Author Topic: How many of you actually replace the primary drive cush rubbers? (Read 7760 times)

drumstyx · « **on:** April 04, 2016, 03:47:09 PM »

In another thread of mine, the topic of primary cush drive came up, and I said I was pretty well 100% sure I wasn't going to bother on my build. It seems like a massive pain in the ass, and more than that, I suspect most people don't even bother with it in their rebuilds, considering reproduction parts have really only popped up in the last 10 years it seems.

MickB · « **Reply #1 on:** April 04, 2016, 03:49:20 PM »

I was advised to replace them and the primary chain it would ensure smoother riding.
I replaced them both.

DaveBarbier · « **Reply #2 on:** April 04, 2016, 03:51:55 PM »

I replaced them on my recent 550 rebuild. I'll do the same on my upcoming 650. It's easy and cheap.

teotdk · « **Reply #3 on:** April 05, 2016, 03:02:52 AM »

Replaced both on my 500 Four build, chain and rubbers..

lash · « **Reply #4 on:** April 05, 2016, 04:37:37 AM »

Any english link to the fourever website? Google search is zero...

strynboen · « **Reply #5 on:** April 05, 2016, 04:45:16 AM »

only if i get inthere for a other rep..evt gear problems. i.dont split engines vho runs ..just for safty.
.only serius problems make me crack them open...i often takes the top cylenders off..and thange cam thain tensioner/valvets so on..a more commen place for problems on sohc engines

bwaller · « **Reply #6 on:** April 05, 2016, 09:53:49 AM »

The 500/550/650's have damping rubbers in both the primary driven sprocket & the clutch basket. Dampers simply buffer drive line snatch, one the primary chain, the other gearbox & clutch.

The clutch primary gear dampers aren't as easy to change, nor are the parts available from Honda but I think I have found a source for new parts. The trick will be replacing those. I'll let everyone know.

strynboen · « **Reply #7 on:** April 05, 2016, 10:07:21 AM »

i have drilled rivvets aut on mopeds. clutch"s. and build in use homemade rubber..but on a mc.it need the right stuff.. hope you find some good replacment parts...have faund a lot of strange formed rubber dampers..not many look standart..
on cb 500 twin types ..just drill all rivets aut vill free the stuff..after this failing rubber tensioner on 750..il be very carefull use unnown plastic/rubber materials..only other type mc parts can be used..

Henning · « **Reply #8 on:** April 05, 2016, 10:36:58 AM »

Maybe also interesting to hear if anybody has noticed a positive difference after replacing the rubbers - smoother running for example.

PeWe · « **Reply #9 on:** April 05, 2016, 11:17:36 AM »

I did my CB750 primary hub this winter. I have not thought about it before. It was new for me last year when I read about it on this forum. I understood that these very old rubbers must be replaced after 40 years. Not fully functional damping might cause additional wear on primary chains, primary sprockets and the crank cogs.

Forum member Wobbly wrote about the service in Germany: (rubbers 55 EUR, work 20 + shipping back)
http://www.fourever-classic-parts.de/index.php?option=com_content&view=article&id=26&Itemid=31

They have done 2 hubs for me, early without circlip and a later with circlip on the splined shaft.
Replacement of the 2 needle bearings in last hub fix.

FunJimmy · « **Reply #10 on:** April 05, 2016, 11:26:28 AM »

Quote from: bwaller on April 05, 2016, 09:53:49 AM

The 500/550/650's have damping rubbers in both the primary driven sprocket & the clutch basket. Dampers simply buffer drive line snatch, one the primary chain, the other gearbox & clutch.

The clutch primary gear dampers aren't as easy to change, nor are the parts available from Honda but I think I have found a source for new parts. The trick will be replacing those. I'll let everyone know.

Interested to hear Brent.
Thanks

heyitsrama · « **Reply #11 on:** April 05, 2016, 02:16:22 PM »

why is it that everything has to be, "while youre in there you might as well replace everything" :| on the pro side, at least im being lazy about finishing my motor, and have the chance to order some parts, ill take a look at mine today.

heyitsrama · « **Reply #12 on:** April 07, 2016, 11:05:57 PM »

Hey, sorry to revive the topic, but if anyone has recently held a new crush rubber in their hands, are they squishy? or solid? i just checked mine out at they seem to be rock hard. (seems like they would just pass vibrations and movement through....)

