TKO Upgrade

[MaSnaka]

Thanks for all the info guys. Eshader you are the only one I have heard with a complaint about the Tremec TKO600. Very discouraging to hear. Does any one else have trouble with shifting and worse 3rd gear getting chewed up? Not sure I'm interested in a 6th gear though.

Rick thanks for mentioning the Richmond super street 5, that sounds like a good alternative. I'm looking and listening.

Truth of the matter is I want the 5 speed to use 5th gear to settle in for freeway cruising. Drop the rpm's to a reasonable level and keep 1st-4th for performance driving.

My toploader is close ratio and just changing the rear end will drop rpm's some in 4th but 1st gear becomes very tall.

I have not heard any one with specifics regarding the external slave conversion. What units or part numbers do you have that will fit the CR with a big block?

I still have some homework to do and will get back with what I find.

Thanks,
John

[eschaider]

Originally Posted by MaSnaka

Thanks for all the info guys. Eshader you are the only one I have heard with a complaint about the Tremec TKO600. Very discouraging to hear. Does any one else have trouble with shifting and worse 3rd gear getting chewed up? Not sure I'm interested in a 6th gear though. ...


Thanks,
John

If you will be driving the car in a less than 'spirited' and/or non -competitive manner the TKO600 is a fine transmission. If you drive it in a competitive fashion and attempt to rapidly change gears from second to third it will not cooperate the way it is delivered from Tremec.

Some guys call it notchy some guys call it other names but rapidly changing gears from second to third is a problem in the transmission as delivered by Tremec since time immemorial. Attempts at doing it more often than not end up in a missed shift from second to third.

The problem is the interlock timing that Tremec built into the shift detents on the internal shift rods to prevent engaging two gears at the same time. They erred on their design in a fashion that precludes rapid gear changes. Changing shifters, synchronizers, trans fluid, shucks even the air pressure in your right from tire has no effect on the underlying design miscue. On the oither hand, Tremec does have replacement shifter rods that will correct the interlock timing whoops and importantly also the second to third shift quality.

The third gear alignment problem is present in all TKO600's according to Tremec engineering. The issue (reportedly) had to do with their transition from a two piece countershaft on the TKO500, that was prone to shear it's woodruff key under load, to the newer design TKO600 one piece countershaft. Now instead of shearing a countershaft key we can shear teeth off of two gears at exactly the same time!

To provide clearance for the machining chips the gear hob creates as the countershaft third gear is hobbed, Tremec needed to leave a gap for the chips to escape. That gap (between the countershaft second and third gears) is the origin of the 3rd gear countershaft misalignment with the mainshaft third gear. When they changed the gear placement on the countershaft they did not do the same for the main shaft.

As long as you do not hook up your tires in third gear under full power and/or do not have a relatively robust engine you are not likely to have a problem. On the other hand if you nave a relatively robust engine and you also hook up in third you are in a dance with the devil. It is unlikely (but not impossible) to break it on the first attempt however repeated WOT third gear operation with the tires hooked will kill it.

Part of the good news is that WOT in third gear is a relatively inspiring phenomena in one of these cars and most people (unless they are racing) don't do that very often, if at all. If you do then the game of Russian Transmission Roulette is alive, well and on.

When I had my TKO600 modified by Liberty I believe the cost of all the parts was about $400. I don't remember if there was also a labor charge or if it was included. Either way, price wise your TKO very quickly looks like a T-56 Magnum — pricewise. A telephone call to Liberty can quickly get you the current pricing. Don't forget to add freight up and back unless you intend to do the mods yourself. And of douse don't forget this only corsets the shifting problems. You still have the nicely misaligned third gear problem.

As the Liberty rep at the time suggested to me I would have been better off to use the T56 if I were starting fresh w/o any parts bought yet.

Here are the dimensions from Tremec for a TKO;



Here are the dimensions from Tremec for a T-56 Magnum;



While not exactly the same they are close enough either transmission can easily be made to fit.

It simply comes down to builder preferences and what is important to you — as do most choices in these cars.


Ed

[blykins]

I would refrain from using absolutes...

I have numerous 600's in road race, drag race, and super hot street stuff and have never had a customer break a gear. This is up to 600-650 hp, launching on wrinkle walls and shifting at 7000.

[eschaider]

Originally Posted by blykins

I would refrain from using absolutes...

