Tom400CFI

Wife was driving the car ('05 CTS-V, 125,000 miles) last night (on the highway, 6th gear) and the trans started making noise -like very loud bearing roar followed by some intermittent "banging". She pulled over and I went to pick her up. I went to go look at it yesterday AM. Basically, idling in neutral, it "hitches"/"Catches" and makes the rear wheels want to spin backward (?) When I put it in gear and try to drive forward, it goes, but makes what sounds like a "box of rocks" noise and does the "hitching/catching" thing some. It will make the "hitching/catching" whether the input shaft is turning, or the output is turning (even w/the engine off). Lastly, I tried to back up and could not get it into reverse. Shifter would go to the "reverse" position but all I'd get was a faint grinding sound. After repeated attempts, I got reverse.

Removed the drive shaft and towed it home. Now I have to pull the F'n trans and tear it apart...I guess.

Yeah it's not a C5, but the trans is functionally the same. Anyone have something like this happen that can share? I'm a little irritated right now..T56 shouldn't be falling apart on a stock car, at 125k.

Tom400CFI

No T56 rebuilders here, huh?

Got the trans out last night. WHen I turn the output shaft by hand, it feels smooth and easy (the way it should), then it start to bind and get a "gritty" feel. I guess I'll tear it apart today and see what got hurt. Rebuilt plenty of T5's, but never been into a T56 before...

Tom400CFI

Well, on the outside chance that a C5 owner decides to venture into their trans, and has the symptoms that I have, here is what I found. It's not good.

The reverse gear bearing failed. Took out the reverse gear I.D., Main shaft, reverse synchro, and a plethora of other hardware. IDK why it failed, which is a little frustrating.

I guess I will try pricing parts and compare that w/a new trans


Here are some pics for the very bored...


















It's a lot of carnage for no beatage.

4DRUSH

Man, that's disappointing for a stock car (thanks for the very bored person pictures)

Ray 2000 C5 FRC

I know you are not concerned WHY it failed, but from the pictures, it looks like a lot of heat was built up on the cluster gear where you can see the metal fused to the shaft. I am curious to know how long ago since the fluid was changed, and with what brand.
Ray

Tom400CFI

Fluid was changed about 15,000 miles ago, Amsoil.

I think there was a lot of heat b/c there was no longer a bearing in there. That is my guess.

I'd lOVE to know why it failed. Stock car. Woman/DD, mostly highway miles...doesn't make sense. To me anyway.


EDIT: Correction, I thought that I did the 'Vette and the Caddy at the same time, and bought Amsoil for both, but I guess that's not right. It looks like I used Mobil 1 Synthetic ATF. Thread Here

Sigforty

Had the same thing happen to me a few years back. No clue what caused it, but I used it as an excuse to upgrade to the 300M main shaft from RPM.

Bill Curlee

What are your plans for a repair?

Bill

Tom400CFI

IDK yet. I'm trying to get pricing on the main shaft, gear, bearing, synchro, and the other hardware.

Also looking at prices for used transmissions (which they're pretty outrageous, IMO).

I will probably end up rebuilding it myself, but have to see what the options are still...

LateBreak

Ouch, sucks that it chewed up the mainshaft

I'd rebuild if you can find the parts, the used ones are outrageous due to their value for swaps.

QCVette

That looks like a lot of damage for not extreme use.

It has been a long time since I worked on manual transmissions, but I remember that when it got into the main shafts or gears it got real expensive in a hurry (anything more than the simple common wear items like synchronizer rings, bearings, shift forks, etc.) It used to be less expensive to get another transmission, but I looked at some T 56's and they are wanting a lot for used ones.

Good luck on finding a less expensive way to fix it.

Tom400CFI

Thanks!


Fix the trans I have. Parts are on the way. Rockland Standard Gear has the Main shaft, synchro assy, blocking ring, bearing, washers and hardware, all in stock. $600.00

Parts should be here end of next week, so I'll be able to move forward w/it then.

Bill Curlee

Here is a good post to review for your rebuild.. Its an excellent pictorial over view with some great info.

- C5 ragtopws6, T-56 Build (whats in my tranny?) : http://forums.corvetteforum.com/nort...-smoother.html


Bill

Tom400CFI

Wow, that thread is fantastic! Thanks so much for sharing!

-Tom

Bill Curlee

Tom

I know that you have parts and most likely KNOWLEDGE but,,,, if you have qusetions,, Contact Rick Kim at RKT56 if you have any questons or need additional parts.. He is the GO TO GUY for trans & Differential info.. He will have those last minure HOLY CRAP parts you will need!!!

