Tko600 Warning!!!!

[Anthony]

Yours:

Originally Posted by Fordfan69

3. Every single knowledgealbe and even not-so knowledgeable people that I have shown the gears to absolutely said it must have been some sort of a part failure or improper installation (gear meshing not right). I am the first one to admit that I am in no way perfect, but I and others looked very hard and I also thought back to the moment very hard and there is not a doubt in my mind that I did not miss that shift. I've attached another picture showing more clearly 3rd gear's dog teeth and synchro blocker. They are in excellent shape. The shape of ones that came out of a box with only slightly more than 1000 miles on them.

If I wasn't in the gear all the way or missed the shift, the dog teeth would be damaged and/or rounded. Not the case.

If any damage would occur from improper usage, as they say, wouldn't it be to the dog teeth. How is it possible that they are mint. That tells me and others that the synchro hub was fully engaged to the 3rd gear. I am not saying that Keisler assembled the tranny incorrectly, but there is something wrong for the main teeth to fail in that way on that angle opposite that of the cluster gear.

4. Another reason why I felt this failure was not a failure of my own doing is due to the fact that I found another user of the Tremec 5speed that also had a failure. When I looked at his picture, It looked almost identical to mine. The teeth sheared off on the same angles and all. Another reason why I thought it might be a part failure. You can see his picture and read his post if you want at http://www.pro-touring.com/forum/showthread.php?t=23218
.

I think you're right. The "gears" are always in constant mesh, when you shift, it is the slider sleeve, or whatever you want to call it, that moves and engages the small synchro teeth on the gear, with the brass blocking ring bringing the gears up to similar speeds for engagement of the synchro teeth.


Because the main gear teeth are angled, the front of the tooth will always engage the counter gear tooth first, before the rear of the tooth, thus initially placing the load on the front of the tooth, both on the main gear and on the counter shaft. If the 3rd gear ojn the counter shaft is larger than the 3rd gear on the main shaft, then that may be why the front part of the teeth on the main gear sheared, as they be weaker relative to the 3rd gear on the counter gear. Maybe that's why the front of the teeth are broken more than the rear, and the opposite on the counter gear.

If you miss a shift, it usually damages the small synchro teeth, not the larger main teeth. Actually, when buying a used trany, it's usually the small synchro teeth that are worn or bad, and often overlooked by the prospective buyer, and the main teeth look fine, but the tranny is really hosed because of the poor synchro teeth condition.

Originally Posted by rj8806

.... The evidence speaks for itself. The gear was sheared off in the front of the gear. If there was a defect in the material, the outcome would have been different.

This is a mute point anyway as Tremec has inspected it too and came to the same conclusion we did, abuse. They will not warranty it for that reason.
Richard
Tech Support
Keisler Engineering

I think the evidence does speak for itself. If it was 1/2 into gear, the synchro teeth would be half sheared, not the main drive teeth, as they never move, i.e. slide forard or backwards, the slider sleeve does. I've rebuilt several muncies and toploaders, and they're basically the same design, all the gears are always in constant mesh, while in any gear. It's the slider sleeves engaging or disengaging the synchro teeth that determine how power is transfered, between which gears. Have you rebuilt any trannies, or understand how they work?

Originally Posted by scott coyle

Tremec had issues in the past with the case expanding on 3550's when the tranny is loaded, and third gear breaks. If you add in a heavy car(dodge) and the difference between second and third gear ratio's, they are far apart, it looks like it loaded the tranny, the case expanded and the teeth snapped off.

First and second are pretty low gears, so even in a heavy vehicle, they usually won't break. 4th gear is direct, so it won't load the tranny. Thats why third gear breaks. In a cobra, the vehicle is so light, the tranny is not really loaded as much as a heavier vehicle, so breakage is less likely.

Excellent explanation and it sounds logical. If the case expands alittle, the main gears get alittle out of alignment, and the load is not evenly placed on the teeth of the main gears, shearing off the front of the teeth first, as that is the part of the tooth that engages first. The other possibility is gear weakness, or poor design ( teeth angle too much, or gear diameter too small)

Interesting failure.

