Definitive on the FZ600 clutch plate upgrade...

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JonW
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Definitive on the FZ600 clutch plate upgrade...

#1 Post by JonW » Thu Oct 26, 2017 10:18 pm

Ive been through the search on here and elsewhere and while its understood that the FZ600 clutch frictions[1] not only fit in the LC/RZ clutch, they also offer about 50% upgrade to the surface area which makes for a better and stronger clutch when fitted to one of our bikes of course.

What Ive not seen much about is the steels, should we be fitting the FZ600 ones as well, or just keep your OEMs? I ask that as if are they the same thickness as the old OEMs then buying a complete FZ clutch kit may well be a good way to buy new steels. Any thoughts?

FWIW new OEM FZ600 frictions can be had from suppliers like Partzilla for under $10 each, makes you wonder why some of the aftermarkets are so much more... 'upgraded' versions notwithstanding. Bare mentioned Ferodo kits and I looked them up but they were $100+, yet a set of OEM FZ600s would be considerably less, unless people know of a good supplier for other kits?

I also guess that while you might well still use the OEM LC/RZ springs... but... while Im not up on the maths is there some degradation to performance as its a psi rating over the surface area since they are now clamping more surface area? so perhaps its time to upgrade (cue whinging about how the light the LC/RZ clutch is and its one of the best things about these bikes etc :smt005 ). Ok, its said that the FZ springs are longer (meant to hold more plates) but still fit and would be under more tension so perhaps an upgarde, else you should at least fit brand new OEMs for the LC or RZ (diff springs) or do the 3/3 upgrade etc. what ever floats your boat on that score, but FWIW I tested a bunch of old clutches and its the springs that get knackered first before anything else. So, IME whatever you do, you will need new springs. Period.

1- FWIW the FZ600 frictions are the same size plates as the 750 and other bikes of the era, they just added more plates with the bigger engine capacities
80 XT500 Supermoto!
81 RD350LC Resto
82 RD421LC Hybrid
82 RD350LC decapitation project
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RuZty
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Re: Definitive on the FZ600 clutch plate upgrade...

#2 Post by RuZty » Fri Oct 27, 2017 12:25 am

Jon, I used the FZR1000 frictions, which may well be the same as the 600. The 1000 uses the same part number steel as the 350, but uses more, so there is nothing to be gained there. I have had these in for ages with zero problems, stick with the OEM plates for best effect. I installed 3 heavier springs at the time and measured them for spring rate but don't recall the exact difference, but I think it was about 20% more in total. The clutch effort is fine but I don't spend time sitting in traffic, I would recommend starting with new stock springs and upgrade if you have problems, which is unlikely.
It is also important to make sure the clutch basket fingers are not full of divots from the plates. They can be filed but it isn't just a matter of hacking away at it with a file until smooth, all fingers have to be the same width and all faces parallel to each other and to the plate tabs or all the load will be on just a few fingers. You also have to be careful to keep a radius in the bottom corner or you will have created a place for a failure to start.

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Re: Definitive on the FZ600 clutch plate upgrade...

#3 Post by hondaror » Fri Oct 27, 2017 3:00 am

EBC clutch springs are 15% stronger then stock. Stock springs will weaken over a couple years of hard riding and will start slipping. Do not use stock springs.
If friction plates are within thickness spec, they are safe to use. Steels only need to be replaced if they are blue in colour or wharpped.
Rory
2 1984 RZ350s
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JonW
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Re: Definitive on the FZ600 clutch plate upgrade...

#4 Post by JonW » Fri Oct 27, 2017 8:27 am

Good info guys!

I actually fitted a full set of uprated springs in my 421 and didnt think it was that hard to pull... until i pulled my OEM F1's clutch lol.

Rory, thats my mantra as well for clutches in these bikes. I was only considering the FZ stuff as its a simple gain for not much coin etc.
80 XT500 Supermoto!
81 RD350LC Resto
82 RD421LC Hybrid
82 RD350LC decapitation project
82 RD250LC JDM '251LC' YPVS
83 RZ350 Resto
84 RZ500 Resto
85 RZ350 F1 Resto
86 RZ350 F2 Resto
86 RZ350 F2 Hybrid

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Re: Definitive on the FZ600 clutch plate upgrade...

#5 Post by T.RexRacing » Fri Oct 27, 2017 8:30 am

Been using a full Barnett since late '84. Springs and all. Currently housed in a Hinson Billet basket,hub and plate. Can still operate with two fingers w/o issue. Might be a pain in heavy traffic but we don't see heavy traffic 'round here.
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hondaror
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Re: Definitive on the FZ600 clutch plate upgrade...

#6 Post by hondaror » Fri Oct 27, 2017 11:33 pm

Stiffer springs...yes, tougher to pull compared to stock. When the bike is running, that resistance action is reduced. Do not judge the feel when the bike is not running, as that is not how it feels when it is running.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

tacky1
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Re: Definitive on the FZ600 clutch plate upgrade...

#7 Post by tacky1 » Sat Oct 28, 2017 1:44 pm

I ran 3 new OEM and 3 Barnett springs and it feels great, No slippage, Heavily ported engine, modded heads, 32mm carbs, VForce blocks, toomeys etc etc...
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
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MK
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Re: Definitive on the FZ600 clutch plate upgrade...

#8 Post by MK » Sun Oct 29, 2017 1:11 pm

A guy named Newton found quite some time ago, that friction in his RZ clutch solely depended on normal force and friction coefficient.
https://en.m.wikipedia.org/wiki/Friction" onclick="window.open(this.href);return false;

In a nutshell: Just enlarging the pad area does not add to max transmittable torque.

Increased friction coefficient of the pads does.
Increased spring preload/stiffness does.
Increased average radius of the pad does.
Increased number of contact surfaces (i.e. number of plates) does.

The standard is springs which has the drawback of increased actuation force.
Pro's either use high friction pads like the mentioned Barnett carbon/kevlar stuff or invest in a basket/hub combination that uses 8-11 plates.
For drag racers lock-up plates are quite popular.

Another cheat is mixing solutions like 3 stiff and 3 stock springs.

I am using a lock-up plate and only 3 of 6 springs. Gives a very easy actuation and still does not slip at high rpm (70 rear wheel HP).
Bye
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Re: Definitive on the FZ600 clutch plate upgrade...

#9 Post by (F5) » Fri Dec 22, 2017 4:05 pm

I made my actuation arm a little longer which helps when using 6 HD springs but went the extra plate way which seemed to sort things out. Pushing 100hp though so not usually a prob on a 350.
496 Cheetah. TSS PVs, PWK35s, Ignitech, RGV(ish) chassis

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