3-4 slip or flare on my first 200r4 rebuild

[steve66/2004r]

This is my first rebuild, followed Chris's book. I've got good line pressures and good, firm 1-2 and 2-3, and down shifts but 3-4 slips or flares. According to the book, this could be a problem in the 3-4 accumulator valve in the vb or the 3-4 accumulator piston or seals.

My question is, is there anything to try before removing pan and checking these out or is there a common rookie mistake that could cause this.

 

[chris718]

steve there is a 4th pressure tap on the transmission for reading pressure.install a gage there and read it.it will make it easier to find the problem.

 

[steve66/2004r]

Chris, thanks for the reply and all the other help you've given me on the phone.

I tapped into the one by the servo and tried it this morning. The gage stays at zero during the upshifts till it changes to 4th, then I got 90 psi. It drops back to zero when it downshifts to 3rd.

This morning is the first time I've actually felt the 3-4 shift. Yesterday when I was testing, it was 90 plus degrees outside and I did some in town traffic and the trans and motor were really warmed up good. I wonder if the heating and cool down cycle broke loose the accumulator piston or valve or maybe it's the fact that the fluid and trans were cool this morning and made it shift without flaring. I'm gonna try it again tonight after work and see if anything changes after its warmed up good.

Are these pressures correct?

 

[JDSfastGN]

Chris, thanks for the reply and all the other help you've given me on the phone.

I tapped into the one by the servo and tried it this morning. The gage stays at zero during the upshifts till it changes to 4th, then I got 90 psi. It drops back to zero when it downshifts to 3rd.

This morning is the first time I've actually felt the 3-4 shift. Yesterday when I was testing, it was 90 plus degrees outside and I did some in town traffic and the trans and motor were really warmed up good. I wonder if the heating and cool down cycle broke loose the accumulator piston or valve or maybe it's the fact that the fluid and trans were cool this morning and made it shift without flaring. I'm gonna try it again tonight after work and see if anything changes after its warmed up good.

Are these pressures correct?

Steve i don't know if other builders have had this, but it seems that a few of the transmissions i have built don't even like to go into 4th during the first test drive. Sometimes I have to take it up near 85ish and it will pop in. After that its usually good to go and shifts firm and normal. I don't know the reason why but since the transmissions thats its happened to have all been great since then i chalk it up to normal. Hope it turns out ok.

 

[mikestertwo]

When you installed the 3-4 accumulator did you put the piston in the bore first or the spring in first? Should be piston first then the spring.

 

[steve66/2004r]

yep, used CK's 3-4 piston and spring and installed piston first. I'm guessing the pressure readings I took this morning off the 4th gear tap are correct. 90psi while in 4th, 0 psi in any other gear.

 

[77 cruiser]

Pressure would/should go above 90 anytime you have your foot in the gas at all, unless you have a TV issue. Just for curiousity check your line on the other tap by the manual linkage. Min TV & max TV

 

[steve66/2004r]

On the other tap I had 90 at idle, 210 in manual 2nd and 245 with cable disconnected and pulled all the way out. Thanks for all the replys!