LCGB Forums

Does anybody still do the tapered bearing conversion to replace the top caged race? Forks are out of my winter, so good time to do.
Thanks.

Taffspeed used to sell them. Don't know if they still do?

Had a look. Couldn't find anything. Thought I'd seen someone else doing them. Looks a worthwhile upgrade.

I’d have thought by using a tapered roller bearing you would want it as the bottom bearing with a ball race as the top bearing.

My very minimal engineering understanding, from what I've read and seen, is that the top bearings are prone to more stress when an anti-dive front brake set up is used? Also, my respect for Mr Frankland, who was marketing the upgrade.

The club van had them for sale at rallies for a while. You really need an opposing pair of taper roller bearings to be fully effective.

Absolutely no benefit whatsoever by having a tapered roller bearing on the top race on a Lambretta forks with a ball race on the bottom; thing about it, what happens with the force applied to the taper under heavy breaking ? The taper begins to part causing lateral movement..... on the other hand put a tapered roller bearing on the BOTTOM race, now under heavy breaking the taper will be forced together effectively tightening everything up and working as it was designed to do.

Fast n Furious wrote:Taffspeed used to sell them. Don't know if they still do?

I think it was the late Ian Frankland that was marketing these, and not the re-incarnated Taffspeed.

You could still ask them, and report back.

Scooterdude wrote:Absolutely no benefit whatsoever by having a tapered roller bearing on the top race on a Lambretta forks with a ball race on the bottom; thing about it, what happens with the force applied to the taper under heavy breaking ? The taper begins to part causing lateral movement..... on the other hand put a tapered roller bearing on the BOTTOM race, now under heavy breaking the taper will be forced together effectively tightening everything up and working as it was designed to do.

You would need a taper roller bearing both top and bottom or the top ball race would be slack under braking.

Tractorman wrote:

Scooterdude wrote:Absolutely no benefit whatsoever by having a tapered roller bearing on the top race on a Lambretta forks with a ball race on the bottom; thing about it, what happens with the force applied to the taper under heavy breaking ? The taper begins to part causing lateral movement..... on the other hand put a tapered roller bearing on the BOTTOM race, now under heavy breaking the taper will be forced together effectively tightening everything up and working as it was designed to do.

You would need a taper roller bearing both top and bottom or the top ball race would be slack under braking.

not necessarily no but it would be beneficial.

I used this setup on my group 4 for 2 seasons. With a antidive brake with no loosening issues. Although the reason I changed to it was because the forks where coming loose prior to fitting. I did though do away with the cage on the standard bearings. Breaking 2 sets down to take up the space with the balls. This was a worth while upgrade. All though fiddly to install.
If you can’t get a set it’s worth doing this upgrade.

I posted this on a similar thread last year.

Only the top taper roller bearing conversion is commercially available as far as I know.
So the bottom conversion is something that has to be done in-house.
I used a 32006 bearing which is common to a lot of Jap bikes.
You need to make up a bearing cup on a lathe to take the loose tapered outer race to replace the original Lambretta ball one.
Grind off the old roller inner race from the forks.
You no longer need the domed dust cover cos the taper roller bearing has its own oil seal.
You also need a removable solution for the steering stop tag on the forks if you want an easy way to remove the bearing in the future.
Saying that though......... The conversion should easily outlive you...... and you could just grind the tag off, replace the bearing and re-weld back on if you had to.

Taper roller steering conversions should only be done as a pair top and bottom to get the proper benefits. Done right it works well but its a lot of work.
TBH. cage-less loose ball conversions are nearly as good.
If you are planing on installing new ball races just make sure they come up to spec. I've come across some that are not ground deep enough and some are so oversized that you risk cracking the steering tube if too much force is used to press them in.

Fast n Furious wrote: I've come across some that are not ground deep enough

yes seen this before on a Scootopia headset bearing must have been one that slipped through the net as their stuff is generally very good.