Material choice?

[Cato]

Limited movement is harder on the bearing than continuous - the same rollers roller back and forth on the same bit, possibly not even fully rotating themselves, the lube doesn't distributed, the rollers hammer themselves into the shaft (as mentioned up above rather more poshly already - the brinelling), rapid oscillation causes the rollers to "skid", wrong finish and hardness on the new parts sets the rollers up to fail early too.

Been some correct engineering advice on materials, treatment and finish above for long life . . . and other that gets it running and probably okay for an undermined time.

The needle roller sleeve is a good idea - still needs a good fit on the top hat/spindle to not set up early wear though.

If I was making it myself, I'd do the sleeve (either into the existing top hat, or the inner race). If it was a work job - do drawing and issue it, accept finished, checked component from supplier in a month or so.

The sleeve would be inside the existing top hat and around the spindle, so in theory close to zero/very small amount of rotation. Given what you say it may make sense to make it an interference fit within the existing top hat and give it the same gap/tolerance between the sleeve and spindle as existing. Possibly over the top, but good practice nonetheless and not as if it'll cost a fortune.

 

[bricol]

The sleeve would be inside the existing top hat and around the spindle, so in theory close to zero/very small amount of rotation. Given what you say it may make sense to make it an interference fit within the existing top hat and give it the same gap/tolerance between the sleeve and spindle as existing. Possibly over the top, but good practice nonetheless and not as if it'll cost a fortune.

Sounds like a plan. Bearing fit also good for locking your new sleeve inside the existing top hat. Just don't lock it to the shaft too . . .

I can put all sorts of fits/tolerances on drawings and mostly get components that match . .. making it myself however . . . My excuse is I used the computer/brain very day . . . the lathe less often

 

[Cato]

Just don't lock it to the shaft too . . .

That wouldn't end well.

I haven't used a lathe in decades, and even then it was very limited. So going a bit OTT with jobs initially will be a good thing as it will help get me up to speed. Plus I'm quite looking forward to working on/with something different.

 

[addjunkie]

You saying that reminds me I'm sure I read somewhere about EN16 being recommended for spindles.

There seems to be a few places that will sell short (300 mm) lengths of various grades and sizes so I will probably pick up a few bits at the same time.

If your inexperienced at turning, Id suggest you just make up a complete new piece, it will be a good learning excercise. A big thing to work out in your head in advance is the sequence of the job, so you dont need to end up needing to put your nice polished finish in the chuck for example.

yes EN16T is the normal recomendation for wheel spindles and such.

You could also go the other way and make a new spindle to fit!

Hours of shed fun for you!

Many years ago I had a KX250, the swing arm had no bearing just bushes. They were worn badly, and I couldnt get new ones “inTime” so a visit to the local auto parts shop and found something near enough from a Triumph if my memory is still working. Split it with a hack saw, filed the split till it closed up neatly and put it all back together with plenty grease.
I sold the bike to a friend who raced it hard for 3 seasons, and never replaced said bodge bushes as they were still good.

 

[Cato]

By far the easiest solution would be to go online and order a bronze Bush the correct size, press it into the top hat and tickle with a reamer if required.

As you say though, it's a good opportunity to learn and gain a bit of experience.

 

[merryman]

The original inner race would be hardened and ground, no matter what material you use wouldn't be hardened enough to use as a needle inner race without heat treatment, they are pot hard. Regarding not much movement, Coventry Climax were daft enough to chose taper roller bearings for fork lift king pins. A 3 ton weight sitting on the back axle and solid tyres, rapidly ensured the cup had a surface like a thupeny bit.

 

[Cato]

I'm still not fully clear - are you swapping the bearing to one with a smaller ID, or putting a smaller ID shaft through the top hats?

If the latter, I think I'd be sleeving the shaft to suit the top hat, or drilling out the mounts to use a larger shaft through the existing top hats.

As has been mentioned - needs grinding, and hardening, then possibly finish grinding to be sure of diameter to be properly correct.

I can't imagine anyone has got away with stainless with an open needle roller running directly on it for long.

Missed a couple of replies somehow.

A smaller OD spindle is going through as it's sized for the GSX frame (using) and arm (not using) at 16 mm. The bandit arm I'm using has the top hats sized for the 20 mm Bandit spindle.

You'd be surprised (or possibly not) at what people have used for similar changes. On one motorbike forum there's mention of shoving a piece of tube through with a wall thickness "about 4 mm" to take up the slack.

 

[addjunkie]

Missed a couple of replies somehow.

A smaller OD spindle is going through as it's sized for the GSX frame (using) and arm (not using) at 16 mm. The bandit arm I'm using has the top hats sized for the 20 mm Bandit spindle.

You'd be surprised (or possibly not) at what people have used for similar changes. On one motorbike forum there's mention of shoving a piece of tube through with a wall thickness "about 4 mm" to take up the slack.

I wouldnt be surprised….sometimes needs must etc, but there are others who should have their tools taken off them, as they are dam right dangerous! Which forum was that, the good ones seem to have died.

Gas pipe, pidgeon stick welded frames springs to mind!

 

[PhillipM]

Id happily machine that part and fit it, its only a swing arm bearing, not like its runing * at 15000rpm.

As Bricol said, for a needle bearing tiny oscillating movements are far worse than continous movement. Hence me mentioning false brinelling earlier.
That part to be useful for anything more than a short term piece *NEEDS* to be hardened, ground bearing steel against the rollers.
The easiest way to do that is to just buy a suitable needle bearing inner ring in 51200 chrome steel that's already ground to size and press fit a top hat out of some En8 or better in the centre of it.


There's a lot of people in the bike modding world go "This worked!" - what they don't tell you is it did. When they posted that. Until they had to remake them a month or two later and kept quiet about it. Or their swingarm makes funny creaking noises they can't figure out because the insert looks like a 50p piece now and it just skips and jumps on the grease rather than the rollers.

There's all sorts of ****e floating around as addjunkie says, I've repaired frames that I'm amazed lasted the couple of months they reckon it was since they built it on trikes and other stuff, just bobbles of weld somewhere close to the joints...bit's of tube or pipe just bashed in for a pivot and pumped with grease until it shut up...