Another destroyed transmission....

[Wild one]

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

Have you checked your pinion angle Josh. Get ahold of Jason Dauria or John/Boosted Motorsports on High Performance Rams on facebook and see if they have any ideas.They've both broke transmission cases more then once,lol

 

[Josh22855]

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...

Yeah I remember seeing that on youtube.

 

[Josh22855]

Have you checked your pinion angle Josh. Get ahold of Jason Dauria or John/Boosted Motorsports on High Performance Rams on facebook and see if they have any ideas.They've both broke transmission cases more then once,lol

I actually bought the torque converter from Jason. I had set the pinion angle to -2° difference from the crank pulley angle.

 

[Wild one]

I actually bought the torque converter from Jason. I had set the pinion angle to -2° difference from the crank pulley angle.

You're in the ballpark at -2,i prefer -1.5 but -2 isn't really all that far out though. I always set them off the driveshaft yoke,but the crank pulley is in line with the driveshaft yoke. The 90's when built are holding 1100+ rwhp in the cars,so you're definitely not past the power level of the transmissions case,and usually they break the input shaft before breaking the case,which leads me to think it's got to be driveline related,as the cars use a solid mounted rear diff,while the trucks diff is suspended

 

[Wild one]

I actually bought the torque converter from Jason. I had set the pinion angle to -2° difference from the crank pulley angle.

You could try the old school trick of chaining the drivers side of the motor down,that takes a bit of play out of the motor moving around. This is how mine is chained down.

 

[Josh22855]

You could try the old school trick of chaining the drivers side of the motor down,that takes a bit of play out of the motor moving around. This is how mine is chained down.

Yeah I will have to do something similar to this, I'd like some type of support under the bell housing as well.

 

[Wild one]

Yeah I will have to do something similar to this, I'd like some type of support under the bell housing as well.

I don't know if the old school motor chain trick will keep you from breaking transmission cases,but it sure won't hurt to try.I'm old and every fast toy i've ever built always had a chain on the drivers side,and i've never broke a transmissions case,but i can't say if that's the sole reason or not,but i know it also doesn't hurt,lol

 

[mopareg]

Sounds like you are the problem, it's a truck not a Dodge Demon !

 

[blackbetty14]

powerglide it and stop wasting money on the 8spd. Normally when I see a case split its due to movement of the engine/trans. What mounts are you running? I always tend to use solid motor mounts and a interlocking poly trans mount and I've pushed 800hp through smaller and more brittle trans like a 2004R and never had any issues. You could also do a mid plate or motor plate... engine limiters etc.

 

[14ramdjh]

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.

you first few words said it all no sympathy from me buy a race tranny

 

[Marshall]

Yeah they all gave out at the track.

Maybe go to the V6?
I never had enough power to bust a transmission, have cooked a couple clutches back in the day.

 

[Dusty]

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.

Many years ago when Chrysler introduced the A727 they used a cast iron case for a number of years. Guys were putting stock A727s behind just about everything and they were holding up just fine. Friends of mine had one behind a horned-up 327 Chevy, then a 400 small block.

Then the factory went to an all aluminum case...and they started to crack and split, sometimes just like the one in your picture.

The 8HP internals may be up to the job, but maybe the case isn't.

Regards,
Dusty
2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 78778 miles

 

[Wild one]

Many years ago when Chrysler introduced the A727 they used a cast iron case for a number of years. Guys were putting stock A727s behind just about everything and they were holding up just fine. Friends of mine had one behind a horned-up 327 Chevy, then a 400 small block.

Then the factory went to an all aluminum case...and they started to crack and split, sometimes just like the one in your picture.

The 8HP internals may be up to the job, but maybe the case isn't.

Regards,
Dusty
2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 78778 miles

Guys are pushing over 1100 rwhp through the HP90's in the cars with-out breaking the cases,input shafts they're breaking,but not the cases.Regular cab shortbox trucks though are breaking cases fairly often,and the only real differances are the rear diff in the cars is an independent solidly mounted diff,while the trucks are a suspended diff that moves up and down and forward and backward under power on a hard launch,so i think it has something to do with the driveline behind the transmission more then anything.The cars also have a steady/center bearing while the 8 speed regular cab shortbox trucks have a goofy driveshaft with a slip joint and no center bearing,and it seems to be the 8 speed regular cab trucks that are breaking the transmission,as i've never heard of a 4X4 RCSB breaking a transmission case,or a longer 2 wheel drive truck that employs a center bearing

 

[Dusty]

Guys are pushing over 1100 rwhp through the HP90's in the cars with-out breaking the cases,input shafts they're breaking,but not the cases.Regular cab shortbox trucks though are breaking cases fairly often,and the only real differances are the rear diff in the cars is an independent solidly mounted diff,while the trucks are a suspended diff that moves up and down and forward and backward under power on a hard launch,so i think it has something to do with the driveline behind the transmission more then anything.The cars also have a steady/center bearing while the 8 speed regular cab shortbox trucks have a goofy driveshaft with a slip joint and no center bearing,and it seems to be the 8 speed regular cab trucks that are breaking the transmission,as i've never heard of a 4X4 RCSB breaking a transmission case,or a longer 2 wheel drive truck that employs a center bearing

Interesting. Are the folks with cars damaging or tearing out their center bearings?

What about vehicle frame flex?

Regards,
Dusty
2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 78778 miles

 

[Silver21Ram]

I definitely wouldn't ever make another pass without the hold down chain.
You've got a twisting problem combining with the differential angle while under a load.

 

[TomB 1269]

If you are cracking the bigger tranny where the smaller trans would burn out clutches maybe you need to look at your launch. From your pic. I see left front off the ground well but right front still in contact with the track. That's a lot of torsional twist.
Are running any frame stiffening?
Are you running a chain or torque plate engine mount to keep the engine from trying to roll over in the engine bay?
I am willing to bet the 8HP90 is transferring the power were the 70 could not fully hold up, and the result is torsional roll/twist in the drive train and frame that's exceeding the tanny case limits.

 

[Wild one]

Interesting. Are the folks with cars damaging or tearing out their center bearings?

What about vehicle frame flex?

Regards,
Dusty
2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 78778 miles

Not so much ripping the center bearing apart,but they are literally twisting the stock driveshafts into pretzels,but they're not breaking the tranny cases

 

[Wild one]

If you are cracking the bigger tranny where the smaller trans would burn out clutches maybe you need to look at your launch. From your pic. I see left front off the ground well but right front still in contact with the track. That's a lot of torsional twist.
Are running any frame stiffening?
Are you running a chain or torque plate engine mount to keep the engine from trying to roll over in the engine bay?
I am willing to bet the 8HP90 is transferring the power were the 70 could not fully hold up, and the result is torsional roll/twist in the drive train and frame that's exceeding the tanny case limits.

The high horse Hellcat guys are picking the left tire up noticably higher then the right front tire,and they're not breaking transmission cases,but that doesn't rule out frame twist under launch on the trucks not being the issue though. Both the cars and trucks use a viscose motor mount that allows a fair bit of motor twist under power. Combine motor mount flex and frame flex together and that might be why the regular cab shortbox trucks are breaking transmission cases

 

[Josh22855]

That profile picture was with a 1st gear leave with a built 8HP70, that was the last time that I have left the line from 1st gear. Now I launch from 2nd gear and front end stays on the ground. Does anyone offer any more suitable motor mounts for my application? Also where could I find that turnbuckle/chain that you used on the driver side of your engine?

 

[pacofortacos]

Any wheel hop/shudder at all? Even later down the track?
Wild one might be onto something with the live rear vs. solid mount rear.

It's definitely hooking up on launch