hey guys i have recently rebuilt my trans with my mechanic we put in the tci rebuild kit and i used it for 4 days now and all of a sudden my truck slips in D and 3 but it will move in 2 and 1. please help me out with this problem it did this on the first rebuild too. also if i was right down the road from my house and it did that and i immediately put it in 2 do u think that i burnt the clutches? thanks Eryck

 

https://ls1tech.com/forums/automatic...ard-4l60e.html

 

no forward movement in drive or 3 but i have in 2 and 1.

 

Yes, the 3/4 clutch is certainly slipping; I don't know how much slip they can take before they are burnt, but if the trans is taken out and you might as well replace them. IMHO, the 3-4 clutch does not have enough hydraulic pressure for one of several reasons:

1. The pump is not producing enough pressure, the Pressure control solenoid is not working, or the PCM is not programmed correctly. These can all be tested by connecting a pressure gauge to the trans. It should be 60-90psi at idle in Park or Drive. It should be almost double that in Reverse. Blipping the throttle in Drive should give you 170psi, or even 220 if you have a bigger boost valve installed.

2. There is a leak in the servo area. A possible problem is a worn out 3-4 accumulator check ball" which is in the case behind the servo. If this leaks, the 3-4 clutch will slip. Or just replace it.

3. There is a leak in the input drum, either at the teflon seals or at the 3-4 piston. I would test the input drum immediately after removing it and before disassembly. Do an air test on the 3-4 clutch hole in the input shaft. There is a small bleed in the input drum which you can plug with your finger. Other than that it should hold air. (Exception - if the 3-4 checkball was replaced with the Transgo bleed cartridge, plug that with your finger too. Obviously this test should be done after rebuilding the input drum too.

If not already, I would suggest installing a .500 boost valve as this will give you higher line pressure if programmed. This only requires dropping the pan.

If you do remove and open the trans, rebuild the 3/4 clutch with a quality 4L65E 7-friction kit; Borg Warner Hi-Energy is recommended.

After the rebuild and before any heavy duty usage, hook up a pressure gauge and check the line pressure as above.

Good luck and keep us posted.
I'm not an expert, but these are my suggestions.

 

Good info here.

I'm wondering if the OP actually has 1st and 3rd, and no 2nd & 4th ( could be a band or servo issue).

 

Good point, but there is yet another interpretation.
Aukai25: Are you referring to which gear you think the trans is in, or which shifter position you have the trans in. In my post above, I assumed that 3rd and 4th gear were slipping after the car had accelerated out of 2nd gear.

However, if instead you mean that the trans slips from a dead-start with the shifter in [D3] or [D4]/[OD], but not in [D1] or [D2], then the forward sprag is slipping. This will require pulling the trans and replacing the sprag inside the input drum. Use a Borg Warner dual-cage for maximum durability.

 

um lets see when i put it in drive the it will go but then it will slip but if i use the shifter i can start off with 1 then 2 then it will go to 3 now but no drive. when in 3 it like shifts up and down.

 

A little clearer explanation with grammar and punctuation would help; I have no idea what "it will go but then it will slip" really means.
It is starting to sound like the forward sprag is slipping.
With the shifter in [D1] and [D2], the overrun clutch is engaged and assists the sprag. With the shifter in [D3], the overrun clutch is not engaged in 1st or 2nd gear. With the shifter in [D4], the overrun clutch is not engaged at all.

 

when i put it in drive, it will go then it will slip i guess when it reaches 3 or drive but it cant be 3 bcuz if i shift into 3 manually it will work.

 

If you put the shifter in 3 or D range IE 3rd gear (1 down from overdrive range) what does it do when you take off from a stop? does it shift or does it slip? If it shifts, how many times does it shift before it starts slipping??

 

let me get back to u on that tomorrow thanks for the help guys.

 

hey i was reading on the internet that you need a certain clearance on the 3-4 clutch pack. is this true? if so how much is it? and also ill just wanted to say that i bought a tci rebuild kit and a transgo hd-2 shift kit for this trans and installed it and after driving 4 days it gave out. could it be anything with the shift kit or is it just the 3-4 clutch pack? what about line pressure too? thanks

 

The 3-4 clutch has a GM recommended clearance of .060-.070" but many performance builders aim for about half that.
As I mentioned earlier, you NEED to get the line pressure checked to determine the next step. The HD2 kit includes a .500 boost valve, but if it was installed incorrectly or any part of the kit was installed incorrectly, the trans could fail.

As carlsonauto asked, we need to know exactly in what shifter positions and which gears the trans slips. That is the first step.

 

today i tried out the shifter and i can shift from 1 to 3 but if i put it in drive it doesnt shift into gear. if i leave the shifter in 3 and take off from there it shifts twice. is that a little more clearer? if not let me know so i can try it again. thanks for the help.

 

does it slip in all three gears when in "3" or just when it shifts into 3rd? If its just when it shifts into 3rd it about has to be the 3-4 clutch.. Is your "mechanic" a trans builder or a mechanic buddy that you convinced to help you build a tranny? Im not asking that to be a jerk just trying to get an experience level idea..

 

He is a tranny builder for the gm company here I live and he has his own business too so he pretty experienced. Could it be the accumulator doing this the last time that was the problem the seal flipped and ripped a little causing that piston which was plastic at the time to crack. Now it's an aluminum one so I'm thinking the seal did the same thing. Also there is 3 washers that we put in from the Transgo kit so I'm thinking of taking out 1. Do u think that would help?

 

You are still very ambiguous and not clear about when it slips.
You say "if i leave the shifter in 3 and take off from there it shifts twice", but don't mention if it slips. I am very precise in my posts - for shifter position I use [D1], [D2], [D3] and [D4]/[OD]. I use "1st gear", "2nd gear", etc; I never say just 1,2,3 as that is ambiguous. We need to know exactly in which position the shifter is and which gears, if any, then slip.

A seriously cracked 3-4 accumulator piston could cause a slip. Or a seriously worn bore. The Sonnax Pinless piston is a good cure for this, possibly with a new sleeve.
The "3 washers" only affect how firm the 1-2 shift is; that does not appear to be the problem here.

 

If I leave it in D3 it shifts regular twice with no slips but it doesn't shift to D4. If I manually shift it startin from D1 then I can shift it to D2 with no slip and then when I shift it to D3 it shifts to without slip and when I shift it to D4 it does not shift into gear it stays in D3. Now if I am driving it in D4 and drive normal it shifts with no slips until I reach OD. Hope that's clear enough

 

Sooooo it only slips when it is in overdrive.. correct? I would start by pulling the servo apart and looking at it. The part that applies o/d is in the servo cover. Check the seal on the piston to make sure it isnt damaged. The 4th servo apply oil goes through the servo pin itself and can leak if the case or pin are damaged/worn. If that is all in good shape then you will have to dig deeper, pull the pan and see what is in the bottom of it. Who knows maybe the band is dying for one reason or another and is still good enough to hold second but not 4th, not really likely tho.. The problem could still be a fluid leak in the 3-4 clutch circuit that isnt bad enough to show up in 3rd but when trying to apply 4th the extra fluid necessary to do so isn't availabe. I would start at the servo and go from there..

 

ok ill try and check on that on saturday when i open it up. thanks for all the help guys.