MR2 SpyderChat banner

1 - 14 of 14 Posts

·
Registered
Joined
·
4,213 Posts
Discussion Starter #1 (Edited)
I got manufacturing sorted out for all the important seals in the GSA. So the HPU looked logical for the next step. I intend to get seals manufactured to overhaul the HPU also.

It's pretty simple to disassemble. But the guts are fantastic! It's a tiny swash-plate pump with five pistons.
The swash plate surface and piston slipper-feet are so flat and smooth I had to yank them away from each other. (a cohesion effect I think) The tightest tolerance I have ever seen on a design drawing was for the flatness limits on a swash-plate surface for the hydraulic pump in a Navy A-7. It was 7 Angstroms! (That's 3.9x10 to the -9th inches!!)
I got measurements done for all the seals in the HPU, so I'll see if I can get them manufactured.

Here's a hard-learned tip.
If you disassemble your HPU pump, DON'T leave the pistons and plate sitting around in the humidity. They will promptly rust! I would store them submerged in brake fluid until you're ready to reassemble the pump.

Pictures!
Re-posted after Photobucket took a crap on all my hard work.
Slide Show: http://imgur.com/a/22tzm




Cylinder barrel and five tiny pistons:
The fixed-angle swash plate, with the shiny smooooth surface!
(Pistons laid out on the right side)
View inside the pump with two pistons "stuck" to the swash plate. You would swear they were glued in place. I had to tug them off that plate.
Here's the pump seal that usually fails and floods the electric motor with brake fluid.
 

·
Registered
Joined
·
4,213 Posts
Discussion Starter #3 (Edited)
Finally, the custom metal-cased rod seals arrived!
I'm planning to make up some repair kits for the HPU. I (finally) have the critical seals to get the HPU taken apart and reassembled. I didn't bother with some of the static seals. I still need to get the seals sorted out and make a good set of photos.



 

·
Registered
Joined
·
8 Posts
New HPU Seals

How are the new metal shell seals working out? Did you notice any corrosion on the shaft like that found by the British guy who rebuilt his HPU?



Finally, the custom metal-cased rod seals arrived!
I'm planning to make up some repair kits for the HPU. I (finally) have the critical seals to get the HPU taken apart and reassembled. I didn't bother with some of the static seals. I still need to get the seals sorted out and make a good set of photos.



 

·
Registered
Joined
·
4,213 Posts
Discussion Starter #5
How are the new metal shell seals working out? Did you notice any corrosion on the shaft like that found by the British guy who rebuilt his HPU?
I noticed some corrosion on my HPU shaft, but I have no access to a nice repair shop to install a sleeve for me. I jut spun the motor and hit it with some 400 grit and scotchbrite. There is some latitude in where you place the seal, so I cleaned up the surface and installed a test seal in a slightly new spot.

I haven't popped in a metal seal just yet - too many distractions in springtime! I still need to sort out my last shipment of seals. I have enough for 6-8 complete sets of HPU and GSA seals.

And thanks for all the groundwork you did getting these seals started!!
 

·
Registered
Joined
·
321 Posts
I'll send a PM when I get the HPU kits sorted out.

I don't have any recommendations for reassembly torque. German spec "goot-n-tite" has always worked fine for me.
So what are the actual causes of the gsa and hpu failure? Mainly the seals? If the fluid leaks on the electric motor is it destroyed or can it be cleaned and put back into service?
 

·
Registered
Joined
·
4,213 Posts
Discussion Starter #9
So what are the actual causes of the gsa and hpu failure? Mainly the seals? If the fluid leaks on the electric motor is it destroyed or can it be cleaned and put back into service?
Here's my opinion. I'd be happy to see corrections or additions!

HPU failures:
- motor shaft seal fails and fluid shorts the electric motor. This allows fluid to leak outside the HPU and onto the crossmember. I don't know if the motor is shorted permanently, or if you can clean them out and drive on
- pump gets worn out and can't produce enough volume/pressure to shift gears or run the clutch. There's no fix for this. The swash plate pump pistons are pretty little metal parts with no seals to replace.
- There are two solenoids on the HPU unit. One solenoid controls the clutch actuator, the other regulates pressure/volume to the GSA.

