The roll pin secures the roller that follows the selector lever.

About 20:20 in the video.

Gary

Yes. Looking at the picture and video, it seems to me that the real issue is the hole size for the roller, which seems to be very large in comparison to the diameter of the shaft, and appears to be the location of the fracture, as opposed to the roll pin which is a much smaller hole just beyond the fracture point. Maybe the solution is to make the roller a smaller diameter ? with a new corresponding shaft ?

[eschaider]

I was thinking something very similar, Anthony. I am not sure of the exact mechanics of the failure but if it occurs because of force applied to the shaft by the pin then reducing hole diameter for a stronger shaft would sound like a good compromise. Somewhere (I don't know where) the reduced pin diameter might begin to produce pin failures where the head of the pin is being sheard off.

Bottom line, I think the 5th gear overdrive design was never intended for use in a power-shifted environment. Just not power-shifting into 5th overdrive might be the easiest and most straight forward fix for the problem. Moreover, if you haven't won the contest before 5th gear overdrive, I am not persuaded that 5th gear will make a difference in the outcome anyhow.


Ed

[Anthony]

Originally Posted by eschaider

Bottom line, I think the 5th gear overdrive design was never intended for use in a power-shifted environment. Just not power-shifting into 5th overdrive might be the easiest and most straight forward fix for the problem. Moreover, if you haven't won the contest before 5th gear overdrive, I am not persuaded that 5th gear will make a difference in the outcome anyhow.
Ed

Well, from reading some of the posts, maybe it's not powershifting into 5th, so much as "power" shifting from 2nd to 3rd, and somehow hitting 5th gear instead, putting stress on the 5th gear shaft ?

[eschaider]

Originally Posted by Anthony

Well, from reading some of the posts, maybe it's not powershifting into 5th, so much as "power" shifting from 2nd to 3rd, and somehow hitting 5th gear instead, putting stress on the 5th gear shaft ?

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

[Gaz64]

Originally Posted by Anthony

Well, from reading some of the posts, maybe it's not powershifting into 5th, so much as "power" shifting from 2nd to 3rd, and somehow hitting 5th gear instead, putting stress on the 5th gear shaft ?

This sounds like the cause.

Any more info about how this happens Hauss?

[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

[Gaz64]

Originally Posted by eschaider

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

Yes, it is possible. After all, you can select any gear from any position, except reverse from 5th, if the trans has 5th/reverse lock out.

I have done 2-5 shifts at 70mph, just getting off it, to cruise.

I'm sure many of us do this.

But I think in the case of a TKO, it seems it does not like a harsh shift into 5th.

[patrickt]

Yes, you can do it on purpose, but I can't see how you could do it by accident. Alright, I'll ask... has anyone out there accidentally shifted from 2nd to 5th?

[Anthony]

Originally Posted by patrickt

Yes, you can do it on purpose, but I can't see how you could do it by accident. Alright, I'll ask... has anyone out there accidentally shifted from 2nd to 5th?

Well, I was thinking maybe if you were trying to power shift from 2nd into 3rd, and the shift was blocked for whatever reason, maybe you could accidently try to power shift into 5th.

Actually, in my stock '95 viper, with a stock shifter T56, yes, I have miss shifted gears at times, both upshifting and down shifting. I find with upshifting, if you push at an angle like a hurst comp +, it goes right in, rather than trying to notch it over.

Other than driving my friends superformance with 3550, don't have much experience with tremec. Have a bunch of different 4 speeds, and then T56's.

[patrickt]

Hmmm, alright. I should really know better than to say that regarding any aspect of life on this planet: "No, it's impossible for anyone to make that mistake."

[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