Removing tapered bearing top from steering head
- Thread starter cbertozz
- Start date
D
Davo
Guest
cbertozz said:
Yep.
G
Grant
Guest
Nope
G
Grant
Guest
When I fit them there is always a little of the bearing outer sitting proud of the steering head.
You can tell when it's fully seated as the sound changes as it bottoms out when tapping into position.
You can tell when it's fully seated as the sound changes as it bottoms out when tapping into position.
tom3c75
Hero member
- Location
- Cape Town South Africa
Between 1.5 and 2mm on my 3C, Jota and Mirage.
G
Grant
Guest
It does if you want the fork shrouds to fit between the yokes.
Thank you..
And thank you..
It sounds seated. Will soon find out
As always thanks to everyone for their input.
Davo I'm going to set up a threaded rod thingy as well as an experiment using the rotor puller plate at the top as it looked like that would put nice even pressure.
tom3c75 said:
And thank you..
Grant said:
It sounds seated. Will soon find out
As always thanks to everyone for their input.
Davo I'm going to set up a threaded rod thingy as well as an experiment using the rotor puller plate at the top as it looked like that would put nice even pressure.
Dellortoman
Hero member
- Location
- Tasmania, Australia
Did you check the bearing recess in the steering stem for eccentricity beforehand? If it's oval shaped, you could end up with "bad juju" as Steve (Breganzane) explained. If notchy steering is what you're trying to fix, you may not be any better off with the new bearings.
When I replaced the steering head bearings in my brother Tim's 3C, I also found the top one difficult to install.
Measurements revealed exactly what Steve was talking about. Something like 0.5mm difference between diameters measured across the frame and lengthways. The frame hadn't been crashed or otherwise molested so it must have come from the factory like that. Presumably welding distortion.
Delving into a dusty corner of my memory that I thought was lost to dementia, I found a vague recollection of Tim saying that the bike tended to weave a bit at low speed. I was wondering if I may have found the cause.
The long axis of the oval was in the fore and aft direction, so I figured it was worth trying judicious application of a lump hammer to the front of the steering head tube. What could possibly go wrong?
A couple of gentle taps did nothing. A mediocre whack didn't do much either so I gave it an almighty wallop which shook the filaments out of the tail/brake light globe! On re-measuring I was pleasantly surprised to find the bearing cup within 0.05mm of circular. Not quite as gentle and measured as Steve's method, and somewhat more risky (could have ended up with a triangular bearing cup). But in the end I think it gave a better result
When I replaced the steering head bearings in my brother Tim's 3C, I also found the top one difficult to install.
Measurements revealed exactly what Steve was talking about. Something like 0.5mm difference between diameters measured across the frame and lengthways. The frame hadn't been crashed or otherwise molested so it must have come from the factory like that. Presumably welding distortion.
Delving into a dusty corner of my memory that I thought was lost to dementia, I found a vague recollection of Tim saying that the bike tended to weave a bit at low speed. I was wondering if I may have found the cause.
The long axis of the oval was in the fore and aft direction, so I figured it was worth trying judicious application of a lump hammer to the front of the steering head tube. What could possibly go wrong?
A couple of gentle taps did nothing. A mediocre whack didn't do much either so I gave it an almighty wallop which shook the filaments out of the tail/brake light globe! On re-measuring I was pleasantly surprised to find the bearing cup within 0.05mm of circular. Not quite as gentle and measured as Steve's method, and somewhat more risky (could have ended up with a triangular bearing cup). But in the end I think it gave a better result
Dellortoman
Hero member
- Location
- Tasmania, Australia
Get your hands on a set of digital vernier (bit of an oxymoron there) calipers and measure the roundness of the bearing cup before you put the new bearing in. It may benefit from some intervention.
Digital calipers can be found on ebay for a few bucks. Go for the ones with steel jaws rather than plastic. They'll give you an extra decimal point of accuracy. Plastic ones read to the nearest 0.1mm, steel ones read to .01mm.
Even if the measurement isn't absolutely accurate, it's certainly good enough for comparison of diameter readings around your bearing cup.
https://www.ebay.com.au/itm/150mm-15cm-6-Electronic-Digital-LCD-Steel-Vernier-Caliper-Gauge-Micrometer-NP/132548590427?epid=9015892110&hash=item1edc82fb5b:g:BscAAOSw5E5atKDb
They're not the quality a professional toolmaker or engineer would choose, but they're good enough for occasional use by the average backyard tinkerer. If you leave them sitting in a drawer for months between use, take the battery out, otherwise it'll be flat the next time you go to use them. The bloody things draw almost as much current when they're switched off as they do when they're on.
Digital calipers can be found on ebay for a few bucks. Go for the ones with steel jaws rather than plastic. They'll give you an extra decimal point of accuracy. Plastic ones read to the nearest 0.1mm, steel ones read to .01mm.
Even if the measurement isn't absolutely accurate, it's certainly good enough for comparison of diameter readings around your bearing cup.
https://www.ebay.com.au/itm/150mm-15cm-6-Electronic-Digital-LCD-Steel-Vernier-Caliper-Gauge-Micrometer-NP/132548590427?epid=9015892110&hash=item1edc82fb5b:g:BscAAOSw5E5atKDb
They're not the quality a professional toolmaker or engineer would choose, but they're good enough for occasional use by the average backyard tinkerer. If you leave them sitting in a drawer for months between use, take the battery out, otherwise it'll be flat the next time you go to use them. The bloody things draw almost as much current when they're switched off as they do when they're on.
D
Davo
Guest
andre g said:
How much does this matter if the bearing is held tightly in the headstock bearing cup and the centre of the bearing is in alignment with the centre of the bottom bearing? It isn't as if the shaft is spinning at 20,000 rpm and the bottom bearing cup is what takes the weight. Just curious.
Dellortoman
Hero member
- Location
- Tasmania, Australia
Davo said:
It can make the steering notchy.
chrisk
Hero member
- Location
- Brisbane, Australia
My SF frame was used as a speedway sidecar before I rescued it.
The bottom of the steering head has a boss welded on it about 15mm thick. I?ll bet it was put there to stop ovaling on the track ...... pardon pun.
The bottom of the steering head has a boss welded on it about 15mm thick. I?ll bet it was put there to stop ovaling on the track ...... pardon pun.