T-5 and TKO Failures....

[Clois Harlan]

I posted a question earlier last week and Lew added the following after he returned from his trip. I decided to start a new thread since the orig post had been out for over a week. If anyone can shed any light on this he is finally back and able to answer questions:



Howdy, Thanks Clois for starting all this discussion. YES I NEED some help.
Here is the story, Finished the Cobra in 1997, began going to events , like Run GUN & the Shelby club events on road course and yes I was real slow. The cobra I built with and running a mostly stock 5.0L 1991 Mustang GT motor and T5 tranny, drive train. never had issues til one day it stuck in 4th gear. I was told sometimes doing drags T-5s would do that, it got worse over a year and I made the plan to "UP GRADE to Tremec 3550, not the TKO. I used a Ford Motor sport vender to do the work, new bell housing, King Cobra Clutch / pressure plate and so on. This worked GREAT for 1 year and that includes lots of street miles and 7 events. That was Aug 2002. and ran good til Sept 2003. Just before an event at Road America I added some safety by removing the Hoop style rolll bar and adding a big bar to cover both sides and it goes back to ends of rear frame and a bar forward to attach to frame at foot box side of passenger. It did add more strenght to frame, At that time I noticed a small leak on Rear end pinon ger seal and so went to a shop to have it replaced and check pre-load on reaend and was tolld all is in good shape. Then a few days later there at Road America the car after 2nd day would not down shift to third. just moves easy out of 4th but like hits a wall at neutral. play a little and after a little nail bitting while hammer the brakes and it would go... it got worse real fast and did not feel like it wanted to shift right. going up in gears would go but, down shift was out of question. in the pits a guy was selling a rebuilt 3550. he actually had 3. I could take my pick and price was right. Clois and Jay Nordstrom helped pop out the old one and in with the new. naturally we looked inside the bell housing all "LOOKED" ok. went out and after a few sessions bang it would not shift and then the clutch would not go in to disengage. WE QUIT for the weekend. getting home and pulling all apart we found a spring had broken away from casting on KING COBRA clutch and fallen into pressure plate. HEY that had to be it the reason the tranny was blowing was the clutch was not fully disengaing!!! RIGHT... NOPE WRONG!! MORE to come.... The Newest tranny I paid good money to have the best shop in Milwaukee rebuild. $700. I also downloaded from TREMEC to service manual and started reading and found a source for parts at Liberty Trans Co over by Detroit. ( GOOD BUNCH OF GUYS and they also gave me several good tips to rebuild and supplied all the parts I needed and at a Good Price!) Anyway less than a month after Road America experience, I went to Run Gun in St Louis. first day went the $700 rebuilt unit so I had to think ( new clutch / pressure plate and now a Center Force all in there LOOKED good. so maybe the $700 rebuild was not so good?? put in the one I built. Poof lasted about a day same issue want down shift to 3rd from a fast speed of straight away in forth. Now you are gonna say" how fast in forth when trying to down shift. here is what I do. Flat out in 4th on a straight hitting rev limiter @ about 135MPH and 6 grand RPM... approach a turn and hammer the brake!!! for a couple seconds drops RPM to about 4 grand and MPH near 100 THEN SHIFT down to 3rd and all heal and toe and continue to hold brake till at the turn and on the GAS!. ) So, over Winter, pulled it all apart. NEW BLOCK, for motor, inspected Bell housing, took clutch and presure plate to shop to check and they say it's like new. new fly wheel AL type with new 28 ounce balance to match new crank and motor balancer. rebuilt tranny very carefully and measured all to spec per book from Tremec, another new pilot bearing, new throw out bearing and a new fork arm with all new clips and parts so it is all new!! went to MAM in June with club and shift issues started again but quit before could do much damage, also as motor is new was having a few over heat water pump issues so went home and again started to look all over again. rebuilt tranny again and made special time to review ALL possible measurements to insure all play was in tolerance per book.
Went to Tulsa and it lasted into the 3rd day this time, yes I know the first day I was not pushing it real hard as I was baby'ing the new motor and makeing sure no over heat issues were coming up and also learning the track again as it had been 2 years since driven there, truely urned up the speed on 3rd day. and boom again the down shift to 3rd started to hang up.
got home and looked again close at tranny and as I had not continued to push the bad syncros it was not to bad only 3rd gear was showing slight breakes in 3 dogs and minimal syncro damage. but replaced all new again anyway. Road america came and again after a day it went. Always the same the 3rd gear dogs crack on edges and start to break up like made of GLASS. they eat up brass pretty quick and it is over.
Ok I and really ready for help here.
anything will be appreciated.
Lew Payne

[G.R.]

Not being a smartass here but I would be inclined to look seriously into a 4-spd top-loader, like one from David Kee , if I had invested the time and $$ you have only to have the same problems re-occur time and time again.
I'm of the the opinion that T-5's, TKO's. TKO II's, are and can be dependable transmissions when set up with the right components for street use and "ocassional" mild hi-speed bashing. But the scenario you described may be pushing their limits--I don't know if I'm blowing smoke or not since I'm not near the mechanic you are--hell changing jets in a carb is a trial for me-lol . FWW

[Ant]

I have blown the odd gearbox, but the Toploader in my opinion is a beauty, the only problem I have seen is on a standard gearbox they can baulk or not shift the best, that was on a low mileage Falcon GT, but I think some of that comes down to the shifter.

My recommendation is fit a Jerico 4 speed WC4-4 which looks like a Toploader has got wider stronger gears, much much quicker shifting alloy case, and you can get one with a speedo drive. The only issue is matching revs while street driving, but they are strong enough, and any track experienced driver will soon come to grips with that.

