seeking guidance shuttle shift issues

[Kevin Brouse]

I spent several hours reviewing threads on here, and did not find anything that related to my particular problem.

so, here goes:

A newbie here to the forum. I am exasperated, and running out of ideas.

So, the story begins... Recently rebuilt a power shuttle 580K (pre 200000 serial, lighter trans) Filter screen was clogged, burned the clutches.

Put complete kit in, with new charge pump. Worked fine 1 and 2nd gear puttering around doing some light work. Went to move it down the highway a few miles in 3rd gear it suddenly disconnected/freewheeled in forward, reverse worked for a while longer.

Took trans back out to make sure I didn't miss anything, all was good. Re installed, this time was doing the pressure checks. In the process of warming the transmission oil up (stalling in 4th) it "uncoupled" again. Cooling circuit pressure was a little on the low side, so we decided to install a rebuilt converter.

Installed the rebuilt converter, same thing, as soon as we warm it up a bit, forward goes away, reverse works for a little while longer. Charge pressure remained good at all times.

full disclosure #1 while going through the cylindrical valve body and replacing all the items that came in the kit, I lost a critical part. I then bought a complete new valve body and installed it.

so... my next step is to check the pressures on the actual forward and reverse galleys, while leaving the cooling pressure and charge pressure gauges also installed. Thoughts?

full disclosure #2, I also may have installed the cooling lines backwards... I am at a loss at this point, if you've taken the time to read this far, what are your thoughts?

Kevin~

 

[Vetech63]

It’s sounds like the stack height of your clutch packs isn’t right. Those kits come with multiple snap rings that are different thicknesses so you can get the proper stack height. The cooler lines shouldn’t make a difference. Are you sure the 4 speed tranny isn’t popping out of gear?

 

[alrman]

Are the transmission cut-out buttons still working?
Maybe one is sticking?
Try disconnecting the solenoid wires & retest.

Can you trust the rebuilt converter supplier?

 

[outlawspeeder]

I am a FNG too. I thought I would be disconnect the any power to the clutch solenoid. Stack height in car transmissions are about the same. Too tight and it always want to drive, too short it slips. Not say it is not it but I would remove the chance of the clutch solenoid.

I currently re wiring my clutch solenoid. The prior owner ... wow, I have remove coil phone cord, house wire, and what is left of the wiring harness has no color left so all the wires are white.

 

[Kevin Brouse]

It’s sounds like the stack height of your clutch packs isn’t right. Those kits come with multiple snap rings that are different thicknesses so you can get the proper stack height. The cooler lines shouldn’t make a difference. Are you sure the 4 speed tranny isn’t popping out of gear?

 

[Kevin Brouse]

Stack height was set up in the middle of specs. The transmission stays in selected gear. While in the process of bring the temperature up via the stall in 4th gear, it changes engine rpm <unloading> placed in a lower gear and the machine will not go forward until it cools back down. Reverse still engaged, but was sluggish.

 

[Kevin Brouse]

Are the transmission cut-out buttons still working?
Maybe one is sticking?
Try disconnecting the solenoid wires & retest.

Can you trust the rebuilt converter supplier?

 

[Kevin Brouse]

Thanks for the suggestion. I did in fact disconnect the solenoid the first time it happened. After going through the prescribed tests in the service manual, the cooling circuit measured on the low side, replaced the converter per recommendations and still had the exact same characteristics. I am suspecting something in the valve body/disconnect hydraulic circuit, but I have NO idea on specs of the valve assembly itself. Maybe someone knows of specifications for it. (Did replace valve body from original transmission as I fuzzed up the original one.

 

[outlawspeeder]

If you're going to pull it again... sorry, look at the piston seals. Each set of clutches has a piston. Hyd pressure compresses the clutches when the valve body ports fluid to them. The other thing to look at is the shaft seals (most likely cast iron rings). The pressure is ported though the main shaft to the pistons. If any of these seals or ring are cut or broken they will leak. As the fluid gets hotter, it is more likely to leak more and the reason it works when cold and not when hot.
Disclaimer: This is true for car transmissions.

 

[Vetech63]

Stack height was set up in the middle of specs. The transmission stays in selected gear. While in the process of bring the temperature up via the stall in 4th gear, it changes engine rpm <unloading> placed in a lower gear and the machine will not go forward until it cools back down. Reverse still engaged, but was sluggish.

The only way it could change is clutch slippage or a drop in oil pressure. It would be best to hook up a pressure gauge and see if your pressure drops when this happens. At least you would have narrowed this problem down and could focus in the right direction.

