[Tom400CFI]

WIfe was driving the car last night and the trans started making noise -like very loud bearing roar. She pulled over and I went ot go look at it this 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).

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

 

[mac_henderson2001]

Well hopefully there will be some good parts left in it and you won't have to buy a whole new one.

Good luck man!

 

[Andringa]

That sucks.

Not sure if you plan to rebuild it yourself, or pay for the work. But many people have been happy with the work that RPM does and they offer a core exchange if you want to get back on the road as soon as possible.

$2400 includes a rebuilt trans and shipping to you. You still need to pay to ship your old trans back.
http://www.rpmtransmissions.com/page31.html

Best of luck.

 

[Tom400CFI]

Thankis for the link. I'll add them to my list of people I get prices from

Well, 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. Fluid was changed about 12k miles ago, w/Mobil 1 Synthetic ATF.


Here are some pics for the very bored...


















It's a lot of carnage for no beatage.

 

[07cadv]

Ouch.....

 

[SashafromTO]

Sorry to see this!

 

[Tom400CFI]

Parts are on the way. Rockland Standard Gear has the Main shaft, synchro, assy, blcoking 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.

 

[Charlie Costello]

Mine did the same thing three years ago. Had RPM rebuild one for me. Due to the lack of the tail shaft housing on these transmissions, the oil does not wick back on one shaft, thus the trans fails like it did. I have 66k miles on the rebuild without issues, but the original had 99945 miles when it locked up on the highway. Abuse is not a factor since I have not hogged on mine at all like some people do. Just a personal preference. Good luck with the rebuild.

 

[Tom400CFI]

Interesting. Thanks for posting. I had one fellow comment on the C5 Corvette Forums, (I also posted there too) that he had the same issue in a 'Vette application. I wonder if it's just a bad/faulty bearing...or if a lack of lube is the real issue. Would more oil in the trans help? IDK.

 

[darien99]

Your initial post sounded like a lot of the problems I experienced in my transmission. I sent mine off to RPM and got one they rebuilt, I meant to ask them to let me know what they found out was wrong with mine, but i forgot. Now I'm curious!

 

[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 groove 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, a simple snap ring? The re-design cost me an extra ~$300.00. :annoyed:

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. :lol: 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!

 

[mac_henderson2001]

The synchromesh fluid really help these things shift better?

 

[AAIIIC]

What did you use as a guide for the tear-down and reassembly?

 

[Tom400CFI]

I found some images on the 'net to get started and get an idea of this particular trans' architecture, then relied mostly on memory, and previous trans rebuilding experience. Ironically, I discovered after I was finished, that you can down load the service manual from the Tremec web site....Get it HERE.

The synchromesh fluid really help these things shift better?

Comparing the ease of shifting with previous to the repair, using Mobil 1 Synthetic ATF, i'd say that the shifting is ~50% easier. By that, I mean the resistance imposed by the synchros has dropped by about 1/2. The T56 is a trans that likes to "fight you" when engaging each gear....more so the faster you try to shift it. Yes, my experience here says that the Pennzoil definitely helped. FWIW, I just switched my 'Vette ('92 C4 w/the ZF-S6 trans) from it's factory fill, to AMSOIL Synchromesh and the shifting got worse, especially when cold, so I'm not loving that brand of "Syncromesh" oil. I will probably swap that one out to the Pennzoil too.

 

[odla]

Thanks for the link on the manual.

 

[ctsv247]

I see the shifter base modifications you made are still hanging in there. Do you have shifting experience in a non modded v to compare this too since doing this mod?

 

[Tom400CFI]

Sure thing. Wish I'd have known about it before I started!

 

[ctsv247]

Sure thing. Wish I'd have known about it before I started!

Not sure i understand what you're saying...

Based on your shifter base mod, I modded my base the same way but had to abandon it right after putting it in because I had to realign the driveshaft and I made the base too tall to allow for that. I tried to quickly mod it so I could put it back in the car but I ran out if time so I slapped the stock one back on.

So what I was wondering is have you had a chance to drive a stock v and compare it directly to yours with them modified shifter base?

Thanks!

 

[Tom400CFI]

Sorry, I was replying to the poster above who said thanks for the manual.

I have not driven a stock V since doing the shifter base mod. Only comparison I have is when mine was stock to when mine was modded. I still like the design and think that it is the right way for a shifter to be supported. When I had the trans apart, I was this close to having a machine shop lengthen the rear shift rail so that it protruded from the rear of the trans, and tying it into the shifter directly w/a s precision U joint. That, IMO, would complete the solution to the 'V's shifting deficiency -eliminating the ~20 pieces between your hand, and the internal shift rail. But...I didn't do it. What I've got now is the modified base, Pissnuoff's Hurst shifter and it works pretty darn good. It's quiet and I didn't use any of the rubber isolators to deaden sound. Good enough.

 

[ctsv247]

Sorry, I was replying to the poster above who said thanks for the manual.

I have not driven a stock V since doing the shifter base mod. Only comparison I have is when mine was stock to when mine was modded. I still like the design and think that it is the right way for a shifter to be supported. When I had the trans apart, I was this close to having a machine shop lengthen the rear shift rail so that it protruded from the rear of the trans, and tying it into the shifter directly w/a s precision U joint. That, IMO, would complete the solution to the 'V's shifting deficiency -eliminating the ~20 pieces between your hand, and the internal shift rail. But...I didn't do it. What I've got now is the modified base, Pissnuoff's Hurst shifter and it works pretty darn good. It's quiet and I didn't use any of the rubber isolators to deaden sound. Good enough.

Food for thought...I've got a spare transmission laying around....