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 How much clutch lift?

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lcjohnny
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PostSubject: How much clutch lift?   How much clutch lift? Icon_minitime1Sat Jul 31, 2021 6:07 pm

Hi does anyone know how much the clutch is actually lifted on a 2009 1200?

I need to get a clutch command piston machined down to fit inside the thrust cylinder bore.
So i need to understand
1) how much the piston moves for a full lever movement
2) how much extra to allow for clutch plate wear

Does anyone have those figures or is anyone able to guesstimate?
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Pete Roper
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Sat Jul 31, 2021 6:50 pm

Not very much at all. A memory two max id think. It should be easy enough to calculate. What is the sixe of the master? What is the size of the slave?

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lcjohnny
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Sun Aug 01, 2021 9:44 pm

I cannot get at the master cylinder bore or piston to measure it without destroying the dust cover. and needing to rebuild it:(

From outside It looks like a 12mm bore (but that design could be 15mm) & the pump stroke is 12mm.

If it is a 12mm bore the clutch pump will move the standard 25mm "command cylinder" piston by 2.8mm. (& if is a 15mm bore it will move it by 4.3mm).

I cannot find the acceptable minimum for the clutch plate so i will assume 1mm total wear (0.5 on each side).

In that case i need to plan for up to 6mm of the command piston to enter the thrust cylinder bore.

If anyone spots an error im my understanding or calculation = please say
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paulbrice
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Sun Aug 01, 2021 10:11 pm

Couple of thoughts (no idea if any help), sadly I scrapped my old clutch master...:

1. The range of variation for the clutch control rods is up to 4.5mm (in the workshop manual)
2. V50 clutch limit is -1.5mm (new is 8mm, replace at below 6.5mm)
3. If you put the part number for GRiSO clutch mastercylinder (for mine at 2009  AP8106713; newer may be different) and trawl you can find stuff that says it is 12mm ....example below (at this link  Aprilia forum )

[You must be registered and logged in to see this image.]
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lcjohnny
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Sun Aug 01, 2021 11:24 pm

That is very useful Paul as it agrees with traces that i have found. For example i got a pdf of one page of the engineering schematic for Brembo PSC-12 10-7770-11 and it looks exactly like mine.
Happy to upload it if anyone else thinks it would help them

So 12mm bore means 2.8mm clutch lift as standard and 2mm with the larger Oberon slave cylinder.
And (if i can make it work) a 30% reduction if lever pressure.

Thanks


Last edited by lcjohnny on Mon Aug 02, 2021 1:28 pm; edited 1 time in total
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paulbrice
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Mon Aug 02, 2021 8:43 am

The hopes of many left wrists go with you jon Wink

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BrianD
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Tue Dec 21, 2021 12:42 pm

@lcjohnny - I think you were getting Oberon to look at machining a piston to suit the Guzzi gearboxes; is this still a possibility? Would we need to register our interest?

ta
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lcjohnny
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Tue Dec 21, 2021 4:58 pm

Hi Brian
A guy at Oberon did machine mine - but they have not responded to my mails since so i don't think they are interested in repeating it.

The details of the mod are
   (1) buy an Oberon CLU-1200 command cylinder for the Morini 1200 motor (30mm bore) [You must be registered and logged in to see this link.] You  can see that the Oberon command cylinder has a wider piston in a slimmer housing in this picture
[You must be registered and logged in to see this image.]


   (2) The Oberon part is made to have a single hydraulic union and a bleed nipple, our Guzzi ones have two hydraulic unons so you need to bore out the threaded bleed nipple drilling in the CLU-1200 to a 10mm x1mm threaded hole for the GRiSO remote bleed hose banjo. As shown in this picture [You must be registered and logged in to see this image.]

I used 10mm Dowty O-Rings Bonded Seals (Self Centering Hydraulic Pneumatic washer) instead of the copper washers ijust to be sure  https://www.ebay.co.uk/itm/132776054122?hash=item1eea11cd6a:g:XbIAAOSwxKNblmin .

   (3)  Our 12mm master cylinder displaces 1cc or milliltre of fluid when the clutch lever moves it around 9mm; this then moves the 30mm command piston about 6.5mm. So machine the end 8mm of the clutch command piston down to 24mm dia becuse when it lifts the clutch it has to go into the bored hole for the GRiSO clutch thrust cylinder - shown in this picture
[You must be registered and logged in to see this image.]

.  But i must admit that I did not take a picture or final measurements of the modified piston - because i did not expect it to work so well - so i thought that i would be strippoing it done again!!

   (4) Because the Oberon cylinder has a narrower external diameter than the standard one you need to use a bigger (37mm x 5mm od) viton ring to replace the original seal between the clutch command cylinder and the gearbox  https://simplybearings.co.uk/shop/p514494/5mm-Section-37mm-Bore-VITON-Rubber-O-Rings/product_info.html .

Hope that helps
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BrianD
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Wed Dec 22, 2021 8:48 am

Thanks, that does help - is there a improvement on the clutch action?
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lcjohnny
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Wed Dec 22, 2021 10:16 am

It made all the difference to me the intital clutch lift force is reduced from 12Kg to 9Kg (measured with luggage scales) and the force required to hold the clutch is reduced from  8Kg to 5Kg. a result Smile.
Now i can slip the clutch and indicate in traffic to change lanes Smile

But the change in leverage does reduces the amount of lift by the same amount as it reduces the load....about 30% so you need to be aware of that.  On my GRiSO the only change is that it used to be unwilling to get into neutral if i had held the clutch in for 2 min or so.... now that starts at 1-2 min.  I have had no problem with clutch drag or creep in 4000 miles.

I have asked my contact at Oberon again whether they would machine down the piston for an additional charge.

I am sorry that i did not measure stuff properly before assembly Sad
But i really hate taking apart stuff that is working Mad

If January February weather is really shit for weeks i might strip down the back end to
1) see what swing arm bearings i was supplied with study
2) re-measure the clutch command piston Thumbs Up

Happy Christmas

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BrianD
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Wed Dec 22, 2021 12:38 pm

That's useful to know, my clutch is heavier than my neighbours strangely both standard

My other thought would have been to get batch of pistons made up either by Oberon (prob' best choice) or a machine shop with CNC.

This always depends on takeup by people and cost of getting a batch.

Bit chilly this morning -4.5 Celsius

Happy Christmas - few days off cheers

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lcjohnny
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PostSubject: Re: How much clutch lift?   How much clutch lift? Icon_minitime1Thu Dec 23, 2021 2:28 pm

Bloody hell its cold where you are. Been down to 2 deg c in Brizzle.

My contact at Oberon is considering making a special for the CARC with the directors. Will ask the forum re numbers if Oberon want to know. I think Pete said it only affected 1200s to 2012 or something but will ask him if oberon are serious. Happy Christmas.
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