Gearbox Teardown & Refurbish - 6HP28A61

[RS_BROKE]

Hats off to you sir! Do you work with gearboxes for a living ? You looked like a pro! I might be in a position to repair one of these in the not so distant future, also if any one wants to see write up on repairing c7 gearbox I might take some pictures when I get round to it

[RS_BROKE]

- did you find the cause of the original problem (stuck in fifth) when you were stripping and rebuilding?
- the title says your box is a 6HP28A61. I thought the C6 RS6 had the 6HP26A61. That's quite a big change. The second generation 6HP boxes had quicker changes and slightly more torque capacity.

For those really observant there is an image in one of these posts (third in this link viewtopic.php?f=47&t=129779#p894614 ) that shows the ZF tag with model and serial number stamped - This is on the underside of the box and tells you what the code is. Check yours and advise if its diifferent. I believe all C6 RS6 are 6HP28's but Im sure someone will correct me if this is not the case. Mine is a 2008.

I put my sticking gear down to one of 2 (or both) main problems found; loss of pressure at the valve body seals (compressed rubber tubes) and bad clutch stack clearances.

Mines 2008 zf6hp26 stamp

[zex]

2010 plus version, 6HP28A61

[welwynnick]

The RS6 gearbox part number puzzles me. Some sources say it's a 6HP26 and some say it's a 6HP28, as fitted lots of more recent Audis. If you do some research you'll soon see that it LOOKS like a 6HP26, and that the 6HP28 actually looks rather like the 8HP with the equal length front drive shafts etc. However, the RS6 6HP isn't like other 6HPs. I seem to recall that it has an improved controller with quicker shifts. Therefore I think the RS6 unit is a hybrid between the two - mechanically a 6HP26 and electrically a 6HP28.

Nick

[ATinOf]

The front drive shafts are not equal length, one passes through the gearbox behind the torque converter.

There are differences in some of the clutch pistons seal profiles on the 6HP28, whether that was just an improvement or it operates a slightly higher pressure I do not know.

According to ZF the improvements between the 2 are faster shifts and better economy in the 28 as compared to the 26, maybe the 28 was fitted in the models with the sports plus suspension? Must be some reasoning behind it, I cant believe its just random, especially as mine was an early model having the 28.

[ATinOf]

The front drive shafts are not equal length, one passes through the gearbox behind the torque converter.

Doh, just like me to forget about the split point on the shaft that passes through the gearbox, scratch the above, talking nonsense again!! I blame the beer

[welwynnick]

I meant the drive shafts external to the transmission.

On the earlier cars up to the RS6 C6, the LHS drive shaft is longer. On the later cars the drive shafts are the same length, and the transmission has an extension to the near side flange.

The C6 RS6 doesn't have this, but all other 4WD drive cars with the 6HP28 do, as far as I can tell. I presume it means the L & R drive shafts can be the same part.

Here's a 6HP26 (the RS6 'box looks like this):

And here's a 6HP28 (this is from an A8, not an RS6):

Nick

[RS_BROKE]

There may well be a cut off point in 2008 some are 26 some 28
My 26 looks identical to ATinOf’s 28
The 6hp28 pictured above does not look like the 28 in the c6 rs6
Front diff and torque converter look different?

[ATinOf]

No that image of Nicks of a 28 looks nothing like it, ELSA lists 6 flavours of the 6HP28 for the C6 RS6, all of them use the 09EA base-code, so I expect they all use the same outer case casting, which is NOT the one above.

The flavours are KBD, KUE, KZH, KZQ, LLJ and MKT.

Your options Sticker in the boot should will tell you which is yours.
In big letters 2 lines above the matrix of option codes will be the codes for the engine (BUH) the rear diff (HNL) followed by your gearbox (KZQ for mine)

[ATinOf]

Technically I should say above six flavours of gearbox, not 6 flavours of 6HP28; as some of you guys have the 6HP26

[ATinOf]

It should also be noted we are all assuming some prior owner havent gone and swapped the bloody gearbox historically and not told anyone

[IanH755]

Your options Sticker in the boot should will tell you which is yours.
In big letters 2 lines above the matrix of option codes will be the codes for the engine (BUH) the rear diff (HNL) followed by your gearbox (KZQ for mine)

It's also on the side of the gearbox as a metal ID plate too. Here's my KZQ noted GB -

[RS_BROKE]

My 6hp26a-61 is kzq dated 08/09/08 At first I did think it was 3.0 tdi box But all the numbers come back as rs6

[ATinOf]

If you are planning on doing your box RS-Broke, I will finish the commentary on the last images I never got round to over the weekend (If I can remember what was relevant that far back!), I should have the time, and post up the parts list etc I have to aid you.

Its a team effort, we help where we can, you return the favour to ANOther, the world goes round that bit smoother

[ATinOf]

Ok guys its been a while since I've updated this post but what follows here are some data files that you will find useful whether you have the 6HP26A61 on your RS6 or the 6HP28A61.