Clutch pedal stiffness

[JH32]

I think my clutch pedal is too stiff/heavy, and so consequently I have now snapped the bracket holding the pedal to the car three times :hellpisd:

How can I make the pedal lighter on the foot, without changing the actual clutch? I already have a heavy duty clutch in there. I think the fact that I have to push so hard down on the pedal to push the clutch in, causes a torque at the top of the bracket (where the bracket is bolted to the underside of the dash), and it literally shears the bracket metal.

Could I change the master cylinder to an R33 one? Or a GTR one? Would that make any difference?

How bout the slave cylinder? What happens if you change that?

Cheers

[Mase]

This is the same in my silvia. I had the welds and the whole bracket reinforced and i haven't had any more trouble YET! However, the pedal is still as hard as shit and i was thinking of whether an r32 clutch master cylinder would be bigger. You could probably get your clutch master cylinder rebored and a bigger piston fitted possibly?

[Jay95R33]

Damn you r clutch must be heavy !!

I think you could try one of two things.

Get the bracket made from thick stainless steel.

Or, have you ever had a good look at a master cyclinder on a R32 GTR ??

They are power assisted and work on the same principle of the power brakes assist etc.

It's a plate of about 10-15mm that sits between the master cyclinder and the firewall, has a vacume line etc.

You may need to get the master cyclinder off a R32 GTR as well to get it to fit, and maybe a few other parts. But it might be worth while looking into.

They work pretty good to. Pressing the clutch in while the motor is off compared to when it's on you can feel a big difference.

J

[Mase]

Does anybody know the bore sizes of the rb20 brake master cylinder and the silvia master cylinder?? Im hoping the rb20 one is bigger so i can swap them over. Otherwise im going to have to check this gtr thing out.

[JH32]

Jay, that is very interesting! Cheers for that dude I never knew that!

Hmmm ... now to find the required parts

Mase: I've had mine welded up twice so far, and it just keeps snapping. I've got a new bracket lined up from a front cut, but this GTR idea would be heaps better.

[SKYLINED]

Yeah i got a tight ass clutch pedal too, gives me the shits!

[GTRgeoff]

Don't know what numbers you guys are running at the flywheel, but I have a 6 puck brass comp plate with an uprated pressure plate that feels very light underfoot(no real discernable difference from std) and is relatively easy to use since it is sprung centred, gets a bit juddery when parking but thats why I didn't go button. Given the quick 0-100 (flat 5's) times I get and the 255/40/ZR17 's will light into 3rd at redline from 2nd I calculate approx 300kW brake. The std clutch was slipping in 3rd due to the torque and I'm taking this thing to track days without dramas.

Anyway my point is either you are running huge numbers, or have been sucked into buying over the top clutches that are not suitable for your application. Clutch braces are fine, as are brake braces but no race car I've driven in the last 17 years has been that bad. I did have an XF that cracked away the firewall around the brake MC but some bonded and rivetted ally plate soon sorted that.

Oh and the clutch in the 'line only set me back $550.

[Jay95R33]

Full faced clutches with increased clamping pressure pressure plate is why the clutch is so heavy, although you can get the puk type clutches in the increased clamping rates too.

With the 5 or 6 puck clutches they work on the theroy that you has less surface area (clutch) but the same pressure plate, so there is more clamping pressure per square inch of clutch face.

That's why most of the puk clutches feel stock but bite better.

Full faced (up rated pressure plates) are a little easier to drive (puks tend to hate it when you ride them) but you have to put up with the heavy peddal.

BTW - flat 5's is a nice time.

J

[GTRgeoff]

Yeah I covered all that at TAFE while a mechanic and at UNI getting Mech Eng Degree, but to be breaking shit???

Then again I did do a bit of truck driving in Army Mack recovery vehicles with a 5 puck brass button clutch std and a 5 spd crash box and until recently was cycling 60km a day so I don't lack leg strength. Still this one feels similar to my laser Lynx for pressure and is obviously not transmitting the same torque.

I hate to sound like a know it all smart arse but guys seem to be paying a squillion for their gear and not researching the best value for money componentry. The badge name has more cred or the workshop name and they are being seriously ripped. Unless serious machining or pressing I do all my own work in my garage with a trolley jack, 4 vehicle safety stands and a chain block into the ceiling (my house so I reinforced it). I rebuilt this engine I use now, did the clutch last week and i am getting new discs to install Monday that cost $650 for slotted fronts and plain rear. I hate to say this but apparently the rears are the same as some HSV's (now i have to disinfect) out there and fit right up. Lot better than $1K for DBA but hey...no brand name. Rather spend my money on track days.

