Hi, this is my first post here. I'm think this is the correct section since my machine indeed isn't functioning without the cam lever.

I own a Rocket R58 for about 5 years now. I have never had any maintenance performed on the machine, only backflushing regularly, sometimes with detergent. The other day I removed the cam lever assembly to investigate an issue with how the action of the cam lever feels. The best way I can describe it is like the feeling of rubbing two pieces of sandpaper together when I open and close the valves. It was no longer smooth after I had not used the machine for maybe a three week period.

When putting the cam assembly back on, I caused a new issue by crossing the stainless bolt threads and the soft brass threads in the socket of the E61 group head. Now the brass is bent on the leading end, some brass shavings also came off. I will post pictures to show the top and bottom sides of the socket.

I got a quote from SCG, which is where I bought it, about fixing it. Their response was very helpful and they said that a full replacement of the group head, if repair can't be done, would be north of $400 which is hard to swallow(not to mention shipping from Dallas to Seattle). So my question is, does anyone here have experience with fixing bent or busted threads on an E61? I would be willing to try fixing it myself since the part is already damaged. Can a small amount of thread be shaved away and still be structurally sound, or a repair with a tap made? Does anyone have ideas or experience fixing threads?

Thanks

The part does not take a lot of stress at all, and being that it is the outer thread that is damaged I personally would attempt repair if it were mine. If you can figure out the actual thread dimensions you can try a search for "Internal metric thread restoration tool."

For example, I found THIS ONE on eBay. Otherwise, a small carbide bit and a rotary tool, good lighting, and a magnifying hood and careful work should be able to clean it up, working from below the bad thread and working from inside out.

Otherwise, a local machine shop may be able to help.

The tool you want is a thread restorer file like those in THIS SET. I bought mine one at a time from SnapOn about 35 years ago, and you can still get them that way from pro tool suppliers. I don't know the exact thread pitch and count for that location, but you should be able to get the info from your selling dealer. These have rows of teeth that will cut in 2 directions normal to each other, so you can do both male and female threads with it. For female threads, you have to hold the file at a steady right angle to the threads and rotate it back and forth along the threads holding its axis perfectly parallel to the axis of the hole. This corrects the thread deformity by removing it more than by reshaping it. Since this is at the outer end of the thread, you almost certainly will not have a problem with what remains holding its mate.

There are thread chasing and thread repairing taps. They're not easy to find, and I suspect that one in that size and thread will be shockingly expensive.

You should disassemble the group so that you don't get any metal debris into the workings. I've done this on intact automotive assemblies as an emergency in the pits, but it's not a great idea. You can push a ball of cloth or heavy wadding impregnated with food safe oil or grease past the threads to catch shavings etc, and you can carefully pull it out with fingers crossed in hope that nothing's left behind. But the right way is to take it all apart.

As this is brass, you may also be able to roll and push/pull the thread back in shape with a small, solid tool like a dental burnisher. It'll take you at least a few hours of steady back and forth pushing, but it may be doable. I have a set of "T" and "ball" burnishers that were used for gold foil restorations (which are no longer used in clinical dentistry) - I've had them for decades because my father was a dentist, and it's amazing how useful they are.

I saw the thread restoring files like that but every one (including the ones you linked) had the statement, "Used to restore damaged or worn external threads on bolts." That was why I did not link to those.

I have never cross-threaded anything so I wasn't sure those would work.

You have to be really good with them to do internal threads, but with patience it can be accomplished as long as the ID is at least a few times the thickness of the file being used. From the picture, it appears that the damage here is limited to the last few mm of the end of the thread. So it would only require massaging what appears to be 30 to 45 degrees of the circumference to fix this. By seating the file against the intact threads and gently moving the file back and forth over that small arc, I think it could be done easily. One trick is to hold your index finger along the file with the ball of the finger directly over the area to be repaired, rather than trying to hold the other end of the file and move it against the threads. Press the file firmly against the threads and gently sweep it back and forth thru the affected arc.

The minimal extent of thread damage actually might make it just as practical and a lot easier to simply remove the last few mm of the crest of the thread with a fine stone on a rotary tool and taper the new leading end.

To be honest, I'm a facial plastic & reconstructive surgeon who's been building and restoring cars for 50+ years - so my manual dexterity is probably a bit beyond average. But I think that most people with at least a modicum of mechanical experience and ability could do this. Without a jig to hold it, it'll be at least as hard to avoid marring the assembly as to fix the thread. So making up a fixation device (e.g. holding it with wooden V-blocks in a vise) will be essential to getting the best result with the least difficulty.

And, of course, the worst thing that would happen (apart from accidental damage to some other area) is that it'll still need to be replaced. But it looks to me to be repairable with hand tools and patience. I'm just a bit concerned that Jeff cross-threaded it. The repair is a lot more delicate than simple reassembly of an undamaged e61, and tactile feedback is usually more than sufficient to prevent cross-threading of large, clean, undamaged parts like this.

I thought about learning to play guitar but my manual dexterity is more suited to harmonica.. I wanted to go solo (guitar/harp) but my wife said I should concentrate on being bad on one instrument at a time.

I would have gone with the files myself..

Another thing we should mention is that the male threads on the big nut should also be carefully checked.

bluesman wrote:I'm just a bit concerned that Jeff cross-threaded it.

In my defense, what made it difficult for me to seat the threads correctly was the irregular shape of the cam shaft lobe. I'll admit I didn't take care enough to mind that the cam shaft, when seated on the two valves, pushed the assembly to the side ever so slightly when I started turning the wrench.

Thanks for the help! I'll look into these tools and try to figure out the thread diameter. I'll report back with how this repair turns out once I get to it.

1)
For more detail on the E-61 group, see these two articles on my website:
How-To 18 - Simple Lubrication of the E-61 Group
How-To 19 - Overhauling and Lubricating the E-61 Group

2)
In this case, always start threaded assemblies by hand and run them down as far as possible. Start them in the reverse direction that they tighten by pressing it into place, turn counter clockwise until you feel the "click" of the threads mating, then turn clockwise to tighten. This is particularly handy with assemblies under spring compression.

Randy G. wrote:always start threaded assemblies by hand and run them down as far as possible.

...and never, ever use a wrench to tighten an ordinary unloaded thread that you can't turn at least 2 full rotations by hand first. There are some shallow fittings that only have a turn or two to full engagement, and there are fittings with spring loading or other force-generating designs. But if it's not some special fitting and doesn't start smoothly and easily by hand, it's probably dirty, damaged, or cross-threaded no matter what or where it is.

I just looked at my own e61, and the female thread in the lever housing is perhaps 2 to 2 1/2 times the diameter of my smallest metric thread file (I didn't disassemble it to measure). As thread files are square in cross-section and have cutting teeth on all 4 sides, if I were to try this repair, I'd probably sacrifice a file and hollow out one side to accommodate my finger.

It is an M30 x 1.5 thread and a tap is about $120 from McMaster-Carr.