BrawnFG
Well-Known Member
- Messages
- 490
- Location
- Northampton, UK
I recently left my FG in the cellar for a bit too long and the rear wheel bearings all seized up. I'm glad I spotted this because the axles were just loose enough to turn by hand, and if I had run it they would have heated up and melted the hubs, and made a right mess of the axles and dog bones, and possibly the wheels.
I looked the bearings up on a few model websites and found them to be way too expensive for what they are (£25 for a set of 8 wheel bearings!), so I dug out the trusty bearing catalogue and made the following list:
Wheel: 8x22x7 (FG# 6078) Designation:608
Clutch: 10x22x6 (FG# 6040) Designation 6900 (or 61900)
Layshaft: 10x19x7 (FG# 6036) Designation 63800
Alu Diff: 15x28x7 (FG# 8496) Designation 6902 (or 61902)
Plastic Diff: 12x28x8 (FG #6063) Designation 6001
For metal shields add "ZZ" to the designation.
For rubber seals add "2RS" to the designation (some manufacturers use 2RSR).
Google the designation to find a good price, for example:
Metal shield wheel bearing
http://www.bearingboys.co.uk/608-ZZ__pack_of_10__Shielded_Miniature_Ball_Bearing-7731-p
Rubber seal wheel bearing
http://www.bearingboys.co.uk/608-2RS__pack_of_10__Sealed_Miniature_Ball_Bearing-7729-p
Manufacturer
Most websites have a 'budget' option, and I'm pretty convinced that these are the ones that FG use as standard. If you take the view that bearings will die anyway (as I do) and all you ever do is bash, you'll probably want to use these and keep a few spares handy. Expect to pay about £1 per wheel bearing.
SKF, FAG, TIMKEN, and a few other brands are premium bearings. Expect these to be smoother running (less drag), better sealed, filled with better grease (more resistant to high speed running and high temperatures), and likely to last longer. Also expect to pay £2.50 or more for each wheel bearing.
Rubber seals or metal shields
Bottom line: Rubber seals cause more drag (so get hotter and have a lower speed rating, though this is well within the speeds of an RC car), but keep the crap and moisture out and the grease in. Metal Shields have almost zero drag (over an unshielded bearing), have a higher speed rating as they run cooler, keep most crap out, keep most grease in, and let water in.
If you run in a dry and relatively clean environment (e.g. on-road in a dry place), then the low drag shielded bearings will give you the edge. If you run off-road, best go for rubber shields.
ABEC Rating (note that ABEC is an american standard, Europe tend tp specify tolerance bands, e.g. C3)
As an Engineer, people quoting the ABEC rating as a measure of how suitable a bearing is for a particular job really riles me! I'll try not to rant, but here's the low down:
ABEC just lists the tolelrances/precision of the bearing, from 1 to 5. 5 is the highest precision and smallest tollerance. You want high precision bearings were the alignment of the shaft is critical to the machines operation (e.g. instrumentation, very high speed shafts, surgery etc).
You want low precision where the bearing housing or shaft is not precisely made and you need to account for some misalignment in the system (e.g. in an RC car plastic moulded hub), or in non critical operations.
If you use an ABEC-5 bearing in a plastic moulded RC car hub, the misalignment within the moulding will cause unequal load share in the bearings, and will increase the bearing drag, and ultimately give premature wear and turn your expensive bearing into an ABEC-1 (or worse) bearing! However if you use an ABEC-5 bearing in a well made alloy hub you will get better alignment, reduced drag, higher load capacity, and a longer life in the bearing.
Note that ABEC does not specify some of the most important bearing parameters (like the surface roughness of the raceways and rolling elements), so if you want a long life bearing you are better off buying a premium standard tolerance bearing than buying a 'budget' ABEC-5 bearing.
If you want to know more, see http://en.wikipedia.org/wiki/ABEC_scale
I looked the bearings up on a few model websites and found them to be way too expensive for what they are (£25 for a set of 8 wheel bearings!), so I dug out the trusty bearing catalogue and made the following list:
Wheel: 8x22x7 (FG# 6078) Designation:608
Clutch: 10x22x6 (FG# 6040) Designation 6900 (or 61900)
Layshaft: 10x19x7 (FG# 6036) Designation 63800
Alu Diff: 15x28x7 (FG# 8496) Designation 6902 (or 61902)
Plastic Diff: 12x28x8 (FG #6063) Designation 6001
For metal shields add "ZZ" to the designation.
For rubber seals add "2RS" to the designation (some manufacturers use 2RSR).
Google the designation to find a good price, for example:
Metal shield wheel bearing
http://www.bearingboys.co.uk/608-ZZ__pack_of_10__Shielded_Miniature_Ball_Bearing-7731-p
Rubber seal wheel bearing
http://www.bearingboys.co.uk/608-2RS__pack_of_10__Sealed_Miniature_Ball_Bearing-7729-p
Manufacturer
Most websites have a 'budget' option, and I'm pretty convinced that these are the ones that FG use as standard. If you take the view that bearings will die anyway (as I do) and all you ever do is bash, you'll probably want to use these and keep a few spares handy. Expect to pay about £1 per wheel bearing.
SKF, FAG, TIMKEN, and a few other brands are premium bearings. Expect these to be smoother running (less drag), better sealed, filled with better grease (more resistant to high speed running and high temperatures), and likely to last longer. Also expect to pay £2.50 or more for each wheel bearing.
Rubber seals or metal shields
Bottom line: Rubber seals cause more drag (so get hotter and have a lower speed rating, though this is well within the speeds of an RC car), but keep the crap and moisture out and the grease in. Metal Shields have almost zero drag (over an unshielded bearing), have a higher speed rating as they run cooler, keep most crap out, keep most grease in, and let water in.
If you run in a dry and relatively clean environment (e.g. on-road in a dry place), then the low drag shielded bearings will give you the edge. If you run off-road, best go for rubber shields.
ABEC Rating (note that ABEC is an american standard, Europe tend tp specify tolerance bands, e.g. C3)
As an Engineer, people quoting the ABEC rating as a measure of how suitable a bearing is for a particular job really riles me! I'll try not to rant, but here's the low down:
ABEC just lists the tolelrances/precision of the bearing, from 1 to 5. 5 is the highest precision and smallest tollerance. You want high precision bearings were the alignment of the shaft is critical to the machines operation (e.g. instrumentation, very high speed shafts, surgery etc).
You want low precision where the bearing housing or shaft is not precisely made and you need to account for some misalignment in the system (e.g. in an RC car plastic moulded hub), or in non critical operations.
If you use an ABEC-5 bearing in a plastic moulded RC car hub, the misalignment within the moulding will cause unequal load share in the bearings, and will increase the bearing drag, and ultimately give premature wear and turn your expensive bearing into an ABEC-1 (or worse) bearing! However if you use an ABEC-5 bearing in a well made alloy hub you will get better alignment, reduced drag, higher load capacity, and a longer life in the bearing.
Note that ABEC does not specify some of the most important bearing parameters (like the surface roughness of the raceways and rolling elements), so if you want a long life bearing you are better off buying a premium standard tolerance bearing than buying a 'budget' ABEC-5 bearing.
If you want to know more, see http://en.wikipedia.org/wiki/ABEC_scale
