Topic: 750 Gear change assembly

[nancy]

Fellas
I'm in need of advice and bourbon - in either order - after wasting about 3 hours pondering the reassembly of my gearshift doodads. I thought I was home and hosed after finally working out how and where the springs were rigged - and managed to get to the point of lining up the spindle shaft - and I can't seem to get it to line up with those cursed pins on the drum plate.
- I realise that the 5 pins are 4 x one length and 1 shortie - but how do I know which hole the shortie lives in? Does it matter?
- Does the end of the shift drum in the gearbox have to be oriented in a particular way that I can't fathom? I oriented the drum to install the dentent switch/ball on the bottom case - so expected all to be well.
- When the spindle shaft is mounted into the drum plate, how many pins should be engaged on the shaft and does it matter which one?
I feel inadequate.

[lucky]

You cannot just guess where parts go.

Clymer"s manual page #109 illustration #12.

That lever your thumb is on engages two pins at a time.

[mick7504]

Have a look at Reply #12, 3rd picture.
That is neutral orientation.
http://forums.sohc4.net/index.php?topic=60626.0

Check that the shift drum is pushed all of the way in home and that the shift drum indent is engaged correctly with the neutral switch and you should be good to go.

[bollingball]

I will start off saying I have never had that cover off my bike but have others years ago. It seems to me if only one pin is shorter than the others then it would make a difference what hole it goes in. I would call that common sense.
 I think someone who knows will chime so here is a bump.

Ken

[nancy]

You cannot just guess where parts go.

Clymer"s manual page #109 illustration #12.

That lever your thumb is on engages two pins at a time.

Thanks Lucky - I have a Clymer but it's in the hands of my machinist who is hopefully (after 2 weeks waiting) using it to bore my jugs. I'll go see him today. Does that page of Clymer show and explain the insertion of the pins - and where the short pin goes?
Mark

[nancy]

Have a look at Reply #12, 3rd picture.
That is neutral orientation.
http://forums.sohc4.net/index.php?topic=60626.0

Check that the shift drum is pushed all of the way in home and that the shift drum indent is engaged correctly with the neutral switch and you should be good to go.
Yeh - saw that pic before Mic - and assume by that - it's in neutral when the arm rides into that indent in the drum cover plate?
Update: I did manage to get the 2 pins to engage as replied to by Lucky, by going to the other side of the motor and wiggling the shaft coming into the empty clutch bay - bing - plate reversed and 2 pins now engage. Couuld be home now....but I'm still keen to know if thwere is a designated hole and clockface location for the SHORT pin.
Mark

[bollingball]

Nancy Do yourself and your machinist a big favor and download the Honda factory manual. Clymer's  manuals should stay in the bathroom. No reason to use one if the Honda manual with the supplements for your year is available.IMHO

Ken

[MCRider]

First I've never put one back that the shift drum wasn't fully assembled. The screw that holds the outer plate on takes some torque and was staked from the factory. Overkill maybe but be aware. You'll need to rotate the drum fully clockwise through all its shifting positions so it comes to rest on something solid. Unfortunately that's a shift fork pin.

As to the outer plate and the pins. IIRC it is fool proof everything can only go one way. There is a detent to hold the short pin and some other arrangement for the longer ones.

In your picture you are missing the arm and smaller roller that points to about 7:30.

[nancy]

Nancy Do yourself and your machinist a big favor and download the Honda factory manual. Clymer's  manuals should stay in the bathroom. No reason to use one if the Honda manual with the supplements for your year is available.IMHO
Yep - I have a Honda s/m on my PC - as a PDF..I have worse than Clymer - I have a CYCLESERV manual as well! Yuk.

Ken

[nancy]

Ron,
Yes I had removed that arm for clarity.
See new pic.
I seem to have it together now (I hope - thanks Mick, Ron, Lucky) and can attach the gear lever and clunk down into 1st position and upwards to from neutral slot 3 clicks above neutral slot..doesn't click for 5th position..not sure about that..given I have no rotation of the shaft...I may need to have a closer look. hat to think I need to split the cases and check my fork install.
Mark

[MCRider]

Great. No first hand experience, but I seem to remember another thread where lack of 5th gear was a shift fork problem.

Also, at the bottom where that screwdriver tip is, there is supposed to be a rubber plug in that big hole, that doesn''t otherwise take a screw. The gasket will suffice, it should have a big bump in it to cover that hole. Maybe not all models had the rubber plug? Anyway, it will pass alot of oil. If you take the cover off after running the bike, a good thing to tilt it to the right just a little for that oil and all oil behind that cover for that matter, to drain back into the engine.

[nancy]

Thanks Ron - I may have to venture inside the cases again damn it...I'll search for the thread you mentioned.
The hole you pointed out - in my case - the gear chnage cover has a rubber bung it.
Regards
Mark

[mick7504]

G'day Mark
Here's some pictures for future reference mate.

[MCRider]

Thanks Ron - I may have to venture inside the cases again damn it...I'll search for the thread you mentioned.
The hole you pointed out - in my case - the gear chnage cover has a rubber bung it.
Regards
Mark

The hole looked empty cuz it was dark i guess. Glad yours has the bung.  Sorry about 5th.

I just got my project running and though it needs to come apart for an oil leak, I'm going out to check it now for all the gears.

