A while ago I had the dreaded A-drum failure. The transmission is out and I have measured the new strengthened drum and a new clutch pack. Spec says the gap should be 1.95 - 2.25 mm. But reusing the old 3.0 mm locking (snap) ring I get 2.4 mm. I am sorely tempted to go with that. Does anybody know how critical it is to stay within the spec? After all, if I was on 2.25 mm wear would soon see it outside I think.

Or do anybody have a ring in the 3.15 - 3.45 mm interval I could have?

Old damaged drum picture for attention.

 

Wish I could answer your question but unfortunately I can’t, but you may have better luck on a bmw forum (if it’s the 5hp24 ) as it’s a bmw made transmission. Just curious, did you tear it all down, diagnose and repair it yourself ? What symptoms did you have prior to disassembly others may possibly encounter? Did you do any upgrades while in there? Any other tips or tricks you learned along the way you could pass on? Again just wondering because I was considering buying a used trans for cheap near me and rebuilding it myself, and updating and upgrading everything I could just in case my trans decides to call it quits so I have one on hand ready to go. I’ve never fully rebuilt a transmission, let alone completely disassembled and reassembled one but I feel I could and I love learning new skills. Most I’ve done is fluid changes, pan drops for filter changes and simple pressure regulator upgrades and also servo kits on gm transmissions, as well as a full swap once.

 

I don't understand. The transmission is stated to be a ZF 5HP24 so it obviously a ZF box. I don't think that BMW have ever made their own auto transmissions but have always used ZF.

Richard

 

Can't answer your question, but when I replaced my A drum I didn't take any measurements, just put it back together.

 

Correct. The transmission is used by Jaguar, Audi and BMW.

I have pulled and dismantled the transmission myself. The only changes are a strengthened A-drum and TransGo pressure relief valve. And of course all clutch components in the A-drum are new.

Generally the transmission was behaving fine and fluid was squeeky clean. It was flushed about 20k km ago. I could have reused the clutch, I drove 150m once the A-drum went bang.

 

My apologies, I misspoke due to ignorance. The zf trans is not made by bmw as I had thought/assumed. I do believe that there are many more bmws with the zf trans than the jags, as whenever I tried to research any info on the trans it seemed that it was almost always a bmw forum or site, hence my suggestion in previous post.

 

I will replace the needle thrust bearing between B and C drums also. It appears it is a common failure point. I inspected the needle rollers in mine and sure enough there were cracks in some. Still waiting for the replacement though, caught in customs 🤬