Bill

C66 Racing

I used Rick to rebuild my diff two years ago - very knowledgeable guy.

Sorry to see that failure. I think this is the first time I've ever seen this - ouch.

Had an 06 CTS-V as a daily driver for years. Had to sell it when I moved to DC (and daughters also went to college). Really liked that car. Hope you get yours back on the road.

Tom400CFI

Finally got it back together and running. Took a while...first deciding the best route to take, which turned out to be fixing it myself, then order parts, parts came, and that is when I discovered that parts had changed, which required....more parts. That took another week to get, then I got it together and in the car Friday. Grand total for parts was ~$900.00 from Rockland Standard Gear. Ouch....but small potatoes compared to a trans assy.

Here is a pic w/it disassembled. Reminds me of Dr. Seuss, and "poor Herbie Hart, who apparently has taken his “Thromdibulator” apart" Anyway...



So, apparently there was a "design change" to the mainshaft at some point, the way the 1-2 synchro hub is retained to the shaft. That necessitates a new first gear and the retainer parts. Here is a pic of the two shafts, side by side. Note the width of the snap ring groove by the synchro hub:



The snap ring groove on the new shaft is nearly 1/4" wide!. The "new design" uses two 1/2 circle pieces that fit in that wide groove, and then a collar slides over those, to retain them. The "new design" first gear has a grove machined out of the ID on the synchro side, and that fits over the retaining ring to hold it in place. I wonder what was wrong w/the first design, simple, snap ring? The re-design cost me an extra ~$300.00.


Here are a few more random pics during reassembly....









And finally, back in the car...





Here are the parts that were left over; either damaged, or not reused as a result of the update:





So.....does it work??
Like I said, finished it up Friday night, then Saturday morning, it drove great on the way to the dyno-day, where it put down a slightly disappointing 325-338 RWHP...but didn't break or make any noises. From there, I drove to the local drag track and did a few T&T passes w/the car and it handled all of that hard use gracefully and w/o issue. I filled the trans w/Pennzoil Synchromesh, and it shifts the best it ever has, at this point, but in general, it seems great! Quiet, smooth....hopefully the reverse bearing holds up for another 125k miles....or longer! We'll see. I'll tell you what...that trans is a LOT more complex than the Borg Warner T-5, and other manual trans' I've rebuilt!


.

Bill Curlee

Great job on the repair and reassembly!! Glad it worked out without a hitch.

What exactly caused all the issues. Can you take a close up and detail the damage??

Bill

Tom400CFI

Sure thing!

What caused it was the failure of the reverse speed gear needle bearing. IDK why it failed, but it did. The gear hogged it's ID out, and beat up the mainshaft. It wobbled and took out the reverse synchro ring, thrust washers, release wave washer, snap rings and it ground on the reverse synchro hub a little too. Here are the pics. Not high res, but you get the idea...

In this first pic, you can see the reverse speed gear and if you look closely at the ID you'll see that it's buggered. Also, where that gear runs on the main shaft, you'll see that surface is ruined...I actually had to grind on it w/a die grinder some to get the rev. synchro hub off the shaft, b/c the bearing running surface was so "peened" and beat. Last, the needle bearing is gone (attached to the magnets) and all the associated hardware was ground to dust.




Here is the synchro ring.

strand rider

Thanks for the post, it gives me some understanding of what I may be dealing with at sometime in the future. I say that because in my reading on this site, it has been repeated that the service interval for the transmission bearings is 125, 000, miles.

Perhaps that info can be my contribution to the post, my only transmission experience is looking into the transmission case as the various broken parts were pointed out to me.

Your pictures have helped my understanding. Like yourself, the thought of transmission service at that milage was in opposition to my experience with cars where you could think of the transmission as a lifetime part, as much as you can consider a part lifetime , like an engine or a rear end , you don't expect to tear them apart in normal use.

So as my corvette milage went up, I started to wonder how necessary this service interval really is. I've seen so many cars run without problems for longer, I was wondering if perhaps I could ignore the printed info, perhaps it was lawyer driven, and didn't apply to normal use .

Just some "what if" thoughts since I will be hiring out the work, and just the labor cost to get to the tranny could probably set me up with all the tools needed, then I would just need the space, experience, skull and interest, then I could do it myself. That's why I was turning over different possible outcomes and actions in my thoughts.

Your pictures killed my extended milage fantasies deader than Smokey the bear's campfire. I always knew how modern cars are built, but was hoping to find some conformation that expectations of excessive milage over the service interval were not crazy beyond reason. I will still be gathering understanding before the work, I just won't be expecting miracles .