Another destroyed transmission....

[Josh22855]

My 1st pass down the track and my 8hp90 blew apart and caught on fire, I have no idea what caused this. My truck has destroyed a stock 8hp70, 2 "Built" 8hp70's and now a stock 8hp90. Does ANYONE make an 8 speed that can hold decent power? I have wasted a TON of money on these transmissions that cannot survive a single pass down the track.

 

[Doug Ram]

Were the other transmissions destroyed on the track too? If so, I'd say that the problem is that the truck just wasn't designed or built for the "track".

 

[crazykid1994]

How much power are you putting down? Also it’s cracked at the bell housing so what happened? Wheel hop? Bad trans mount? Bad motor mount? Any vibrations before hand? That doesn’t seem right that the actual transmission casing is broken. I don’t think that’s a transmission issue. More of a truck setup issue. How’s the other transmissions fail? What wheel and tire setup do you have. Is your frame twisted or flexing severely when this happens? Lots of guys running built 8hp70s with no issues. Lots of guys with built 90s and no issues running over 1000hp. @Wild one crazy

 

[Josh22855]

Were the other transmissions destroyed on the track too? If so, I'd say that the problem is that the truck just wasn't designed or built for the "track".

Yeah they all gave out at the track.

 

[Josh22855]

How much power are you putting down? Also it’s cracked at the bell housing so what happened? Wheel hop? Bad trans mount? Bad motor mount? Any vibrations before hand? That doesn’t seem right that the actual transmission casing is broken. I don’t think that’s a transmission issue. More of a truck setup issue. How’s the other transmissions fail? What wheel and tire setup do you have. Is your frame twisted or flexing severely when this happens? Lots of guys running built 8hp70s with no issues. Lots of guys with built 90s and no issues running over 1000hp. @Wild one crazy

Zero vibrations, failure happened at 133mph between 5th and 6th gear just prior to the end of the 1/4 mile. Motor mount and Trans mount look fine. Bogart wheels, hoosier drag radials. I am in the ballpark of 800HP without the nitrous. The Built 70's were failing by burning up the clutch packs.
I'd like to know how it failed...it blew the starter out of the housing also!

 

[EdGs]

Zero vibrations, failure happened at 133mph between 5th and 6th gear just prior to the end of the 1/4 mile. Motor mount and Trans mount look fine. Bogart wheels, hoosier drag radials. I am in the ballpark of 800HP without the nitrous. The Built 70's were failing by burning up the clutch packs.
I'd like to know how it failed...it blew the starter out of the housing also!

Holy horsepower, Batman!

Following....

 

[Burla]

What is the torque on that 800hp? Oddly the 8 speed has larger max torque then the 68rfe, but you are probably well over the limit of 663? If not over I'm sure you are close, pushing the limit.

 

[caulk04]

How's the tune? Has anyone looked at data or tried anything different in the tune?

 

[Josh22855]

Tuner will review data log tomorrow. It's a crappy feeling destroying 18k in transmissions from 3 trips to the track. Very bad weekend to say the least

 

[Josh22855]

What is the torque on that 800hp? Oddly the 8 speed has larger max torque then the 68rfe, but you are probably well over the limit of 663? If not over I'm sure you are close, pushing the limit.

Not sure the torque, it's a stroker with a procharger....the torque is definitely there

 

[Doug Ram]

I am in the ballpark of 800HP without the nitrous. The Built 70's were failing by burning up the clutch packs.
I'd like to know how it failed...it blew the starter out of the housing also!

How much torque?
Were the transmissions really made for
- such power?
- track days?

 

[Doug Ram]

Tuner will review data log tomorrow. It's a crappy feeling destroying 18k in transmissions from 3 trips to the track. Very bad weekend to say the least

I wish I could afford that kind of hobby.

 

[Josh22855]

I wish I could afford that kind of hobby.

.....it's nothing but a headache.

 

[Burla]

Do you know what gear you were in with all 3 fails? Each gear has a torque number. I guess now you are in something different, maybe you can figure that out, but you can look at correcting the torque in 5th, maybe fix it for next time. @Wild one

 

[crazykid1994]

Not sure the torque, it's a stroker with a procharger....the torque is definitely there

Which engine? I was looking at a 6.4 bge. Pro charger keeps crossing my mind. I have the 6.4 manifold so buying the pro charger setup for a 6.4 is definitely sounding nice dropped on my 5.7 till I detonate the engine but I may cam it. Idk. Or pull apart my 5.7 and build it but I’d rather buy an engine to drop in. Just don’t have 20-30,000$ to play with currently. I need the truck to still be streetable and used for towing plus I’m lifted on 35s. That’s definitely odd it blew the starter out. Any issues known with the TC? Was it locked up when it cracked the bell housing? Any issues with the flex plate? Guess when you do a tear down you can see if the transmission locked up in a shift

 

[Josh22855]

Do you know what gear you were in with all 3 fails? Each gear has a torque number. I guess now you are in something different, maybe you can figure that out, but you can look at correcting the torque in 5th, maybe fix it for next time. @Wild one

The other fails on the HP70s were 1st to 2nd burning up then 2nd to 3rd burning up....this failure was from an 8hp90 I bought from Ebay claiming it had 8000 miles on it. I have not looked into the failure yet, it is still loaded up on the trailer.

 

[Josh22855]

Which engine? I was looking at a 6.4 bge. Pro charger keeps crossing my mind. I have the 6.4 manifold so buying the pro charger setup for a 6.4 is definitely sounding nice dropped on my 5.7 till I detonate the engine but I may cam it. Idk. Or pull apart my 5.7 and build it but I’d rather buy an engine to drop in. Just don’t have 20-30,000$ to play with currently. I need the truck to still be streetable and used for towing plus I’m lifted on 35s. That’s definitely odd it blew the starter out. Any issues known with the TC? Was it locked up when it cracked the bell housing? Any issues with the flex plate? Guess when you do a tear down you can see if the transmission locked up in a shift

It is on a 5.7 based 6.5L.

 

[G-Ride990]

I really don't know enough about this to add anything too valuable to this discussion but that looks an awful lot like the cummins transmission failures I have seen watching youtube videos. I guess that is a big enough issue that a few companies offer transmission case braces to help with that. Maybe that is something to look into?

 

[EdGs]

You mentioned in your other thread about the transmission swap that you had to drill holes for bolts, and could not put one or more in, might that have anything to do with the case integrity?

I know absolutely d*ck about this stuff, but that crack in the bell housing makes me think there was twisting for it to fail like that.

I wish you the best on finding the cause, and for a solid solution.

 

[Hemi395]

I know Boostedmotorsports had a similar failure on his Hellcat swapped Dakota, he thinks it has something to do with driveshaft vibration. He still hasn't found the exact cause but it literally blew the trans apart. Very similar to your failure...