Okay for starters let me just ask the mods to please not lock this thread even though it is 4th gen related, thank you. I have my camaro on ebay to pay for my "new" 1998 trans-am 6spd t56 (not ws6) the ls1's first year. i am planning on using the money i get from that to get my transmission fixed. All the gears cycle smoothly and without effort, except 6th, i have tried double clutching, lifting the rear end up on jackstands and tried to get 6th to work. even though its overdrive i would still need it fixed, i dont want to drive it like this much longer for fear of damaging something major. once i go to shift from 5th down to 6th the problem starts. you get a positive shift into the 6th gear gate slot and the stick goes in flawlessly, upon letting out the clutch however you get the infamous coffee grinder sound, but it does not attempt to jump out of gear so it in my mind is obviously not the gear itself (but I could be wrong). It sounds like the sycros themselves aren't completely engaged ( these are constant mesh aren't they?) or are not engaging properly like they are worn smooth or have somehow been knocked out of place and slid down the shaft inside. i have been through many sites trying to find anyone else who had a problem like this, the vettes had a similar issue but no f-body problems listed. so i have no other alternative but here. is this a problem (if anyone out on the many mechanics on here knows) that can be fixed easily or will i have to have the entire tranny rebuilt to even have a hope of fixing it? btw the drivetrain has 121000 original miles on it. Thanks, Alex

As long as it's just 6th, and not both 5th and 6th, there's a slight glimmer of hope.. It still will need to be rebuilt, but you're looking at a simpler job (only have to remove the tail housing, not the entire internals. Some shops may even fix it in the car, but it takes alittle more skill to do that)

Most likely the synchro engagement teeth have been shorn off the 6th gear. You'll need a new 6th ($125) and possible a new 5/6 slider ($125). If you're real lucky, it might just be broken fork pads and the grinding hasn't damaged 6th beyond repair. They would be $25 to replace.. You'll only know for sure once the trans is opened up.

mike

Dead on diagnosis. This isn't a big deal. Usually in a T56 you get problems with 3rd or 4th and then you have to tear the whole trans down to correct them. With the parts I could fix this in about an hour out of the car, so the labor shouldn't be too bad, and as noted the parts aren't real bad either. My T56 had a worn 5th/6th synchro when I rebuilt it, which I replaced, so I guess wear in this area isn't that unusual.

so it is just the syncronizer then? I'm not looking for a major teardown after all i guess. steven ( at bruce hawkins place you know hawks thirdgen) put me in contact with their tranny guy in pickens not far from where i live. he said it'd be in the $750-$700.00 range to do the syncro. I dont think its a broken shifter fork though because i have 5th gear and unless i'm mistaken 5th and 6th share the same fork don't they? thanks for the help and any more input and suggestions are more than welcome.

Alex

Not a bent 5/6 fork, broken fork pads. (black plastic stock ones) It's unlikely, but I've seen some come off with only one side remaining. I replace them all with bronze pads when i rebuild them.



(This is a reverse fork, but the pads are identical to the 5/6 fork)

Ohhh, okay i see what you're talking about now. would that cause it to behave in this way by not fully engaging the gear syncro with the fork (stopping short on the shaft inside) but still allowing the stick to notch into place in the gate?

Alex

Yes, because the pad takes up space and without it you have play between the fork and the slider. D&D has the bronze pads for about $35 a set I think. $700-$750 is highway robbery to a fix a simple problem like this. The T56 is a complicated trans, but you could probably fix this yourself if you can get the car up in the air and use a trans jack to get the trans out. I've even put T56s in without a jack using the old benchpress routine (I am pretty strong though in all fairness).

That price was for the set of syncronizers and to remove the tranny and install the new parts ( i would take the trans out myself, but I dont have equipment to do that, and i don't have the time to have my daily driver knocked out of commision for the time i would take to do it). also i am very familiar with the bench press technique ( ive just done it with a truck trans and no jacks were needed to get out from under the car on my back with a 85+ lb tranny on my chest). im also planning on looking into the condition of the clutch while i have the trans out ( i have no idea if the clutch is original to the vehicle but 121000 miles is a little bit long, imo). there is another shop here in town that i'm going to check with tommorow about a price.


all that aside, what i am getting from this is that the fork is the problem, not the gears or syncros (if they were worn i would assume i would not be getting any noise but im not that sure) causing 6th gear not to engage inside the housing, but still allowing the stick to float into the proper position ( that slight bump you get when the gear engages), then causing the grinding noise ( which is not as loud as i would think that a gear would be, it's somewhat quiet inside suprisingly), while not causing the stick to jump out of the gate.

Thanks,
Alex

Well, it probably started as a fork problem, but without disasembly it's tough to tell how far the damage goes now. It is entirely possible, in fact likely, that the engagement teeth on 6th gear are ruined from the slider running over the nose of them without being able to lock in. The synchro itself probably got spared. The slider may also be damaged. You could have $300 in parts to fix this properly. If the shop has a lift it shoudl only take an hour to pull the trans, another hour to fix it, and another hour to throw it back together. I'd say $200 for labor is about right. The problem is that if it's your daily driver you can't wait for parts, in which case you need to order everything and then send back whatever you don't need. I'd get 6th gear, the 5/6 synchro (you have to buy the whole assembly), and a set of bronze fork pads. Try www.ddperformance.com The bronze pads are $35 for the set, the 6th gear is $129, the 5/6 synchronizer is $119. That's $283 in parts plus shipping. That should be anything affected, and then you can just send back anything that you don't need, but I'd be prepared to have to repalce all of those parts.

