Paralver pivot bearings. Food for thought

[Rob Farmer]

http://www.rubberchickenracinggarage.com/upgrades.htm

Not that I have a problem with the standard bearings at all. I've had a few fail but only when the bikes are quite new. Once replaced and torqued properly they are fine.

I haven't seen this approach before though. What do you think?

 

[Welshman]

http://www.rubberchickenracinggarage.com/upgrades.htm

Not that I have a problem with the standard bearings at all. I've had a few fail but only when the bikes are quite new. Once replaced and torqued properly they are fine.

I haven't seen this approach before though. What do you think?

Nothing wrong in what he is saying.

Welsh

 

[pomm001]

Good idea in theory but my concern would be that with such a large surface area of the 'bronze' cone that sticksion would be a problem and when it tightened up the lubricant would be forced out.
be better if some vertical slots were put in around the radius.
But agree if kept well lubed its more serviceable than taper bearings but not as free moving

 

[Phil Clarke]

Shouldn't need grease at all in theory but water ingress and corrosion of the steel outer race will be a problem without it. And they will have more stiction than a needle roller.

How big a problem is the standard needle rollers?

 

[Carefulkev]

Looks interesting. The parralever bearings are certainly a weekpoint (I've changed a few) so its nice to see an alternative approach . I would be interested to know though, what stops the bush turning on the inner diameter instead of the outer bearing surface - I suppose the inner diameter could be a tight fit to eliminate movement? Regardless, this idea may be the way to go.........

 

[Gas'd Off]

Looks like a good idea

 

[cookie]

why don't bmw just stick the other side of the swing arm back on?

single sided swing arms are a just a pointless styling exercise IMO.

 

[Wreford Miles]

why don't bmw just stick the other side of the swing arm back on?

single sided swing arms are a just a pointless styling exercise IMO.

Then you'd have 2 paralever bearings to adjust... no what you want is a shaft drive with no bend, you could call it a monolever

 

[longdog]

Shouldn't need grease at all in theory but water ingress and corrosion of the steel outer race will be a problem without it. And they will have more stiction than a needle roller.

How big a problem is the standard needle rollers?

If you are worried about about water ingress and corrosion with this, then you should be absolutely scared to death with what the feared water ingress and corrosion will do to needle rollers!!!!!!!!!!!! Stiction should not be a problem at all.

As for the problems with needle rollers, they are a pain in the ar*e!!!!!!

 

[longdog]

why don't bmw just stick the other side of the swing arm back on?

single sided swing arms are a just a pointless styling exercise IMO.

Unless I'm mistaken, BMW (and Moto Guzzi), use the paralever to allow the "swingarm" to pivot in a vertical plane instead of an arc, and they would probably still use this principle even if they did use a conventional swingarm. I believe Magni designed and built the first Guzzi with the paralever principle but he used a double sided swingarm as can be seen in the picture below.

(I should now get loads of messages telling me I'm talking b*ll*ks!!!!)

Yes, I do agree with your point on single sided swingarms, they add weight in order to maintain structural integrity and rigidity.

 

[The pater]

I don't like the idea.

The plain bearing has much much more friction torque than roller bearing. This can have an influence on the shock absorber operation.

Roller bearings are not the best solution when there is very high load and/or the oscillating movement is too small, so that roller do not get out of the roller/raceway contact surface (the one when the bike is in the garage).
This last point makes lubricant stay away from a certain contact surface et it increases false brinelling risk.

At high volume, plain bearings are cheaper than roller bearings, so why would BMW stick on roller bearings if plain bearing is technicaly better ?

PS : I'm an SKF engineer.

 

[Steptoe]

At high volume, plain bearings are cheaper than roller bearings, so why would BMW stick on roller bearings if plain bearing is technicaly better ?


.

Answered your own question.

They're a business, so they can sell you the more expensive item.

 

[(RIP) Proff]

Whats a Paralever ??

 

[The pater]

Answered your own question.

They're a business, so they can sell you the more expensive item.

No, I think that you misunderstood.

The sales price to the end user has nothing to do with the sales price to the OEM.

At high volume, plain bearing cost less than roller bearing. So why would BMW mount in it's factory an item less performant that will cost him more ?

Sell price to end user is a total other story.

 

[Steptoe]

No, I think that you misunderstood.

I'll spell it out in bigger letters for you.

They get a more favourable price ( bigger profit margins) on the needle roller bearings.

 

[The pater]

I'll spell it out in bigger letters for you.

Bigger please because.....

They get a more favourable price ( bigger profit margins) on the needle roller bearings.

They ? BMW ?

Favourable price (bigger profit margins) ? You means that BMW does bigger profit margins on roller bearings ?

Perhaps when the item is sold as a spare part, but I'm talking about factory mounting of the item.

The cheaper the item is for BMW, bigger is the BMW profit on a new bike.
Taking a more expensive item than a cheaper one which could do the job is stupid.

Explain now why BMW fits, at the factory, more expensive item (roller bearing) than another (plain bearing) that could do the job better (some say.....).