Bind before shift TH350

[Jvette73]

We're working on a 79 Malibu wagon. We have 200 4r swap in the works. Meanwhile it's got a Th350 that's acting up.

At WOT 1-2 shift, it binds like its in two gears for a second or two, then up shifts. At first I thought it was a fuel starvation problem because that's kinda what it feels like. But I ruled out fuel related issues.

Is there anything I can try short of a rebuild that might clear this behavior up? Maybe a valve or piston on the valve body I can doctor up?

Thanks for any input in this matter.

 

[turbobitt]

Is this on a manual 1-2 upshift or automatic (in drive)?
AG.

 

[Jvette73]

Is this on a manual 1-2 upshift or automatic (in drive)?
AG.

Selector in D. Automatic upshift.

 

[turbobitt]

My only thoughts are that there must be a cross leak or a check ball not sealing. It should just apply the intermediate clutch for second and shod have nothing else engaged to create a bind unless the low/reverse clutch is holding but that should only happen in Manual first(1). You may want to check the VB gaskets and bolt torque.
AG


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[Jvette73]

Thanks. I'll check those things. Maybe I'll get a shift improver kit. One that comes with new VB gaskets and seporator plate. Obviously new gaskets can't hurt. But if you say a check ball may not be sealing, could that be due to a worn sep plate? My point for trying a shift kit.

 

[turbobitt]

Thanks. I'll check those things. Maybe I'll get a shift improver kit. One that comes with new VB gaskets and seporator plate. Obviously new gaskets can't hurt. But if you say a check ball may not be sealing, could that be due to a worn sep plate? My point for trying a shift kit.

Sometimes the separator plate can be so badly worn that a check ball will wear the seat or sometimes even go through the seat and create other problems. Its been a while since the last time I dove into a TH350 and don't know the hydraulics as well as the TH400 but the VB, gaskets, separator plate and bolt torque is going to be the best place to start.
AG.

 

[bison]

Cross leaks are common if it has an aftermarket stamped separator plate. I've had to do quite a bit of filing on some to get them flat


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[Jvette73]

Cross leaks are common if it has an aftermarket stamped separator plate. I've had to do quite a bit of filing on some to get them flat

Good point. I'll make sure to check for burrs and smooth them out.


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[Jvette73]

I got a trango shift kit and dug in. What I found inside the transmission was rubber check balls. There should have been 4 of them. There were only two. The two that were missing were the ones on each side of the kick down servo. In the spots where the check balls should have been I found a thick black substance. It appears the rubber check balls in these locations dissolved. Thats what it looks like anyway. If this is possible, what causes it?

I'll keep you posted on the result after install the shift kit per instructions.

 

[Jvette73]

I put the Transgo shift kit in including replacing the missing check balls. Two rubber / plastic check balls were removed and 4 steel balls went back in. It solved the binding that was previously happening just prior to the 1-2 WOT auto upshift. 1-2 shifts at a good rpm and hits real positive. Happy with that.

I also made sure the kickdown cable is properly adjusted. The piston gets fully compressed when the throttle is wide open. But there is a minor issue still. The 2-3 upshift comes way too early at about 1/2 way through the power band. I know I could manually hold it in 2 then upshift to 3 when desired but I like having the auto functions just do what they're supposed to.

So next question;

How do I get the WOT automatic 2-3 upshift up to the top of the power band? 2-3 at about 55oo rpm is what I'd like. Right now it does it at about 3500 rpm.

 

[Topjimmy]

Subscribed

 

[Wahoo]

I put the Transgo shift kit in including replacing the missing check balls. Two rubber / plastic check balls were removed and 4 steel balls went back in. It solved the binding that was previously happening just prior to the 1-2 WOT auto upshift. 1-2 shifts at a good rpm and hits real positive. Happy with that.

I also made sure the kickdown cable is properly adjusted. The piston gets fully compressed when the throttle is wide open. But there is a minor issue still. The 2-3 upshift comes way too early at about 1/2 way through the power band. I know I could manually hold it in 2 then upshift to 3 when desired but I like having the auto functions just do what they're supposed to.

So next question;

How do I get the WOT automatic 2-3 upshift up to the top of the power band? 2-3 at about 55oo rpm is what I'd like. Right now it does it at about 3500 rpm.

Figure out the problem?

Im looking 8nto swapping a th350 in my 85 t type

 

[TexasT]

Figure out the problem?

Im looking 8nto swapping a th350 in my 85 t type

Why would you want a th350? Something happen to the 2004r?

 

[Wahoo]

Why would you want a th350? Something happen to the 2004r?

I was trying to figure out what would be more cost effective.

Currently my 2004r is stock and slipping 1st/2nd gear.

I plan to rebuild it myself, which for a basic overall without hard parts seems to be around $300 w/ racing clutches.

If a th350 bolts in easily, and i find a good one used, i only need a converter probably a used one. Which should be pretty stock.

But i might end up just doing the 200r4 rebuild because the costs seem either very close or a few hundred more for the th350

 

[bison]

I was trying to figure out what would be more cost effective.

Currently my 2004r is stock and slipping 1st/2nd gear.

I plan to rebuild it myself, which for a basic overall without hard parts seems to be around $300 w/ racing clutches.

If a th350 bolts in easily, and i find a good one used, i only need a converter probably a used one. Which should be pretty stock.

But i might end up just doing the 200r4 rebuild because the costs seem either very close or a few hundred more for the th350

This may work for a stock car but if cost is a concern on a transmission build for a high performance application you will struggle with longevity.