AW42AWD / 4T65 Transmission

[volvomadness]

Have had numerous volvos over the years. 4 speed trans and the notorious AW55-50SN.

Does anyone no if the AW42AWD / 4T65 Transmission which is a GM has the same failure rate as the Aisin (valve body etc)

Thanks Madness

[SuperHerman]

The 4T65E is not a great transmission on Volvos. The AW55-50SN has a much better service history.

On the XC90 it is dreaded, but on the S80 FWD it appears to have a much better reputation.

The problem with the transmission is that it wears out too quickly due to design choices made for smoother shifting. Fortunately it is fairly easy to work on and most shops have no issues rebuilding them.

In the XC90 some have failed under 40k miles, but I have seen S80s going strong with over 200k miles.

[RickHaleParker]

On the XC90 it is dreaded, but on the S80 FWD it appears to have a much better reputation.

You mean the S80 AWD?

2005 XC90 T6 AWD curb weight 4770 Lbs.
2005 S80 AWD curb weight 3633 lbs

The XC90 AWD is 1137 lbs or 31% heavier then the S80. The XC90 requires more work then the S80.
Collectively, trucks get worked harder then a car.

[SuperHerman]

No I meant the FWD, even lighter than the AWD. I had a 2004 which I passed on to my sister. It was shifting great at 165k miles and counting until it hit a larger trailer. No issues with the transmission.

The XC90 was too heavy for the transmission and the soft shift design choice was amplified, with no way to compensate for clutch disc wear it has a tendency to be short lived. The S80 being lighter doesn't suffer as much.

[June]

The 4T65 suffered from adaptive software causing soft shifts for those who drive like a old lady. In reality, as a front wheel drive transmission in the S80 it's a excellent transmission. My 2004 in service date is 12/23/2003 and I regularly floor the accelerator even to this day. The first 12 years and 115K or so it ran with the factory fluid fill and it still looked sparkling clean when it got it's first service. It never shifted "soft" or had a shift flair or any trouble of any kind, and I assure you I gave it Hell!

I opted to replace it 4/2018 / 157K since it had to be removed to replace the engine rear main seal as it only added $3,800 for the new transmission which now is warrantied for life by Volvo. It just didn't make sense to reinstall a 14 year old transmission without refreshing the clutches and seals, but Volvo does not offer that service, just replacement of the unit as a whole. Otherwise I would have had a kit installed with torque converter.


The replacement has been in service for 30K without issue or "soft" shifts. I understand driving the 4T65 gently causes the software to lower the line pressure causing the "soft" shift condition. The transmission was not designed physically that way in a faulty manner. I imagine the AWD, adaptive software, and extra weight is responsible for the XC90 high failure rate. In the 1990s when the 4T65 was introduced for the supercharged 3800 none were AWD. When Volvo selected the 4T65 for the 1998 S80 it also was not AWD. So I'll bet the AWD is more responsible for the high failure rate than anything else. Volvo should have bumped up to the 4T80 without the AWD for the heavier XC90 T6.

I spent a good part of my adult life pre children as a secretary at a Buick dealer stubbing tickets for the service department. Both the 4T60 and 4T65 were quite reliable as a FWD transmission for Buick. From my experience with the 2002 and 2004 S80 T6 application it's just as good. No automatic lasts forever just as no clutch does in a manual equipped car. June

[MoVolvos]

The 4T65 suffered from adaptive software causing soft shifts for those who drive like a old lady... I understand driving the 4T65 gently causes the software to lower the line pressure causing the "soft" shift condition... June

I will test that theory as I noticed the car wants to grab instantly off the line and I was thinking it was my lead foot. Seems to stay in low gear and lug if I drive like an old lady from a stop. Good info!

[SuperHerman]

I am not so sure about the software. As I understand the problem, the transmission has no way to compensate for clutch wear. How this is achieved I don't know. It could be by decreasing pressure or increasing it, but it cannot be corrected on the transmission.

From the start the transmission has too large a clutch pack gap on two of the gears. This was done for a softer shift. The smaller the gap the harder the shift. Rebuilders, whether on the Volvo variant or straight GM transmission, add two thicker steels on one pack and a larger thicker disk on the other. I did this on my rebuild. Shifting is "crisper" and the transmission lasts longer, but the original inability to compensate for wear still exists.

The larger gap, and inability to compensate for wear, causes the two gear packs to wear out faster. Couple the extra weight of the vehicle and its life is further shortened.

[June]

I am not so sure about the software. As I understand the problem, the transmission has no way to compensate for clutch wear. How this is achieved I don't know. It could be by decreasing pressure or increasing it, but it cannot be corrected on the transmission.

From the start the transmission has too large a clutch pack gap on two of the gears. This was done for a softer shift. The smaller the gap the harder the shift. Rebuilders, whether on the Volvo variant or straight GM transmission, add two thicker steels on one pack and a larger thicker disk on the other. I did this on my rebuild. Shifting is "crisper" and the transmission lasts longer, but the original inability to compensate for wear still exists.

The larger gap, and inability to compensate for wear, causes the two gear packs to wear out faster. Couple the extra weight of the vehicle and its life is further shortened.

How I love misinformation! This video from GM "Buick Motor Division" clearly states between 5:20-6:00 that the 4T65E compensates for clutch wear. June

[taxi]

Thank you for this, June! I will continue to just enjoy my car, service it, and not worry about wear.