I have numerous 600's in road race, drag race, and super hot street stuff and have never had a customer break a gear. This is up to 600-650 hp, launching on wrinkle walls and shifting at 7000.

I understand what you are saying Brent and while the third gear breakage was (to my knowledge) not experienced at launch in first or third gear it was experienced in a gear change from second to third, in a drag car, with a medium power level (but torquey) big block, in a heavier car than a Cobra.

The Tremec designed third gear misalignment in their TKO600 transmissions unnecessarily loads the engaged third gear, gear teeth higher than they would otherwise be loaded with a full face contact design. Whenever you do that to a driving and driven set of gears they will fail sooner than the same gears with full face contact — it's just the mechanics of the gear system. This is a similar phenomena to getting the pinion depth wrong on a ring and pinion. Will they fail right away? Probably not. Will they fail sooner than a properly set up ring and pinion, yup.

While it is not an absolute that you will get shot every time you play Russian Roulette, it is true that the more often you play the more likely you are to get shot, again sort of a similar phenomena here. I think the number of Cobra's who can load their third gear, gears to their breaking threshold is relatively small, more because of the car weight and the spectacular experience available in car at WOT in third gear. That however does not mean that they will not fail. Importantly if and when they do fail the attendant gear tooth shrapnel is capable of expanding the scope of the failure if it gets into other gear sets inside the transmission.

So where is that magic line in the sand you don't want to cross? I can't say with any certainty. We do know Tremec claims the transmission is rated at 600 ft/lbs. They don't say if that is true for all gears some gears or only one set of gears. They also, to my knowledge, don't say if that is a sustained torque loading or a shock loading like we might see launching the car in a drag race style fashion. My suspicion (and that's all it is — a suspicion) is it is a continuous duty loading for a single gear set probably first gear.

If that is true (and that's a big if) it means 600 ft/lbs of torque and more represent a potential component failure threshold in third gear, again if everything is hooked up and really transmitting that much torque. How often can you do it with the misaligned gears? I don't believe there is any test data to give insight to that elusive number. However, we do know it happens and we do know those gears are misaligned 0.140" (if you believe Tremec).

Does this mean we should all forsake our TKO600's, probably not. Is it appropriate to make the knowledge available to someone who is contemplating the purchase of a new Tremec transmission? I think so. I know I would have liked to have had the knowledge before spending my monies and I think others might also. Will it or should it change everyone's mind? I doubt it and I don't think so but it will make some reconsider what they are about to buy and potentially allow them to make a better decision — for themselves.

In the final analysis if you are going to spend $2,400+ on a transmission why not buy the most robust unit with the highest torque rating and the best shifting qualities that will fit into your car for the dollars that you are about to spend?


Ed

[blykins]

Ed,

I appreciate all your input that you provide on Club Cobra and I usually take time to read your posts and digest your information.

However, in this one instance, I'm going to have to strongly disagree with the information you have provided.

Just in case I was out in left field, I emailed my Tremec supplier, since he is a dealer and is a Tremec-authorized repair facility, and asked him how many instances he has seen where the 3rd gear has eaten itself away or the cluster shaft gear has been eaten away because of misalignment.

His reply is that it's a new one to him, and if that were the case, he would be seeing a lot of irregular gear patterns, 3rd gear bearing cage damage, or just warranty repairs in general to fix the issue.

As I mentioned before, I've never heard of this, and I sell quite a few TKO's, as well as put them behind a lot of hipo engines that I provide. Some of them go behind road race engines, some go behind drag race engines, and some go behind 650-700 hp street engines.

Now, with that being said, the TKO's don't have a reputation of being the best shifters, especially at higher rpms. This gets better as the trans wears in, but we often do upgrades to correct gear cone and synchronizer hub surface finish, as well as upgrading the shift finger, blocking rings, etc. That usually takes care of the shifting issue, all the way up to 7500 rpm.

The TKO 600 is rated for 600 lb-ft of continuous torque on a trans dyno. If I'm not mistaken, this is rated in all gears except for overdrive. I can recheck this.

The Magnum T-56 is not (IMO) the solution to everyone's needs. In addition to the extra requirements to fit them behind some engine combinations, they are much more expensive, about 4" longer in length past the bellhousing, and much bigger around. This proves to be a big issue in some transmission tunnels, and in the case of a Cobra replica, with an already short driveshaft, shaving another 4" off the body length doesn't leave much.

