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XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

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Tone944
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Tone944

XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by Tone944 » Tue Jun 20, 2017 4:17 am

Ok, so... I'm hoping this will help somebody else who might come across this problem. This is my first auto trans overhaul and I'm learning heaps!

Here's a bit of a quick history:

1. For few hundred km's before the car had no drive, I noticed what appeared to be some slip in the transmission with a slight shuddering. I actually initially thought the shuddering was an engine mount issue. (we had an issue with an XC90 that had noise/vibration due to an engine mount)

2. It got worse to the point where I meant to tell my Wife not to drive that car, but forgot, she took it out and got stranded with absolutely no drive, in forward or reverse. After it had cooled, I managed to drive around the corner from where it was stranded, then nothing at all. After it was towed home and totally cooled, still absolutely no drive, forward or reverse.

3. After a fair bit of research (big thanks to this forum and others!), I realised at the very least, I need to overhaul the valve block and possibly put a master kit through the box. I also found a lot of evidence to check the bushes as they can cause low oil pressure.

4. I launched into it, removed a plethora of engine components, ready to remove the engine.

5. I then decided that I should just lower a corner of the sub-frame and remove the valve body and give it a good check over. I found a few things that were of very slight concern, a couple of slightly tight valves, but not enough to cause a full "no drive" failure. Of course, the oil was very dark and horrible! But the VB looked as if it had a mod kit through it some time, the solenoids had aftermarket end caps.

6. Since the VB wasn't in that bad shape, I continued to remove the gearbox. What a mission!!! I removed a Subaru outback gearbox in less that 2hrs in the driveway. This thing was a huge job, there were so many things to remove to get access.
In brief the procedure I used was:
a) remove lots of engine wiring and accessories,
b) remove RHS drive shaft,
c) unbolt steering rack and sway bar,
d) remove cat support, take lower control arms off at ball joint ( I unbolted the 2 bolts holding the ball joint to the stub axle housing, instead of the 1 bolt holding it in the wishbone, much easier!),
e) support engine with a support frame across the engine bay,
f) remove sub frame (actually was quite light and easy to handle by hand),
g) Drop engine and gearbox far enough to work on it,
h) unbolt drive shaft from angle gear (jacked the rear off the ground to rotate when necessary, dropped it when needed to hold the shaft still while unbolting.)
i) Unbolt and remove angle gear. No need to unbolt the exhaust at the turbo, it has enough flex and since the mount on the cat is removed.
j) unbolt most of gearbox, leave 1 bolt at the top in
k) unbolt flex plate bolts through the starter hole, there are 6 torx bolts, turn the engine at the crank pulley which is now easy to access since the engine is dropped a bit.
l) connect my engine crane to the gearbox - there is a lift point that a shackle can go through.
m) remove the final bolt and wiggle and jiggle until the trans comes free
n) drop the trans and roll it out under the car. I didn't actually have the car that high, just mounted on stands slightly behind the sub-frame mounts. I'll post a pic...
IMG_3462.JPG
7. I then got the box into my workshop and started to dismantle. So far I've only taken the first cover off, but I've found enough already!

So here's the verdict...

The first few clutches I took apart seemed in OK condition, nothing obvious. All the bearings and gears looked immaculate, even though the oil was very dark. At this point I decided I would take things to a very helpful local automatics guy to advise my on the amount of wear once I had a few more things removed.

I then noticed a build up of stuff on the turbine shaft hall sensor, closer exam it seemed to be metallic particles. Then I thought I should run my finger around the lower area of the casing, which was full of grit. At that stage I knew I was sure to find a serious failure somewhere.

Turns out that when I pulled the input shaft, that the drum appeared to be discoloured. Then, the steels and frictions where really difficult to remove, they were all caked together and lots of grit around. When I did get some apart it was very obvious that this had been seriously overheated. All the frictions were in a real mess. See photo.
IMG_3475.JPG
I took what I had dismantled to the Automatics service guy, he mentioned that these often crack the housing of the C1 Drum, he inspected and found it had (see photo). Apparently, they crack, this results in loss of pressure on the C1 clutch, and then burning of the frictions. I also would expect that this might start off slight but quickly get worse, here's my theory; frictions start to wear, filter starts to clog, oil pressure drops, things spiral to worse very quickly from there.
IMG_3471.JPG
From here, I'm going to strip down the rest of the trans, assess parts needed, get parts quotes and see if it's feasible to resurrect this car.

Tone944
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Tone944

Re: XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by Tone944 » Tue Jun 20, 2017 4:19 am

Oh NO! I accidentally posted twice! Mathew or other moderator, can you please delete this one, photo's haven't worked on this.

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Re: XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by precopster » Tue Jun 20, 2017 5:34 am

Exactly the same damage on that transmission as in my now sold 2001 XC70, with cracked drum and fused friction clutches and mettalic grit.

Make sure you get ALL the grit out of there with solvents and replace the filter.

I found a good used one and threw the old one out.
Current cars:2002 XC70, 2006 Ssangyong Rodius (Stavic), 2006 XC90 2.5T, VW Transporter 2.5TDI

www.precisioncarmodules.com.

jonesg
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Re: XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by jonesg » Tue Jun 20, 2017 5:45 am

Tone944 wrote:
Tue Jun 20, 2017 4:19 am
Oh NO! I accidentally posted twice! Mathew or other moderator, can you please delete this one, photo's haven't worked on this.
The pics didn't post.
Pics are in the other thread you posted hahaha, oh well.
It would be cool if you document a rebuild.

