SOHC.co.uk Forums > CB500/550
Pyramid Parts Tapered head bearings.
Orcade-Ian:
I'm faced with a similar dilemma on my 350 Forza Maxi Scoot. It's coming up to 3 years old next May and therefore will need an MOT. Lots of owners on that Forum have had steering head bearing failures at MOT time - a definite 'notch' at the dead ahead position but no slackness. Checking a manual download (in the Thai language!) the very good diagrams show a glorified bicycle set-up with caged balls top and bottom and NO TOP YOKE! Stanchions finish at the bottom yoke which must put an excessive load on the bottom bearing which is not 'shared' with the top bearing conventionally. My bike is just coming up to 9000 miles, others have been far less and yes, mine too is notchy - not dangerous but I don't even want an advisory on the MOT history. It's a time consuming job to replace the bearings - almost all of the plastic has to be removed, a process fraught with disaster at the hands of any ham-fisted 'technicians', so I will do the job myself over winter. Honda claim 'no knowledge' of a problem and suggest 'wear and tear'. I certainly aint putting Honda bearings back in for them to fail so quickly. So I will be sourcing taper rollers, hopefully from Timken. I'm fortunate having machining facilities if needed for collars, spacers, shields etc, providing I can find bearings of the right size - I'll only know that when I strip it.
Ian
Oddjob:
As there are no spring balance figures for the early sohc bikes I used those figures as a guideline. I found around 3.5 to be about right. I must say though that my kit was bought around 1980 and they fitted just fine, I tried without the spacer under the bottom race first but the steering locks fouled on the frame. There were 3 different sized spacers iirc and I fitted the middle of the 3. It’s apart right now as the frame got powder coated but I can’t tell you any sizes as yet until I get some mobility back due to my recent health problems.
I personally don’t rate the Pyramid kit, however it does seem to be one of the few left on the market, shame it doesn’t fit as well as it should. My tapers have done around 60-70k and they are still perfect so they’ll be going back in for another session soon.
taysidedragon:
--- Quote from: Orcade-Ian on October 25, 2025, 09:30:41 AM ---I'm faced with a similar dilemma on my 350 Forza Maxi Scoot. It's coming up to 3 years old next May and therefore will need an MOT. Lots of owners on that Forum have had steering head bearing failures at MOT time - a definite 'notch' at the dead ahead position but no slackness. Checking a manual download (in the Thai language!) the very good diagrams show a glorified bicycle set-up with caged balls top and bottom and NO TOP YOKE! Stanchions finish at the bottom yoke which must put an excessive load on the bottom bearing which is not 'shared' with the top bearing conventionally. My bike is just coming up to 9000 miles, others have been far less and yes, mine too is notchy - not dangerous but I don't even want an advisory on the MOT history. It's a time consuming job to replace the bearings - almost all of the plastic has to be removed, a process fraught with disaster at the hands of any ham-fisted 'technicians', so I will do the job myself over winter. Honda claim 'no knowledge' of a problem and suggest 'wear and tear'. I certainly aint putting Honda bearings back in for them to fail so quickly. So I will be sourcing taper rollers, hopefully from Timken. I'm fortunate having machining facilities if needed for collars, spacers, shields etc, providing I can find bearings of the right size - I'll only know that when I strip it.
Ian
--- End quote ---
A lot of manufacturers don't put much grease on the bearings when in the factory so they're never going to last very long. 😖
ST1100:
--- Quote from: Oddjob on October 25, 2025, 11:19:19 AM ---As there are no spring balance figures for the early sohc bikes I used those figures as a guideline. I found around 3.5 to be about right.
--- End quote ---
Just had a peek into the "Honda Common Service Manual" (always interesting read 8) ):
- loose ball bearing type:
tighten bearing adjustment nut to 15Nm/10ft-lb, then back off 1/8th turn, check free movement
- retainer type bearings:
tighten bearing adjustment nut to 25Nm/18ft-lb, swivel, recheck for 25Nm/18ft-lb
- tapered bearing type:
tighten bearing adjustment nut to 11Nm/8ft-lb, swivel, recheck for 11Nm/18ft-lb
This should give a good baseline while installing; note that the actual figures might change with model, refer to the specific manual.
The spring scale load reading/check varies with the radius (distance between steering stem center and fork tube), so above preload divided by distance = desired measurement.
i.e. 15Nm/10ft-lb : 7.5cm/3inch -> should read 2kg/4.5lb on the spring scale.
hope this helps someone
K2-K6:
--- Quote from: ST1100 on October 25, 2025, 08:40:47 AM ---
--- Quote from: Oddjob on October 24, 2025, 08:27:37 PM ---Yes, I use a spring scale. I find it more accurate than a torque setting.
--- End quote ---
Would the 1.5~2.0kg/3.3~4.4lbs (given in Honda manual for larger bikes like the ST1100) also apply on the lighter 400/500/550?
Since I (yet) have never found a Pyramid (or any) kit that would actually fit the motorcycle at hand, I'm still biased... :-\
No fitting seals, shims/washers provided either too thick or too thin, bearing races too tall, not enough thread left for stem nut, top bridge height ends up wrong, neither steering lock nor limiters would engage properly... :o
OEM set OTOH is a no-brainer; installs right out the box, pack with marine lube, torque nut to the specs given in the manual, swivel, recheck, done... quick, precise, no headache... and most important: no 'headshake' when out on the road...
--- End quote ---
I've mentioned before about more fitted kits.
Contemporary purchase, we used Dave Degens at his shop over in Putney as he sold them in kits.
From memory, he had one of the tracks ground to facilitate this fitting within the original schema/dimensions of the Honda factory fit. Basically, decent taper rollers don't fit within the space of ball type bearings.
Tapers will by far out perform the ball track type generally, especially given some of the cheapest materials used(not necessarily honda) across motorcycle manufacturing.
The bit I'm not sure of is exactly what he altered. I recall one component, and possibly thats the top fit outer track for depth. They could have just been put in lines on a mag base carriage of a surface grinding machine to get a easy pass over them and reduce that dimension. They don't necessarily need dome of those dimensions fully in 0lace for this application as they would in something like a wheel bearing fitment.
Also at that time, we made any spacers we wanted, being apprentice in engineering.
I've still got some dimensions and drawing for required spacer my friend made for the 750F2 he has from that time period ;D
Currently, I've moved to CV molybdenum black grease for installation like this as there's no requirement for speed/drag consideration as exists in wheel bearing use, for example.
Although we do use the same in son's bicycle wheel bearings to live with the torque he can blast through them, still snaps spokes with regularity though, with legs that would do service powering a Sir Nigel Gresley locomotive ;D
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