Making A Twin Plate Clutch Better To Drive

[CruiseLiner]

hey guys i got a twin plate clutch from direct clutch and it holds power no problem. its bloody noisy and rattles like i bitch which i can live with.

i got a gtr master cylinder, gtr slave and its vacuum assisted, yet the clutch is f**kin rock hard to press.

how do u make it easier to press? i have had the slave sleeved twice to allow more travel, would this make it easier or harder to press considering the slave has less volume now?

any other options to make it daily drivable? i'd hate to be stuck in peak hour thats for sure.

and no i dont need stronger legs to press it b4 u mention it

surely the vacuum assistance should make it softer but it seems to do bugger all?

any ideas appreciated

[CruiseLiner]

jesus i thought someone might know??? wheres these damn hydraulic experts when ya need em

[GTR1993]

ok, well if the slave has been sleeved twice reducing its diameter (area) take the equation, force = pressure x area, now i think this is the correct way to interpret it, force on clutch to depress it is always the same, so the variable is pressure (applied by your foot) and area. reduce area, same pressure by your foot means less force, so to bring the force back up to what u need you must apply larger pressure int he hydraulic system.

I have a Xtreme twin plate in my GTR and seems quite light to the other big singles im used to, but this can vary i have a single with 1600 kg clamping force and it is as light as a stock clutch in a 180sx as the pivot points on the clutch plate have been modified.

HTH

[R31Nismoid]

What type of clutch are we talking about?

Oh and brad - get stronger legs

[Mumbo#5]

my OS giken twin is pretty damn light...

[9krpm]

ie you need to make the slave bigger *not* smaller. Get it resleeve or get the nismo slave cylinder.

BTW how much did it cost you for resleeving the cylinder.

[Guest Mashrock]

My os tripple is a motherf**ker.

but the way i see it is if i drive him my leg will like it i beleive he does not have a choice in the matter.

[CruiseLiner]

its a twin plate from direct clutch rated for 800hp and its a solid centre one (i bought it over 3 years ago but its only done about 1600km or so), but its damn rock hard.

im unsure if the vacuum assist is even workin at all.

sleeving was under $100 (around $80 i think from memory) each time i got it done.

so if i went and bought a stock slave it should be alot easier???

thanks guys

[Beer Baron]

yes, you need bigger bore, not smaller. you will have less travel, but easier pedal effort required.

I have had in the GTR an OS triple plate R3C and with the nismo slave it was not so hard to press. When I replaced the slave for a standard nissan one it was miles harder to press, but had a little extra travel.

Now using an OS twin plate and it's not so bad. Doesnt rattle nearly as loudly as the triple plate did. plus is a bit kinder on take up, but still pretty harsh (both were solid centre).

anway, the nismo slave will definately help with your problem.

[shanef]

top secret have a longer release fork which they claim it lightens the 'heavyness' of the clutch due to it being longer

http://www.perfectrun.com.au/performance%2...releasefork.htm

[saliya]

Hey Brad,

To summarise:

Increasing master diameter or reducing slave diameter results in more pedal effort and less travel.

Decreasing master diameter or increasing slave diameter results in less pedal effort and more travel.

So you want to decrease the master diameter or increase the slave diameter to get less effort

(and more travel).

BUT, if there's power assistance, I'd make sure that it's working properly before changing anything else.

Maybe the power assistance is working against you, not for you? Do you have a test procedure to follow?

Regards,

Saliya

[Gav]

Very easy to test if the vacuum assist is working. Compare the clutch pressure with the engine running and with it off. If it is working you will lnow straight away (the difference is that great).

[rob82]

Very easy to test if the vacuum assist is working. Compare the clutch pressure with the engine running and with it off. If it is working you will lnow straight away (the difference is that great).

And check the 1 way valve is not clogged or backwards or something stupid and then go to the GYM!!!

[R31Nismoid]

I dont think you wanna be using a solid centre item...

Wasnt that what killed Ferni's box?

[mad082]

Increasing master diameter or reducing slave diameter results in more pedal effort and less travel.

Decreasing master diameter or increasing slave diameter results in less pedal effort and more travel.

half right. big master, little slave = more effort, more tavel

little master, big slave equals less effort, less travel.

think of the travel working like this:

you have 2 bottles. 1 big, 1 small. if you have water in 1 and none in the other and put it from 1 to the other you will get the following effects.

big bottle with water tipping into small bottle. it only takes a little bit of water to fill the bottle half way (short travel)

little bottle tipping into big bottle- takes more water to fill the the big bottle half way. (long travel)

[saliya]

half right. big master, little slave = more effort, more tavel

little master, big slave equals less effort, less travel.

think of the travel working like this:

you have 2 bottles. 1 big, 1 small. if you have water in 1 and none in the other and put it from 1 to the other you will get the following effects.

big bottle with water tipping into small bottle. it only takes a little bit of water to fill the bottle half way (short travel)

little bottle tipping into big bottle- takes more water to fill the the big bottle half way. (long travel)

Hi,

No, there's no such thing as win/win (less effort + less travel = ideal)

The slave is pushing back - so it's not like tipping water from one bottle to another

Think of it as a relative thing. If you increase the diam of the master cylinder you will push more fluid for a given

stroke length, but the pushing will be harder. That's less travel, with more effort.

Regards,

Saliya

[CruiseLiner]

solid centre isnt too bad at all to drive, its easy to take off and not jerky at all even at low rpm takeoffs without revving the shit out of it to move.

hey gav i didnt realise the vacuum assist makes that much difference, but i know mine is no easier when the engine is running so i guess it aint working at all

better check the one way valve is the right way round, and check its not blocked also.

i might try a stock slave cylinder again and if its still abit hard ill get the nismo one which isnt too badly priced at all, at $140+ delivery.

the clutch is actually better to take off from standing starts then a mates spring centred single plate which is really really jerky when not givin it heaps of rpm to move.

i had this clutch from my vl calais rb26 which with 10" slicks on at the drags and a 6k rpm launch it would pull the engine down almost stalling it, its that strong and has never ever slipped once. i even bent the rear control arm on my vl 90 degress from a big launch so its got the holding force i need

i know the gearbox wont like it but i dont think the box will like lugging over 500hp and 1690kg off the line and from 2nd-3rd will kill it, its just a matter of when

thanks heaps everyone for the helpful info, ill report back once i do a few changes

[CruiseLiner]

heres a couple of pics of the clutch, i dont have any of the plates themselves but they are definately solid centres.

does it look like a decent qaulity one?

[MANWHOR3]

Wow, that looks very different to my twin plate. Mine has a cover over it.

what brand is it?

[CruiseLiner]

Wow, that looks very different to my twin plate. Mine has a cover over it.

what brand is it?

its from a shop in adelaide i think called Direct Clutch, i bought it over 3-4 years ago and only used it for under 1500km or so since, in my last 2 projects which have been off the road 99% of the time.

its still almost brand new conditon and cost me $1700 back in the day, rated for 800hp supposedly, and same one used by the summernats horsepower hero commodore with plates "JUDGE"