Transmission Input Shaft Broke and Took the Clutch
 

Has anybody had any issues with the input shaft on the Tremec 6060s. I do 0 launches or dig racing, mainly just doing pulls and air strip stuff. The other day, I downshifted gave it about 60% throttle to merge traction control kicked in and as soon as it did my trans went....I’m making about 930hp and I understand that’s a lot, but I know several cars that are still going strong with similar power, and besides like I said I don’t do any launching or anything. I’m a little pissed because it also took the clutch with it, and that was a brand new monster clutch.

Sorry that happened to you, but 930hp on parts that were designed for 455hp??? That is over double the design power...

probably the most common part failure i can think of on tremec trans. a friend of mine did the same thing to 2 of them with a terminator car. stock one and upgraded both. stock one lasted way longer haha.

Its torque anyway and in 3rd up you can use WOT torque, 560ish HP is what the trans is rated at; probably about the same in torque. It had cracks and micro cracks for a while. In higher gear there is no / little tire slip and this is where the input shaft has to turn a harder (less multiplication) ratio on the countershaft, so this is where the input shaft will fail.

You had me at 930 hp, lol,
That’s a lot of power to expect any stock part to hold, I’m a little jealous

anything is only as strong as its weakest link, your 60% shock load twisted it pretty easy by the looks

The Tremec TR-6060 six-speed manual transmission features six forward speeds and one reverse speed. The TR-6060 contains removable wear pads on the shift forks, and uses aluminum alloys for the main case, extension housing, and clutch housing. It is manufactured by TREMEC (formerly Transmission Technologies Corporation) and is rated for 600 lb⋅ft (810 N⋅m) of torque. around 650 HP.

https://www.tremec.com/anexos/TREMEC_TR-6060_1017.pdf

The SS has the C trans 560 ft lbs

id guess traction control jolting it wasn’t helping matters. tq ratings are to be taken with a grain of salt. i’ve seen plenty of t56 hold up to 700+ hp in light(er) vehicles. i think they’re rated “450”?

well they are basically the same trans, and trans strength is basically determined by the distance between the main shaft and the counter shaft. That said, the trans is rated at 560 ft lbs and it is a torque thing. Depending on the supercharger this can be WAY overloaded, it is the repeated twisting of the shaft that causes micro-tear. Put it this way
in the old days we would scribe a new axle down its length and when it reached 1.5 twist (forget now) we would toss the axle. That is how much twist progression we are talking about. This causes micro-tears in the material that will cause a spiral failure point.


https://threepedals.com/blog/technic...trofit-tr6060/

AFAIK the T56 Magnum ahem TR6060 has thinner synchros that allow it to have more gear with (larger contact surface). Since the gears are more conventinal single gears, there is more room for a larger gear, vs a single piece cut into two gears (need room for cutter). The input shaft has more splines and a larger bearing.

Just found the article:

http://www.superchevy.com/how-to/tra...rque-capacity/

This is what I don’t understand about the torque management on launch. The higher gears put more stress on the parts than first so why are they protecting the wrong gears :bonk: Does the shock from dumping the clutch multiply the force or something?

I remember looking the tranny up before buying my car and thinking it was strange that it was rated for less power than the car is rated to make. I just assumed Chevy had upgraded them somehow after not seeing people complain about them breaking a lot.

Is an upgraded unit available?

Gl on the repairs OP, can only imagine what a beast that car must be :happy0180:

There are two non-related issues.
1) The input shaft failure is related to torque at the flywheel, being transmitted to the trans. In the higher gears, where there is a combination of traction and less to even negative torque multiplication (5th and 6th) the max torque is being transmitted to the input shaft. This is especially true for tightly spun smaller PD type superchargers. The failure point probably started in one of the spline base and slowly worked its way into the shaft. The type of cyclic twisting failure is NOT unusual.

2) Trans strength overall is the ratio between the gears. This is due to the fixed distance between the main shaft and the countershaft, for first gear to get the ratio one gear has to be BIG and the other small, the smaller gear also has drastically less lever arm to its associated shaft, combined with less teeth contact area (smaller diameter). Hence it is easy to see that the larger the 1st gear ratio the weaker the trans, it is a basic physics issue. To make the trans stronger one has to decrease this ratio (obviouse for the loading chart alread posted). Sure diffeent alloys, heat / cold treatment, surface hardening etc can all help, but I'm trying to illustrate basic design here. So most transmission failures should be in 1st gear.

Sure no doubt about it, the more traction the better the clutch, the more potential for trans failure either 1st or input shaft / output shaft. I had autos in most of my V8 cars so I'm unfamilar with the T56 and its siblings. So I don't know the common failure points. I would assume there are input shafts with more splines that are at least surface harden at the splines. I'm also sure there are ways to make sure 1st gear does not blow up (either less ratio replacemnt or a performace intem of some sort).

https://www.hotrod.com/articles/buil...mageId=1000077here is a picture of a polished cryo shaft

Welp, life is expensive at 930 hp.