[nancy]

Cheers for the pics Mick..I may need them now rather than the future.
I have flipped the motor over and removed the detent valve insert and had a beejeebers of a time reinserting it again - but did get the ball to mesh into the recess, marked the face of the drum and the casing with marker pen so i can see wher that position is. Then I setup the gearchange components to mirror the "neutral" position installation as in the pics you referred to Mick.
Now if I mount the gear change..with the cover plate NOT installed over the pins - so I can see whats happpening - I can move onto/through only 3 of the 4 long pins...that's it.  I cannot position the lever onto pin #4 and if I try to move them by hand - no movement. SO - am I testing this right? I have read other threads where BryanJ mentioend - you cannot test gear selections unless you have both shafts rotating. Am I correct that before the gears can be tested, I should be able to move the pins on that drum through SIX click/clunk movements - 1st, neutral, 2nd..etc..? Am I best to pop the case and check forks positions? I did have these installed as per book and checked them pretty closely - fearing the worst. But maybe as I clammed the top and bottom cases - that RH fork has to be guided onto the top gear set - maybe that slipped? Comments appreciated.

Mark

[nancy]

Guys
Is it possible that I have L & R selector forks mixed up - see photo?
They were NOT marked L, C & R as the book says - couldn't find any marking and had to juggle them to fit and checked photos online - so they loked correct.
Regards
mark

[mick7504]

Try rotating the output shaft with a shifter (adjustable wrench) as you run it through the gear selection Mark.
I'd also recommend installing the outer plate onto the shift drum to fully support the pins as well mate.

The neutral switch can stay out while your doing this.
You'll be able to see the indent in the shift drum through the switch hole when the gearbox is in neutral.

Also, check for damage to the o ring around the switch if it's been in and out a few times.
They can leak a lot of oil just to top your day off. 

[nancy]

Ta Dave.
Output shaft - as in  final drive sprocket shaft?
Yeh - will replace cover plate...agreed - could cause stress on pins. Have given up for the night - its dark, freezing and Coronation St will on soon (cough)! Hope I can sort this sucker out soon - it's giving me the screaming heebee jeebees.
Regards
Mark

[mick7504]

Guys
Is it possible that I have L & R selector forks mixed up - see photo?
They were NOT marked L, C & R as the book says - couldn't find any marking and had to juggle them to fit and checked photos online - so they loked correct.
Regards
mark

Here's the culprit Mark.
That shift fork is not engaged with anything and is "floating in the breeze"



Here's an assembled cluster.
You can see where the shift fork engagement is on the gears.

[lucky]

Wooooops!!!

Don't you mean this one in yellow?

CLICK once on the photo for a larger version.

[mick7504]

Wooooops!!!

Don't you mean this one in yellow?
CLICK once on the photo for a larger version.

No 

[MCRider]

Wooooops!!!

Don't you mean this one in yellow?
CLICK once on the photo for a larger version.

No 

Lucky: The one in yellow goes to the countershaft which is in the other case. It was probably engaged or the case wouldn't have closed.

[nancy]

Fellas. Case closed.
Mick/Lucky/Ron - sorry that photo was misleading - I didn't realise it was a pic of the tranny before I sorted out the CORRECT orientation of that gear on the left side in the pic. I had it around the wrong way - swapped it around and the forks now sit on proper engaging steps. Appologies. I had wanted to get confirmation that the forks were positioned correctly...and saw that pic and posted it without thought.
I think I have been chasing my tail over nothing. After checking your earlier advice Mick - that gelled with what I had been thinking - and threads I had seen from BryanJ and others - that the gears need shaft rotation to be tested. So I went out to the workshop in the frost this morning and turned the end of the countershaft as it enters the empty clutch basket area - as I operated the gear shift lever = all gears select fine. What I saw was - as the countershaft rotates - it allows the shifter plate to reverse up a tad to swing the next pin into line - which is exactly what was lacking before. So I'm happy..and not a moment too soon - my jugs are ready to collect from the machinist - overbored .50mm - done to .001" clearance. New pistons sets from cb750Supply Inc.
Many thanks for your help. Mick - those pics of the drum in your hand - are a brilliant help.
Regards
Mark
EDIT - scrub "countershaft" - I meant to say MAINSHAFT..extends from clutch basket.

[mick7504]

Fellas. Case closed.
Mick/Lucky/Ron - sorry that photo was misleading - I didn't realise it was a pic of the tranny before I sorted out the CORRECT orientation of that gear on the left side in the pic. I had it around the wrong way - swapped it around and the forks now sit on proper engaging steps. Appologies. I had wanted to get confirmation that the forks were positioned correctly...and saw that pic and posted it without thought.
I think I have been chasing my tail over nothing. After checking your earlier advice Mick - that gelled with what I had been thinking - and threads I had seen from BryanJ and others - that the gears need shaft rotation to be tested. So I went out to the workshop in the frost this morning and turned the end of the countershaft as it enters the empty clutch basket area - as I operated the gear shift lever = all gears select fine. What I saw was - as the countershaft rotates - it allows the shifter plate to reverse up a tad to swing the next pin into line - which is exactly what was lacking before. So I'm happy..and not a moment too soon - my jugs are ready to collect from the machinist - overbored .50mm - done to .001" clearance. New pistons sets from cb750Supply Inc.
Many thanks for your help. Mick - those pics of the drum in your hand - are a brilliant help.
Regards
Mark

Perfect