[Anthony]

Originally Posted by scott coyle

Tremec had issues in the past with the case expanding on 3550's when the tranny is loaded, and third gear breaks. ----it looks like it loaded the tranny, the case expanded and the teeth snapped off.

I had always thought that tranny strength was determined soley by gear diameter, and tooth width and angle, determining max loading on teeth. I had never thought about possible misalignment causing uneven loading on gear teeth and gear failure.


Again , interesting failure.

[Rwillia4]

can someone label the picture. I trying to follow what happens when shifting and what is engageing what and where...

[Anthony]

Thinking about it overnight, the mainshaft inserts into the back of the input shaft, so there is not alot of side support to resist some/ alittle deflection, so that is another place that can cause gear mesh separation/teeth misalignment during hard loading of the tranny, maybe to the greatest degree, as the 3rd gear is right behind the input shaft, where I would think there would be the greatest deflection from a trigonometry perspective, as the mainshaft is supported at the rear of the case and tail shaft, and obviously the input is supported at the front of the case.

[scott coyle]

The more I think about this and look at the part, the more I believe the trmec was at its limit of use. There probably are not that many 3800 pound cars with slicks and the power of this vehicle. You add in the gap between second and third gear ratios, a little case expansion, the teeth were just far enough apart, and third gear broke. What rear end gear was in the vehicle. A 4.88 gear would be much easier on everything and make third gear lower. A 3.08 would make the problem worse.

Take the broken parts in and have them tested. My bet is the parts were solid, nothing wrong with them and the tranny limits were exceeded, ever so slightly.

Scott

[craigayl]

A late comer..

This thread caught my attention, I have read all the posts and am disappointed it turned into a "who shot whom" rather that an investigation from a technical aspect.

I have seen many damaged Tremec's and there is no way this failure had anything to do with a shifting error. If that is what Tremec concluded, the tech simple does not know what he or she is looking at or was being dishonest to cover up a warranty claim.

First.. Note that the blocking ring and syncro teeth are in perfect shape... Absolutely NO evidence of a missed shift.

Second.. Once the syncro teeth are engaged, there is no such thing as "partially engaged". Either you are engaged in which case you will stay in gear and transfer the load to the "constant mesh" gears OR you are not engaged in which case NO load will be transferred to the drive gears. IF at that point you try to force a shift you will knock the sharp corners off the syncro teeth.

Third. I have heard no one comment on the alignment of the third main shaft gear and the third countershaft gear. Maybe this is an illusion from the photo, but it appears that the countershaft gear is a good 1/16" forward of the main shaft gear. This is not right. These two gears are supposed to be perfectly aligned. If what appears in this picture is correct, there was a serious problem in the original assembly and this would very likely be the cause of the failure.

Greg/Fordfan69 - You may want to look at this very closely and also look at it during the rebuild. Those gears should be aligned perfectly. Not one ahead of the other. If the new assembly is aligned like what appears in your picture, you may be headed for another, identical, failure.

Craig

[Anthony]

Originally Posted by craigayl

. I have heard no one comment on the alignment of the third main shaft gear and the third countershaft gear. Maybe this is an illusion from the photo, but it appears that the countershaft gear is a good 1/16" forward of the main shaft gear. This is not right. These two gears are supposed to be perfectly aligned. If what appears in this picture is correct, there was a serious problem in the original assembly and this would very likely be the cause of the failure.

I think it may be an optical illusion, but anyway, the tranny picture I believe is from a Chevelle application, not the same tranny, but the picture of the single gear is from the tranny, comparing it to the damaged tranny from the other car, showing it's the same failure.

[craigayl]

Yes Anthony "the same failure"

Note that on the forward side of the main shaft gear the teeth are copletely gone and on the rear side the teeth are full as if they were not in contact with the countershaft gear. The oposite is true of the countershaft gear. A more indepth investigation is necessary. If these gears were properly aligned, the teeth should have come off more evenly.

Craig

[eschaider]

Yet another late comer ...

It took a long time to read all the posts but things become increasingly apparent the farther you read. Anthony, Scott and Craigayl (the gang) got it right! So did Fordfan. For what ever reason Fordfan suspected he would receive poor warranty treatment and tried to position himself for the best possible. He bent the truth, to that end.

