Convert ATF pump coupler worn, now what?

[Shiny Hat]

6, if doing 3 flats won’t be the same width. Measured across , flats will be correct but flat width will vary.

[bigbikerrick]

                                                                                                                               

                                                                                                                             
                                                                                                                                   Rick.

[Shiny Hat]

Highly technical drawing. This is cutting four sides, 3 can’t happen.
Distance across would be equal, flat width would vary.
Being that the drive is an Achilles Heal, you want it as best as possible.
Your talking removing very little to get to your spec., I get it, but this should answer your question. How important is it to you, I can’t answer that.





That’s incorrect, can be done with 4 and 6 cuts, can’t be done with 1,2,3,5. It will look like a isohexatrapizoid.
Drawing is off, need to update software in my pen.
I’m going to go fit a square peg in a round hole.

Ok final answer, 1, 2, 3 cuts = no go. 4, 5, 6 to get all measurements equal (measured across flat to flat and flat width) (order the OEM hex key, can you? and be done). I would still look into the slotted cut drive, pretty common for pump drives so it’s proven reliable).

[Moparnut72]

Like a 6 point socket or box end wrench compared to a 12 point. In the airplane shop 12 point tools were not used. I don't think they were even allowed.
kk

[Shiny Hat]

Just throwing this out there but if the slotted drive is far superior why not go that route?
The time involved with removing the cam and having the slot cut is not that much. A couple more hours of work and you can permanently put this to bed, just a thought.

[ray bear]

Been following this thread but I seem to be missing something, but as I wrote in this thread at the beginning I done mine some time back on the mill with a rotary table and a stone and light passes as to not get the hex hot , the mill controls the cut depth and the rotary table keeps it central, I machined one end more than the other as the pump had more clearance than the cam  ,when finished if all true  the hex should be a nice equal fit when rotated to all 6 positions at each end  I dunno Ill keep following may be I done something wrong  but you have my attention . Ray

[Antietam Classic Cycle]

Been following this thread but I seem to be missing something, but as I wrote in this thread at the beginning I done mine some time back on the mill with a rotary table and a stone and light passes as to not get the hex hot , the mill controls the cut depth and the rotary table keeps it central, I machined one end more than the other as the pump had more clearance than the cam  ,when finished if all true  the hex should be a nice equal fit when rotated to all 6 positions at each end  I dunno Ill keep following may be I done something wrong  but you have my attention . Ray

Mine was 6.2 mm for the full length, and as I have written previously, it's been working fine for the last 32k miles and I have no reason to believe that it won't go at least that much more, plus.

[ray bear]

Have only travelled about 6000 mile with mine and intend to inspect it at around the 10000 mile mark , and hopefully all will be well. time will tell

[brider]

Highly technical drawing. This is cutting four sides, 3 can’t happen.
Distance across would be equal, flat width would vary.

Drawing is off, need to update software in my pen.

Of course! And thanks for you highly technical dwg, those are the best. I have easy access to engineering graphics software, so I'm just gonna lay it out myself to have good data to give the shop. Might post a sketch here.

You're right about the slotted cam-end, I love that idea but those few hrs work to remove the cam equate to MONTHS in my world, done 15 min at a time amongst the other more pressing projects I have, and if I can get 36k miles out of a custom-grind drive hex like Charlie, that should last me YEARS at the pace I put miles on this bike.

[Shiny Hat]

Of course! And thanks for you highly technical dwg, those are the best. I have easy access to engineering graphics software, so I'm just gonna lay it out myself to have good data to give the shop. Might post a sketch here.

You're right about the slotted cam-end, I love that idea but those few hrs work to remove the cam equate to MONTHS in my world, done 15 min at a time amongst the other more pressing projects I have, and if I can get 36k miles out of a custom-grind drive hex like Charlie, that should last me YEARS at the pace I put miles on this bike.

I might be looking at the cam change through rose colored retirement glasses.
Maybe the OEM hex, might not be as tight as custom, but it will allow some movement to compensate for misalignment. I know you’ll do what’s best for you and the bike all things considered. Would love to see the sketch if you can post.

[RecentConvert]

I have the same problem to tackle in advance as part of my Convert rebuild. I've created a CAD model from the old, ruined socket that came with the bike and I've just sent it off to be milled from A2 steel. Once it's back, that will then go for hardening, assuming I didn't make a mistake in the design! Will let you all know how it goes. If all's well then I'll make the model files available.