 

[Kevin Brouse]

If you're going to pull it again... sorry, look at the piston seals.

Thanks for your input. I will probably pull it and look at everything again after I put pressure gauges in the forward and reverse galleys to check comparative pressure. I found no issues on stack height, or piston sealing the first full disassembly after the rebuild when this problem reared it's ugly head. I do appreciate all that take the time to respond with advice.

 

[Kevin Brouse]

The only way it could change is clutch slippage or a drop in oil pressure. It would be best to hook up a pressure gauge and see if your pressure drops when this happens. At least you would have narrowed this problem down and could focus in the right direction.

My next step is a second high pressure gauge to keep an eye on actual clutch pressure from the galley vs. charge pressure. In looking though here before posting anything originally I stumbled across a post where the details were about the plunger and valve assembly for the dump circuit. After the comparative test I will go searching for that again. If anyone has specifications pertaining to the valve body/plunger relationship I would love to have them. Thanks again all that have taken the time to respond. When I find the issue I will certainly let all know!

 

[Kevin Brouse]

UPDATE: After exhaustive times installing and removing the transmission, four, to be exact, where each time I have disassembled the transmission and reassembled step by step to the Case original manual specifications... I found the problem.

The original problem was after a rebuild the transmission worked for a few minutes until it warmed up and then lost forward, then after about another 30 seconds or so, would lose reverse.

I got exasperated, frustrated, and decided to purchase two more pressure gauges that I would be able to monitor the actual forward and reverse clutch pressures along with the galley and cooling circuit gauges I already had plumbed in. Unfortunately winter set in before I got the gauges in.

When the temperatures warmed I installed the two additional clutch pack gauges and here is what I found.

Galley pressure NEVER dropped, but as I was following the manual to bring the temperature up into the green the transmission would start slipping. The pressures on the forward clutch pack galley would drop to 35 p.s.i. on the forward side, and reverse side would do the same about 30-45 seconds later.

I finally called the supplier I purchased the valve body from. (replaced the valve body as I had an issue with it) Asked them about purchasing another and if it was the problem would they accept the other back. After they checked they graciously agreed if there was a problem they would accept the one I thought defective back even though it had passed the 6 month mark. I spoke to a representative of the company who told me they had sold hundreds of them and never had an issue.

Received the new one Friday, put it in this morning and ran it through the tests. Line pressure great, cooling side pressure was good once I got it warmed up, and the clutch pack galley now held a consistent pressure with no drop off when they warmed up.

It's been rainy here in central pa all weekend so I really cannot work it too hard right now, but it seems as if I am the "lucky" guy who got the first valve body this company sold that was defective.

I cannot say enough good things about the company and their representative I spoke with. (Full disclosure I purchased a second valve body on my credit card and when I called them issued me a call tag to ship the defective one back) If anyone exhausts all plausible solution to their issue and wonders if they may have a problem with a new part, I would encourage a friendly questioning of the facility you purchased it from. I have almost always found a friendly attitude and manner works well when one needs to work with customer service.

Thanks to all who take the time to read this, and again to those who suggested items to look at previously. I'm just doing a snoopy happy dance now that it works as it should!

Kevin Brouse

 

[stinky64]

Nothing like beating yourself up trying to figure out what "you" did wrong only to find out it wasn't your mistake at all..Super cool that supplier swapped out the valve body after 6 mos. Happy digging...

 

[kjones95206]

Thanks for "closing the loop" on your thread.

 

[JL Sargent]

I bet you are good at R&R'n that trans now though. Glad you got it sorted out.

 

[Kevin Brouse]

I bet you are good at R&R'n that trans now though. Glad you got it sorted out.

so much better than I ever desired to be. I wanted to close this with an update, and perhaps a future search may find this and give a lost soul some hope. As my brother in law often states, go back to what you changed... duh... lol

 

[Kevin Brouse]

The only way it could change is clutch slippage or a drop in oil pressure. It would be best to hook up a pressure gauge and see if your pressure drops when this happens. At least you would have narrowed this problem down and could focus in the right direction.

I did fine the problem finally, after the weather warmed I installed two more gauges on the clutch packs pressure feeds and showed the problem was essentially something in the valve body.

 

[outlawspeeder]

Good to hear! I got mine back together too. My solenoid is a little slow to release but it is getting better on its own. I think it just has to reseat itself. But it is get having power to move this beast. I found a broken spring that broke the forward cultch piston. $68 part.
These rigs will run forever if you can get the parts.