Keisler either doesn't understand how these boxes work or intentionally tried to sidestep their warranty obligations. I don't believe any reputable Tremec rep would have come to the conclusions that the Keisler folks have stated he did. I also don’t believe that Keisler doesn’t know how these boxes work!

As several of the ‘gang’ pointed out the gears are constant mesh gears if a shift is missed then the synchro dog teeth on the gear take the beating not the gear teeth! Craigayl tagged the most probable source of failure. The driving and driven gears are misaligned! If you loose 20% of the tooth face contact area, through misalignment, you have only 80% of the original design torque capacity left.

When you look at the picture there is no two ways about it the driving and driven gears are misaligned. As a commercial rebuilder of these boxes that should have been a red flag for Keisler, unless of course they have a reassembly problem that produces the misalignment. If the gears in Fordfan’s box are not misaligned then we are dealing with Scott’s analysis which is an ultimate strength failure caused by the driving and driven gears moving apart under power.

Tremec could shed considerable light on this with their finite element analysis they performed on the box during the design phase. That would quickly tell us if the third gear gearset was/could spread the case enough to induce the tooth failure. Judging from the pictures though I really believe the box was improperly assembled. The driving and driven gears for third were misaligned and the failure was directly attributable to less than complete gear tooth face contact reducing the torque capacity of the unit.

The real question is why Keisler tried to cover up and place the blame on the user. Experienced transmission shops would quickly identify the misalignment as the source of the failure. Why didn’t Keisler?

I think this bodes poorly for the type of treatment the rest of us are likely to get if something like this happens to our box. I also think it may be worth a little effort to take a look inside our own units to see if we have a similar misalignment in the third gear gearset. It will be quite telling if the misalignments exist and the reseller does not want to correct the problem prior to component failure!

It would also be quite telling if the Tremecs that had not been opened by the reseller did not have this problem. Maybe it’s time to take a quick look at our transmissions before it’s too late. If your tunnel cover can be removed it makes the job much easier than removing the whole box (or engine and box).

Ed

[Excaliber]

Ed, your assuming the gears are misaligned due to the picture posted in this thread (of a different trans no less, not Fordfans).

It has all ready been stated the picture creates an optical illusion of misalignment. So which is it? Illusion, normal Tremec alignment or actual misalignment?

[craigayl]

Excaliber

I stated in my first post that "Maybe this is an illusion" because I think we have all been fooled by pictures, but I really do not think this is the case.

As I stated later, examine the failed gears closely. Properly aligned gears should have failed straight across. There is something going on here that has not been nailed down yet. AND... It's my understanding that the picture of the lone gear IS from Fordfan69.

One thing I would bet on though is that this failure had nothing to do with improper shifting...... NOTHING….. UNLESS it’s claimed that shifting to 3rd and standing on it is improper…. Now how ridiculous is that???

Reading through the posts, I have to agree with Ed/eschaider that maybe everyone does not understand the operation of this transmission and can be misled by a statement that the transmission was not shifted fully into gear. Those two gears that failed do not move, or should not move, side to side at any time. They are constant mesh gears that are designed to be perfectly aligned at all times.

A shift occurs when the syncro ring, that round smooth shiny ring with the grove in the middle of it slides across the syncro hub, that part with teeth that you see under the syncro ring. It continues and slides over the blocking ring, that brass looking thing with tiny teeth and then finally slides over those tiny teeth, called dog teeth, next to the blocking ring. When the syncro ring bridges the syncro hub, blocking ring and dog teeth, you are locked into gear. NOW.. Look at the size and condition of the dog teeth, which are by the way in perfect condition AND look at the size and condition of the failed teeth. IF shifting had anything to do with this failure, the dog teeth would be gone, NOT the gear teeth.

Sorry if this is elimentry. I just want to be clear on why I don't belive this failure had anything to do with shifting

Craig

[Excaliber]

I note that Fordfans gear has the same pattern of broken teeth as the full trans picture. Teeth broken off toward the REAR of the gear. The question is: IS there a misalignment OR is the less than full mesh of the teeth in a Tremec 'normal'? If less than full mesh of the teeth IS normal, does it constitute a design flaw and an inherent weakness of this model trans? I don't know...

