T-5 Nightmare

[Shelby_r_b]

Please don't read my post about T10 issues recently, I almost teared up reading your post. I had nightmares, rebuilt trans was a mess. Best of luck with your issue. Peter

I hear you, Pete!  I did read your thread recently...it sent shivers down my spine.  I hope you're getting things sorted out in the end.   

[SFM6S087]

Hmmm... I considered following in your footsteps on this swap, but now my T-10 is looking like a keeper. Can't wait to see how this sorts out. Certainly seems like a lot of trouble for a brand new trans. Who's paying the shipping & multiple installation bills?

Steve

[shelbydoug]

Redline MTL seems to be a magical formula for fixing issues like this. Try it.


I think though what you have run into is the traditional problem of over driven gears with "high powered" vehicles. Simply put, don't do it. Traditionally, the over driven gear can't handle it.

Not to sell anyone a "Doug Nash 4+1", i.e., a Richmond 5 speed, but originally the most significant criteria justifying building it was/is that 5th gear is 1:1, not over driven. The weakness of overdrives has been known as an engineering issue seemingly forever.

Anything based off of a T5 is going to have patchwork engineering fixes to a weak design.


Your T5 needs another repair and likely will continue to fail in 5th. It's just a bad design. It was intended to run behind a 210hp 302. That's all.

I would take an educated "engineering guess" here and say that if the transmission is rated for 330lbs-ft of torque, take whatever the overdrive number is, .68? Multiply that time 330 and that's really what 5th gear can hold? That number comes out to 224.5. That's what I think that trannie can hold in 5th.

BS to the manufacturer. They lied.

[2112]

Lots of overdriven Tremec transmissions behind 662+ HP modern Mustangs without failing.

Those supercharged engines come on like a freight train. Popular modifications bring quite a few up to 800 HP at the rear wheel.

Of course, those aren't T-5's

[427heaven]

I have used t-5 transmissions behind 400 HP small blocks with no problems. A couple of very important things to consider is that there are a couple of t5 model trans made. One was for the 4 and 6 cylinder cars and then they made a beefier version for the higher HP cars. You need the beefier version or there will be problems. Also if you do not use ATF in at least the earlier version of the t5 you will have shifting issues. MDL is your friend here they are very knowledgeable with all things t5.

[shelbydoug]

Some guys can break anything. Some guys are numb nuts. Maybe it's the same thing?

Personally I've snapped two shift LEVERS off of transmissions. As Eddy Murphy once said, "gooney-goo-who Gus?" The Hurst people thought it was funny but wouldn't cover it.

Kopec always wanted me to be "FE Wedge". I declined the appointment.

When it's broken i want to know why. If it wasn't me, then it's the component. Hey? Why's everyone looking at me and shaking their heads? That's not fair.

[KR Convertible]

I had never heard of a shift lever snapping until about a month ago.  My 16 year old did it on his 96 Cobra.  My 14 year old welded it up for him an he's been driving it ever since.

I would never recommend a T5 for a track car or drag car, but it is great for cruising.  Fifth gear will never see 330 foot pounds of torque on the street, unless you're really flying.

[pbf777]

We checked the clutch several times, and it is fully disengaging (this was one of the first tests TREMEC had me preform the first time).

     Out of curiosity, and in an attempt to assist, please expound on the procedure executed?   

     Also, perhaps your typical technique of engaging 5th leading to the difficulty?     

     Realize that attempting to discover the solution on a forum from afar is not really likely, but perhaps, some food for thought may be conjured.  And , you asked.     

     Sorry for backing up in the post, and my intentions are not to badger, but, generally in order to arrive at an accurate conclusion one must be systematic in ruling out distractions.  For example: the proper fluid to be utilized would be a Dextron II ATF product (not "gear lube"), and no one particular brand should be at fault in this issue.  Also, the instance of the grinding during shifting, this being supposedly executed with the clutch disengaged, therefore engine power potential is somewhat irrelevant, thou the boxes can be for racing applications somewhat R.P.M. limited.  I believe one should find the Tremec "Z" code T5 transmission a fine product, and capable behind most street intended Mustang/Shelby vehicles with S.B.F.s, with the potential of say 11 second quarter mile performances. 

     But, it ain't working for you, why?  Well, the problem seems to be that upon the engagement effort, the synchronizer-blocker-clutch ring as part of the synchronizer assembly fixed to the counter shaft, is not clutching the 5th gear and thereby not "synchronizing" the rotational speeds of the components.  Well, no s##t Einstein, but why? 

     It could be just defective relationship of manufacture in the applicable components, as implied previously, this is often the most difficult to establish "in the field", but is often the most comforting conclusion to those involved, other than the manufacturer.  And, I wouldn't hold my breath for some determination from Mexico confirming such, and if stated otherwise, it would only be by others accepted with some skepticism.  But it is possible!

     More often than not (in my experience), manual transmission shifting complaints such as in this instance, prove to be clutch operation related, hence Tremecs' early concerns in this arena.  One possibility, is that a relatively small rotational torque input is being applied, a sum that the other gears can, at least for now overcome, but that the 5th gear unit proves marginal in the task.  One should understand that the synchronizer assemble for the 5th gear is the smallest, least effective as compared to the others, within this transmission.  That understood, is the reason for my inquiry of how one established the "air-gap" value in my previous post.