[wrxhoon]

jimih u must have some clutch on that r32 !

anyway to lighten u r clutch u need either smaller master cil or bigger slave cil or both .

a vac assisted one from gtr 32 or 33 will do the job as well but u'll still have the breaking prob unless u reinforce it .

puck clutches are always going to be lighter than full face .

[JH32]

skylinegeoff: cheers for the info there, but I didn't put the clutch in it came with the car from Japan

wrxhoon: haha yeah I don't know what it is but it sure grips well If I put a bigger slave cylinder in, what can I use do you know? The master cylinder doesnt look very big hehe

[GTRgeoff]

JiMiH, no worries. Wasn't trying to slag down anyone in particular and not you. Japs get crazy too and there was some truly weird stuff in cars I was importing.

A bigger MC wont help, it will make it harder. You would need a narrower diameter MC wich would require a longer throw for the same amount of clutch actuation. Now a bigger Slave cylinder would help, but wouldn't move as far. i think there would be plenty of pedal anyway but maybe try a brake shop for a Slave cylinder to do the job.

Maybe even your MC or SC is corroded and needs a reco to loosen it up. Most likely MC in that case. Maybe I should have given advice asked for in the first place instead of carrying on like a wanker too.......

[Steve]

JimiH,

I have seen an excellent method of lightening the throw on a clutch - it was a twin plate os giken, but felt like stock.

The guy used two throw out levers, cutting one just before the bulge/indentation, the other was cut 20mm down from the bulge/indentation.

Both the levers are the same width, so he got an insert of c-beam steel welded on the inside to hold the two together.

Then he used two 20mm spacers for the bolts and two 20mm longer bolts for the slave cylinder.

This was on a cefiro, another added advantage was that the clutch had more throw between take-up and full clamp, so it was a very controllable setup and made the car very easy to launch or take off smoothly.

Downside to this is sourcing the second throw out lever, and having to drop the box to fit.

[wrxhoon]

i dont know what master - slave u can use but i know if u want lighter pedal u need bigger slave or a smaller master cil and keep in mind that the travel will increase as well .

its cheaper to get a new slave , u have to see what size the one u have on is and get a couple sizes bigger then the pedal will be lighter , how light it gets it will depend on the slave cil size the bibber the slave the lighter the pedal .

[Jay95R33]

JiMiH - have a quick look at this..

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

Expensive though.... $243.... !!

[Mase]

I got an OS geiken single plate button clutch and lightened flywheel for $500 when i was putting my rb20det in the silvia. The clutch in the cut was stuffed so this being relatively cheap i took it up. Now im thinking of keeping the flywheel and just putting a different clutch on the flywheel if possible.

[JH32]

Originally posted by skylinegeoff

Maybe I should have given advice asked for in the first place instead of carrying on like a wanker too.......

hahaha sorry mate I wasn't trying to be rude or imply that you were being a wanker .. I just didn't know what else to say Cheers for the info though, I do appreciate it!

Steve: that sounds like a good idea, is it complicated? Could a clutch place just do that for you?

wrxhoon : cheers mate, yeah that seems to be the easiest route

Jay: that looks interesting!! Could be just what I need! Only bad thing is it says can't be used with a multiplate clutch :confused: Why would that be?

Mase : you might have to look into these things too for your car

[JH32]

I just remembered, my clutch master cylinder has started to leak and now there is a stain on the carpet at my feet. It's only just started to do this though, and I've had this clutch problem for the last year.

Could the leaking MC be contributing to the problem? I know I need to get it fixed, but I'll probably just replace it with something better by the sounds of things.

[Steve]

JimiH, dont see why not, its pretty simple and very effective:)

[wrxhoon]

of course the leaking master cil wouldnt help but maybe its been stuffed for a long time ( leaking between the 2 seals inside and not leaking outside ) so its not working proply . replace the master or put a kit in it if not badly coroded ( u have to hone it out first ) and u r prob will go away . i never seen a skyline with a very heavy clutch before , usualy they are fairly light .

if u cant do the master cil yourself take it to a clutch -brake shop and they will resleeve it for u with stainless steel sleeve and new seals as good or better than new . i'm not sure how much is a new master from nissan prob to pricey .