I understand the argument of the synchros partially engaging and thus damaging those small teeth, which clearly are not damaged. Making a 'partial shift' argument difficult to understand. But I can't totally discount it without thouroughly understanding the internals of a Tremec (which I don't).

No argument from me on either side, just trying to analyze the comments, pictures and design specs of a Tremec.

[Anthony]

After thinking about it some more, I'm not so sure about case expanding as the main problem, although I think it's possible. As I said before, if there is gear misalignment, I would bet that it happens when a load is placed on the tranny, and the input shaft-main shaft junction flexes ever so slightly sideways to cause misalignment between 3rd gear and corresponding counter 3rd gear, before the main case begins to widen.

Don't forget, the main shaft inserts freely into the back of the input shaft, riding on roller bearings, right in front of 3rd gear, so there is always some play, allowing the main shaft and input shaft to flex sideways. My guess, the mainshaft/input shafts flex towards the passenger's side to some degree when a load is placed on the tranny. The counter gear is spinning in a counterclockwise direction viewed from the front, trying to turn the mainshaft 3rd gear in a clockwise direction from the bottom, pushing 3rd gear, and the mainshaft/input shaft towards the passengers side.

[craigayl]

Thanks Excaliber for your clarifying.

You ask some good questions that could only be answered with a lot more investigation and analysis which is where I would hope this would go.

Having more than a little experience and knowledge of the Tremec, I am very confident in my conclusion that shifting did not cause this failure. AND I am equally confident that the root cause has not been identified either.

Gear misalignment "appears" that it "could" be a contributor, but if it is, a good follow on would be how did it get that way? Or, like you asked, is that normal? There are also many other possibilities... Just not shifting LOL

Craig

[craigayl]

Anthony

More excellent analysis and possibilities.

The one thing that leads me away from a basic design flaw in the transmission is my experience with my own TKO and many more that I know of that have been beaten severely. I've seen many destroyed synchronizers, gear dog teeth, blocking rings and shift forks, but never the gears themselves. When I first saw the pictures, before I realized there were two identical failures, I thought something must of come loose inside the transmission and got crunched between the gears. Two identical failures tends to discount this.

But, along the same lines as you are thinking. What if a transmission was assembled missing one or two needle bearings???? That would increase the side movement and possibly cause a failure.... It could also cause some vibration that Fordfan69 described early on…… It's a possibility

Something I'm curious about.

The countershaft third gear thrusts against the countershaft fourth gear that is held on the countershaft with a snap ring. On the failed transmissions, is there any slop between these gears and is that snap ring in place? Something else to consider.

Craig

[trularin]

Dang Craig, Good call. I saw the engagement teeth, but completely missed the third gear alignment.

Did you put your car up yet? I mean, it is snowing right now.

BTW, I thought all of the trans pictures were of the same trans over time.

[Excaliber]

Whoa, there is just no telling whats accurate in this thread and what aint.

Fordfan says:
"The tranny was installed in a 1968 Dodge Charger R/T and I had a Lakewood scattersheild in it."
And I now assume (after careful rereading) the trans pic IS Fordfans. HOWEVER, on the Pro-Touring site Fordfan (Chevellefan69) mentions a Tremec in his CHEVELLE and shows the above picture. Uh, what car was this tranny in?

OK, heres the pic from the Pro-Touring web site forum of a DIFFERENT Tremec 3rd gear faiure (also in a Chevelle).

[eschaider]

The potential for optical illusion is real however if you look at the tooth damage on Fordfan's gear and on the other transmission they replicate each other. The telltale evidence is the reduced levels of damage on both driving and driven gears where they don't engage each other. The lack of engagement (and damage) is caused by the misalignment of the two gears.

The only question that remains, in my mind, is whether or not this is a problem endemic to all TKOs (maybe 500s also?), a particular production run at Tremec or the result of the 'tune up' that Keisler provides for those who opt to buy it.

This is a product quality assurance problem that originated either at the manufacturer or the reseller after they tweaked the unit. The fact that the reseller would attempt to blame the damage on a partially engaged gear is astounding and troubling. Third gear does not slide and missed shifts simply cannot produce this type or level of damage.