The only reservation I have is my wife may have to drive home on the odd occasion and graunch graunch of the gears isnt going to make me happy, so I would probably go for a David Kee Toploader with good shifter. I will have to make up my mind in a few months!!!!!!!!!!

[dlampe]

Lew, as you Know, I bought a new t-5 from Blumenthal in OK. They have a 1 year warrenty and they have been great on the phone. Use yours as a core and get a guarantee. I just can't believe that all those mustangs at road america are having the same issues you are facing. There must be a way to get a t-5 or Tremec to hold up. I don't think a top loader is the answer. Call the guys at Blumenthal and talk with them. 1 800 262 9557. Talk to you soon.

Dean

[coyled]

Lew, this is a common problem with tremecs. The 3 detents break off at the ends and it won't down shift. Have a macine shop build those detents in a hardend material or do what I did and get a jerrico. The jerrico is awesome upshifting and downshifting. Scott

[LewisPayne]

Thanks Scott, for info, Clois had told me you had mentioned this issue and had seen it before. I found a company that says they re-work the 3550 and make it using Jerrico guts just for this issue. I just can't believe that I ran it a year with no issues then bang, as if the tolerance on a new one factory fresh works ok but after a re-build even though all set per there service manual is right it will not hold up?? I have learned to re-build one without even looking at the book have been in them so much. but I follow the book anyway. everytime the small dogs or blockers are cracked on edges, and the small pieces start to chew up brass, if I quit running it on first time it hangs to down shift then only the 3rd gear one has some small corners chipped off. naturally on the times I kept trying to run it the worse they get and then 2nd gear syncro and blockersshows damage. usually worse case is 4th and first look pretty much new and not harmed. only once has 5th shown damage. Hey thanks for advice.
Lew

[coyled]

Lew, I had a guy that said he would make little blockers out of something other than the pot metal they are made of from tremec. You could find somebody to do it. The only problem could be chewing up other parts. I would like to here tremecs response to stronger blockers or are they designed as the weak link? Scott

[Jack21]

Been following this thread. Odd, with all the guys racing Cobras, that this is the first time this has come up. Also odd, that this started happening only after welding in roll bar.??? There's omething going on that we're all missing.

Upgrade engine and trans mounts to polyurethane to eliminate any flexing.???

Unless you need 5 gears in a race car, I'd go with one of Dave Key's toploaders. And talk to Dave about the problem first. If you do need 5 gears, go with one of the new Tremecs like the T-600. Again, buy it from someone who can put the pieces together such as Liberty Racing Transmissions to determine cause of failure if you break it.

[RACER X #99]

Making no accusations here but I have instructed lots of guys in driving schools and some guys are just brutal on their running gear. You guys have all heard this"if you wanna be fast you gotta be smoothe". That applies to your running gear as well.
Of course this means that I will probably explode my trans the next time out.

[Ant]

coyled,

Its been a while since I drove a race box on the road, and there has been a few threads on them.
Are you able to drive quietly on the road with your Jerico trans, by pausing a second between gear changes with no throttle to match revs and just sneak it in to the next gear, or is it a bit more of an act?

Also a friend of mine, with my first car I built, has just gone through another single plate clutch with a 450bhp FE, it runs a comp McLeod hat or pressure plate and a 11" kevlar lined solid disc.
What type of clutch are you running with the Jerico?

I have read recently where outfits like Centerforce make a good street/competition twin plate unit which has different linings or paddle design on each side of the discs!

[coyled]

cranky, yours will be hanging up on downshifts soon, unless you drive like a little old lady. You saw the video, I drive it like a little old lady, smooth and easy. Ant, the jerrico is a noisy box. It wants to be on or off throttle. It chugs and lugs at partiall throttle. The reason being is the big window for the dogs to engage is going back and fourth. I am running an 8.5 inch quaertermaster clutch and I like it. By the way, this is a real problem for tremec in road race applications. It has started happening with there 6 speeds too. I would bet money that the internal dogs are upgraded or changed to a higher strength material on the tko-500 and tko-600. If you don't road race a lot with big hp, the tremec is a great tranny. Scott

[Anthony]

Here is an interesting description of the various tremec trannys:

http://www.moderndriveline.com/Techn...its/tremec.htm

I'm not sure if Tremec upgraded the clutch dogs and/or synchro rings with the new line of trannys, therefore, if they didn't upgrade these parts, you may still have problems with the trannys.

[Ant]

coyled,

Thanks,
I would guess though they are pretty tough and handle the chugging and lugging at partial throttle, do you use yours on the road much at slower speeds, and do the dogs get a bit munched by doing this?

I am trying to get a handle on if a Jerico is practical, bearing in mind I consider the car to be race fit before road use, but if its going to be upleasant and a chore I may go to a TL wide ratio!

[LewisPayne]

This is real interesting, Henry Vicioso that loaned me head and intake gaskets at Road america also has lost syncros at Road Am . he found this link to a good article on the subject.. http://www.musclemustangfastfords.co...0406mm_gforce/

[Big-Foot]

Lew - the only thing that third gear has going on in your tranny that is not shared with the other gears is the distance between the gear (3rd) and a supporting bearing. Typically the mainshaft is strong enough to take the abuse without flexing. My thinking here is that you have a defective mainshaft that is flexing too much and causing you a lot of grief. I've used and installed a numberr of these transmissions and have not seen or heard of your experience before. It is really curious.