Master Cylinder Query - R33

[fattox33]

Hey all,

Just a quickie, got a mate doing my clutch for me (i'm hopeless at fault finding, he's picked up a few issues as he goes), anyway, he was saying I need a bigger master cylinder to run my new clutch.

Interesting part is, apparently the one I have in there is 5/8th inch bore, whereas standard is apparently supposed to be 3/4 inch, he was saying he needs 3/4 inch or 11/16 inch to run it properly.

Just curious, why would the 33 have a 5/8 inch bore master cylinder when standard is supposed to be 3/4 inch? something to do with pedal stuff?

Also can anyone confirm that standard bore is 3/4 inch before i go blow $160 on a brand newy from JJR

[The Dan]

What the....?

What clutch is he fitting?

[fattox33]

it's a custom one by Jim Berry, but from what I can tell the master cylinder isn't standard, but smaller than standard

I just wanted to try confirm whether standard should be a 3/4 inch bore rather than 5/8

[The Dan]

it's a custom one by Jim Berry, but from what I can tell the master cylinder isn't standard, but smaller than standard

I just wanted to try confirm whether standard should be a 3/4 inch bore rather than 5/8

It should be 5/8.

Slave cylinder is 3/4

[fattox33]

Ahhh shit according to RHDJapan the standard is 3/4, cos the Nismo upgraded cylinder is a 13/16 inch..

I called Jim about and he thinks it was 3/4 as well, well shit I bought the cylinder.. so i guess if it doesn't do the job, I have a brand new master for a 33 for sale!

haha

[The Dan]

Ahhh shit according to RHDJapan the standard is 3/4, cos the Nismo upgraded cylinder is a 13/16 inch..

I called Jim about and he thinks it was 3/4 as well, well shit I bought the cylinder.. so i guess if it doesn't do the job, I have a brand new master for a 33 for sale!

haha

Nismo don't do an upgrade for the master cylinder

Nismo do a big bore SLAVE CYLINDER. Factory standard on the slave cylinder is 3/4. To get a lighter pedal feel, you enlarge the bore size on the slave by one size (3/4 up to 13/16. You also get less effective pedal travel with the enlarged bore slave so be careful with heavily modified clutches with a lot of pivot mod for extra clamp. They already have a deficiency for pedal travel due to the pivot being so far. That, combined with a large bore slave 'might' cause you issues when it's trying to disengage

The master cylinder (which is what you asked about) is 5/8.

[fattox33]

*pretends to shoot self in head* f**k! hopefully this new one might just be the ticket, maybe the other one is shagged out or something... i'm supposed to be driving up home for a week in a weeks' time!

[fattox33]

and you're right, it just says OPERATING cylinder not master.

[fattox33]

ok, so if I have the cylinder machined out to a bigger size (not sleeving the slave, it's brand new), is there any internals you're aware of that would replace the internals properly (say, 3/4 inch guts)

maybe a patrol or cruiser or something?

[89CAL]

Ummmmmm

Why go to all the effort of boring it out etc. If its wrong go to an import wreckers and pull one off of a turbo skyline. Will cost you $50 and take about 20 mins rather then sending it somewhere, waiting for them to bore it or whatever then getting it back and re-installing it. Seems like a waste of money to me

Can you confirm which cylinder you are talking about also, and maybe provide photos of both so people can confirm if its a non turbo item. It seems weird that it would be smaller as I dont hear of them stuffing up to much.

It sounds like your a bit confused between the master and slave and there sizes

[fattox33]

it's all sorted, i got mixed up as the Japs call the slave the operating cylinder, but it's all good, just ended up sleeving the slave down to 11/16 from 3/4 and yeah i was mixed up, not too up to speed on clutch components yet (haven't got that far in replacing/repairing or my degree! only up to engine stuff now!)

Oh it is a turbo skyline btw..

And for those interested, the STANDARD bores for Master and Slave are 5/8 inch and 3/4 inch respectively.

[89CAL]

So why did you decrease the size of the slave if standard is 3/4 and does the job fine?

[The Dan]

zomg

http://www.skylinesaustralia.com/forums/topic/365215-master-cylinder-query-r33/page__view__findpost__p__5827646

and +1, why reduce the size? that's gonna make the pedal so frickin heavy

[fattox33]

No no no no no!! I may have not worded it right, the standard slave wasn't fully engaging the clutch, it was about to engage at the floor when it was standard bore, so it wasn't actually engaging the clutch. The sleeving down to 11/16 made it heaps easier to use, and as for how heavy it is, well, it's light as compared to what it was when I had the OS Giken twin plate in it... MUCH lighter, this is like almost a standard clutch in comparison

[89CAL]

Sounds like you've Bandaided it? Was your pedal alright, as in did it have to much play?

Seems weird, never heard of a clutch made for a skyline not engaging properly in a skyline when everything is correct. I'd check for another problem.......

[fattox33]

The mechanic doing it had a lot of work to do to get it engaging, including f**king about with the pedal box and such, eventually we decided to give it a more positive and not an at-the-floor engagement to sleeve the slave, the pedal is barely noticeable, it is lighter than it was with the OS twin under it, and there shouldn't be problems I have a brand new master in it, rebuilt slave when it was sleeved, next fix will be braided lines but still, there's no problem with the pedal travel, it engages maybe 100mm from the floor, before we sleeved it, the problem was with the pedal, it was just engaging at the floor