BritBike Forum logo
BritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike Sponsor SteadfastCyclesBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorHepolite PistonsBritBike Sponsor
Upgrade to: Gold Membership | Premium Membership | Vendor Membership | Site Sponsor Membership
Member Spotlight
thackero
thackero
Houston Texas USA
Posts: 100
Joined: October 2011
ShoutChat Box
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
a word from..
Manuals on DVD (Shipping included)
Previous Thread
Next Thread
Print Thread
Rate Thread
Advice wanted on layshaft problem
#800055 03/04/20 8:57 pm
Joined: May 2014
Posts: 63
BritBike Forum member
OP Offline
BritBike Forum member
Joined: May 2014
Posts: 63
I stripped my RRT box this winter to change the kickstart shaft and check it over and seem to have a problem with the layshaft. It has needle rollers each end, no scroll on the bearing surfaces so I thought it was correct.

I measured the diameters of bearing faces on the shaft and found these to be 0.003” too small which makes them correct for brass bushes I think. I spoke to Jon at GSOC and he also advised me that there should also be a groove in the shaft on the kick star side which goes between the sandwich cover and the out cover. He implied the circlip is to stop the needle roller moving out into the outer cover.

For that to happen then the bush would need to have been a very poor fit in the sandwich case and I cannot see that being the case. The needles cannot escape the bush housing due to the ends being sealed over a little to hold them in place. So what is it’s purpose and is it really required?

I was thinking of getting the two bearing ends of the layshaft built up either with hard metal spray (satellite?) or diamond chrome plating and ground to the correct diameter for the needles. Any thoughts on that please?

Mal


Daytona Gold Star replica
DBD34/Norton
996 Ducati Boposta
350 MV Augusta
Aermacchi racer
Support Your #1 BritBike Forum!

Check out British motorcycles for sale: British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Re: Advice wanted on layshaft problem
Mal Marsden #800126 03/05/20 4:32 pm
Joined: Nov 2011
Posts: 5,782
Likes: 5
BritBike Forum member
Online Content
BritBike Forum member
Joined: Nov 2011
Posts: 5,782
Likes: 5
Originally Posted by Mal Marsden
I was thinking of getting the two bearing ends of the layshaft built up either with hard metal spray (satellite?) or diamond chrome plating and ground to the correct diameter for the needles.
Somewhere within my Spitfire thread you can find a discussion of the worn main shaft in its SCT2 gearbox. I wanted to reclaim it but the places I consulted who had the most credible responses said the coatings wouldn't be up to the pressure of the rollers. I should note that several places who did plating said it would be no problem, but my conclusion was the other places, that said 'no', were more credible. Luckily, it's the same shaft as in the RRT2 and Autocycle had high quality reproductions of those.

Re: Advice wanted on layshaft problem
Mal Marsden #800150 03/05/20 8:30 pm
Joined: May 2014
Posts: 63
BritBike Forum member
OP Offline
BritBike Forum member
Joined: May 2014
Posts: 63
Thanks MM, I hadn’t expected to be able to buy a replacement which would be of good quality but Autocycle have a good reputation and know what they are doing. I’ll give them a try, probably no more expensive than coating and grinding anyway.

Mal


Daytona Gold Star replica
DBD34/Norton
996 Ducati Boposta
350 MV Augusta
Aermacchi racer
Re: Advice wanted on layshaft problem
Mal Marsden #800170 03/06/20 12:30 am
Joined: May 2004
Posts: 4,328
Likes: 12
BritBike Forum member
Offline
BritBike Forum member
Joined: May 2004
Posts: 4,328
Likes: 12
They can be hard chromed but it if done properly will be bear the price of a new shaft.
Usual trick is to grind down an old one to fit the plain bushes then either fit a bespoke plain bush or use it on a std box.
Considering the price of gearbox parts & the time needed to remove, replace and rebuild the box it makes spending the money up front a no brainer.
The layshat get a fair bit of side thrust each time you change gears and competition boxes take a beating and get very hot.
Aluminium expads a lot more than steel thus the fit will get looser as the box gets to oprating temperatures.
The roller bearing can not be fitted as tight as the bronze bushes cause you can not ream them out to accommodate the crush of the box case.
While th e bearing can not fall out, it can slip back & forth with each & every gear change thus become sloppy in the case.


Bike Beesa
Trevor
Re: Advice wanted on layshaft problem
BSA_WM20 #800171 03/06/20 12:38 am
Joined: Nov 2011
Posts: 5,782
Likes: 5
BritBike Forum member
Online Content
BritBike Forum member
Joined: Nov 2011
Posts: 5,782
Likes: 5
Originally Posted by BSA_WM20
They can be hard chromed but it if done properly will be bear the price of a new shaft.
To repeat what I wrote earlier, the best information I was able to gather is that hard chrome plating will not stand up to the pressure put on it by the rollers. I got this information from people who do hard chroming for a living and who understood the question I was asking. If hard chrome would have worked to build up the main shaft of my SCT2 I would have had it done rather than risk buying an aftermarket part. As it turned out, all the measurements I did on the shaft I bought from Autocycle, which can be found somewhere within my Spitfire thread, showed that it met all the dimensional and hardness specs.

Re: Advice wanted on layshaft problem
Mal Marsden #800191 03/06/20 8:37 am
Joined: Dec 2004
Posts: 10,451
Likes: 6
BritBike Forum member
Online Content
BritBike Forum member
Joined: Dec 2004
Posts: 10,451
Likes: 6
It can work but has to be thick enough to stand the pressure, using plating to correct 3 thou of wear will not work as the thickness of the chrome is too thin. You have to grind the shaft further until the chrome has enough thickness. By the time you have ground enough away so the chrome has enough strength your better option is to use a needle roller inner ring instead. These needle roller inners are hardened and have excellent surface finish.


Moderated by  Rich B 

Link Copied to Clipboard
Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | DVD- Manuals & Parts books
Upgrade to: Gold Membership | Premium Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.7.4