Author Topic: Splitting the cases on my CB750...first of many ?'s (Read 82159 times)

ron.cieri.313 · « **Reply #175 on:** December 16, 2009, 07:13:00 PM »

Okay, about ready to sew this patient back up...i.e., put the halves back together.

Here is where they stand right now...what do you think?

So I'm starting to lay the bolts for the lower half. The process seems like lay on the glue, put on the lower half onto the top MAKING sure the middle shift fork is on the M2-3 gear...is there any trick/favorite process for making this happen...my dry run with no gasket goo didn't go so great although I figure a few things out...but open to any thoughts.

...thx ron...this is so freaky...I'm afraid I'm going to leave a screw driver in there or my wallet.

ron.cieri.313 · « **Reply #176 on:** December 16, 2009, 07:15:08 PM »

Oh, question...maybe I should put the shift mechanism and arm completely on so I can shift through the gears before putting together?

HondaMan · « **Reply #177 on:** December 16, 2009, 07:24:09 PM »

First advice: pull those transmission shafts out and submerge them completely in oil, then reinstall. There will not be any oil in the shafts for over 1 full minute after startup, and you can damage the bearings during that time. Also be sure to dose the kickstarter gear bearing with lots of oil, as it drives the oil pump from the moment the engine starts running.

Same story fo the shifter drum and each shift fork, they must be wet.

If you wish to pretest the shifting action, install the mainshaft on the lower case with the countershaft bearing in place, and go through the motions while spinning either the mainshaft or the final drive sprocket. Then you can install teh mainshaft back into the upper half. "Clamshell" from the front to the back when assembling, so you can watch the center fork lay into the groove last. Then hand-shift through the gears while turning the output shaft before you start installing bolts, to make sure all forks are in the right places. Then start with the crankshaft bolts, then bolt the smaller 6mm bolts from the center of the cases outward, middle to front and back. Install the three 8mm bolts/nuts across the back last.

ron.cieri.313 · « **Reply #178 on:** December 16, 2009, 08:11:07 PM »

I did soak the gears in a bag of oil prior to assembly onto the crankcases, maybe I'll dose the bearings with more.

I will definitely install the mainshaft onto the countershaft and try to shift with the case still open.

When I close up the cases, when you say "'handshift," am I turning the shift drum by hand and the output shaft would be the one of the countershaft to the small sprocket which is attached to the chain?

...thx!

HondaMan · « **Reply #179 on:** December 16, 2009, 08:49:34 PM »

Quote from: ron.cieri.313 on December 16, 2009, 08:11:07 PM

I did soak the gears in a bag of oil prior to assembly onto the crankcases, maybe I'll dose the bearings with more.

I will definitely install the mainshaft onto the countershaft and try to shift with the case still open.

When I close up the cases, when you say "'handshift," am I turning the shift drum by hand and the output shaft would be the one of the countershaft to the small sprocket which is attached to the chain?

...thx!

Yep, sounds like you've figured it out!

KB02 · « **Reply #180 on:** December 17, 2009, 04:37:46 AM »

That's what I did with mine. As the three of us now know, we don't want to have to do this again.

ron.cieri.313 · « **Reply #181 on:** December 17, 2009, 06:30:38 PM »

I know I was petrified of that but tried HMan's clam shell trick tonight and had a successful dry run...tomorrow I go for the goo...the real thang.

I also checked out the functioning of the new tranny installation by installing the mainshaft on top of the countershaft with the halves open and was able to click through the gears...wow, I'm nervous and hoping this works.

No worky on friday so here's goes...

mystic_1 · « **Reply #182 on:** December 17, 2009, 06:52:49 PM »

Don't use too much goo. Just paint on a thin even layer.

mystic_1

ron.cieri.313 · « **Reply #183 on:** December 17, 2009, 06:56:21 PM »

Do you just do the outside contact areas also?

(and thx...I would have used too much)

mystic_1 · « **Reply #184 on:** December 17, 2009, 07:51:18 PM »

Use enough that it's not transparently thin, but not so much that it squeezes out in gobs when you bolt things together. Small amount of squeeze-out is ok. Oh, and apply the sealant to the top crankcase half only, then lower the other half onto it as described earlier.

I apply sealant to everywhere to two case halves touch each other. You want even pressure across the whole contact area. Clearances are machined with the thickness of the sealant in mind (don't remember the spec on that, Hondaman knows).

So, as the first pic I highlighted in red. Rest of the pics are a case I recently disassembled that still shows evidence of the sealant in the areas in question.

mystic_1

mystic_1 · « **Reply #185 on:** December 17, 2009, 07:55:10 PM »

Be careful around the main bearing area though, don't want any sealant getting into the bearings. Expect that the sealant you apply will squeeze and spread as you torque the bolts so stop shy of the edges.

mystic_1

ron.cieri.313 · « **Reply #186 on:** December 17, 2009, 08:04:15 PM »

So excellent...thanks!

ron.cieri.313 · « **Reply #187 on:** December 19, 2009, 01:52:24 PM »

I'm not sure but I thinking the arse rape fairy has left Michigan...my halves are back together! I am able to shift through the gears while rotating the output shaft...sometimes its a little difficult but I guess that shouldn't be a surprise as doing it by hand is a lttle awkard.

