Transaxle Failure

This is a great thread, too bad the pictures do not come up anymore.

 

There is a topic about transaxle fluid analysis in the 2Gen. Could you copy there, please?

 

In another forum where I "lurk" one of the members bought a set of the Toyota SAE papers dealing with the Prius "C". He found an interesting reference in "2012-01-0623-Development of New Hybrid Transaxle for Sub-Compact-Class Vehicles" which possibly gives some insight to transaxle burnouts in the NHW11 and the rare ones in the NHW20.

"As with the P410 [ZVW30 transaxle, RJW], the heat generated by the gears and motor/generator of the P510 is dissipated through two routes: thermal conduction to the case based on part-to-part contact and thermal conduction to the case via ATF. The heat dissipation characertistics are extremely important because they greatly affet the insulation performance of the motor stator and the generated torque."

His own observations on a NHW11 indicate that sustained operation in excess of 70mph results in a distinct increase in MG1/MG2 temperatures. The can cause deterioration of the insulation.

While I'm not sure if this has already been covered in a previous post I couldn't find anything doing a search. I've put it in the Gen-II group because the transaxle cooling on Gen-III is redesigned so there might be some applicability.

I've got a 2005 with 75,000 mi and on my last service I had the dealer change the transaxle fluid. However, this was not the reason because I didn't see this item until after having the service done.

 

Yup heat is what does in the insulation. Either from high current flowing through the windings or just atf temp.
Which is why hills are very hard on the trans especially if the Hybrid battery is low. That creats high current flow through the windings espcially if the driver is clueless and senses lack of power up the hill and just floors it. Thats pretty much death for this cvt.
Best practise is change the cvt fluid every 30,000 miles and same for Inverter coolant. Inverter coolant change is simple and cheap. Inverter coolant is easily contaminated by all the raw aluminum it has to circulate through as evidenced by the white dust on the Inverter coolant tank cap. I change my trans fluid and Inverter coolant every 30,000 miles.
Very cheap insurance. I also use high quality Redline ATF.

 

Read more: http://priuschat.com/threads/transaxle-failure.58920/page-10#ixzz1zFBNBtN3​

I'm not following. I thought 28% of ICE sourced torque and all of the battery power is routed through MG2. Why would all ICE be more MG2 current ?​

 

One trick when changing/pumping in the transmission fluid. Heat the bottles up in hot water in the kitchen sink. Makes refilling much, much easier.

 

I'm doing the same thing myself, I am trying to drop the crossmember but the rack and pinion are attached. Did you have to unbolt the rack and pinion or am I missing something?

 

BTW, the Toyota repair manual appears to indicate you can drop the crossmember with the rack & pinion steering gear still attached. Have you found a problem with that procedure?

 

Yeah, its attached to the steering knuckle lol. I think something has to be unbolted, just not sure which.

 

techinfo.toyota.com may be helpful. In the meantime, from the Toyota repair manual:

27. SEPARATE STEERING SLIDING YOKE SUB-ASSY

(a) Install the seat belt as illustrated so that the steering wheel does not turn.

HINT: It prevents open circuit of the spiral cable.

(b) Remove the 2 clips, then remove the column hole cover silencer sheet.

(c) Loosen the bolt on the column side (A) of the sliding yoke.

(d) Remove the bolt on the gear side (B) of the sliding yoke.

(e) Put paint marks on the sliding yoke and intermediate shaft, then disconnect the sliding yoke.

 

I just undid the 4 bolts holding on the rack and pinion, and the 2 bolts holding down the sway bar end links

 

Thank God! the dealer has mechanics!

 

The job was easier than I expected- hard, but a straight forward removal and replacement of a transmission. The proper tools helps. Up until I hit 35 I was game for any car repair job- still have a nasty scar on my arm from a slipping VW engine- ripped my arm on VW Bus sheet metal trying to get out of the way fast enough.

 

well toyota recommends replacing the transaxle fluid at 100k miles. i did mine early and alot of people here say to change it every 30-40k. it is a easy enough job to do so it might be a good idea to do so to keep this type of failure from happening again. my oil was pretty dark too but thankfully i did not have any metal shavings in my unit.

 

glad you got your car up and running again.

 

My car broke down while driving to the gas pump to the gas station parking spot. Reverse, park, and drive didn't work, had to use the emergency brakes. I brought it to the dealership, they first said it was a broken axle. I was relieved and said "Well good thing the transmission isn't broken." The next day, they called to tell me they took the axle out and saw that the area where the axle enters the transmission is scored. They can't replace that part of course, only replace the entire transmission. Costing about $2,500. Does that sound right to you?

A broke right axle = entire transmission replacement? They said that it needs to be smooth for the axle to make revolutions smoothly and if not can cause future damage transmission damage.

Attached are photos:

 

You didn't mention the miles on the car. But fairly common on front wheel drive cars.

When the inner cv shaft fails catastrophically (breaks off at the cv joint) it tends to beat the crap out of the bearing race in the diff.
Its probably been vibrating or clicking or popping for quite a while or original part at 150K+ miles. Usually in a Prius its the passenger side that will fail first since its the largest shaft.

Of course poor trans fluid maintenance may accelerate race wear also. This is a bad combination as poor condition fluid will wear out the race causing the inner shaft to vibrate out of round. If the inner shaft joint fails that joint is designed to go in and out and and won't last long and alot of times will damage the diff race. Lots of wear there. The differential end of the trans takes the most beating.

When you change the trans fluid the majority of wear your seeing in the fluid comes from the differential part of the trans.

Good idea to have the cv joints inspected at 100K miles and every 20K after that. At that miles just cause you don't hear any noise or vibration your cv joints still may have a problem. When you buy new tires ask the tech to check them. Its free.

And really good idea every time you change the oil to apply rubber conditioner to the 4 cv rubber boots. One crack in the boot and that joint will fail.

I like Black magic Protectant.

 

Excellent photos.

I can see the scoring on the transmission half, but there does not seem to be much wear. I'm surprised you are being told to replace the transmission. Do NOT take the above as advice, but perhaps a second opinion is in order. I'm curious what the smart folks in the forum say.

 

Car is 87,000 miles, 2005 prius. The dealership said the problem is that the axle got "bounded" which is rare and also I wonder a defect. I will try to get a 2nd opinion. thanks for the advice.

What is also peculiar is that the previous few months my mileage has only been 35mpg which is extremely low for a prius. Then when i was driving to utah from California, the battery showed up as only 1 bar (out of the 10) and the my mileage jumped to 49mpg.

ALSO, the dealership said my axle caused the transmission to shut down. However, I heard that putting the breaks is part of the hydraulic system so why is that not working as I roll down the ramp backwards?!