     Allow me to present a perhaps, simple-stupid test procedure, that seems to work most often:  first, park the vehicle, engine off, on a prepared road/driveway surface with a slight incline, say 3° +/-, being held from rolling by transmission gear engagement only.  Now slowly depress the clutch pedal, at what point in the pedal travel does the vehicle begin to roll if only slightly?  Then continue to depress the clutch pedal, the vehicle should accelerate in its' rolling, now modulate the pedal finding the travel positioning that allows one to effect the rolling rate, above this the vehicle stops, below this there is no change in the rolling speed, this rage of pedal movement falls where in the available pedal travel?  There should be a travel sum both above and below the effected range before the carpet.

     Next, on flat ground, start the engine, allow a reasonable idle speed, at normal operating temperature, depress clutch pedal, place gear selector into any synchronized gear position, then place selector into the neutral position still holding the clutch pedal depressed, pause for five seconds, engage reverse.  Does the reverse gear engage without grinding?  Sometimes, particularly with beat-up gear sets (reverse) the gears will "blunt" and not allow engagement, but also not create any grinding, this is not our concern here, just try again.  What one is looking for, is by engaging any other gear in the box with the vehicle not moving you have halted any rotation of the clutch disc, input shaft, gear sets, etc., and maintaining the clutch pedal depressed and with the pause in neutral, the observation is whether these components are re-accelerated, therefore indicating an input value as the reverse gear is not synchronized.

     Also, there is driver technique to explore, but this is best accomplished with direct observation, and at times with care, as humans can be emotionally sensitive; but one topic we can preview, as pointed out previously, the 5th gear synchro is the weakest (and so is the gear set), and the differential in component speed is significant, so remember, the race is over once one chooses O.D., no speed shifting into O.D., it won't survive such abuse, allowing the R.P.M.s to drop in the execution of the shift is just good practice, besides you just traded the leverage advantage to the rear axle.       

     Scott.

[shelbydoug]

"Emotionally sensitive"? What'da mean by that?

[gt350hr]

   The latest T5 transmissions have synchronized reverse. Go figure. As Scott mentioned the brass synchro for 5th is tiny and the same one is used for reverse now. Another thing that troubles "me" is the 1-4 gears use carbon fiber material on steel rings and 5th and reverse are brass. the carbon fiber is fine with ATF but  "I" feel ATF lacks "extreme pressure" qualities and increases the wear rate on brass. This may be why Redline MTL is favored as a lube in these transmissions. You are not the first one to have these symptoms .
    rANDY

[Shelby_r_b]

This is all great information - thanks to all!  I'll keep you posted 

[Shelby_r_b]

Hmmm... I considered following in your footsteps on this swap, but now my T-10 is looking like a keeper. Can't wait to see how this sorts out. Certainly seems like a lot of trouble for a brand new trans. Who's paying the shipping & multiple installation bills?

Steve

Hey Steve,

Actually, Tremec paid for shipping both ways for the tranny and they have asked me to submit the ticket for R&I of the transmission this most recent time, and most likely for the upcoming swap.  I'm guessing they will try to pickup some or all fees for both.

[shelbydoug]

   The latest T5 transmissions have synchronized reverse. Go figure. As Scott mentioned the brass synchro for 5th is tiny and the same one is used for reverse now. Another thing that troubles "me" is the 1-4 gears use carbon fiber material on steel rings and 5th and reverse are brass. the carbon fiber is fine with ATF but  "I" feel ATF lacks "extreme pressure" qualities and increases the wear rate on brass. This may be why Redline MTL is favored as a lube in these transmissions. You are not the first one to have these symptoms .
    rANDY

The Redline MTL has "fixed" a lot of issues in the Pantera ZF transaxles. It costs about $9,000, to go completely through that transmission at the moment. So this could save about $8950 and a six month waiting period.

Do yourself a favor. Put this stuff in your transmission. See what happens. The worst thing is nothing. There is no way an ATF belongs in a manual box. That's some sort of Vodoo wishful thinking by some pencil neck somewhere.

ATF in manual boxes is to raise the Corporate Fleet fuel consumption average because of virtually no viscosity to it. It is not a performance upgrade.

My SHO came with ATF in it. At about 60,000, it started to get funky. I swapped out the fluid for the Redline MTL stuff. It immediately shifted better, smoother, and ran quieter then it did new. It's worked in every trannie I've done. It won't stop you from breaking shift levers though. 

[pbf777]

   The latest T5 transmissions have synchronized reverse. 
    rANDY

     Randy, perhaps you might be confused between the T-5 and the T-45 or the TR-3650, but I may be wrong, and that wouldn't be a first either, but I haven't seen any?       

     Scott.

[gt350hr]

    You know . old age is not a good thing. You're right . Reverse in a T5 is "in the case" and runs off of the 1-2 slider . T45s and 56s have synchro reverse because it's in the tail housing. My apologies to those I threw off course.
   Randy