Author Topic: Are These Worn Out? Primary Gears & Trans Gear (Read 6650 times)

MattFreeman · « **on:** January 31, 2010, 08:54:31 AM »

Howdy Folks

I've finally got my cases open and the real fun has started already.

The teeth on my large internal primary gears seem awfully pointy, not really ramped just pointy. From what I can find/tell the "low mileage" used ones out there seem to have pointy teeth as well. Is this on purpose due to large gear/small link issues or are these ready to go to the great Gold Wing in the sky?

Also there is a step geared cog in the transmission, the only one like it. Mine has nice little 45's at the top of the wider teeth. Is this normal? Is it OK? Should I replace it? Does anyone have one? Oh and does anyone know what gear this is?

Thanks and Beans
MF

Kevin400F · « **Reply #1 on:** January 31, 2010, 08:59:36 AM »

What bike and year model? Something as significant as a stepped gear tooth is usually depicted on the exloded view in the shop manual or microfiche, to help assure correct assembly. Have you looked on an online fiche such as:
http://www.mrcycles.com/fiche_select1.asp?cat=Motorcycles&mfg=Honda

754 · « **Reply #2 on:** January 31, 2010, 09:19:15 AM »

That first pic is a sprocket, not a gear..

MFHP · « **Reply #3 on:** January 31, 2010, 09:39:10 AM »

Hi,
stepped gear is the combined 2nd-3rd gear on the main shaft. Looks o.k.to me as it is or at least as far as I can judge from the picture.
The pointy primary teeth wouldn't bother me as well knowing how hard and pricey it would be to get a new one. I would worry more about worn damping rubbers inside the primary. They get hard with age and start to disengage into small rubber bits which you will find in your oil pan if your lucky (but could also clog up the oil pump mesh screen. If their worn the primary chain gets excessive wear and the primary gets awfully noisy, even more than the usual known primary noise. When I reworked my transmission 2 years ago, most of the rubbers where half gone.

Mike

750Four K7, 500Four K1

MattFreeman · « **Reply #4 on:** January 31, 2010, 09:48:50 AM »

Quote from: MFHP on January 31, 2010, 09:39:10 AM

I would worry more about worn damping rubbers inside the primary. They get hard with age and start to disengage into small rubber bits which you will find in your oil pan if your lucky (but could also clog up the oil pump mesh screen.

Any other hidden nastiness I should worry about?

MattFreeman · « **Reply #5 on:** January 31, 2010, 09:59:25 AM »

Kevin: it's a '76 CB750F. I cant find a good enough drawing to see if the taller teeth are supposed to be cut like that.

754: Thanks for puttin' me right.

MFHP: Were you able to get new replacements for your dampers? Or did you have to resort to used parts? Is it even serviceable? All the rubber in/on this bike has been surprisingly good.

Anyone else seen this kind of wear?

FYI you can click on the photo to make it bigger, case you didn't know.

MFHP · « **Reply #6 on:** January 31, 2010, 10:14:30 AM »

Quote from: MattFreeman on January 31, 2010, 09:59:25 AM

MFHP: Were you able to get new replacements for your dampers? Or did you have to resort to used parts?

Anyone else seen this kind of wear?

FYI you can click on the photo to make it bigger, case you didn't know.

The sprocket is rivetted together and as spare only available as assembled part which is unbelievable expensive if available at all. Our German Honda CB750 Four Club re-manufactures just the rubbers and supplies them with new rivets. Their offered on the club shop page.
http://www.cbfourclub.de/ ClubShop, Nachfertigungen; pages only in German. Unfortunately only sold to members because the tooling was financed from the club.

Cheers
Mike

MattFreeman · « **Reply #7 on:** February 01, 2010, 12:26:15 PM »

Well incase anyone is interested, those teeth on the trans cog are worn, they should not be worn at 45 degrees on the end. The debris in the oil filter screen should've been a tip off.

The good news is a whole used trans in good shape shipped for $50 on it's way. Chalk one up for the land of a million CB's.

fmctm1sw · « **Reply #8 on:** February 01, 2010, 03:25:07 PM »

Quote from: MattFreeman on February 01, 2010, 12:26:15 PM

Well incase anyone is interested, those teeth on the trans cog are worn, they should not be worn at 45 degrees on the end. The debris in the oil filter screen should've been a tip off.

The good news is a whole used trans in good shape shipped for $50 on it's way. Chalk one up for the land of a million CB's.

Join the knackered transmission club.... I'm about to go through my 175...

MattFreeman · « **Reply #9 on:** February 01, 2010, 03:49:03 PM »

Hope your luck is as good as mine. Found it on Ebay the day I started looking with no other bidders.

Now I'll probably break a cylinder stud or something
.

mystic_1 · « **Reply #10 on:** February 01, 2010, 04:06:26 PM »

Quote from: MattFreeman on February 01, 2010, 12:26:15 PM

Well incase anyone is interested, those teeth on the trans cog are worn, they should not be worn at 45 degrees on the end.

Yup, should look more like this:

fmctm1sw · « **Reply #11 on:** February 01, 2010, 04:24:22 PM »

Quote from: MattFreeman on February 01, 2010, 03:49:03 PM

Hope your luck is as good as mine. Found it on Ebay the day I started looking with no other bidders.

Now I'll probably break a cylinder stud or something
.

Yeah, got one for $40 shipped. I haven't seen it up close yet but it looked good on eBay so we'll see. Yep , and I snapped 4 studs on a 400F engine I took apart...

MattFreeman · « **Reply #12 on:** February 02, 2010, 06:39:24 AM »

Wow. Did you use heat, and twist from the bottom (close to the case)?

