I'm considering a mod' to the rocker bearing and to make it less awkwardly needs the pin and rocker arm removed, are these components compromised when disassembled, ie fit, or is it acceptable to use old pin.
E: Engine Rocker Bearing
- Thread starter brian gains
- Start date
I've just replaced the rocker bearings and pins on my B. The pins are a surprisingly tight press fit, so if you mean will the old pins go back in, I'm sure they will and remain tight. I had read that the steel pins wear and the alloy bush does'nt. That proved to be the case - but I had ordered the lot , so it got the lot.
The wear on pins was quite visible, not worth replacing, it creates a lot of play at the valve collar .
The wear on pins was quite visible, not worth replacing, it creates a lot of play at the valve collar .
When I built the norvin I had a pile of worn bearings and some sad looking rockers. The price of the parts seemed excessive. So, I bored out the worn bearings, bored out the arms, made up some alu bronze bearings to press into them, made some new pivot pins so the whole system was reversed. One of the comments, from Big Sid was, very clever. Saved a small fortune.
Roy, you mean the bronce bushes sit in the rockers ? So the new pins are some mini press fit in the alu "bearings" and the rocker is meant to float on the pin by the very short bush pressed in ? Not a lot of bearing space for the load . I kept the pressed in pins in rockers and had crowded needles in hard bushes in the alu "bearings" - perverse . . . .
Vic
Vic
Vic, yes the the bushes are in the rockers. The way I figure it needle rollers are fine in rotating jobs, not in rocking motions as they will brinel in time. Back in the sixties every man and his dog put as many needle bearings as they could in their cafe racers. The results were not always good.
Depends - I don´t have common needle bearings in there, but crowded, so this means about factor 2-3 higher load carrying. Same with camshafts running on crowded types. You could find lots of rockers with needle bearings in them, crowded in sports Earles BMWs like R 69 S and common types in later /5 or /6 types. So it is a matter of dimensions, not just rocking motions. Same applies to taper rollers in swing arms and all, not great but provided no grit or water gets in they last very long. Brinell effects are due to exceding load properties of that bearing, not from small rocking operation.
A bronce bush in the Vincent rocker might not last extremely long I´d think, just the total surface as a plain bearing is not really ample ?
I did a number crowded needle followers , in the Guzzi and three sets for prewar Horexes, original no bushes in them does not work long, too poor lubrication and only limited space for a lasting plain bearing type. You can find roller followers in modern cars too, or KTM. Just dimensions for the job have to be suitable, so no brinelling by rotation or just rocking.
Vic
A bronce bush in the Vincent rocker might not last extremely long I´d think, just the total surface as a plain bearing is not really ample ?
I did a number crowded needle followers , in the Guzzi and three sets for prewar Horexes, original no bushes in them does not work long, too poor lubrication and only limited space for a lasting plain bearing type. You can find roller followers in modern cars too, or KTM. Just dimensions for the job have to be suitable, so no brinelling by rotation or just rocking.
Vic
Hi Roy, May I please ask: So, the aluBronze bushes are a press into the rocker bearing ? Then the pins have just enough play to rotate in the bush but no up or down and the rockers on the pins the same, just enough play but no up and down ?? As I understand it, the pin would normally be pressed into the rocker block/bearing whilst the rocker was in place, and the only slight play was between the rocker and the pin. So now there is play between the pin and rocker arm, and, the pin and the alubronze bush ? Is there a shoulder on the alubronze bushes to keep the rocker from drifting out and wearing into the port ? No concern regarding the expansion coef. between the two metals (alubronze bush and alum bearing) ?
A quick fix I used was use case Hardened 1/2in Dowels from work in place of the 0.497inch Vincent parts. Ream the rockers for the usual interference fit and the rocker bushes a running fit. The extra few thou usually meant everything cleaned up nicely. I ground the case hardening off the ends of the dowels and drilled the centre hole down the middle of the dowels. This proved to be a free, very durable and for me an easy fix.