Help, 2 gearboxes distroyed in one day

[SteveBCloud9]

It would seem that these tranmissions don't like the load on them at 100mph+ for extended amounts of time..... Paolo, maybe you can elaborate......

 

[Ron]

<FONT face="Comic Sans MS">Thomas;

Just out of curiosity were they running Dextron III or Syntorque trans fluid?

A while back there was a post by someone that had a transmission shop that could get whatever trans parts one could want. You might want to do a search to find his number.</FONT f>

 

[Tom and Vipers]

An inspection of the transmissions would be of great interest.

While I have not worked on the T56, I have spent a lot of time rebuilding and modifying 4-speeds from the 60's.

What is interesting about the T56 is that it is essentially a 4-speed with 5,6,Rev added on.

There is a "conventional" cluster gear for 1-4 which is supported in tapered roller bearings. The sliders are on the mainshaft as in virtually all manual transmissions.

What gets bizarre is how they implement 5-6.

At the tail end of the cluster gear (1st gear end) there is a cluster gear extension shaft. In fact, this shaft is more like a main shaft in that the 5-6 slider is on it and NOT THE MAINSHAFT.

The Rev slider IS on the mainshaft.

For a single failure to drop 5,6,Rev, it would have to be the cluster gear extension shaft spline somehow becomming disconnected from the cluster gear.

If it was the 5-6 slider, you would still have Rev, and if the Rev slider, you would still have 5-6.

This single failure seems quite unlikely because it would involve the complete failure of the spline connecting the cluster gear to its extension shaft.

Hummmmmmm.

Perhaps, there is a selector/slider single failure that would disable both the 5-6 and Rev.

An autopsy would be worth a 1000 words.

What were the symptoms of the failure?
Were there any noises suggesting a gear or spline failure?
When the failure occured, did the shifter pop out of gear?
Does the shifter seem to shift properly?
When hunting around 5,6,R with shifter, does it seem like the synchros are still "there?"
Can you hunt around 5.6.R with your foot off the clutch?
Was there any debris in the trans oil?

Please don't be hesitant about opening the gearboxes and rebuilding them. Internal parts should be readily available in the US. I would think that any shop that repairs manual transmission could rebuild the T56. I would also be skeptical about anyone who said these transmission were special and could not be rebuilt. I would also check on internal part prices in the US to be sure I was getting a fair shake by the rebuilder.

 

[Robert1994]

My car has a "missing" 5th gear. The shifter moves into 5th
and goes into the detent postion, but when you let up on the clutch, there is only painful grinding sounds.
1st thru 4th are just fine, as are 6th and reverse. I've
been able to drive the car and just go 4th to 6th without
any problem, but I'm afraid that one of these days a broken
tooth will get sucked up into the cluster gear and destroy
everything.
I bought another trans and am having it gone thru before
I swap out the old one. When this is done, I will rebuild the
the original and have it for sale.
In any event, complete transmissions or parts are readily
available. If you have supply problems please contact me.
I will be happy to help you. Shipping is no problem.
Aloha, Robert

 

[RoyV101621]

I have found we have the same part rarity in the states.
JonB and Frank from Phoenix Transmission where the closest I could get to parts for the T-56 before I decided on a new transmission.
Frank is a Viper owner and was willing to help me if I could get the part description to him. Try leaving Frank e-mail at the web site.

 

[Bob Woodhouse]

Interesting: Many of our transmissions used in Viper Racing League have been losing their 5th gear. We are rebuilding them on a regular basis. Parts and service questions are available with my Crew Chief/Viper tech Rick Maxwell and Viper administrator Nancy Shanno at [email protected] or 800 889 1893 or contact thru the web site at www.woodhouse.com/viper. We are not sure we know all of the reasons for the failures but I suggest that you be mindful of shock loading such as being too quick with the clutch when rpm's are not matched well.

 

[Tom and Vipers]

Looks like my cluster extension shaft guess was correct.

This 5th gear loss, is it the slider nubs or the gear itself?

I have seen T56 gear teeth that have worn/eroded away to the extent that the tip of the tooth was a sharp "knife" edge.

I have never seen this type of wear in a muscle car 4spd.

Big difference with T56 is the high helical angle, smaller tooth Pith Diameter PD, and use of ATF.

The high helical angle may produce a different "type" of wear relative to the lesser angles and spur, however, hypoid (differential) do not seem to have a problem.

Another concern is the use of ATF.

This is not used in differential or muscle car 4spds which do not exhibit tooth erosion.

I suspect the use of ATF may be more related to CAFE. There appear to be synchro friction surface mods associated to the ATF.

A better fluid may be CAT Power Train Fluid which is a "thicker" ATF fluid. This has been recommended for use in Variable Pitch TH400 transmissions by Poston.

I am concerned that traditional Gear lube may reduce wear observed in T56, however I am in no position to determine this.

I am very disappointed in the "cheesy" cluster extension shaft implementation.

Most unfortunate. If the Gen3 uses the T56, there may probably be an upgrade here. If they don't use the T56, may be time to upgrade to the new trans.

 

[Tom and Vipers]

You may with to talk to Norm Brandes at Westech Automotive about T56 parts. Norm's number is (262) 889-4346.

I believe he is familiar with this failure as well as rebuilding and upgrades.