AshimotoK0 · « **Reply #13 on:** February 02, 2010, 01:22:13 PM »

Quote from: MFHP on January 31, 2010, 10:14:30 AM

Quote from: MattFreeman on January 31, 2010, 09:59:25 AM

MFHP: Were you able to get new replacements for your dampers? Or did you have to resort to used parts?

Anyone else seen this kind of wear?

FYI you can click on the photo to make it bigger, case you didn't know.
The sprocket is rivetted together and as spare only available as assembled part which is unbelievable expensive if available at all. Our German Honda CB750 Four Club manufactures just the rubbers and supplies them with new rivets. Their offered on the club shop page.
http://www.cbfourclub.de/ ClubShop, Nachfertigungen; pages only in German. Unfortunately only sold to members because the tooling was financed from the club.

Cheers
Mike

I have some ex-colleagues who have an automotive rubber moulding company and I also have access to extensive engineering facilities. Maybe I will make enquiries about manufacture. (or will the German 'Club' ones ever come up for sale to non-members).
A friend of mine also analyses polymers so he could identify the grade and hardness etc. i would imagine that cutting up a used one and analysing the core would be the best guide. I would imagine it would be similar to the 400/4 cush drive rubbers (which were available as a separate part in 1986!!)

mystic_1 · « **Reply #14 on:** February 02, 2010, 01:28:05 PM »

Quote from: MFHP on January 31, 2010, 10:14:30 AM

Unfortunately only sold to members because the tooling was financed from the club.

That does seem a bit illogical to me in a way, what harm to the club if these are sold to non-club members? If anything such sales would benefit the club greatly in the form of profit!

mystic_1

MattFreeman · « **Reply #15 on:** February 02, 2010, 01:30:50 PM »

Mystic, I forgot to thank you for the pic.

Franks

MF

MattFreeman · « **Reply #16 on:** February 02, 2010, 01:31:38 PM »

Quote from: mystic_1 on February 02, 2010, 01:28:05 PM

Quote from: MFHP on January 31, 2010, 10:14:30 AM
Unfortunately only sold to members because the tooling was financed from the club.

That does seem a bit illogical to me in a way, what harm to the club if these are sold to non-club members? If anything such sales would benefit the club greatly in the form of profit!

mystic_1

Maybe we can join?

AshimotoK0 · « **Reply #17 on:** February 02, 2010, 01:43:52 PM »

Quote from: mystic_1 on February 02, 2010, 01:28:05 PM

Quote from: MFHP on January 31, 2010, 10:14:30 AM
Unfortunately only sold to members because the tooling was financed from the club.

That does seem a bit illogical to me in a way, what harm to the club if these are sold to non-club members? If anything such sales would benefit the club greatly in the form of profit!

mystic_1

+1 on this from me too. or at least share the engineering data to enable someone else to make them.

Anyone know what the torque vs deflection data for the assembly is? That way you could test if the rubbers have hardened or not. My 69 K0 (46k) does not seem to have any angular play in it.

mystic_1 · « **Reply #18 on:** February 02, 2010, 04:13:51 PM »

Quote from: MattFreeman on February 02, 2010, 01:30:50 PM

Mystic, I forgot to thank you for the pic.

Franks

MF

No worries. How are the rest of your gears? Looks like some PO was not too kind to that gearbox.

mystic_1

MattFreeman · « **Reply #19 on:** February 02, 2010, 04:53:57 PM »

Actually it's pretty good, thanks for asking. I've been told that burning up 2'nd gear is pretty common. It actually functioned pretty good before I took it apart. We'll see if I can't F it up better than the PO

fmctm1sw · « **Reply #20 on:** February 02, 2010, 05:13:04 PM »

Quote from: MattFreeman on February 02, 2010, 06:39:24 AM

Wow. Did you use heat, and twist from the bottom (close to the case)?

The bolts had this threadlocking compound or something all over them. I have pictures of it in a thread over in the project shop...

mystic_1 · « **Reply #21 on:** February 02, 2010, 06:11:26 PM »

Quote from: MattFreeman on February 02, 2010, 04:53:57 PM

Actually it's pretty good, thanks for asking. I've been told that burning up 2'nd gear is pretty common. It actually functioned pretty good before I took it apart. We'll see if I can't F it up better than the PO

Isn't the pictured gear 5th? M2-M3 in the diagram below.

mystic_1

MattFreeman · « **Reply #22 on:** February 02, 2010, 06:44:47 PM »

Dunno. I'm going from MFHP's post. And what I've heard about it's likelihood to burn up. It would seem that the power is transferred through that cog for both 2nd and 5nd gear.

Groovy diagram BTW.

mystic_1 · « **Reply #23 on:** February 02, 2010, 09:23:26 PM »

Thank Clymer

Better yet, thank Honda because Clymer probably stole it straight from one of the factory books

The worn teeth that you posted engage M2 to M5 when you shift into fifth. Otherwise M5 is free-wheeling on the mainshaft on an internal bushing, and the M2 teeth aren't touching.

The round dogs on the side of C5 are notorious around these parts, what does yours look like?

mystic_1

AshimotoK0 · « **Reply #24 on:** February 03, 2010, 01:52:52 AM »

I started a new thread specifically on the view to getting hold of new primary drive cush drive rubbers.

http://forums.sohc4.net/index.php?topic=65107.0

Moderator : if I am doing any wrong here please let me know!

News:

Author Topic: Are These Worn Out? Primary Gears & Trans Gear (Read 6650 times)