# E61 Group Head Cross Threading (Rocket R58)



## ZNerses (Sep 4, 2016)

Having searched and searched it looks as if nobody has had this problem. I recently disassembled the lever mechanism on the E16 group head for cleaning and lubricating (was getting a little stiff and squeaky). The machine is less than a year old so all components were actually fine. But upon re-assembly I hit a dead end when I found out that the main bolt that screws into the side female hole was going in at an angle. After checking and trying I realized that the threads of the female were very badly crossed/worn. I had never unscrewed this before. It totally renders the machine useless as I cannot put the lever together again (not only does it leak but the cam is not true and stiff). Can anyone recommend a remedy? Is there a way of fixing this (there is plenty of good thread left deeper in). The male bolt in question (part 527177 see attached) actually looks fine (I wish it was the opposite) so does this mean the entire group head shell will need replacing?

Furthermore has anyone experienced a vibrating pump? The pressure gauge fluctuates during coffee extraction (+/- 1.5bars) and has become noisier. Pump replacement job?

Zhirayr


----------



## DavecUK (Aug 6, 2013)

Unfortunately you have cross threaded it when you re-tightened. The best way around the problem is to see if you can clean the threads out and try to rectify the portion where you have cross threaded it. Your success chances will depend on how much force you used when screwing it back together. My guess would be plenty.

You can try a thread file, or thread restorer they might be called. You can get special ones for the inner thread, other than that you may have to use a tap and go carefully. It can be repaired, but I suspect you may not have the skill to do it. Perhaps seek out a local machine/metalworking firm.

Of course this is all a guess, because you have not posted a photo of the damaged thread?


----------



## MediumRoastSteam (Jul 7, 2015)

Re: the pump, there was someone else here with the same issue but with a Cellini.

Rocket Cellini Evoluzione bar meter jumping

https://r.tapatalk.com/shareLink?url=http%3A%2F%2Fcoffeeforums%2Eco%2Euk%2Fshowthread%2Ephp%3Ft%3D31748&share_tid=31748&share_fid=6813&share_type=t


----------



## ZNerses (Sep 4, 2016)

Thanks for the replies. After filing down some outer threading I managed to screw the bolt back on evenly but yes it was very very tight (needed a wrench). To be honest it was tight when I undid it so I'm not sure if it was me who crossed the threading :S. The male bolt seems so much harder than the female threading (the plated brass is just too soft). The interesting thing is that my two issues seem to have been inter-linked but I cannot understand how. After re-assembling the lever mechanism (with some lubricant) the aggressive pump vibrations have ceased. The coffee extraction is now extremely smooth with stable pressure. This leads me to ask - how does the lever work? Why is there a spring mechanism between the main bolt and the lever? Is there some kind of hydraulic mechanism in place?


----------



## DavecUK (Aug 6, 2013)

ZNerses said:


> Thanks for the replies. After filing down some outer threading I managed to screw the bolt back on evenly but yes it was very very tight (needed a wrench). To be honest it was tight when I undid it so I'm not sure if it was me who crossed the threading :S. The male bolt seems so much harder than the female threading (the plated brass is just too soft). The interesting thing is that my two issues seem to have been inter-linked but I cannot understand how. After re-assembling the lever mechanism (with some lubricant) the aggressive pump vibrations have ceased. The coffee extraction is now extremely smooth with stable pressure. This leads me to ask - how does the lever work? Why is there a spring mechanism between the main bolt and the lever? Is there some kind of hydraulic mechanism in place?


For sure you cross threaded it, the factories that make these make so many and would never let one through that had a cross threaded group lever support housing, the worker would just bin it and it would get melted down again. It is possible with the Rocket group that they use some steel parts mixed in...I remember Meo explaining once that an upper part of the group was steel apparently. If you want to know how it all works..

http://coffeetime.wikidot.com/search:site/q/e61%20group


----------

