Tapered Roller Bearings - Why?

[TooManyToys]

Yep tapered rollers might last longer, but they are not invincible.

This is what came out of my son's 650L:

.

That looks like the bearings were set without proper preload.

A number of years ago a US auto manufacturer was hanging an issue with it's new vehicle platform launch were the vehicles were having excessive warranty for bad front wheel bearings in a short time after purchase. Came to find that the bearing races were developing the same condition during rail and truck transport. While the first assumption was that the bearing supplier was providing races without the proper hardening, it later turned out the the bearing torque spec was improper during vehicle assembly, allowing the constant hammering of the rollers against the races was the issue.

 

[TooManyToys]

i am going to preface this by pointing out that i usually respect and sometimes, even support the advice that nessism lends. Definately has helped me out from time to time.

But: Please, unless you are familiar with the stress/stain calculations for axial and trust bearing loads, please do not, anyone, go redesigning these critical parts of your bikes.

A pair of tapered roller bearings locks the steering stem from moving up and down. Ball bearing will always ave a small amount of play, even if preloaded. The larger contact area and inclined angle of tapered roller bearings also increases the stiffness of the rotating joint - less flex/better feel

+1...............

 

[UncleMike]

As it turns out, my boxes of parts for these bikes came sans-steering stem bearings, so it looks as though the tapered upgrade will indeed happen.

Anyone have recommendations for a good brand/source?

 

[Sandy]

As it turns out, my boxes of parts for these bikes came sans-steering stem bearings, so it looks as though the tapered upgrade will indeed happen.

Anyone have recommendations for a good brand/source?

A company called Alls-Balls???? Has stuff on ebay quite often with fitment for most bikes. Tapered is the way to go but on a bike that size it's probably not necessary but if you're changing them anyway....... Honda even used balls on the early CBX and VF bikes

 

[UncleMike]

I though 'All-Balls' was supposed to be cheap Chinese crap?

 

[Sandy]

I though 'All-Balls' was supposed to be cheap Chinese crap?

I don't know that for a fact, but wouldn't be surprised. Maybe see if they have a fitment chart with the bearing numbers or just take the old bearings or measurements to a local bearing shop and they can probably match up a set from stock. Either way, shouldn't cost much.

 

[UncleMike]

These seem a pretty good deal, but they don't list the '78 as an application.

However, looking at these it seems they all use the same dimensions?

Agreed?

 

[Steveb64]

These seem a pretty good deal, but they don't list the '78 as an application.

However, looking at these it seems they all use the same dimensions?

Agreed?

No guarantees... But they should be OK. I found the manual I was referring to above - an old Clymer one - it just shows balls being used - but it only covers up to 1976. But back in those days, Yamaha was pretty good about 'standardising' as much as they could across model years - and across models too, if they could!

It would be an idea (if not too much hassle?) to try and fit seals to the steering stem too - one above the top bearing, and one below the lower one - which is the usual setup for OEM standard tapered bearings on dirt bikes.

 

[Agemax]

i know these are in the uk but these seem a pretty good buy. both bearings, 2 seals and bearing grease.
http://www.ebay.co.uk/itm/Yamaha-DT...ycle_Parts&hash=item5ae09e2c2e#ht_1576wt_1271

 

[Guest]

I kind of remember back in the early and mid 80s there were some upgrade tapered bearing kits being offered to replace the old ball type bearings in the steering heads. I don't know if those are still around any longer since most bike manufactures have switched to the tapers.

 

[ddaniels]

The main issue with tapered roller bearings is that they not only withstand radial loads, or rather, sideloads, but they also withstand axial loads, or front to back loads. If you draw a line from the center of the race out to the center of one of the ball bearings, that is the radial direction. If you draw a line straight through the center of the race that is parallel with the shaft, or whatever, that the bearing is mounted on, that is the axial direction. So, ball bearings provide, usually, only radial support. There are bearings that provide only axial loads and they are call "thrust" bearings. tapered roller bearings provide both. Needle bearings also only provide radial support. I would not think that tapered roller bearings would be necessarily required for steering heads, but couldn't hurt.

 

[UncleMike]

i know these are in the uk but these seem a pretty good buy. both bearings, 2 seals and bearing grease.
http://www.ebay.co.uk/itm/Yamaha-DT...ycle_Parts&hash=item5ae09e2c2e#ht_1576wt_1271

Ordered! Thanks.

 

[UncleMike]

The main issue with tapered roller bearings is that they not only withstand radial loads, or rather, sideloads, but they also withstand axial loads, or front to back loads. If you draw a line from the center of the race out to the center of one of the ball bearings, that is the radial direction. If you draw a line straight through the center of the race that is parallel with the shaft, or whatever, that the bearing is mounted on, that is the axial direction. So, ball bearings provide, usually, only radial support. There are bearings that provide only axial loads and they are call "thrust" bearings. tapered roller bearings provide both. Needle bearings also only provide radial support. I would not think that tapered roller bearings would be necessarily required for steering heads, but couldn't hurt.

GREAT explanation! Thanks!

 

[850 Combat]

I'll bet that it (DT175) has plastic bushes in the swing arm like my RD400 came with.

 

[BentRod]

Tens of millions of motorcycles have been sold with nothing more than special design ball bearings in the steering neck. I agree that taper roller bearings will be more durable, but I wouldn't go off replacing the ball bearings that came with the bike from new unless they are worn out.

Agreed. If it isn't busted, leave it alone.
I simply wanted to advocate that there is a lot more to bearing selection than a simple cost/quality or better/worse type decision.

Additionally, ball bearings, thrust bearings, tapered roller bearings, each comes with different installation and geometric considerations. For example, given a pair of ball bearings, one installed at each end of the steering neck, both will take axial load. However, with tapered roller bearings, one bearing will be inverted, and will carry no axial load. This difference will effect how the load is then supported by the frame.

 

[UncleMike]

i know these are in the uk but these seem a pretty good buy. both bearings, 2 seals and bearing grease.
http://www.ebay.co.uk/itm/Yamaha-DT...ycle_Parts&hash=item5ae09e2c2e#ht_1576wt_1271

I got these and they look to be of pretty good quality, but the installation instructions they promised were included were not in the package, but instead supposed to be offered on the website.

Visiting the website, the page that's supposed to house them is blank, with a promise that they'll be coming in the future. The live support system is never on, emails bounce back and calls go to a full inbox.

Guess you can't count on much customer support from Pyramid Parts.

 

[tkent02]

Yup, longevity from having a load spread out instead of covering one small point on a ball. It was a big deal back in the '50s when Harley went from roller bearing cranks to Timkens.

Timken is just a brand name, not a bearing type.

I'm curious what type did Herdely go to for crank bearings?

 

[850 Combat]

Norton 850's used barrell shaped main bearings. Balls wern't up to it, and rollers didn't appreciate the crankshaft flex. They called them "Superblend" Norton didn't invent them or anything.

Bottom ends started lasting longer. The Combat 750's had bottom end problems with roller bearings on the primary side main.