The clutch center

[malcolmgb]

http://www.honda305.com/forums/trans-pr ... 35489.html

[Dick Eastman]

Thanks, Malcom, I just read that.
I am going to machine up a retainer plate that will mount from the bottom up, shift the centerline of the screws so that that there will be full contact between the plate and drum, and make it out of .125" tool steel. The drum groove measures .129", the stock plate .118". Regarding the detent roller, I will cut a small clearance in the periphery of the plate where the roller arm contacts, so when the roller is in the drum detent, the arm clears. From all indications, this will be very minimal, so the strength of the plate won't be compromised.
The only reason I can see why Honda designed the plate installation this way is clearance for the roller arm, as the plate is die-stamped, and something machined to closer tolerances would be more costly to produce. The tool steel will also wear better than the mild steel Honda used, and I don't see any issues with the new plate wearing the drum groove sidewalls. Incidentally, the centerline of the drum is about .065" away from the centerline of the screws, so when the stock plate is mounted from the bottom, the difference in the centerlines doubles, and the reason the drum contact on the plate is only on the corners of the plate.
There is still good riding weather left, and I think this will be a good solution without pulling the engine for now. Even with the plate installed upside down, the tranny shifted well, but neutral was difficult to get. I did tighten up the linkage clevises by bushing them, and this greatly improved up and down shifting.

[G-Man]

Good thinking. Sounds like you are applying some ingenuity to the situation!

Please report back when you get that part made.

G

Thanks, Malcom, I just read that.
I am going to machine up a retainer plate that will mount from the bottom up, shift the centerline of the screws so that that there will be full contact between the plate and drum, and make it out of .125" tool steel. The drum groove measures .129", the stock plate .118". Regarding the detent roller, I will cut a small clearance in the periphery of the plate where the roller arm contacts, so when the roller is in the drum detent, the arm clears. From all indications, this will be very minimal, so the strength of the plate won't be compromised.
The only reason I can see why Honda designed the plate installation this way is clearance for the roller arm, as the plate is die-stamped, and something machined to closer tolerances would be more costly to produce. The tool steel will also wear better than the mild steel Honda used, and I don't see any issues with the new plate wearing the drum groove sidewalls. Incidentally, the centerline of the drum is about .065" away from the centerline of the screws, so when the stock plate is mounted from the bottom, the difference in the centerlines doubles, and the reason the drum contact on the plate is only on the corners of the plate.
There is still good riding weather left, and I think this will be a good solution without pulling the engine for now. Even with the plate installed upside down, the tranny shifted well, but neutral was difficult to get. I did tighten up the linkage clevises by bushing them, and this greatly improved up and down shifting.

[sdaigle240]

awesome, thats what i wanted to do to my upside down bracket. I didnt exactly mind the excuse to get inside this engine and learn its workings a little though. keep us posted how it works! funny how this topics popping up as of late. people have probably been putting these things in wrong since the 60s!

[G-Man]

Steve

Yep, I'm sure that's been catching people out ever since the original designer went to assemble that into a completed motor and said Duh! (in Japanese, of course! )

G

awesome, thats what i wanted to do to my upside down bracket. I didnt exactly mind the excuse to get inside this engine and learn its workings a little though. keep us posted how it works! funny how this topics popping up as of late. people have probably been putting these things in wrong since the 60s!

[Dick Eastman]

I made my new part, and installed it. There is now only a few thousandths end play in the drum. I picked up a new oem plate Friday, just to see what a new one spec'd out at, and it was .118", the drum groove .129". Putting an indicator on the drum yielded about.010" end play; my new tool steel plate yields .003" end play. Because I made the new one with the centerline offset opposite the original, it makes full contact in the drum groove like the oem one does mounted from the top. Also, there is no detent arm issues, as the new bottom-mounted plate is moved up into the groove for full contact, unlike an oem plate mounted on the bottom being offset .065" in the opposite direction [total offset is double this amount, and why the detent arm wants to rub the oem plate mounted incorrectly, and why the oem plate engages the drum groove out on the tips of the plate].
I also lapped the flat head screws to the countersink in the plate to make sure I had good contact there, and used Lock-Tite red thread locker in ass'y. Note: metric countersinks are 90 degrees versus 82 degrees for SAE, in case anyone out there finds this useful. I did make up a drawing to make one of these plates, but I don't know how to get it onto my computer [ have a scanner, but never used it ].
I don't have the side cover on yet to road test, but drum does rotate very well, including neutral.
I can see how nearly .040"end play previously [ the old plate tips mic'd .082"] could result in the gear sets not being moved properly by the forks riding in a drum shifting back and forth.
I see no issues with this modification, and saved much time over splitting the cases. The tool steel [ 0-1 oil hardening flat ground stock, .125" thick] will certainly wear better than Honda mild steel. The screws I used are equivalent to SAE grade 8, and won't come out unless some heat is applied to soften the threadlocker. The clutch basket splashes plenty of oil on this area, so it is well lubricated. I also installed a newer shifter shaft, with better splines on it, while in there.
A road test will see if all this shows improvement - will give an update soon.

[G-Man]

Dick

Nice work! Post pictures if you can work that out....

G

I made my new part, and installed it. There is now only a few thousandths end play in the drum. I picked up a new oem plate Friday, just to see what a new one spec'd out at, and it was .118", the drum groove .129". Putting an indicator on the drum yielded about.010" end play; my new tool steel plate yields .003" end play. Because I made the new one with the centerline offset opposite the original, it makes full contact in the drum groove like the oem one does mounted from the top. Also, there is no detent arm issues, as the new bottom-mounted plate is moved up into the groove for full contact, unlike an oem plate mounted on the bottom being offset .065" in the opposite direction [total offset is double this amount, and why the detent arm wants to rub the oem plate mounted incorrectly, and why the oem plate engages the drum groove out on the tips of the plate].
I also lapped the flat head screws to the countersink in the plate to make sure I had good contact there, and used Lock-Tite red thread locker in ass'y. Note: metric countersinks are 90 degrees versus 82 degrees for SAE, in case anyone out there finds this useful. I did make up a drawing to make one of these plates, but I don't know how to get it onto my computer [ have a scanner, but never used it ].
I don't have the side cover on yet to road test, but drum does rotate very well, including neutral.
I can see how nearly .040"end play previously [ the old plate tips mic'd .082"] could result in the gear sets not being moved properly by the forks riding in a drum shifting back and forth.
I see no issues with this modification, and saved much time over splitting the cases. The tool steel [ 0-1 oil hardening flat ground stock, .125" thick] will certainly wear better than Honda mild steel. The screws I used are equivalent to SAE grade 8, and won't come out unless some heat is applied to soften the threadlocker. The clutch basket splashes plenty of oil on this area, so it is well lubricated. I also installed a newer shifter shaft, with better splines on it, while in there.
A road test will see if all this shows improvement - will give an update soon.