Topic: Replacement swing arm bushing question CB750K4

[BobR]

 Well I ordered some swing arm bushings for my K4. They are genuine Honda. Guess I was expecting bronze or something and I dont have it apart yet. Do these look right? TIA Bob

[HondaMan]

Well...first, check their ID against the OD of the collar where they ride together. The clearance must be between 0.0008"- 0.0012" installed, so maybe add it to about 0.0010"-0.0014" uninstalled. The collar must correspond: even if you have a new Honda collar, the bad news is: they don't. They haven't since about 2008 or so. Also, this bushing is a MIMs-metal cast steel bushing, very abrasive: it will wear your collar out in less than 10,000 miles, even if it is brand new. The reason: it is impossible to lube a steel-on-steel bearing system (even the professional's Machinery's Handbook state this must never be done), and it has long been a mystery as to why Honda did this, starting in the 1990s...

This bushing also does not include a flange, if yours is a post-1974 750 or the post-1973 CB500/550. For those, you must also get the fiber inner seal "washer" and the outer "bush" as Honda calls it, which is a pair of phenolic end caps for the swingarm tube after the bushings are installed. The collar is 0.0020"-0.0040" longer than the stack-up of length over these end bushings (or flanged phenolic bushings if yours has those) so the big bolt will compress this to just-barely zero clearance at 25 ft-lbs. installed torque.

I don't say all of this to discourage you, but maybe to head off a very unhappy situation after you install everything? This situation is what got me to buy my own lathe in 2008, to rebuild my own swingarm: since then, I've ended up rebuilding hundreds of them for these forum members, with lifetime Oilite bronze bushings and custom-made collars. Let me know if I can help, in the end?

[MikeSimon]

The reason: it is impossible to lube a steel-on-steel bearing system (even the professional's Machinery's Handbook state this must never be done),   

Not even with MoS2??

[BobR]

Well...first, check their ID against the OD of the collar where they ride together. The clearance must be between 0.0008"- 0.0012" installed, so maybe add it to about 0.0010"-0.0014" uninstalled. The collar must correspond: even if you have a new Honda collar, the bad news is: they don't. They haven't since about 2008 or so. Also, this bushing is a MIMs-metal cast steel bushing, very abrasive: it will wear your collar out in less than 10,000 miles, even if it is brand new. The reason: it is impossible to lube a steel-on-steel bearing system (even the professional's Machinery's Handbook state this must never be done), and it has long been a mystery as to why Honda did this, starting in the 1990s...

This bushing also does not include a flange, if yours is a post-1974 750 or the post-1973 CB500/550. For those, you must also get the fiber inner seal "washer" and the outer "bush" as Honda calls it, which is a pair of phenolic end caps for the swingarm tube after the bushings are installed. The collar is 0.0020"-0.0040" longer than the stack-up of length over these end bushings (or flanged phenolic bushings if yours has those) so the big bolt will compress this to just-barely zero clearance at 25 ft-lbs. installed torque.

I don't say all of this to discourage you, but maybe to head off a very unhappy situation after you install everything? This situation is what got me to buy my own lathe in 2008, to rebuild my own swingarm: since then, I've ended up rebuilding hundreds of them for these forum members, with lifetime Oilite bronze bushings and custom-made collars. Let me know if I can help, in the end?

 Thanks I appreciate the info! I was immediately 'put off" by the fact the ones I got are steel. Ive been an automatic transmission mechanic for 39 years and never do you run steel on steel. Babbitt, bronze alloy and lately teflon coated- but never plain ol steel on steel.     Do you sell the bushings or prefer having the swingarm to fit them to it? Bob

[PeWe]

Honda stock swingarm bushings are crap! Thats why there are aftermarket solutions  like bronze bushings or needle bearing kits.
I installed needle bearing kit not long after after I bought my CB750, swingarm flexed sideways which was visible on the rear drive chain sprocket.

Most threads here of rebuilds use bronze. If I should live in USA, my swingarm should be under shipment to Hondaman for correction if I was in your situation.

[HondaMan]

The reason: it is impossible to lube a steel-on-steel bearing system (even the professional's Machinery's Handbook state this must never be done),   

Not even with MoS2??

Nope, not even with MoS2??


In fact, this is true of ALL metals and most materials in general: you never run the same material against itself, because it will greatly increase the wear: it is not then possible to isolate the electrical movement (of the electrons) of the atoms, and they pluck each other out of the other one's orbits. In real life, we call this motion "wear", and one side of the bearing must absorb the knocked-free electrons in order to slow down the wear. The better this happens, and the better the stronger of the 2 materials can hang onto its electrons as vs. the other side, the better the bearing.


I'll bet that's a WHOLE lot more than you really wanted to know, though.

[HondaMan]

Well...first, check their ID against the OD of the collar where they ride together. The clearance must be between 0.0008"- 0.0012" installed, so maybe add it to about 0.0010"-0.0014" uninstalled. The collar must correspond: even if you have a new Honda collar, the bad news is: they don't. They haven't since about 2008 or so. Also, this bushing is a MIMs-metal cast steel bushing, very abrasive: it will wear your collar out in less than 10,000 miles, even if it is brand new. The reason: it is impossible to lube a steel-on-steel bearing system (even the professional's Machinery's Handbook state this must never be done), and it has long been a mystery as to why Honda did this, starting in the 1990s...

This bushing also does not include a flange, if yours is a post-1974 750 or the post-1973 CB500/550. For those, you must also get the fiber inner seal "washer" and the outer "bush" as Honda calls it, which is a pair of phenolic end caps for the swingarm tube after the bushings are installed. The collar is 0.0020"-0.0040" longer than the stack-up of length over these end bushings (or flanged phenolic bushings if yours has those) so the big bolt will compress this to just-barely zero clearance at 25 ft-lbs. installed torque.

I don't say all of this to discourage you, but maybe to head off a very unhappy situation after you install everything? This situation is what got me to buy my own lathe in 2008, to rebuild my own swingarm: since then, I've ended up rebuilding hundreds of them for these forum members, with lifetime Oilite bronze bushings and custom-made collars. Let me know if I can help, in the end?

 Thanks I appreciate the info! I was immediately 'put off" by the fact the ones I got are steel. Ive been an automatic transmission mechanic for 39 years and never do you run steel on steel. Babbitt, bronze alloy and lately teflon coated- but never plain ol steel on steel.     Do you sell the bushings or prefer having the swingarm to fit them to it? Bob

I started out by making the bushings and selling them, only to later discover there are not only 4 different combinations of Honda's parts possible in these arms, but they interchanged them in the years, too. On top of this, the arms made before 1974 usually are worn oval toward their outside pivot hole ends, so they either have to be made round again or a bearing tapered on the OD to take up this 'slack'. So, after that I just went to rebuilding the arm after it arrives in my garage(!). Then I can make it all work right. PM me if you'd like it done, with some info about which bike/year it is?