My sons a4 1.8l quattro would not go into 4th gear it would just slip and the car would go into a limp mode.I was getting error code p0734 gear 4 incorrect gear ratio.

I removed the transmission, and removed all the parts and from the picture you can see that the 4th drum is broken were the C clip is attatched.All the clutches look great, the fluid was black but did not smell burnt.Transmission shops said the clutches were shot. Not sure if this is a common problem, I have not seen it before.

Does anyone know were this part can be sourced, I tried searching online with no luck?

 

Any experts know what would cause this part to break? Could there be something else wrong that caused this part to break. This does not seam to be a weak part of the transmission,

 

i dont think anyone will know what happened to that. most of us performance guys around this site are more into manual trannys'. with that said, id ask around at a couple auto trans shops for parts, although it will be a tough one to find. you may be best off finding another shot tranny and taking that apart. most of the issues with the tip trannys are with elctronics. of course, if the car was modded thats a whole different story.

 

The only mod is a performance chip. Not sure if driving habbits could cause this part to fail.

 

That is between 465.00-502.20 depending on the trans code you have in your car. Looks like it comes with the piston #10 and that large circlip that isn't numbered, and from what the picture shows, everything within the brackets for #1 listed below too. The clutch packs are included. We would need your VIN to identify the exact part number to order for your car. Thanks, Jeff.

 

This is likely a chicken and egg scenario. The valve bodies often fail far before the clutches or gears. Inspect the valve body very carefully. Look for clogged passeges that would starve the clutch pack for fluid. Black fluid means it's dirty, likely neglected and there are probably particles in the passages.

Honestly we don't typically rebuild auto transmissions at the dealer level, it's not really worth it. It's nice to see you tackled he daunting task yourself. Best of luck! Make friends with your local Audi parts guys, parts printouts and special orders will be very important in your rebuild.

 

Nothing can be done to prevent reocurrence of the same issue.

It's nothing to do with driving style, or maintenance. It's a weak point. The circlip groove is pretty close to the edge of the drum, and prone to fatigue. The same issues afflict the ZF5HP-24A in the D2S8.

 

Another case of that famous German engineering prowess ??

 

I believe it's an AisinWarner... Toyota is the major shareholder. These transmissions are not acclaimed to be the greatest. The ZF auto transmissions are generally much more reliable and longer lasting.

 

I found the input shaft at a shop In Hayward CA. The shop has thousands of used transmissions. The part was $80.00 and a complete rebuild kit with new clutches was $275.

I will start the rebuild today, and have the shop in Hayward rebuild the torque converter on Monday. The cost to rebuild the torque converter is $245.

Including new fluid I should be at around $800.00 after rebuild.