7800 shifters on a 7900 RD

[Woofie]

Sorry if this has been asked before.

 

My 7800 RD broke last weekend. Root cause I suspect was the aftermarket KCNC jockey wheels which were on it when I bought it second hand. Has been very happy for about two years but last sunday the whole thing failed horribly. I think one of the wheels broke hooking the chain with the sharp pointy bits which took out the arm that houses the wheels and then finally my hanger. My YBN chain very surprisingly hasnt broken but it has mysteriously been bent 90 deg in two different places. 

 

I do have a old 10 speed microshift RD which I can use, but I would love to get another 7800 RD because it really did shift so so nicely.

I see they are lank rare though.

I do however see more second hand 10 speed 7900's going though. 

 

Because the 7900's featured cables that could be routed under the tape is the RD any different?

Both are 10 speed and I am not aware if cable pull ratios have been changed at all. So would it work?

I dont want something that is going to play up either I would rather look for a old ultegra then instead.

 

Another question.

I know that weight weenies replace the swing arm with carbon ones. So that is possibly a solution. To just replace the arm. Is there another derailer which shares the same arm that I could take it off?

http://www.bikerumor.com/2013/05/29/found-outrageous-64g-dura-ace-derailleur/

 

Any other ideas?

[SeanMort]

I'm using 7800 shifters with a 7900 RD and it shifts just fine.

[dirtypot]

It'll work 100%.

Not sure about replacing the arms though - you make it sound like a mangled mess which would mean more damage than just the arms.  It's hard to tell without seeing it though.

[Woofie]

It'll work 100%.

Not sure about replacing the arms though - you make it sound like a mangled mess which would mean more damage than just the arms.  It's hard to tell without seeing it though.

 

From a brief inspection it appears that just the arm was torn off. But there is always a risk that there has been other damage that I wont see until trying to use it again I suppose.