Surflex clutch plates. Good, bad?

[Matt Story]

http://i872.photobucket.com/albums/ab290/ApexDesignLLC/surflexclutch_zps2bc8eedc.jpg

Not a picture of my actual disc, one I borrowed from the internet.

I have 2 of these Surflex clutch discs.  They are bonded, not riveted, and have a solid web (no spokes).  Also, they have the deeper 4mm spline.  They are new.  I bought these about 6 years ago from a local Guzzi dealer on his recommendation.  Yesterday, I had a conversation that caused me to raise doubt if I should use them as they have questionable construction.  I gather that these discs may have been fine until some point when production changed, and thereafter produced units are not so good.

Is there a consensus?  If their use is unadvised, what's the weakness, failure mode?

Oh ya, these would be for my 850T

Thanks,

Matt

[guzzisteve]

Clutch failures that I have seen are rivet heads cracking or spokes breaking. This was stock clutchs as new as 09.

[Wayne Orwig]

I've never heard of Sureflex plates cracking. The factory plates had a problem from what I have seen, mainly in the late 90s. Those would crack the flex plates and rip out rivets.
I put a set of Sureflex plates in my Cal 1100, likely around 1998. They were really grabby for a while. Eventually they broke in and acted normally.

[Triple Jim]

In Guzziology, Dave Richardson says that the splines of the later version have tested very soft, like 15 Rockwell C-scale.  I guess you could tell with a file if yours have very soft splines.

[Vasco DG]

My experience has been that the deep spline plates are fine. What is, or was, a problem was the ones they made for the shallow spline hubs. On these the spline form was a sort of 'One size fits neither.' But they were not a close enough fit on the hub and would rapidly flog out the centers until one day the clutch would be let out and all you'd get is a horrid ratcheting noise and a failure to proceed!

Some others also reckon that the friction material is grabby. I have to say this has never troubled me but its worth considering.

Pete

[Antietam Classic Cycle]

Yep, very aggressive engagement at first (almost on/off) but do seem to get better with use. Took about 6k miles on my '70 Ambo "Barney" before they started to have any feel.

The Guzzi clutch plates that I absolutely will not use are Barnett's. The splines are stamped out of three thicknesses of plate, riveted together, instead of machined from once solid piece. They wear out the clutch hub real quick.

[charlie b]

Mine had them when I bought it.  I ended up overheating the clutch in a bad traffic spot a few years ago.  Since then my clutch gets 'grabby' when hot, probably due to the intermediate plate warping.  One of these days I'll open it up and 'slot' the plate if the clutch isn't worn out by them.  FYI, the clutch has about 40k miles on it now.

[Matt Story]

Ok then.  I'm going to run them.  Thanks for relating your experiences.

Matt

[kidneb]

Are you sure your plates have the proper 4mm deep splines,- and that they are not of the dubious "one size fits neither" that Pete mentions ? They`re still selling them unfortunately.
If you don`t know what they look like, have a look here : http://www.mgcycle.com/index.php?main_page=index&cPath=193

You see a Newfren shallow spline plate,- and those are the proper shallow splines.

And then you see the infamous Surflex bastard plate,- the one that`s sold as a shallow splined one, but actually slides over both the 2- and the 4 mm hub.   :o
(They just made the splines 1mm deeper in the plate hub)

Then you see the SD-TEC plate with proper 4mm deep splines. That`s a good one,- bonded and riveted and not so grabby as the Surflex.

I`ve had enough bad experience with Surflex to avoid anything carrying that name.

Most relevant to mention here, I had a brand new deep spline Surflex plate shed its friction material on my 850 GT. On the day I rode it out to sell it !
  I`m running the SD plates now, and am satisfied.

If you are running the bastard plate on a 4mm hub,- it will look like this : (1mm spline peak missing on the plate)

[jacksonracingcomau]

My 2c
Hated surflex when I first tried them in 80's, lost all the "feel" of OE clutch, point changes according to temp, after 3 sets of lights it was hard to pull away smoothly. Rejected them
25 years later tried them again, someone  told me they were fixed , had them in for a few weeks and ripped them out again,
But at same time I'd fitted them to my brother's bike, sent out from UK to rebuild and sent back
Now I use that bike every year for my UK/Europe transport, never changed them, seem to have bedded in to point it hardly bothers me and I regularly deal with stop start London traffic.
Can't be certain but guess they're the one size fits all plates (with 4mm spline hub). Done plenty of 2-up touring without ever dragging when hot.
I still adjust on the fly now and then (never on Oz bike) but liveable.

So I agree with consensus, bonded and rivetted are best, actually using Newfren for a few years now on my 2 Aus ones, totally consistent.
But Surflex seem to get better with age, I'll probably not change them out on UK bike till (if) there's any other reason to go in or they start slipping /dragging.

[guzzigray]

Yep, very aggressive engagement at first (almost on/off) but do seem to get better with use. Took about 6k miles on my '70 Ambo "Barney" before they started to have any feel.

The Guzzi clutch plates that I absolutely will not use are Barnett's. The splines are stamped out of three thicknesses of plate, riveted together, instead of machined from once solid piece. They wear out the clutch hub real quick.

 :+1. I had a set in my hotrod 1000 street bike and engagement from a standstill was very on/off. Once underway they were fine. They were in the bike for several years of hard use and when I rebuilt the bike there was hardly and wear (less than .25 mm. I now have that set in my race bike where clutch feel from standstill is unimportant but stout construction and good wear are important. I never have to worry about rivets pulling etc. I would recommend them for racing and hard use. Around town they are a bit of a nightmare.

[Greg Field]

I was sequestered in a Guzzi dealership that I really do not want to be associated with for 5 years.

Based on what I saw while there, buy Guzzi plates, especially those having "islands" of pad material separated by a channel to the next island. The rest are harsh and/or totally suck or will not last.

Who really  is enthusiastic about getting inside a Guzzi belhousing, anyway?

[Tobit]

My only experience with Surflex was in the '80s.  I installed their sintered bronze clutch in the LeMans IV and it machined away the contact surface on the ring gear to the point that there was no more adjustment left to disengage the clutch. 

A machinist friend determined that the flywheel and ring gear were not treated to the proper "Rockwell hardness index" for that type clutch.  He saved my bacon by machining the ring gear clutch surface flat again, removed the proper amount from the outer face of the ring gear which restored the correct clutch spring preload with the new OEM Guzzi clutch.

YMMV.