95ImpSS

iTrader: (2)

Well... hadn't made a public "announcement" about it, but have hinted that the truck is on jackstands due to trans issues.... AGAIN! Well, 3rd & 4th went South on me a few weeks back when riding to an aunt's house to help my dad (whom volunteered his & my services) fix a fence that a tree fell on. Hauling some lumber while toying with this guy in a 90's model ECSB (step-side) w/ a 350ci motor, I "goose" forward from a dig... let out, and mash the accelerator after getting down the roadway a ways in OD. The truck seemed to hesitate engaging 3rd, so I let out. When I let out, the trans jolted into gear, and things were screwy after that. Later that day, I'm halfway home when 3rd gear disappears.

Fast forward to today... I take trans apart, and find this...





WTF?!?!?! I pull the clutches out while asking myself, "What da hell?!?!" Then I examine the clutches, thinking they aren't in bad shape (but I'm swapping in new BW's since I'm rebuilding yet again).





I look in the case to find these little boogers... WHAT THE HELL?!?!?!?!





Then, I take a deep breath, and am saying, "Aww, DAYUM!"







Good thing I built this a couple of days after the breakage.






Got my OLD leather tonneau (partially ripped) cover from 1998, and cut the rest to make a clean, stain-resistent, covered surface. The good news is that I have a perfectly descent SPARE (stock) input drum! At least it's not a total loss, but I did ruin a better-than-stock drum.


I'm gonna be hounding my trans parts supplier for some P A R T S! Good thing he's a true friend. BTW, the clutches are Alto REs, and the trans had over 3000 snot-beaten miles on it since the last rebuild. Anyone who's seen me drive this truck around the city know I'm almost as hard as white1 or Derek@EDO are on drivetrains.

95ImpSS

iTrader: (2)

In case anyone was wondering, or hadn't guessed the culprit, line pressure is important. SMOOTH transition when tuning shift pressures. Surges are NOT good. Bye bye PC solenoid.... hello again vac mod.

trever1t

iTrader: (14)

Sweet, well at least you have the skills and the room to rebuild it yourself.

southern_chevy

iTrader: (9)

So how many times have you rebuilt that thing? lol Well better luck this go around man.

dirt track racer 81

iTrader: (45)

the guys that built my transmission had the line pressure really high and this is what they kept on breaking 5 times..they said i had my line pressure too high in the tune but it was all stock..

TouchOfEvil04

iTrader: (13)

So ya broke the fancy drum from my tranny ehh?
How the hell you do that haha.

dirt track racer 81

iTrader: (45)

too much line pressure

95ImpSS

iTrader: (2)

Too much of a SURGE of pressure. My line pressures in the tune were lower than normal on part throttle. I hadn't gotten to the point of tuning the transition. Higher surge of pressure kicked in, gear caught, and jammed so hard that all I could say was "aww, f***!" I knew something was gonna go. Just didn't expect the drum to be the one. One more thing I can add to my list of "I Broke Dat!"

I'm weighing in on some options on proceeding forward. Gotta have truck back by Oct 1st. Got two weeks to make a move.

Eyy... fancy, schmancy... Got a call last night from a someone who asked me if I knew how it happened. I told him my "edu-ma-cated" guess, and he said, "yep, that's it". I guess that wasn't bullet proof. May have the shaft pressed out and put in another drum. Whether it's worth it or not? Jury's still out on that.

zippy

Usually when I see that happening the bearing/bushing on the sunshell is getting bad allowing the sunshell to smack into the drum. At your power level and being non-boosted you shouldn't need a vacuum modulator. That will likely run even more pressure at wide open. What are your shift pressure's and shift times set to? Is your pressure control solenoid modified?

95ImpSS

iTrader: (2)

Time = .250 (if memory serves)
Pressure = stock & lower (depends on gear)
Pressure Control Solenoid (PCS) = physically not modified

Lower than stock pressure setting allowed for "slipping" effect during downshift transition... The PCS tried to raise fluid pressure to satisfy setpoint (detected by PSA) before PCM commands downshift. Pressure setpoint was eventually satisfied (coincidentally whilst I started to let off the "go" pedal), and PCM commanded the gear change. Unfortunately, higher pressure buildup was already in the works, PCM got the go-ahead for downshift, but me letting out surpassed that requirement & allowed 3-4 fluid feed (de-energized B solenoid) for harder 3rd/4th apply (with the 2-4 band not being applied to the reverse input drum yet). I strongly suspected the apply force (surge of pressure) ultimately compressing the apply plate, steels and clutches against the retaining ring is what killed the "tangs" on the drum.

As for me thinking to adjust pressure settings to soften shifts, that probably wasn't the best route to go (obviously, right?). Vac mod would eliminate "hunting" (IMO), and should give me a faster pressure response. Who's to say the solenoid operates as it should at all times? I have some time to think about this. Remember, I'm no pro, so I gotta study this longer than those who've done this for over a decade.

BTW, trans shifted PERFECT at WOT. The problem was always at part throttle and downshift transitions.