The one failure from 8 years ago, that you have talked about and showed pictures of, seems to have been an isolated case. I just don't agree with making a blanket statement that says that all TKO's are timebombs, or that each prospective buyer needs to sit down and let this weigh heavily on their mind.

In my own mind, it's a non-issue.

[bobcowan]

Originally Posted by blykins

Ed,

The one failure from 8 years ago, that you have talked about and showed pictures of, seems to have been an isolated case. I just don't agree with making a blanket statement that says that all TKO's are timebombs, or that each prospective buyer needs to sit down and let this weigh heavily on their mind.

In my own mind, it's a non-issue.

Maybe I'v been lucky, and I can only comment on one TKO (mine). I'v been beating the stuffings out of my trans for nearly a decade. High rpm shifts can sometimes be difficult. And it is just a little bit notchy; overall I like the feel. But it's holding up well (knock on wood).

[eschaider]

Originally Posted by blykins

Ed,

I appreciate all your input that you provide on Club Cobra and I usually take time to read your posts and digest your information.

However, in this one instance, I'm going to have to strongly disagree with the information you have provided.

...

The one failure from 8 years ago, that you have talked about and showed pictures of, seems to have been an isolated case. I just don't agree with making a blanket statement that says that all TKO's are timebombs, or that each prospective buyer needs to sit down and let this weigh heavily on their mind.

In my own mind, it's a non-issue.

I think we are actually closer together in our positions than you might suspect Brent.

My summary comments about the transmission were:

Originally Posted by eschaider

If that is true (and that's a big if) it means 600 ft/lbs of torque and more represent a potential component failure threshold in third gear, again if everything is hooked up and really transmitting that much torque. How often can you do it with the misaligned gears? I don't believe there is any test data to give insight to that elusive number. However, we do know it happens and we do know those gears are misaligned 0.140" (if you believe Tremec).

I went on to say;

Originally Posted by eschaider

Does this mean we should all forsake our TKO600's, probably not. Is it appropriate to make the knowledge available to someone who is contemplating the purchase of a new Tremec transmission? I think so. I know I would have liked to have had the knowledge before spending my monies and I think others might also. Will it or should it change everyone's mind? I doubt it and I don't think so but it will make some reconsider what they are about to buy and potentially allow them to make a better decision — for themselves.

I suspect what may have wrankled your (and possibly others) sensibilities was the clarity of the failure description and the publication of the Tremec design miscue in terms of gear tooth face alignment. I can well appreciate how the sudden awareness of a design flaw of that type in anyone's transmission can cause anxieties that did not previously exist — after all I own one also. It is however, none the less important and our obligation to be as informed and knowledgeable as reasonably possible so we can best decide for ourselves. I believe I also spoke to that in my closing paragraph where I said;

Originally Posted by eschaider

Does this mean we should all forsake our TKO600's, probably not. Is it appropriate to make the knowledge available to someone who is contemplating the purchase of a new Tremec transmission? I think so. I know I would have liked to have had the knowledge before spending my monies and I think others might also. Will it or should it change everyone's mind? I doubt it and I don't think so but it will make some reconsider what they are about to buy and potentially allow them to make a better decision — for themselves.

I think it is better for a potential purchaser of these types of components to have as much information as possible, both good and bad, prior to making a purchase decision about these or for that matter any other high value component in the car. When we use that information in our own decision/selection processes we will not all come up with the same choices but, we will come up with choices we think are best — for our own builds. Which when you think about it, is what the world's largest non-biased cobra site is supposed to be about and among other things foster? [Although in as much as we all own Cobra's we might have just a smidgen of bias ...)

In fact in my closing few sentences I suggest;

Originally Posted by eschaider

In the final analysis if you are going to spend $2,400+ on a transmission why not buy the most robust unit with the highest torque rating and the best shifting qualities that will fit into your car for the dollars that you are about to spend?

I chose to ambiguously identify that transmission because it could have been a variety of the Tremec offerings, a Richmond, a Top Loader, a G-Force or one of a number of other transmission alternatives. It is after all what the builder determined to be best for his purposes and his build given the information available to him at the time of selection/purchase.

In the end I don't think we are actually all that far apart. BTW I genuinely do enjoy and appreciate your perspective, input and insightful commentary on the site here.


Ed