clutch master cylinder ???

[minivan_don]

so ive got my rb25 dialed in really good but the problem im currently facing is shifting under WOT pulls in any gear. i had this problem with my ka as well - i had simple bolt ons.

the problem is when i go to shift from doing a WOT pull, its hard to get out of the gear im in and it takes up to a few seconds to get into the next gear. from what my tuner and i have gathered we are ruling it down to the clutch master cylinder. not cool as ill be racing on aug 11. i did however replace that 2-3 years ago with a new oem unit but that was ment for the ka and im going to guess the rb needs more volume moved in the lines.

so my thoughts - get a z32 tt mc cause i can only guess that it can flow more (just like the bmc)

feedback ??

[lazyboi444]

Wouldnt this matter if you upgraded to a Bigger slave cylinder or diff transmission. In a sense the RB and Ka transmission are very similar. So why would there be a need to add more volume? In theory you haven't changed the distance between the transmission and clutch pedal or clutch master cylinder. Also i could see if it was a beefier transmission but in this case its the same. There will be the same amount of pressure applied to the transmission regardless because the pressure that is being applied is by the pedal only . Unlike the brakes which are helped by the brake booster. If anything i would say get rid of the clutch dampening box or do what most have done eliminate it by bypass it and sending the line straight to the slave cylinder. Most do this for a better feel of the clutch and to eliminate the effect of the dampener box. If you get what i mean. Not sure if that makes a great deal of sense lol.

[minivan_don]

i kinda get what your saying. your right, i have not changed the path of the lines but the rb25 trany is significantly larger than the rb20/ka/sr trany. like i said, i can only assume the clutch master is larger than the stock or make an improvement over what im experiencing now. i called up my nissan parts guy and he got me a 92+ zx tt cmc coming in and thats a 5/8". anyone know what the stock ka's is?

[lazyboi444]

LOL well i forgot you had a RB25...Hmmm well Put it like this Lets say you have a Three straws filled with water. And at the each of them are 2 pounds balls. Now the first straw is 3 inches long, the second is 9 inches , and the last is 9 inches with a pump. Now which one will be easier to push the ball if you didn't change the pressure behind blowing into the straw. Well of course the straw with the pump would be best but take out the pump and the 3 inch straw is the strongest simply because you are applying a certain amount of pressure over a shortier distance than the longer straw with more water inside it thus have to push much more water with the same amount of pressure or force. But off the physics lesson.

Heres what you are looking for.

Master is 5/8", slave is 3/4", according to S13 FSM...http://www.carolinanissans.com/forums/i ... topic=5574

Master for the 240 and Z32 are the same size.

[Coolwhip]

89-90 240sx = 11/16"91+ = 3/4"

Z31 and Z32 = 3/4"

There is a guy on another forum that is selling 7/8" clutch master cylinders with with SS lines for $130 I believe.

[minivan_don]

thanks for the info. any idea of what vehicle the 7/8" cmc is off of?? or can you post the link ??

btw i have a 95 240

[minivan_don]

guessing this link ?? but thats the slave on the trany that he had made up ... im running the rb25's still which is not a problem that im aware of yet. the only part thats still the same with my rb setup is the master cylinder on the firewall which is only about 2-3 yrs old. im thinking that is what my problem is...

http://forums2.nicoclub.com/sh...F8%22

[Coolwhip]

Its a custom made unit. Sorry for the image size,

You will find the thread on FA under 240sx Basic

[lazyboi444]

"""just installed a Wilwood .875( 7/8)" clutch master I bought from Summit Racing for $66. This is the MC you referenced.""""

Summit Racing sells one made by Wildwood. So how did the Rebuild come out MNIVAN?

[minivan_don]

"""just installed a Wilwood .875( 7/8)" clutch master I bought from Summit Racing for $66. This is the MC you referenced.""""

Summit Racing sells one made by Wildwood. So how did the Rebuild come out MNIVAN?

the build went great ... nothing other than a few little issues but nothing to stress over. i just rolled off the dyno yesterday after i tuned it for a custom set of cams i had made and 19psi. i desperatly need traction

ill be posting something very soon with dyno graphs to show you rb25 guys a great upgrade ...

Modified by minivan_don at 10:40 AM 7/24/2007
Modified by minivan_don at 11:15 AM 7/24/2007

[lazyboi444]

Well thats great. I'm still not for sure whether i should build my RB20 right now. To expensive. Would love to replace the pistons back to stock size but not to sure if thats possible. But hope you get the clutch master cylinder worked out. Post pics of the car. We need updates lol.

[Coolwhip]

ah, I'm an Idiot and totally forgot that I was referring to a KA/SR slave when in the RB section. But still

[minivan_don]

"""just installed a Wilwood .875( 7/8)" clutch master I bought from Summit Racing for $66. This is the MC you referenced.""""

Summit Racing sells one made by Wildwood. So how did the Rebuild come out MNIVAN?

part #?? pics ?? and arent you running an rb20 ...

[lazyboi444]

Yup iam. http://www.jegs.com/webapp/wcs...68_-1

That was the only thing i could find. Not sure how you make it work. The rod looks to be to short.

[minivan_don]

no imput from carl ??

[minivan_don]

fyi, the z32 cmc DOES NOT WORK. the bolt patterns arent the same.