fst100

iTrader: (5)

A brief history:
The trans has at least 80k miles with a 3200stall and trans cooler.

This past march i took it out to the local dragstrip and after a few runs, I lost OD and was only able to drive home from the track babying it in 3rd gear.
My buddy currently is working on beefing up my trans(raybesto z-pak clutches, vette servo, etc), but is hitting a snag. At first 3rd gear was fine and it didn’t shift into 4th at all so he tore back into the trans and first found out that the low/reverse input drum was too worn to reuse so he swapped that out with a new low/reverse input drum and band. After that was done now 3rd and 4th kicks out into neutral. He took the valvebody out and checked to ensure no check ***** fell out of place. Everything was in place. He then swapped the valvebody the yesterday and its still shifting out of 3rd and 4th gear just now. Any suggestions/advice that my buddy can check and verify please?

sopes

make sure the rods in the valve body that the solenoids engage arent hanging up, if not how bout the pump ? is it dropping line pressure ? lastly did he maybe put a seal in backwards internally ?

fst100

iTrader: (5)

thanks for the fast response. i forwarded what you suggested to him to check and see what he thinks. he's dropping the trans right now back out again.

sopes

That sucks when you have to pull it back out, Im helping a guy locally with the same exact issue right now on a 4l60e as well

fst100

iTrader: (5)

im at work so i can only text him while he's doing it. he's saying the only thing that can do something like this is the rev/input lip seal or the sprag. i'm honestly not experienced in trannies which is why im asking those who know about them help me and my buddy figure what the issue could be. again thanks for assisting :-)

sopes

your welcome, let me know how it turns out

fst100

iTrader: (5)

will do. i'll try to keep this post updated.

mrvedit

This sounds an awful lot like the 3-4 clutch is not getting fluid. Things to check are:

1. 2-3 shift solenoid
2. Servo (look for leak on the seal of the 2nd apply piston)
3. 3rd accumulator check ball in the case (behind the servo)
4. Teflon rings on the input shaft

This assumes the 3-4 clutch/piston were assembled correctly and that 3rd worked before the recent replacement of the reverse drum.

It helps to air test on the bench the input drum with reverse drum placed into the pump.

Keep us posted.

fst100

iTrader: (5)

the very first time he assembled everything i was there and he air pressured everything and the clutches were hold and no leaks from what he showed me. after he assembled it the first time he took it for a drive and said that there was no 4th being engaged but then after a bit more driving lost 3rd. thats when he noticed after dropping the trans that the low/reverse input drum that was sanded down to be reused was too worn out and replaced both the low/reverse input drum and band(the previous and was burnt) however he said the clutch paks were still okay. that was when after he put everything together there was still no 3rd or 4th gear engagement.

he's going to drop the trans today(hopefully and thats the plan) and see how the input drum is and go from there. i believe he tested the servo via multi-meter for continuity and it was fine.

mrvedit

Hopefully your trans builder will figure it out.

Just to keep from confusing others reading this:
* The band rides on the reverse drum; nothing touches the outside of the input drum.
* I'm sure you meant to say that the solenoids were tested by multi-meter.

I would pay a lot of attention to the servo area, the pistons, seals and even the bore in the case. And of course the check-ball in the case.

00MaroonZ28

iTrader: (3)

I'd get rid of those Z-pac clutches. They're garbage.

fst100

iTrader: (5)

yes, sorry if im confusing anyone. im trying to go by what i am told and the parts/terminology im not quite familiar with when it comes to trannies lol.

sopes

If you reused anything and put in some new that def. wont help things especially on a performance car

mrvedit

No problem, I'm just trying to be thorough and not being critical. (Definitely not!)

As 00MaroonZ28 points out, the Z-pak is not a prefered choice. I know some long time members here have been happy with the Z-pak, but having spoken to most vendors and pro trans builders on this forum, I know all of them would avoid the Z-Pak. (Many with a vengence.)

00MaroonZ28

iTrader: (3)

Yeah, I used z-pak after the first time my transmission went out. They lasted 3 months and went out again. Was running trans cooler and never beat on the car the whole time. Went to the track and lasted 2 sprayed passes before crapping out on me.

fst100

iTrader: (5)

well we'll see how they are in my car. my brother is running them in his ms4+bolt-on setup in his 01 ws6. he beats teh snot out of the car as well as did 25-30 hotlap/back to back runs one day at TnT and it shifted w/o issues.
small update: my buddy talked to an old colleague that works on trannies for a living and he believes its def valvebody related. other than that nothing else to report.

72blownvert

Make sure the o-ring at the bottom of the input drum was not left off or damaged that could cause a no 3rd or 4th condition.
As far as the z-pack goes my experience with them has not been that bad i used to use them alot when they first came out my biggest problem is they wear way to rapidly and causes to much clearance in the clutch pack, which in turn causes premature failure. but i never had them wipoeout right away. I have not used them in about 3 years or so because there are alot more better options out there, If you only get a few months out of them or less then there is a problem with the trans or the clutch pack was not set up properly. Just my opinion.

fst100

iTrader: (5)

i mentioned about the o-ring already. i also found this link and forwarded to him to check if it may be the spring clips may be installed wrong.
http://www.performancetrucks.net/for...-353628/page3/

Dynamic396

I don't know if you've fixed it yet or not, but I've found the little air bleed cup plug for the 3-4 chamber in the input drum blown out on many an occasion. Especially after there has been a fault somewhere that has caused max line pressure to be commanded. This will exhaust all 3-4 oil. I typically remove this air bleed cup plug, thread the hole and install a set screw in its place to prevent this blowout.

BTW, leaving out the o-ring in the bottom of the input drum will cause 3rd gear starts, not a no 3rd or 4th condition. Having it missing will allow forward clutch oil to feed into the 3-4 chamber and engage the 3-4 clutch.

I am not at all a fan of the Z-pak. A 7 disc stack will give you the same number of contact surfaces, but with much thicker plates.

mrvedit

Wow, I never imagined that cup could blow out; I assume you mean the one with the check ball as there is another bleed hole drilled into the input drum.
For others: The Transgo HD2 kit recommends replacing this cup with their supplied plug which has a very small drill hole. The stated reason is that the check ball can unseat at high rpm creating a huge leak and thereby letting the 3/4 clutch slip. (This is one of the optional parts supplied with the HD2 kit for those rebuilding their trans.)
Also: Superior makes a spring-loaded check ball replacement. I tried it, but its taller size made it scrape on my Reverse drum. I called Superior, they claimed I had a Chinese Reverse drum (maybe?) and admitted they were designed a shorter unit. Seems it depends upon the thickness of the selective washer.

Oh, I hope I never learn that the hard way. Did you?