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Sorting my 1988/9 VFR750F clutch


Fastdruid

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Backstory: Way back in the dim and distant past I used to use my 1988 VFR for commuting. When it was cold the clutch would slip when given full throttle...but only until it warmed up properly. 

 

Swapped the engine out (for an FK) for reasons I won't go into now, the only things remaining original was the hydraulic system and the (bike specific) oil (Motul 5100). It still slipped. 

 

I'd bought a brand new clutch set (OEM Honda) for the original engine so figured I'd swap them in even though when I checked the old plates they were all in spec. 

 

Still did it. Gave up and figured as it only did it while cold I could live with it. 

 

Mostly for child and job reasons (I'm now 99.9% WFH) it got parked up for ~11 years. 

 

Got it back on the road last year (thread here)

... but now the clutch is slipping on full throttle in the lower gears *all* the time. 

 

I'd already replaced the clutch master cylinder (because it was corroded internally). Although the lever isn't original now I've confirmed it's not jamming on slightly. It was a rebuilt M/C and so aftermarket parts. 


I went through it, checked the heights and conditions of all the plates. Picked the thickest of the friction ones and steels. Replaced the OEM springs (which were still within spec but only just) with new EBC ones (so in theory stiffer too). I swapped oil brand too (to Putoline Sport 4R).  I realised I'd missed out the gasket from between the sprocket cover and engine. Replaced that. Double checked fluid was returning in the M/C and the little hole wasn't blocked. 

 

Still did it. 

 

So now we're left with the only original parts in the entire system being the following.

 

1) Clutch line - HEL aftermarket. Should be good but I guess there is a chance it's broken down internally. 

2) Clutch slave cylinder. 

 

Beyond that less likely but could be the "same" issue on the replacement engine which means the following parts.  

 

1) Baskets, pressure plate and release bearing.

2) Pushrod and/or seal. 

 

Finally I guess the aftermarket M/C seal/piston kit may not be 100% and a chance isn't letting fluid return quickly enough (which may be why it's now doing it all the time rather than just when cold). Equally while I don't think it's the case I guess the lever may be impinging very slightly. Sticking an original lever isn't too big a deal to do a back to back test with.

 

My initial thoughts are to replace the clutch slave as right now that's one of the two parts that is original to the start of the issue, relatively high mileage (77k) and rebuild the M/C again with an OEM kit. 

Web!ke had a brand new OEM slave (delivered) for half the UK price so I ordered one of those. 

 

If that doesn't solve it I'll replace swap the original clutch line back in to test as well. 

 

Any other thoughts before I start swapping more parts? 

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Oh, one other thing I did see was someone (who had clutch slip after changing to Putoline Ester-Tech) was to clean all the friction plates in petrol and lightly sand the steels with scotchbrite and swap back to Sport4R. I guess I can try that too (apart from the swap to Sport4R as I'm already running that!) 🤣

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  • Member Contributer

I think scuffing the metals radially is gonna be the ticket.  Has made the difference in my used, but in spec, clutches that don't feel quite as crisp as they should.  Cleaned the frictions, scuffed the metals and thoroughly cleaned them, new EBC springs.  Zero issues.  Now I do it every time I have a clutch apart.   Excellent feel, no chatter or harsh engagement.

 

I go a little more aggressive than 3M, but I think it would still make the difference.

 

I don't think it has anything to do with your hydraulic system.

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  • Member Contributer

Abranet 320 gives a nice crisp finish 

 

I’ve still got those competition springs if you want them 

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16 hours ago, Thumbs said:

Abranet 320 gives a nice crisp finish 

 

I’ve still got those competition springs if you want them 

 

Thanks for the offer but the EBC ones made no bloody difference. 

 

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17 hours ago, Captain 80s said:

I don't think it has anything to do with your hydraulic system.

 

Well, thing is that they hydraulic system is the only thing in common between the original and replacement engine *AND* the only thing I've changed in the re-commissioning (where the slip became worse).  

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