Tone944
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Tone944

Re: XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by Tone944 » Wed Jun 21, 2017 3:40 am

Here's the pics below. Also, as far as a procedure for dismantling, this video is fantastic:
IMG_3462.JPG
IMG_3471.JPG
IMG_3475.JPG
You do not have the required permissions to view the files attached to this post.

jonesg
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Re: XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by jonesg » Wed Jun 21, 2017 7:45 am

I've watched that guy before, didn't realize thats the volvo transmission.

He's good but ...kinda slow . :mrgreen:

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mrbrian200
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Re: XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by mrbrian200 » Wed Jun 21, 2017 9:05 am

I would suspect a recurring heat buildup issue occurs first, the steel becomes brittle, eventually the drum cracks and obviously snowballs fast from there-frictions burn up probably with a matter of 50 miles or so).

Your AT tech didn't have any insight as to the root cause did he? Depreciated fluid? Low pressure/leaky valve body seal/bad solenoid?

Tone944
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Re: XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by Tone944 » Tue Sep 05, 2017 5:14 pm

ok... time for an update on this job. I've been doing it in my spare time, which I don't have much of, so it's taken a long time.

1. Bought a 2nd hand drum from a USA AT dismantler. was very impressed with condition.
2. Bought a Frictions / Steels / Seals / filter kit from Chinese supplier on Alibaba. Seems to be good quality.
3. Bought a set of bushes from a USA supplier on ebay.
4. I had already bought a Sonnax "shift kit" before I had removed the AT
5. Took my time putting it all together, cleaned everything immaculately, printed exploded views and ticked everything off as I went. Only thing I had trouble with was getting C3 clutch/ B4 Drum onto the shaft (Note, this will be important for a later point). I also drilled the VB cover pan to be ready to adjust solenoids (this reference is useful: http://www.sonnax.com/tech_resources/19 ... nformation ).
6. Back in the car and very surprised that it started first go after 6months
7. I was prepared before start with the cooler outlet connected to a clear hose and put into a waste oil container, so that the Torque converter would flush out. Last thing I wanted was any dirty fluid mixing in with my nice clean fluid. Normal procedure it to run engine intermittently topping up fluid between, but instead I took a shortcut and kept filling the box with ATF as it ran, until new fluid was coming out the clear hose.
8. Gave the box a test, first few garage shifts were a bit rough until air was out of the system.
9. I was going to run through the gears with the car on blocks, but ended up being lazy and just driving it. A few harsh changes initally but got better as air got out of the system. And of course it will still need solenoids adjusted and an adaptation.

*** Unfortunately there is still a couple of problems...
1. 4th and 5th don't work, which means C3 clutch isn't applying properly. I've measured pressure at the c3 Tap and it's only getting to 20psi (I'm not totally sure what it should be, but going by the pressures used in C1, I reckon it should be a lot more. Flow from the C3 Tap is OK, so I suspect that it's not the VB. I think it may be the 2 seal rings on the shaft (look like plastic piston rings), I think I might have damaged them when installing the c3 clutch / b4 drum. Good side of this is that this can be checked by only removing the end cover of the box. Could even be done in the car by dropping the subframe and engine and box.
2. I was a cheapskate and didn't replace the rear main crank seal... AND it's leaking badly!!! I can't believe that I broke the important rule of "replace everything while you can".

So next step from here...

Call the scrappy and get them to pick up the car! No, I'm too silly and too determined to choose to do the most sensible thing!

I, think I've devised some short-cuts to get the box out again. I think I can just move the angle gear out of the way instead of removing it. This saves a whole lot of undoing of exhaust components to get to the drive shaft flange. And last time there was a lot of engine piping and wiring that I removed unnecessarily (thought I was going to have to drop the entire engine). So I think I can just suspend the engine, drop the subframe, lower the engine, then slide the gearbox clear enough to access the rear main. While it's lowered, I'll be able to remove the rear cover and check what's going on with the C3 oil passages and seals.

Also, here's a link to a really good service manual for AW55-51 (very similar to AW55-50), ironically I found this after the job was done!

Big question is what else should I be doing while all this is out?
- Already planning on doing PCV system as this has probably caused the crank seal
- Is there any turbo service that should be done while it's more accessible?

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oragex
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Re: XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by oragex » Tue Sep 05, 2017 6:40 pm

Tone944 wrote:
Tue Sep 05, 2017 5:14 pm
9. I was going to run through the gears with the car on blocks, but ended up being lazy and just driving it.
I may be wrong, but I did run the transmission on the blocks and something is messed up with my axles now. Probably didn't like the stretching at the angle with the suspension fully extended.

Good luck with the second removal, it will surely go much faster the second time.

01_Nautic_V70
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Re: XC70 Transmission AW55-50SN No Drive - Problem found... C1 frictions burned and Drum cracked

Post by 01_Nautic_V70 » Tue Sep 05, 2017 7:25 pm

I've run the trans on blocks with no axles or suspension on. It worked to verify the pump whine was gone and the output shaft was moving in drive and reverse.

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