I only had a little goo dripping down in a few places...not be bad I think. tightened the lower case bolts with a torque wrench which i hope correctly set to about 190 INCH lbs...upper case ones I didn't torque quite as hard (150ish).

Started some cosmetic work on her so i can paint it a little bit before the move back on the bike.

I will put the countershaft bearing cover on (new o-ring..thanks Hman) and entire shift mechanism and the the timing apparatus...I assuming I should wait on the clutch disc/plates till the engine in back in place??? I have the clutch basket on whic is a necessity as it is attached to a spocket.

Maybe the alternator cover too?...put back on before moving.

Hope to post pics soon...will keep all posted...I'm optomistic but, I won't believe this works until it works...l8r...ron.

HondaMan · « **Reply #188 on:** December 19, 2009, 01:55:48 PM »

Quote from: ron.cieri.313 on December 19, 2009, 01:52:24 PM

I'm not sure but I thinking the arse rape fairy has left Michigan...my halves are back together! I am able to shift through the gears while rotating the output shaft...sometimes its a little difficult but I guess that shouldn't be a surprise as doing it by hand is a lttle awkard.

I only had a little goo dripping down in a few places...not be bad I think. tightened the lower case bolts with a torque wrench which i hope correctly set to about 190 INCH lbs...upper case ones I didn't torque quite as hard (150ish).

Started some cosmetic work on her so i can paint it a little bit before the move back on the bike.

I will put the countershaft bearing cover on (new o-ring..thanks Hman) and entire shift mechanism and the the timing apparatus...I assuming I should wait on the clutch disc/plates till the engine in back in place??? I have the clutch basket on whic is a necessity as it is attached to a spocket.

Maybe the alternator cover too?...put back on before moving.

Hope to post pics soon...will keep all posted...I'm optomistic but, I won't believe this works until it works...l8r...ron.

Those 8mm bolts (bigger ones) go to 17.5 ft-lbs. The little 6mm ones should be 90-100 in-lbs, or else the threads might pull or strip if more than that.

ron.cieri.313 · « **Reply #189 on:** December 19, 2009, 02:50:49 PM »

Should I loosen the smaller ones than or leave alone?

mystic_1 · « **Reply #190 on:** December 19, 2009, 04:41:30 PM »

If you didn't strip any going in, I'd leave them alone.

mystic_1

ron.cieri.313 · « **Reply #191 on:** December 19, 2009, 06:18:00 PM »

Cool...I was hoping for that...but should I tighten the other side a bit or leave well enough alone?

Also, here's some pics
Back in one piece in front of bike:

close-up of seam

...oh, the exhaust (or part of it hanging in my garage...matte black furnace paint after sand blasting)

mystic_1 · « **Reply #192 on:** December 19, 2009, 09:05:05 PM »

If everything's tight and nothing stripped, consider yourself a luck man and leave well enough alone

Looking good so far. Keep up the good work.

mystic_1

ron.cieri.313 · « **Reply #193 on:** December 21, 2009, 07:51:49 PM »

Sorry...I organized my photobucket pictures and didn't know that would delete them from the posting...thats kinda of crazy...will repost them if I can

Mayor08 · « **Reply #194 on:** December 22, 2009, 12:17:36 AM »

This has been a great thread keep up the good work everyone.

One question- what is the biggest difference to doing trans work on this 750 and a 73 500K?

ron.cieri.313 · « **Reply #195 on:** December 22, 2009, 07:12:09 AM »

I'm sure the sensai's will provide a much richer response but my guess is not much in general terms. I do not have a 500 but I do have a '73 CB450 (twin/dohc) in addition to this 750 and was told the tranny is essentially the same thing...I know one thing, the engine on my 450 would be easier to lift out and put back into the frame! The long slug of getting the engine out , however, is probably very similar if not almost the same thing once you get to the innards...probably different teeth count on the gears and stuff like that.

HondaMan · « **Reply #196 on:** December 22, 2009, 09:13:22 PM »

Inside, they all look pretty much the same, and work the same. The 750 is pretty overbuilt compared to the smaller bikes, with bigger gears and better shaft oiling holes and such.

ron.cieri.313 · « **Reply #197 on:** December 25, 2009, 07:44:53 PM »

Am I ready or what?

...and as a throw in, here's my rear wheel with new rubber, new brake shoes and a new sprocket...

mystic_1 · « **Reply #198 on:** December 25, 2009, 08:49:30 PM »

Shazam! Looking good.

mystic_1

PS I have one of those same seats around here somewhere

HondaMan · « **Reply #199 on:** December 26, 2009, 08:36:03 AM »

My, My! That's some nice lookin' work, Ron!

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Author Topic: Splitting the cases on my CB750...first of many ?'s (Read 82159 times)