Topic: cb750 cush drive

[bimly]

Any body know if there is a actual difference in the hub between an early k6 and a k7?  I know the sprocket carrier is 10mm wider on a k7, but is the hub actually different?  I need to buy new cush driver rubbers and mine have 8 bits not linked together, with nipples to hold them into the back of the hub.

The later cush drives seem to be exactly the same shape and size just without the nipples and are joined together to locate them. 

My question is, is the hub different or is it just the mounting / positioning system changed?

CSM  parts shows the same cush for all models, but I know 2 types are available from david silver.  Are the new ones universal?

has anybody used the linked together ones ina bike earlier than k6 /k7?

Thanks
 

[BobbyR]

I bought mine for my 750 K8 from Honda 2 years ago. They are seperate pieces. Honda dealers have online parts fiches and probably can still get them. Always try Honda first.

[bimly]

They are both honda parts and the fiche for both shows both,  k6 changes hub number halfway through frame numbers - I'v got a "frankenbike" with a k7 hub carrier on what I think is a k6 hub- what I'm asking is, is the hub different inside - does it still have the mounting holes for the cush rubbers or was that the change that changed the rubber design.

The joined ones are also WAY cheaper which would be bonus, otherwise I', looking at £90.00!

Any light appreciated - has anybody used part no 41241-300-050 on an early bike? 

Or in-fact on an late one?

[BobbyR]

From the 1976 Honda Parts fiche http://www.houseofhondaparts.com/fiche_section_detail.asp?section=2448736&category=Motorcycles&make=Honda&year=1976&fveh=131029

1977 http://www.houseofhondaparts.com/fiche_section_detail.asp?section=2451906&category=Motorcycles&make=Honda&year=1977&fveh=131105

For grins I went to 1975 http://www.houseofhondaparts.com/fiche_section_detail.asp?section=2560121&category=Motorcycles&make=Honda&year=1975&fveh=132839

They all look suspiciously similar. You sure you have a Honda Hub?

[750K]

I don't know if the early hub differs from the late ones but IIRC my 77's Cush drives are connected as are the spares I have, I'll have to check when I get home. My spare set is sitting on my bench in easy reach.

[lucky]

The rubber parts for the K7-K8 are very different from the earlier models.
The hub also is a different design on early and late to accommodate the rubber parts.

[bimly]

cheers, guys - Bobby R's links just confuse the issue for me even more! - if you have a k8 with 8 non-linked bits, that's only shown on the 1975 fiche at the bottom (these are the nippled type that secure through the rear of the hub) - Surely they should be the linked type shown on the other later 2 fiches. 

Also if k750 is saying his k7 are linked together.....

I'm not sure that the linked ones are not just a new version to fit all.  The rubbers are physically the same as I have held 2 together and measured them! (linked and nippled)

Hummm?

[bimly]

Actually, to solve it has anybody got linked together rubbers in a hum with the holes in the rear to hold the nippled ones?  If you have and it works ok, then they must be a rubber design change to remove the need to drill the hubs, make mould easier or some reason?

[750K]

I didn't get a chance to look at mine last night, but when I google 77 cb750 cushdrive rubbers they all have little nipples and are connected as well. Just order for your year of hub and you'll be fine I'd expect, I'll try and remember to look at my spares tonight. They're out of a 78 which is the same as the 77.

[BobbyR]

cheers, guys - Bobby R's links just confuse the issue for me even more! - if you have a k8 with 8 non-linked bits, that's only shown on the 1975 fiche at the bottom (these are the nippled type that secure through the rear of the hub) - Surely they should be the linked type shown on the other later 2 fiches. 

Also if k750 is saying his k7 are linked together.....

I'm not sure that the linked ones are not just a new version to fit all.  The rubbers are physically the same as I have held 2 together and measured them! (linked and nippled)

Hummm?

I am confused over your confusion. Honda has the OEM parts in stock and I gave you several years to compare. Those fiches have the part numbers and it looks like they are $10-14 a piece, and I assume Honda knows what parts it used and supplies the correct part.

 Any Honda dealer can order the parts for you. This is not diffacult if you do in fact have a 76 Honda hub.

[750K]

So fwiw the 77-78 spares I have (which are the same as the ones in my 77k) are connected and have the nipples on the hub side of the rubbers.

[bimly]

No part numbers on hubs  - so without a comparison I can't tell what it is.  I know its k7 carrier because its 10mm wider and i also have a k6 narrow carrier.  Problem is that the bike is parts not linked to frame number, the hub is laced to a non standard rim (so that's no help for ID) and if it is k6 like some of the parts on the bike the cush drive rubbers change halfway through the production run! -

So that's why I'm a bit confused - I need to identify if the earlier hubs still have holes for the rubbers to secure into - my feeling is that the only real change to the hub was that they stopped drilling the 8 holes and went over to connecting them over the top. 

The ones with nipples on have actual niples that go through the hum, not just 2 bumps on the bottom.

Anyway, thanks for the help, but I'm off to David Silvers now (one advantage of living in a different time zone) as hes only 10 miles away to talk to them and get them to scatter various parts over the counter, have calipers etc, will report back. 

May help others, as if the linked ones are forward/backward compatible they are much cheaper (less than half the price) and much more readily available (at least here).

[bimly]

Thought you guys might like to see this - went to David Silver today and we scattered various hubs and rubbers about the shop.  the upshot is as I suspected -
 
1 - There seems to be little difference between a early k6 and a k7 hub even though they are different part numbers (it appears the part was superseded not changed and this can be due to change of manufacturer as well as design I am told).

2 - The joined (latter) k6 - k7 - k8 etc cush driver rubbers are identical to the old 8 separate bit ones, apart from rubber retaining nipples and being joined (there is a rubber lug at the base of the small single part, but this make no difference as the spacing is preserved by the joining strip on the other type (and it will only compress as far as the hub spacer will allow anyway)).

3 - The new rubbers are retro fit (ie latter joined will go into earlier hubs - they just don't use the nipples to hold them in). This also true "other way round" as many latter hubs appear to still carry the unneeded nipple mounting holes.

This may be of use to some earlier bike users as the 4 joined rubbers are £38.00 a set and the 8 bit separate ones are nearly £100 in the UK if direct from Honda (CMS do do a slightly cheaper kit of 8 bits, but they are still double the price).

The conslusion we came to for the change was probably more to do with uniformity of use on other models (the cuch rubbers are common parts in this form) and possible ease of manufacturing

Hope this helps and save some cash for somebody.