Counter Steering: Does Anybody Have An Explanation? - Demystification Required
- Thread starter Jez Nemeth
- Start date
My understanding was that all of the fastest modern sport bikes, like the Hyabusas and R1s, use caged balls just like the GP racers. GP racers had complaints about "wedging" where the inner bearing would tighten in the cone momentarily.
There are two problems with fitting taper rollers to a Vincent. First, you have to use a modified existing bearing or a smaller taper roller bearing. I chose to use a smaller bearing because I was making a new headstock also. The 32005 bearing used on Ducati 900 headstocks was my choice, but it requires a shim or short sleeve in the Vincent steering head to fit. This is not ideal, but David Tompkins used my taper-bearing steering stem for racing for two years with no issues.
Second, with taper roller bearings, the stem itself is used to locate the taper bearing. On the VOC conversion, this is done by using Loctite to position the bearing on the stem. The stock steering stem is not a precision machined item and it is often too rough to be used as a locater for the bearing cone. On my taper roller steering stem the stem is machined as the Ducati stem with two positions on which the bearings locate.
Otherwise, it is pretty straightforward.
I used a 1" x 20 nut for the stem because it was easy to get. The top hat flange was made to fit under the FF1 to take up space. The bearing shims are sitting in front.
David and I had both experienced broken stock bearings in the lower bearing using loose balls. I suspect it was cumulative damage to the bearing pockets and/ or bending of the steering head over the years.
David
There are two problems with fitting taper rollers to a Vincent. First, you have to use a modified existing bearing or a smaller taper roller bearing. I chose to use a smaller bearing because I was making a new headstock also. The 32005 bearing used on Ducati 900 headstocks was my choice, but it requires a shim or short sleeve in the Vincent steering head to fit. This is not ideal, but David Tompkins used my taper-bearing steering stem for racing for two years with no issues.
Second, with taper roller bearings, the stem itself is used to locate the taper bearing. On the VOC conversion, this is done by using Loctite to position the bearing on the stem. The stock steering stem is not a precision machined item and it is often too rough to be used as a locater for the bearing cone. On my taper roller steering stem the stem is machined as the Ducati stem with two positions on which the bearings locate.
Otherwise, it is pretty straightforward.
I used a 1" x 20 nut for the stem because it was easy to get. The top hat flange was made to fit under the FF1 to take up space. The bearing shims are sitting in front.
David and I had both experienced broken stock bearings in the lower bearing using loose balls. I suspect it was cumulative damage to the bearing pockets and/ or bending of the steering head over the years.
David
I have had limited exposure to Vincent steering head bearings, but have seem more than my share of cracked races. The bottom race on the stock stem for my girdraulics had a crack that was hard to see with the naked eye. I have a suspicion that it cracked because the interference fit on the stem was too high. I inherited a few UFM’s and they all had a least one cracked race. I think it’s a good idea to inspect them under magnification or do a crack test.
Honestly some arguments look a lot like religion, balls or taper bearings. When you look up steering bearings in Ebay and all , you only find ball types on mopeds or light motorbikes. So I don´t believe in problems from taper roller bearings , instead I think these are better with radial loads and less critical with setting them nicely.
I just got sizes from the standard Vincent stem which is about 28.5 mm . So this makes it suitable for an adapter for 30 mm i.d. taper roller bearings. You´d get the stem on the lathe and maybe remove the old step for the ball bearing inner race. Then turn a bush with ~31mm o.d. and loctite it on the plain stem. Next day you can finish it for exactly 30 mm light press fit for lower bearing and same bush for upper bearing, light slide fit. No need for the stem to be perfect and straight, just for Loctite application.
The link below shows a Yamaha RD 350 bearing with o.d. 48 , i.d. 30 mm and 12 mm height. So this can be used for standard stems and Norman´s mod as well. Just you need two sets of the Yamaha kit for two of the right size on Vincents. Certainly another adapter in the head lug is required for adapting from 50.5mm (2" ) to 48 mm , again loctited in. So no machining the head lug is needed.
Another plus with taper type bearings is the large area of fit on stem or head lug. The ball type races are just around 5-6mm so they often eat into stems or recesses , so then big headscratching with loose bearings.
Vic
Yamaha 40-30-12 taper roller kit
I just got sizes from the standard Vincent stem which is about 28.5 mm . So this makes it suitable for an adapter for 30 mm i.d. taper roller bearings. You´d get the stem on the lathe and maybe remove the old step for the ball bearing inner race. Then turn a bush with ~31mm o.d. and loctite it on the plain stem. Next day you can finish it for exactly 30 mm light press fit for lower bearing and same bush for upper bearing, light slide fit. No need for the stem to be perfect and straight, just for Loctite application.
The link below shows a Yamaha RD 350 bearing with o.d. 48 , i.d. 30 mm and 12 mm height. So this can be used for standard stems and Norman´s mod as well. Just you need two sets of the Yamaha kit for two of the right size on Vincents. Certainly another adapter in the head lug is required for adapting from 50.5mm (2" ) to 48 mm , again loctited in. So no machining the head lug is needed.
Another plus with taper type bearings is the large area of fit on stem or head lug. The ball type races are just around 5-6mm so they often eat into stems or recesses , so then big headscratching with loose bearings.
Vic
Yamaha 40-30-12 taper roller kit
I'm sure that the reason that caged balls are used currently is because of the demands of modern production methods. Can you imagine a slick production line where, amid all the automation, a person has to apply grease to the headraces and then stick individual ball bearings into the grease, hoping that all the balls remain in place while the steering stem is inserted and the top yoke fixed?
