Lookin for some tech advise. About a month ago I was driving on the highway coming home from a car show. Cruise control set, all the sudden the engine RPM's shot up and I lost ALL gears. No reverse nothing. Got her home and hooked up the pressure gauge. Started it up and the needle on the gauge didnt move a lick in any gear. Ok we have a pump issue, not usually a normal failure but ok. Removed trans and pump and seperated. Found this:



Pump rotor broke into 4 pieces. The converter snout was slightly gaulded and heat checked but nothing that cant be cleaned up. Suprisingly the pump halves are ok. By looking at everything I could get away with a slid and rotor kit and be on my way. I will check the clutches for debri first though.

Just lookin for what might have caused this?

 

There are many reasons for a rotor to fail like that... the most common is improper converter hub alignment. It could have become cracked back when the unit was first installed. It may have a flexplate issue. It could have been at max pressure for too long... the key is to go through everything with a fine toothed comb and make sure there are no issues with the pressure control system and converter / pump alignment.

How long was this unit in the truck before the failure? What can you tell us about the tranny build, the converter and your powertrain combination?

g

 

I built this unit August 2010 using this parts list.

Corvette intermediate servo
Sonnax billet overdrive servo
Double cage 29 element forward sprag
Low/Reverse spring roller
Alto red low/reverse clutches and Koleen steels
Alto carbon oversized 2/4 power band w/ reinforced anchor
New input drum/housing
Rebestos blue 3/4 clutches and Koleen steels
Rebestos blue overrun clutches and Koleen steels
Beast reaction shell
New reaction sun gear
GM rear 5 planetary gear set
Rear carrier ring gear
Thrust bearing kit
New upgraded babbot pump bushing
New case bushing
New extra wide sun gear bushing
Sonnax boost valve
Billet forward accumulator
Billet 1-2 accumulator
EPC Solenoid
Superier valve body shift correction kit
4L65-E overhaul kit(gaskets,seals, ect)
Updated valve body seperator plate
Billet 300m output shaft
Billet 300m input shaft
Billet input drum sleeve & piston
RPM high-rev spring kit
Billet TCS 3400-3600 Converter

Mods are, cammed 6 liter, factory long block. D1SC Procharger 13lbs, 50 shot nitrous.

Last July I sprayed the 50 shot from a dig on the street and the trans failed to engage 2nd at the desired shift point, bounce off the rev limiter at 7200 according go my tuning software, then shifted into 2nd. After the slamming 2nd shift at 7200 I lost all gears except low and reverse resulting in this:



Spun forward sprag.

Replaced what was needed and checked over unit and reinstalled. Had it together for about a month, been through a few races. Coming back from a car show late September had it on cruise and then all the sudden nothing.

I bought this unit as a core and built it with the parts above. I split the pump apart the first time and everything was ok.

 

Well it certainly looks like a solid build. Sometimes there's no rhyme or reason for a parts failure... But, it could have been related to the event that took the sprag out.

I would use good new parts going back together with it, verify that the converter hub is not damaged, check the flexplate, check for excessive engine crankshaft thrust and put it back together myself.

You're on the right track.

g

 

Something I forgot to mention. When I tore down the core the first time and split the pump to inspect I found everything was fine. I turned the veins where the most "meaty" part of the vein was riding on the slide. I wonder if one of the veins caught the slide and sent everything south.

Who knows, we can talk about it all day but like I said it is what it is. Thanks for your input Gilbert.

 

Now I know what to expect. The same exact thing happened to me 3 weeks ago. I'm going to swap out to a 4l80e though. Good luck..

 

Was it a GM rotor or aftermarket? Im not a fan of aftermarkets, had some issues in the past. I always stick with GM slide, rotor, and vanes. By the looks of it it is aftermarket.

Did you measure the thickness or check the clearance of the slide or rotor?

Did you check converter spacing?

Just some stuff on the top of my head.

 

This was a GM pump.

And no I did not measure the thickness or check clearance of the slide or rotor. I did not check the converter spacing either due to the fact iv had this converter in for damn near 1k miles. Would figure if there was a problem there it would of shown its head a lot sooner than now?

Thanks for your input as well