Question re 7 plate clutch

Fast Eddie

Fast Eddie

VIP MEMBER
Joined
Oct 4, 2013
Messages
21,597
Country flag
I recently bought an LP Williams 7 plate clutch kit for my T140.

When it arrived I see a note saying “no synthetic oil. Mineral oil only”.

Well, that’s no bloody good to me!

My question is, is it true or are they just playing safe? I cannot see why a motorcycle oil that is designed to be compatible with a wet clutch would not be OK.

Can anyone confirm or deny please??
 
The note is absolutely correct, when synthetic oil was being developed, they were made for cars, which most of us know have a dry clutch. When it was used in wet sump motorcycles most people found that the wet clutch would slip. As I found out for myself .
 
Bernhard, with respect, that info seems to forget about the many thousands of wet clutch Japanese bikes current performing faultlessly around the world with many of them using synthetic oil....

YES if you put synthetic oil in that is not compatible with a wet clutch (as in car oil) then you’re asking for trouble.

More to the point, the current 6 plate clutch in my T140 is running quite happily in synthetic oil!

So, I still can’t see the issue in using a synthetic oil designed for use in a wet clutch in this 7 plate clutch...
 
Last edited:
It’s your bike, your clutch and your oil.

The worst that can happen is the clutch might slip and you’ll have to clean the plates.
 
Well, can’t argue with that TT!

I guess I was hoping someone who tried already would chime in.

Nothing for it it seems but to give it a go.

Will report findings later...
 
I’ve found performance of clutches to be unpredictable. Some people like original Triumph 650 and 750 clutches. Others just cannot make them stop slipping.

I don’t think I’ve heard a bad report about the 7 plate kits though.

I did a cheapo 6.5 plate cork lined conversion on mine, after being plagued by slipping Surflex plates.
 
I fitted a 7 plate conversion from BBB in my ‘68 and it runs sweet with synthetic.

Will soon find out if the LP Williams one will follow suit...
 
Fast Eddie said:
Bernhard, with respect, that info seems to forget about the many thousands of wet clutch Japanese bikes current performing faultlessly around the world with many of them using synthetic oil....
YES if you put synthetic oil in that is not compatible with a wet clutch (as in car oil) then you’re asking for trouble.
Click to expand...

Well, you said it so you are aware of it, IMO the JAP owners who claim that they don't get clutch slip on synthetic oil are not abusing their clutch enough to make it slip, cause I ALWAYS found that I got clutch slip whenever I used synthetic oil that was used in the chaincase, only cured by stripping and cleaning the plates and going back to a non-synthetic oil.
 
Last edited by a moderator:
If you use a Jaso rated "bike"synthetic without friction modifiers there should be no problems..I know a few guys running various 7 plate conversions using Mobil1 Vtwin synthetic..
 
I run synthetic oil without friction modifiers in all my vintage bikes-BMW, Moto Guzzi, Triumph, Maico, CZ, Husqvarna.No clutch slippage some clutches smoother with the use of synthetic. My Norton is not running yet but it too will have synthetic oil in the gearbox and engine.
 
Ok boys n’ girls, the verdict is in:

I assembled the clutch with a little less spring pressure than it had previously to try and ease the pull, my logic being that the extra grip of the 7th plate would allow this.

I also fitted a Venhill FeatherLight clutch cable, the previous one was a heavy duty standard looking job.

The pull at the lever was very, very much improved.

I had also changed the oil to BelRay 10w50 V Twin synthetic (it’s the best one from Comnoz’ testing that is compatible with a wet clutch).

Today I managed a short 20 mile road test... and... drum roll... the clutch is perfect!
 
There are (at least) two variants of the 7 plate kit around. When I restored my brother's 650 Trophy I waited until Norman Hyde had his kit back in stock, as it utilises narrower plates, effectively applying more pressure per square inch (or whatever unit you like!). This is a slightly counter-intuitive design that Japanese clutches (apparently) have used for years, and THEY don't have heavy clutches!
Not saying that the other kits that have more traditional Triumph type plates don't improve the torque capacity of the original design, just that this is an added refinement. I have the "original" type 7 plate conversion (Aerco possibly, but sold by various vendors, and probably they all use Surflex plates anyway?) in my warmed-over T140, and I have a VERY light clutch, but it will JUST slip if I wind it full on and the rear wheel skips over a bump!
Also not sure, but suspect not just Hyde kits have the "narrow" design?
 
there is more to a clutch than than just friction area.the clamping force does not change by reducing that area as it is a constant. the narrower friction (or steel) moves the effective mean radius farther from the center thus increasing the holding capacity. think of it like adding length to a breaker bar but it works in reverse ie the farther out from the center the harder it will be to make it slip.

wavey_davey said:
waited until Norman Hyde had his kit back in stock, as it utilises narrower plates, effectively applying more pressure per square inch (or whatever unit you like!). This is a slightly counter-intuitive design that Japanese clutches (apparently) have used for years, and THEY don't have heavy clutches!
Click to expand...
 
Yes the LP Williams 7 plate kits also use the narrower plates.

For info, I’ve now fitted two of these, both running in synthetic oil, and both working perfectly.
 

Similar threads

Reggie
7 Plate clutch slipping on T140.
2 3
Replies
59
Views
9,444
Reggie
Reggie
Back
Top