Retro Rocket · « **Reply #13 on:** April 08, 2016, 12:51:23 AM »

Quote from: heyitsrama on April 07, 2016, 11:05:57 PM

Hey, sorry to revive the topic, but if anyone has recently held a new crush rubber in their hands, are they squishy? or solid? i just checked mine out at they seem to be rock hard. (seems like they would just pass vibrations and movement through....)

If they were soft the torque of the engine would tear them to shreds...

MickB · « **Reply #14 on:** April 08, 2016, 07:41:30 PM »

From Oddjob!s recommendation. New bearings on primary shaft, other bearings were all good, "new primary chain and new shock rubbers in the primary hub" (rubber was Oddjob's recommendation).

It's not hard to change them over, there's a pictorial showing how somewhere.

There's a lot about this subject in the forum. The majority say replace them and the primary drive and you won't have problems.

drumstyx · « **Reply #15 on:** April 08, 2016, 07:45:21 PM »

Quote from: MickB on April 08, 2016, 07:41:30 PM

From Oddjob!s recommendation. New bearings on primary shaft, other bearings were all good, "new primary chain and new shock rubbers in the primary hub" (rubber was Oddjob's recommendation).

It's not hard to change them over, there's a pictorial showing how somewhere.

There's a lot about this subject in the forum. The majority say replace them and the primary drive and you won't have problems.

Drilling out rivets is no problem, but how the heck do you expand the new ones without a press?

MickB · « **Reply #16 on:** April 08, 2016, 07:49:13 PM »

What bike do you have?

MickB · « **Reply #17 on:** April 08, 2016, 08:01:45 PM »

Somewhere (I've looked & seen) online there's an instructional piece on how to do it, but I can't find it.

drumstyx · « **Reply #18 on:** April 08, 2016, 08:45:44 PM »

'78 CB750K

I've heard it's easier on the smaller bikes, but that they have a clutch basket cush drive too that's more difficult.

MickB · « **Reply #19 on:** April 10, 2016, 04:26:34 AM »

Found it!

Search for "How to change primary rubber dampers".

http://forums.sohc4.net/index.php/topic,119730.msg1354961.html#msg1354961

Jerry Rxman Griffin aka MuthaF'er · « **Reply #20 on:** April 10, 2016, 08:36:07 AM »

More yes than no?? Are we sure that it's not interpreted as the cushes in the rear wheel vs the ones inside the engine? Not like this is easy nor are the parts readily available or really commonplace. However it is GREAT in theory! I am one of the no's.

IVPeters · « **Reply #21 on:** April 10, 2016, 09:07:37 AM »

I'll be honest, I poked the tiny bit of rubber I could see through the cover, saw that it gave and wasn't brittle - and called it good.

seanbarney41 · « **Reply #22 on:** April 10, 2016, 05:44:24 PM »

Quote from: Jerry Rxman Griffin aka MuthaF'er on April 10, 2016, 08:36:07 AM

More yes than no?? Are we sure that it's not interpreted as the cushes in the rear wheel vs the ones inside the engine? Not like this is easy nor are the parts readily available or really commonplace. However it is GREAT in theory! I am one of the no's.

if you go back through you may notice that all of the "yes" guys are all 500/550 guys (except PeWe) I am thinking something about the 500/550 is different enough to make this practical...And PeWe seems to enjoy tearing his bike down to the core several times a year, judging by his posts.

bwaller · « **Reply #23 on:** April 10, 2016, 06:25:44 PM »

The 550 primary drive rubbers are simple to change & available. Far different for the 750.

The 550 primary gear/clutch dampers are not as easy nor easy to find. Someone suggested it's easy drilling the original 500/550 rivots but they are long and drills wander!

Jerry Rxman Griffin aka MuthaF'er · « **Reply #24 on:** April 10, 2016, 08:28:40 PM »

Thanks for the explanation Brent.

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Do you/did you replace cush rubbers in the primary drive?

Author Topic: How many of you actually replace the primary drive cush rubbers? (Read 7760 times)