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Curtis B.
Curtis B., Technician
Category: Construction and Road Equipment
Satisfied Customers: 988
Experience:  Technican turned service manager with multiple lines of equipment and rental units.
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Need help with a rebuilt slipping get cat 515 transmission

Customer Question

Need help with a rebuilt slipping get cat 515 transmission
Submitted: 4 months ago.
Category: Construction and Road Equipment
Expert:  Jr Gilliam replied 4 months ago.

Greetings,

Sound like it may a have a clutch piston seal pinched or rolled. Do you have a way to check transmission pressures?

Thanks

Jr

Customer: replied 4 months ago.
I personally repacked the seals and replaced the orings( to make sure that didn't happen) either way it wouldn't act up in every gear or direction it's a countershaft powershift.
Customer: replied 4 months ago.
I do have a way to check pressures it will won't be till the weekend though and I'm sure they are all going to be abnormally low.
Expert:  Jr Gilliam replied 4 months ago.

I would venture to say yes. If it is slipping in all gears the pressure will 9/10 times be low. It should have roughly 450 psi pump pressure. Speed clutch pressure should be 350 psi, direction clutch 275. converter inlet should be 100+/- 30psi, outlet should be 30 to 60 psi. What was the original reason for the trans to be rebuilt?

Thanks

jr

Customer: replied 4 months ago.
No the original reason was a missing skid plate and a stump busted the case. I found a good donor case, but supposedly that Trans was bad I mic'd those clutches as well all were within specs. I believe there 2 flow control valves in the case part of the trans that's my problem I'm trying to diagnose what it is exactly because it's not easy or fast to pull the transmission from this machine. Pump should be 450 psi , I don't have the sheet in front of me but speeds are like 275 psi and direction 350 or vice versa like you said. I'm certain the pressures aren't right but why is the question. The original transmission and pump worked fine, I even changed to pump to a known working group unit and it improved some but it's not proper. I did not check the pressures because we ran it for about an hour and all seemed good. On the job it made it about 2 or 3 hours I ran it , within the first hour it progressively got worse. You can play with the revving up waiting and once it seems to make flow it will pull but only in 1st which is the biggest clutch hence why I'm certain the lack of pressure. I'm thinking the problem 1 or both of the flow control valves.i don't have access to cats sis.web so I'm not sure how to trouble shoot this there's also a dump valve, a diverted valve and a back flow check and according to the parts guy 2 flow control valves that are exactly the same I only know where one is. I believe the other to be the tq relief valve.
Customer: replied 4 months ago.
The other the tq valve I think is under the Solenoid valve block .. not sure
Expert:  Jr Gilliam replied 4 months ago.

Hello again,

In your flow control valve (under the control valve behind the return line for the trans filter) it has a screen and a spring. It limits pump flow to the trans to 6 gpm diverting the rest to the torque converter circuit. if the spring were broken or the screen is plugged it would considerably reduce flow to the control valve and would explain your slipping in all the gears

Thanks

Jr

Customer: replied 4 months ago.
Well I swapped that one with the one in the old case it appeared to be functional
Expert:  Jr Gilliam replied 4 months ago.

I've uploaded a schematic for the trans. Start at the pump and work your through the valve.

Thanks

Jr

Customer: replied 3 months ago.
Ok so low pressures on all the ports , tested pump it's good 450 psi. Pulled out valve behind the transmission input oil (called a flow control valve) replaced . What's the next move no change yet.
Customer: replied 3 months ago.
Removed the Solenoid valve block don't see where the other flow control valve is ... there's a button looking piece but I can't figure out how to remove it.
Customer: replied 3 months ago.
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