O/U rebuild question

[todd08]

I just hired my local ex-White dealer to rebuild a 3 speed O/U unit for me, only to be disappointed that I have a two speed unit, under & direct. I put a pressure guage on the overdrive port and I have 180 psi, instantly when shifted in, with very little difference from idle to full throttle, So I feel pretty confident that I do not have the piston seal broken or a spool hung up. Returns to 0 PSI when shifted to direct or under. IS IT possible that they turned the ring just under the rear cover so that the pressure feed is blocked to engage the piston. THe gentleman who overhauled it swears he could hear it shift when he applied compressed air when he assembled it. I suspect the 5 bolt holes can be bolted on in any random way, thus leading to the blocked passage... do you guys know if this is true or has anyone else had this experience. Thank you!

 

[B A Star]

Your post is quite confusing.  If it is a Hydra-power drive it has direct drive and underdrive.   Power is transmitted mechanically when in underdrive through a overrunning clutch that is in the countershaft.  When in direct drive a multi plate clutch locks the input shaft to the output shaft.
I assume that you have installed the pressure guage with a tee fitting in line with the hose that goes to the direct drive clutch collector ring.  The hydraulic circuit for the engagement of the clutch is a "closed Center" circuit in that once the clutch is engaged and there is no leakage you don't need any more oil, thus the clutch pressure regulator valve is hydraulically moved allowing the pump output to go to the cooler circuit and back through the filter then to lube the system (the lube pressure is regulated by another valve).  When you change to underdrive the spool valve opens the clutch circuit to sump and pressure should drop to 0.
The real test is to install a pressure guage in the lube circuit.  The internal pump output is used to engage the direct drive clutch and if there isn't any leakage in the clutch all the out put goes into the cooler, filter & lube circuit.  Should there be leakage in the direct drive clutch it will take some or all of the pump output to keep up with the leakage, thus reduced volume in the lube circuit and a reduction of lube pressure. &bnsp;How do you check lube pressure?  Dealers welded a 1/8" pipe fitting in the center of an old filter, then drill a hole though the filter. Screw a guage in and check the lube pressure while running at operating temp.

If you are running it off the engine as an independent unit there is enough drag in the direct drive clutch that you won't see any difference in speed.  Perhaps you can apply some drag to the ourput shaft sproket and observe the speed change.  This unit is so simple that you can't hardly screw it up upon assembly.  output housing can't be installed wrong.

 

[e]

Don't say they can't be screwed up upon assembly. I talked to a local dealer that had to cut an o/u apart with a torch because of another dealer's mistakes. They are simple transmissions, however, the instructions in the manual leave a few part orientations up to a guy's imagination if you've never worked on one.

 

[todd08]

This one is from a 2270. The only other one I have had rebuilt was a G955 MM, Pulled it twice also for this same dealer, he forgot to install one of those little o-rings on the bottom of the overdrive output case housing. Kind of ------ off having been down this road twice, just probably 15 years ago. At least the leaker shifted into all three gears. But none the less we all make mistakes no matter how simple these things are supposed to be. Dealer will be sending his mechanic out this morning to test. I just dread taking it back out, and still wonder if he has just turned pn# 30-3089142 an increment of 72 degrees, thus blocking the feed of either the dump off oil, or the pressure feed. Does the overdrive pressure feed come thru line 165500A? or thru the case 30-3088375?

 

[todd08]

B A STAR would you confirm my findings today. I was wrong jumping to conclusion that dealer installed parts wrong, instead it was a quantity and part number substitution change that troubled us. Both the weak and the stronger set up are available from parts today. You either run 7 thin steel separator plates plus 6 clutch disk or run 6 Thick steel separator plates and 5 clutch disk. We got into trouble by having only 6 thin ones. SO I have to wait until friday to get one more each of the clutch plates and separator plates. Does this jive with your documentation or memory.

 

[mkuhns]

You should only have the 5 and 6. A 2-180 with the heavy over/under used the thin spacers and has an extra friction. The thin spacers are about .015" -.020" thinner than the thick ones. Multiply that by 6 and you're talking A BIG difference if you don't add another friction and spacer. I have added one more friction and spacer to the lighter over/unders like in a 2-150 white. I do all of our rebuilds. All have worked like they should the first time. Knock on wood - everybody makes mistakes - we are all human. I'm sure my times coming. I have to do one in our 4-150, and one in our 2255 soon.

 

[jackscockshutt]

What would happen if the over running clutch was put on backwards?

 

[jackscockshutt]

What would happen if the over running clutch was put on backwards?

 

[mkuhns]

Let out the foot clutch and the engine will die if it's in direct or over.