Thanks for the help!! I'll get right on that first thing in the morning.

Alex

I'll put my vote in for http://www.thegearbox.org for the T56 parts.. Very good prices, fast shipping, and great customer service.

Your problem is most likely the bad engagement teeth now, but it was caused by other issues.. I'm pretty sure you'll need the gear/synchro/pads now though..

mike

Yeah, I ordered the parts just a few hours ago from the gearbox, I'm planning on getting the work done HOPEFULLY by friday. my local tranny guy said if i got it to him in the morning he'd have it ready for pickup that afternoon, for around $200-$275. i went ahead and ordered all the fork pads 1st-Rev, the synchronizer for 6th gear, as well as 6th gear itself.

Thanks for all your help guys, I'll be sure to post some pics of the parts replaced so you can see what happened and in better detail than i can describe ( and maybe it'll be of help to somebody else).

Alex

Mine too. I wonder why? I mean, it was the 5-6, and not the 3-4 that tends to get all the abuse. I thought it was kinda strange seeing 5-6 wiped out, but apparently its more common then I thought.

I think it's because when it comes time to shift into 5th or 6th you are absent minded about it (I'm not saying you in particular, just making a generalization). Usually you are shifting 1-2, 2-3, and 3-4 under power and you are very attentive to it. By the time you are shifting into 5th and 6th gear you are ready to cruise and you are just shifting those gears out of necessity.

5th/6th get wiped out because you're coming off a (4th) locked input/mainshaft to power engaging the countershaft and a loosely coupled extension shaft. The synchro on the counter/extension is suppose to ease the transisition from the 1->4 synchros on the mainshaft, but I've found that the poor/lack of shimming of the counter and extension leave alot of slop which translates to worn enagement teeth.

I've seen a couple of extension shafts shear the drive teeth off the countershaft because of the torque transfer to the overdrive. The viper 1pc counter-extension solved this on those units, but Mopar wouldn't allow Tremec to license it back to other mfgs until the 2006 Z06 units.

A preload on the countershaft and near zero endplay on the extension will help the 5/6 engagement last much longer than a stock setup.

Do you have a picture of the Viper extension setup? I'm curious because I've never messed with a Viper T56, only LT1 and LS1 versions. Can this part be purchased now? Is anything else affected when swapping it into an LT1 T56?

081108_viperGM-build/ Is a viper I had the input machined down to LS1 specs. There's pics of the 1pc counter in there and some showing how the REV drive gear is pressed onto the 1pc counter. With the Mopar financial situation, I'm not sure if they are available again. A few years ago you had to have a VIN from a viper to get one from MOPAR, which is why D&D stopped putting them into their units.

090215_LS7-T56_web/ Is a LS7/Z06 conversion I did, and you can see the new GM 1pc counter there also.. It's still an MM6 unit and could swap into any other MM6, except the 5/6 synchro is setup for the newer 2pc cones, so you'd have to put C5 or compatible 5 and 6 drive gears & synchros on this 1pc counter to use it. Since the extension uses a roller bearing instead of a taper, you'll need a spacer to fit the roller into a Fbody tailhousing to match the taper's race diameter.

HTH
mike

Wow, very informative. It's definately a better setup thatn the stock LT1/LS1. It's weak that Mopar has basically blocked it's use by people other than those who are working on a Viper. I guess Tremec was afraid they'd get in trouble because it might be licensed to Mopar. I would have told them to suck it. That technology should be available to everyone who owns a T56, not just those who own the rare (and I assume soon to be extinct) Shelby Cobra wannabe. The Viper just never impressed me, especially its price tag. If I was in the market for a car like that I'd either buy a Corvette and spend the difference on mods, or just spend a little more and get a twin turbo Porsche.

BTW, glad to see you using the News Journal for it's intended purpose. Man that paper's weak.

IT'S FIXED, Just got it back this morning.
EDIT*** it cost $562.08 (fluids and labor, they did everything and removed the tranny in house) parts were in the neighborhood of $375.00, but i get to return the gear so thats $115.00 back right there, so the grand total comes to around $812.08 for the whole project. it also should be noted that the car was there all last week and just got finished yesterday.
***
As to the above quoted statement I would like it noted that sixth gear didn't work when I got the car,
but no offense taken, i bought it from a WOMAN
(that was probably my first indicator as to what the problem could be)
SOMEHOW she managed to break the weld on the outer fork of the pair of push/pull forks (that connects to the stick linkage) on the shifter rail for 5/6 itself. (see pics) the gear itself was FINE, i only had to replace the syncro & rings (all the fork pads), and the 5/6 shift rail assembly. The only thing i'm having trouble grasping is how she managed to break it in the first place ( the woman is wife of the Co-owner of Harley-Davidson of Greenville ( thats S.C. ,not N.C.), maybe she's used to motorcycles, but in my personal experience those tend to be more fragile than cars), when i got into the car to go for a ride in it ( taking my life in my own hands i know) she was really rough on the gears and clutch way over shifting it. BELIEVE IT OR NOT, I, a 19 year old, actually tend to baby a car outside and even
more-so mechanically, I tend to do my own work on the car, and i guess that gives me a little more respect for what it takes to keep the car in good mechanical shape.
So my only theory that has proved to even be remotely possible
( the old "flying monkey" theory almost worked), is that she was just so rough on it that she broke that rail assembly by somehow managing to pull it sooo hard out of sixth that she broke a mediocre spot weld.
Any thoughts are welcome.
thanks for all the helpful input guys,
Alex

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