2000 v70 AW55-50SN issues and repair

H_Rovers · Post by **H_Rovers** » 03 Apr 2015, 05:03

I have the well known issues of the AW55-50SN gearbox (clunks on downshifts, sometimes short disengages while shifting, slow engaging from R->D and vv). The car now has 180k miles, I'm not sure for how long it has these issues. I understand that are related to the valve body and that there are several fixes that could work to some extend. My question is; is it possible the mechanics of the gearbox (clutch plates, etc) are affected by these issues, and, if so, what would be the issues if that's the case? What I'm saying is; knowing the issues that I have, what is the change that I fix or replace the valve body, and still have a faulty gearbox

Post by **jimmy57** » 03 Apr 2015, 08:56

Draining the oil into a very clean pan and then checking the bottom for debris. There should bot be any flaky pieces of clutch lining or metal slivers. If the fluid is just dark but not fouled on other ways, the mechanical parts are likely fine.

Test drive the vehicle but shift the gears manually. Start with lever in 1 and apply near full throttle and then at 4000-4500 RPM move the lever to each higher gear. Do this for the lower gears as you likely have nowhere to do this test with unlimited speed limit for checking 3-4 and 4-5 shift.

If the manual shift test shows firm shifts with no slipping then that also will indicate a mechanically sound gearbox. The success rate of valve body repairing shifting issues you list is very high.

H_Rovers · Post by **H_Rovers** » 03 Apr 2015, 09:06

Thanks for your reply Jimmy. I don't have the geartronic gearbox, so I can't shift gears manually. I do notice that "sometimes" the automatic gear shifting goes perfectly smooth (from all gears), so I would say that that would mean something about the condition of the rest of the gearbox.

Your first tip sounds good, I will definitely check the oil before I proceed.

Post by **jimmy57** » 03 Apr 2015, 10:02

I assumed that you had the shifter labelled " 1 2 3 4 D N R P" where putting lever in 1 and then moving it progressively to each higher number will give you manual control.

H_Rovers · Post by **H_Rovers** » 03 Apr 2015, 14:43

I have "L 3 4 D N R P" i think

but, indeed, i could do something similar, but it requires high speeds

Post by **precopster** » 03 Apr 2015, 15:38

Position L will act as a manual ahift from 1st to 2nd gear at a slightly higher shift point than normal. At full throttle L will change from 1st to 2nd at aroumd 6000rpm.

After 2nd gear is acquired in L it is then revved to your engine speed choice and you flick the lever to position 3. You then progress up the numbers on the lever until D position which will give you 5th gear.

I use this method with my 5 speed 2000 auto very often and it is very enjoyable to drive this way.

From what you describe the valve body is your mark. If slipping WITHIN each gear is not apparent the clutch facings are still intact. If 2nd to 3rd has had a long term flare the 3rd gear band anchor (which is designed to transition this shift) will be worn past limits and will cause problems down the track.

H_Rovers · Post by **H_Rovers** » 05 Apr 2015, 01:36

Hi Mike,

I tried your manual method yesterday and the shifting seems OK. I don't feel any slip or other things. However, I do notice when driving in D, some slip in my 2nd or 3rd gear (or during shifting, not sure). During acceleration, the rpm goes to a higher value, and the velocity increases towards the speed corresponding to the RPM and gear. I'm not sure this is always the case. I don't notice this with the manual shifting.

What do you mean with "slipping within each gear" and "long-term flare"?

Post by **precopster** » 05 Apr 2015, 03:12

"Slipping within each gear" is if you press the throttle without making the auto change down and you notice a non lineal increase in revs which is not road speed tied. The feeling is like driving a stick shift with a severely worn out and unadjusted clutch. The revs increase and you go nowhere.

Flaring is a brief feeling of slippage between gears on upshift which can last half a second to a second before good forward progress resumes. The revs rise sharply for a moment then drop back down to where they should be while upshifting. The AW55-50SNs are famous for a 2nd to 3rd flare.

H_Rovers · Post by **H_Rovers** » 05 Apr 2015, 09:50

precopster wrote:"Slipping within each gear" is if you press the throttle without making the auto change down and you notice a non lineal increase in revs which is not road speed tied. The feeling is like driving a stick shift with a severely worn out and unadjusted clutch. The revs increase and you go nowhere.

This is different to what I have. It's just that the revs increase about 300 rpm, and then the speed increases towards this value. It seems like a little slip. Is this normal behavior, or is this also an indication of wear?

Post by **precopster** » 05 Apr 2015, 15:00

Same thing as I describe known as flaring.

Valve body issues.