This is sticking with the 6mm hex socket. I did a mock up with a 7mm socket and a custom 7-to-6mm hex bit, but I was concerned about making the camshaft end of things the weak link. From what I can tell, a properly hardened 6mm socket with a touch over 11mm engagement should be up to the task.

[Antietam Classic Cycle]

I have the same problem to tackle in advance as part of my Convert rebuild. I've created a CAD model from the old, ruined socket that came with the bike and I've just sent it off to be milled from A2 steel. Once it's back, that will then go for hardening, assuming I didn't make a mistake in the design! Will let you all know how it goes. If all's well then I'll make the model files available.

This is sticking with the 6mm hex socket. I did a mock up with a 7mm socket and a custom 7-to-6mm hex bit, but I was concerned about making the camshaft end of things the weak link. From what I can tell, a properly hardened 6mm socket with a touch over 11mm engagement should be up to the task.

 

[brider]

Model looks good, RecentConvert. I was able to scrounge up a very sharp-looking original part so I'm going to use that. I had it hardness-tested and it came back within Rc range. Right now my .250" nominal tool hex-drive part is at my machinist's shop waiting to be precision ground down to custom size, but I made the mistake of saying "no hurry, I have another bike to ride" so it's at the bottom of his stack. I call once a week to remind him.

[chuck peterson]

Cleaning the garage and found this today…

31.5 x 6…







Not needed here anymore…

$10 donation to the board and it’s yours

[brider]

Sent PM

[brider]

I'm nearing the end of this saga, I ordered the pump seals to put the "new" timing cover and pump back on, and got my special-grind hex back from the shop. The machinist is a friend of mine and he only charged me $25 to grind down a stock 1/4" hex wrench, but I told him to only take .0035 off each face, and he took .007 off instead  . he said if it didn't work he'd give it another try to take less off of another part, but I tried a fit-check with his ground part and it felt pretty darn tight. I also got Chuck's NOS hex drive for comparison, and here are a set of parts with their dimensions (numbers on top are mm):





As you can see, the in-service hex shaft is basically the same measurement as the stock 6mm wrench on the right, which makes sense because that's what I made it from the last time I went thru this fiasco. The NOS part measures the smallest of the bunch, and I wonder why, as in why did Guzzi feel an undersized 6mm was better than a nominal tool size?

So my ground part is still the largest size despite the excess amount the machinist took off. And it really feels good and snug in both the pump impeller at the top of the image, and in the end of the cam.

My reluctance in just cutting to length and using it is knowing whether or not the grinding went thru the depth of the heat-treated hard surface to softer material below? Can anyone who knows about heat-treating opine about this? I think i still have access to have both the tool on the right and the ground part hardness-tested, so that may tell me something, but I'd really like to install the ground-part with the nice, snug fit.

[bigbikerrick]

I have been following this thread with great interest. I have to get inside the front cover of my 76,and smooth out the surfaces so the pump turns easier,without so much "drag". I am also still looking for one of the later style adapter,and a good Hex, if anyone has one they would like to sell.  I hope it all goes back together well for you. 
Rick.

[brider]

Update: I had the part I had surface-ground and the 6mm stock took Rc hardness tested today, both tested in the same range of Rc 50+, which tells me that the surface-grinding did NOT go beyond the case on the part, so since it fits slightly better than the 6mm wrench (which fits better than the NOS factory part), I'm going to cut it to length and button that girl back up!

[n3303j]

Update: I had the part I had surface-ground and the 6mm stock took Rc hardness tested today, both tested in the same range of Rc 50+, which tells me that the surface-grinding did NOT go beyond the case on the part, so since it fits slightly better than the 6mm wrench (which fits better than the NOS factory part), I'm going to cut it to length and button that girl back up!

I think good quality "allen" wrenches are made of chrome vanadium tool steel. They are then through hardened (oil quenched) then tempered to reduce brittleness. Properly processed they are the same Rockwell hardness throughout. No worry about grinding through a case hardening.

[brider]

Properly processed they are the same Rockwell hardness throughout. No worry about grinding through a case hardening.

That explains it then, thanks!