The only thing that would produce this type of non-uniform damage across the face of the gear is a torque load in excess of the transmission capacity of two misaligned gears. The problem would only manifest itself when the final drive was hooked up and an engine of sufficient torque output was on the input shaft side of the transmission.

The average Cobra especially a high powered one (600 ft-lbs torque or more) would probably not be able to create the load conditions necessary for failure without very sticky tires because we smoke the tires and unload the drive train (still not good). It is a very different story with a 3500-3800lb door slammer with decent tires and only 500 or so ft-lbs of torque. If you loose 20-25 % of the tooth face engagement you now have a torque capacity of 450-480 ft-lbs best case. Suddenly we now have all the conditions necessary for an ultimate strength failure on the reduced face contact gears. I think it is a virtual certainty that this is what happened.

Ed

p.s. I'm still too much of a green horn on the site, I don't yet know how to paste a picture into this email, so I'll direct you to the picture instead. Look at Anthony's post #141 he has a more straight on view of the other box. Look at the back of the third gear synchronizer dog teeth and look at the proximity of the countershaft gear. It is almost touching! Look at the machined space between the dogs and the gear teeth on the mainshaft gear. Big space! This offset is what the countershaft gear should show between itself and the third gear synchronizer dogs. This misalignment reduces the torque transmission capacity of these two gears. This is the source of the failure.

[Fordfan69]

O.K. fellas,

I was going to stay away from this completely once I received the new gearset from Keisler. My dealings with them are completed and they came through and shared the loss for the failure. I want everyone to understand that.

When I sent the gearbox back to Keisler for warranty inspection, someone who I spoke to about my situation, whom just purchased the tranny from them, contacted them and mentioned an aquaintence with a mopar raced the car once and blew third gear. Around that time, I posted on this and Pro-touring to get some answers for this failure and some results as far as honoring the failure. I stated on the protouring site that it was in a Chevelle because if they were monitoring this site, they would know outright it was my Charger and not warranty it. It was installed in my 1968 Charger. the Chevelle was just a cover. I was ambiguis on this site for the same reason and don't think I mentioned what car it was in. Sorry to have had to do that.

Anyway back to the failure. In my opinion (I am one who has rebuilt manual transmissions before and understands the fundimentals, but I am not a professional by any means) The problem lies with Tremec. I have installed the new gearset and painted many of the teeth with gear contact pattern paint to see the mesh, and you guys are so correct. There definitely is a misalignment problem. I have attached photos of the trial installation and dead-on photo to see from straight on angle. All other gears look very well aligned except for third gear.



http://i119.photobucket.com/albums/o...9/100_1076.jpg

It is mis-aligned by a large amount in my opinion. Shimming the driven gear forward would not correct this as there is not much room before you start to squeeze the snchro hub and blocker rings together. It just looks like the one-piece countershaft was ground with too much clearance between second and third gears.

I have an e-mail in to the tremec tech with pictures asking how this could be designed this way and the fix.

Do you guys have any ideas how to correct this. I feel I am in the same boat I was in before it broke. Only this time, I am staying away from the track.

Thanks for your advice, and I think if it is possible, others should inspect theirs to see if there is a mis-alignment in theirs too.

By the way, ALL OF THE NEEDLE BEARINGS IN THE ENTIRE TRANNY ASSEMBLY WERE PRESENT AND PROPERLY INSTALLED, so that is not the cauuse of the failure. Input shaft end play was right at .000" and all gear endplays and backlashes were within spec. with the exception of 2nd gear end play @ .022" when .018" max was specified. I don't think that would affect this case though.

[eschaider]

The misalignment now appears to be real and very likely a Tremec design problem. Be sure to look at Fordfan's photobucket hotlink, it will remove any doubt as to what's wrong and what happened. I think it is essential to check our individual units to see what our own situations might be. I suspect they are identical to Fordfan's

I also think that if this truly is a product design issue, and it appears to be, we want to speak very clearly and with a single voice to Tremec about it. They may have a fix, but then again they may need to create the fix.

Ed