GSA failures:
- seals can leak externally and drip on the floor. Clutch actuator seal leak can be isolated by pealing back the clutch dust cover. Anything wet inside means the seals are leaking. Shift actuator seal leaks just piss fluid from inside the GSA and dribble off the lowest point - usually the stroke position sensors.
- internal seals could leak excessively and then the shift actuators won't stroke correctly. The clutch piston seal is rubber. Both shift actuator piston seals are Teflon.
- GSA also has two solenoids. They control fwd/side shift actuators. If they fail, gears quit shifting.

Solenoids failures I havent' figured out yet. Solenoids route fluid to the actuators. They are supposed to "hover" between retracted and extended - based on pulsed voltage (Cap taught me). I don't know how they fail. I suppose they're just electromagnets pushing a plunger. They have three o-rings separating the ports. I guess the o-rings could wear and allow too much leakage for the system to handle. Or maybe the electromagnet wires could short out and just quit working altogether. I'm still playing with my test box to see if I can detect failed parts on the bench.
 

·
Registered
Joined
·
1 Posts
Here's my opinion. I'd be happy to see corrections or additions!

HPU failures:
  • motor shaft seal fails and fluid shorts the electric motor. This allows fluid to leak outside the HPU and onto the crossmember. I don't know if the motor is shorted permanently, or if you can clean them out and drive on
  • pump gets worn out and can't produce enough volume/pressure to shift gears or run the clutch. There's no fix for this. The swash plate pump pistons are pretty little metal parts with no seals to replace.
  • There are two solenoids on the HPU unit. One solenoid controls the clutch actuator, the other regulates pressure/volume to the GSA.

GSA failures:
  • seals can leak externally and drip on the floor. Clutch actuator seal leak can be isolated by pealing back the clutch dust cover. Anything wet inside means the seals are leaking. Shift actuator seal leaks just piss fluid from inside the GSA and dribble off the lowest point - usually the stroke position sensors.
  • internal seals could leak excessively and then the shift actuators won't stroke correctly. The clutch piston seal is rubber. Both shift actuator piston seals are Teflon.
  • GSA also has two solenoids. They control fwd/side shift actuators. If they fail, gears quit shifting.

Solenoids failures I havent' figured out yet. Solenoids route fluid to the actuators. They are supposed to "hover" between retracted and extended - based on pulsed voltage (Cap taught me). I don't know how they fail. I suppose they're just electromagnets pushing a plunger. They have three o-rings separating the ports. I guess the o-rings could wear and allow too much leakage for the system to handle. Or maybe the electromagnet wires could short out and just quit working altogether. I'm still playing with my test box to see if I can detect failed parts on the bench.
Here's my opinion. I'd be happy to see corrections or additions!

HPU failures:
  • motor shaft seal fails and fluid shorts the electric motor. This allows fluid to leak outside the HPU and onto the crossmember. I don't know if the motor is shorted permanently, or if you can clean them out and drive on
  • pump gets worn out and can't produce enough volume/pressure to shift gears or run the clutch. There's no fix for this. The swash plate pump pistons are pretty little metal parts with no seals to replace.
  • There are two solenoids on the HPU unit. One solenoid controls the clutch actuator, the other regulates pressure/volume to the GSA.

GSA failures:
  • seals can leak externally and drip on the floor. Clutch actuator seal leak can be isolated by pealing back the clutch dust cover. Anything wet inside means the seals are leaking. Shift actuator seal leaks just piss fluid from inside the GSA and dribble off the lowest point - usually the stroke position sensors.
  • internal seals could leak excessively and then the shift actuators won't stroke correctly. The clutch piston seal is rubber. Both shift actuator piston seals are Teflon.
  • GSA also has two solenoids. They control fwd/side shift actuators. If they fail, gears quit shifting.

Solenoids failures I havent' figured out yet. Solenoids route fluid to the actuators. They are supposed to "hover" between retracted and extended - based on pulsed voltage (Cap taught me). I don't know how they fail. I suppose they're just electromagnets pushing a plunger. They have three o-rings separating the ports. I guess the o-rings could wear and allow too much leakage for the system to handle. Or maybe the electromagnet wires could short out and just quit working altogether. I'm still playing with my test box to see if I can detect failed parts on the bench.
Is there any updates on the seal kits ?
 
1 - 14 of 14 Posts
Top