Topic: CB750A tranny klinking and klanking

[jukku]

Broken vibration damper springs on Honda CB750A Hondamatic.
Noice from the tranny when gear is engaged.

https://1drv.ms/v/s!AvgjL1lJG5iElNhh70pL3R76VM2Eew?e=QtLZQ7

[jukku]

https://www.ebay.com/itm/Honda-750-Input-Shaft-23110-393-010-23110-393-020-23110-393-030-Springs-CB750A/331671472951?hash=item4d39290b37:g:LbIAAOSwLF1X48mQ

[vik351]

didnt sound too good, be buggered if I woulda ran it that long with that noise...

How much of a fun job replacing those springs...

Ya will replace them all at the same time I presume...

I only get my bikes next week so then I can have a listen to them... 

vik...goodluck...

[05c50]

Thanks for sharing the video and the repair. My A makes a similar noise, but is worse in neutral. It goes away in gear. Was a complets disassembly  necessary to replace the springs ?

.....Paul

[sammon287]

Thanks for sharing the video and the repair. My A makes a similar noise, but is worse in neutral. It goes away in gear. Was a complets disassembly  necessary to replace the springs ?

.....Paul

Mine was similar to yours. I didn't know these springs breaking was a thing until I took everything apart and found them in pieces. Unfortunately, it does require a complete engine/transmission tear down to get to them. I'm replacing all plain bearings and seals. I'm reusing transmission ball bearings, the clutch disks, and the primary chain guides. One of the primary chain guides is very expensive and the other is unobtainable. They look OK, so I'm hoping they don't disintegrate after my long and expensive rebuild. I'm also hoping the replacement damper springs hold up better.

[raymond10078]

Some noises are only the result of carbs not synced well and/or idle speed set too low.

Mine had exactly this issue, and no noise since.

[ORAZIO]

 
Broken springs.
My solution to avoid that some pieces of springs go between the gears.
I inserted a 6.35 mm section of Oring in the springs in order to retain any broken rings.

[MRieck]

 They all break.......no matter what they are used for. Street, dragracing etc etc etc. They all break.....every time.

[PeWe]

What more can cause vibrations on a CB750A?
Bike vibrates a lot when riding from around 50 mph and rising.
Problems holding the handle bar.
No specific noise at idle.
These springs replaced. Converter replaced too. Same vibrations.

A friend has a CB750A -77 (Japanese stickers) in mint condition he has tried to figure out what cause these vibrations.

[vik351]

I had a K2 back in the 70's and this is my first mike since then, 40 odd years, I recokn my 750A has more vibes that I can remember from the K2, but just in the frame, not the bars.

The K2 had bad speed wobbles but that was right up there 70-80 mph

weird one... good luck, ask on the main forum perhaps...

vik...

[Bazzer]

Hi, could you tell me where you got the springs from for the repair that you have done. I have my crankcase split, and notice the springs on mine were broken. Hope you can help.
                                                                                                                                                                                          Baz.

[sammon287]

Hi, could you tell me where you got the springs from for the repair that you have done. I have my crankcase split, and notice the springs on mine were broken. Hope you can help.
                                                                                                                                                                                          Baz.

Ebay.
https://www.ebay.com/itm/Honda-750-Input-Shaft-23110-393-010-23110-393-020-23110-393-030-Springs-CB750A/331671472951

[PeWe]

My friend plan to take the CB750A to a dyno and let it run to verify if it is engine with rear end related.

[TdLpps]

They all break.......no matter what they are used for. Street, dragracing etc etc etc. They all break.....every time.

So.....what's the fix?  Based on your knowledge of the 'A' bike you have to have tried a few different things.

I've heard of sold rubber dampers being used but with no other info than that -- no part numbers, suppliers, etc.  Is there a stronger spring or one with more space between coils that will more likely avoid coil bind which seems to be why these break.

Do you know if the drag bikes approach the damper unit differently?

Thanks.

[jukku]

Broken vibration damper springs on Honda CB750A Hondamatic.
Noice from the tranny when gear is engaged.

https://1drv.ms/v/s!AvgjL1lJG5iElNhh70pL3R76VM2Eew?e=QtLZQ7

One moore season ended with broken springs and same noise as 2019 season, not more or less.

[TdLpps]

So, just to clarify....you replaced the spring set with the DME springs and the noise went away.  Then, by the end of the 2019 riding season, the noise returned and the new springs were broken?

[jukku]

Oh no. Theese broken springs are the original. I'm sure that all springs have been broken at least two seasons probably three.
Winter 2018-2019 I put the ignition timing, valve clearance and carbs on spot and it reduced the noice. Now it is clincking a little, specially as cold, only in neutral and in gear unloaded. Going to change the springs and do a top end job during the winter.
I still have 2 sets jtmarks new springs on the shelf in my workshop.

[Medyo Bastos]

Sync your carbs too


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