Planning ahead - fitting the primary drive unit back in place'

[McCabe-Thiele (Ted)]

Yesterday as I thought my back was on the mend I removed the end gear & bearing from the primary drive shaft - I ended up using a puller that came with my steering head bearing removal kit.
No damage caused to parts (operator excluded) came off a treat - that gear was quite tightly on - new bearings on order. (thanks Ken for bearing links)

[McCabe-Thiele (Ted)]

Not understanding your comments about the hub not coming off the shaft Ted, as it's the only way you can remove it from the crankcase it must have come off originally for you to take pics of it. Most are really really easy to remove, they almost fall off.

You are right Ken, I must have slipped the centre section back on the shaft after I removed it.  Just fitted the new cushion rubbers the hub seem a tight fit on the splines needing some tapping to fit. Can the splines wear so it needs putting back  on in the same position it came off?

Is it worth some wire brushing of the splines so the shaft fits more  easily?

[Oddjob]

No, don't do anything. It's correct that everything should be tight, that's how you want it, doing anything will accelerate the wear and lessen the life of the dampers.

[McCabe-Thiele (Ted)]

I'm okay with fitting the left side primary drive bearing as I have a drift tool that works just fine -  but unsure of the best way to fit the right bearing without causing any damage.

Old right side (clutch side) bearing & end gear came off the shaft a treat with a puller but not sure of the best way to fit the replacement bearing without causing any damage.
I'm worried about getting it out of line - then getting the inner race stuck - is heat a good option - I do not have access to a press?

Any tips welcome please.

[Oddjob]

Ted, stop overthinking this stuff.  It's a bearing on a shaft, put the bearing onto the top of a vice and beat the hell out of the shaft, it's that easy, assemble the opposite way to getting it off. These aren't put on using a hydraulic press, they are just banged on by hand most likely. So long as you protect the ends of the shaft from damage you're good. I reckon 2 knocks of a reasonably sized hammer and the bearing will fall off.

[McCabe-Thiele (Ted)]

I was worried about damaging the end of the shaft.
I guess with my current back pain my overthinking has become worse. 😭😭😭

Saw a Chiropractor on Tuesday who pummels the hell out of me for an hour. I have not been in so much pain with my back for decades good news is it's not skeletal "just" soft tissue damage FFS.

[Oddjob]

That shaft is hardened steel Ted, just use a piece of scrap plate between the hammer and the shaft and you'll not damage anything. Plus I must have 5 or 6 of those shafts spare lying around if the worst happens.

[McCabe-Thiele (Ted)]

Done - bearing & gear fitted  as you said Ken just a few taps of the hammer.

I need to source a new circlip - are SS ones worth the few pence extra DIN 471 whatever that means or A2?

[Oddjob]

Stainless steel are ok to use Ted, always worth a few extra pennies in my opinion.

[McCabe-Thiele (Ted)]

I've fitted the new primary drive bearing into the left side of the lower casing (oil pump end) - it went in pretty easily using  my drift tool.

The washer, new bearing, spacer & gear is fitted to the primary gear shaft.

Looking at the other end of the shaft - in the middleish section there is a circlip, then a plain washer then the collar/spacer followed by the needle roller - the hub then fits onto the starter gear end with the damper unit. End circlip can also  be fitted beforehand  as I have fitted new drive cushion rubbers.

When I have assembled the casing halves & torqued the bolts up I can then slide the shaft through from the clutch side (right hand) taking care when tapping the shaft in place making sure the washer, spacer & needle roller are aligned centrally as it's tapped through towards the previously fitted bearing on the oil pump side.

At this point some careful leverage is needed to align the shaft with the bearing.

Does this sound right ?

I have an 18 month old tube of Hondabond  that appears to be still soft will this be okay or do I need to buy a new tube?

My back has improved I hope to fasten up the cases in the next week or so.

[Oddjob]

Yep sounds right Ted. Hub is slid into the primary chain before closing the cases, it can be done after but it can be tricky. You leave the spacer that fits between the hub and the oil pump bearing off, as you slide the shaft through as soon as a little juts out of the other side of the hub then you slide that spacer on and keep watching to see if doesn't come off as the shaft moves along. Levering may be needed and usually is if the dampers and the chain have been replaced, you may need to lever the shaft some to align it with the oil pump bearing, leave the oil pump off and look through the opening and you can see which way it needs to be moved to be aligned. It's harder to type that to do.

[McCabe-Thiele (Ted)]

Thanks Ken I think I understand what's needed now - will my old tube of Hondabond be okay or will it dry too quickly as its old?

[Oddjob]

Should be fine Ted, so long as it's still liquid.

[McCabe-Thiele (Ted)]

Just wanted to check if I have the assembly order correct in my head for the  Primary Drive shaft.

Looking at my inverted upper case the hub will have the primary drive chain in place like in the photo below - it's angled out of position but will straighten up when I fit the upper casing & insert the shaft.

The shaft presently has the following components fitted at one end in this order  - Circlip(new), Gear, Spacer, Bearing, Washer against the hub shaft boss so as to speak. Further down the shaft has a circlip and flat washer in place - then goes the small spacer before the needle roller bearing in the starter clutch.
When I insert this shaft with the bearing through the upper casing with the circlip & large washer fitted I can then  slip on the small spacer then feed the shaft into the needle roller bearing as there is access from above through the sump hole.

I then have to align the end of the splined shaft with the bearing I have previously fitted to the lower casing and tap it into place - leverage may be needed to align the inner race with the splined shaft end.

The eagle eyed will have spotted plenty of excess assembly lube down various thread hole plus plenty of hairs etc.
I will be cleaning up and degreasing both mating surfaces before assembly. Plus gearbox oil seals not yet in position (2)

Do my meanderings sound correct ?

All my current casing bolts are Allen key headed SS bolts with SS washers - I might change the top case bolts for the 8 mm bolt headed type as they are more visible. Not sure if you can buy the specific lengths in SS.


.500 casings by Macabe Thiele, on Flickr


.Primary Drive Shaft assembly by Macabe Thiele, on Flickr

[Matt_Harrington]

Ted, are the bolts (flanged) the same style on the 500/550 as the 400/4 ones? - ie reduced head? I'd like to source JIS (reduced head) flanged bolts but the only guy I have found so far wants around £12 a bolt!! - I could make them for much less. Let us know if you manage to source any 8mm bolts with 12mm flanged head in S/S...