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Clutch Pedal Modification.


Tricky-Ricky

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First off this was done on my Skyline 350GT, so i don't know if the clutch peddle assembly is exactly the same, but i would suspect it is,

Disclaimer: if you decide to go ahead with this, ITS AT YOUR OWN RISK! if you are not competent then don't bother.

 

I have felt for a long time that my clutch is rather heavy and too quick, as in short engagement window, and lack of feel, which spoils the driving experience, now i have already removed the clutch pedal assist spring, which did nothing but make it even heavier.

 

So with this in mind i went hunting on the US forums and came across a thread that a guy with some engineering experience came up with an idea of how to combat this, but basically altering the leverage/fulcrum point of the pedal, his opinion was as mine is, that the master/slave cylinder combo was mismatched, and didn't work well.

 

Anyway his idea was to fabricate a rather over elaborate method of shifting the fulcrum point further up, and so reducing the effort needed along with increasing the engagement window, which make clutch control a lot easier.

 

Now at first i thought i would be lazy and see if i could order one of his kits, but he only makes them for LHD cars, so i decided to bite the bullet and pull out my entire clutch pedal and see if i could make a much simpler modification and achieve the same result, and the answer was yes i could with nowhere near the effort that he had gone to.

 

So its just a case of removing the pedal and disassembling, then marking and drilling a hole of the same diameter about 15-20mm higher up from the original clevis pin pivot hole, i actually just used the clevis and held the bottom edge of it flush with the old hole and using the original to make a mark, i then drilled this to the correct dia, so i could refit the plastic/nylon liner back in, thats it for that bit, you could probably put it all back together and live with the slight master cylinder rod misalignment, as it allows for a small amount.

 

However i decided that i dint want to live with it, and so i just fabricated a small metal plate drilled with two clearance holes to fit the same size as the master cylinder rod, the holes in my case where drilled again at about 15mm centers, so i have enough clearance for the two adjusting nuts, the pics will explain it better,but you get the gist i hope.

 

And the result! well i wouldn't go so far as to say that it halves the pedal effort, but i would say it now requires about 35% less effort to depress the pedal, and the other result is to give a much wider engagement/disengagement window, which results in about 60% more feel, so well worth the trouble IMO.

 

Obviously you will need a little mechanical know how for this, but its not rocket science, but i guess you will have to make up your own mind as to whether you fell confident enough to tackle this.

 

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IMG_6107.jpg

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Yeah, I read the the same thread on the US forums (which I pointed to on Dannys thread about his clutch adjustment)

So am I understanding this correct that the hole that the little brass coloured thing is now bolted to is the new hole and the hole below is the original one or did I misunderstand?

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Thats correct the upper hole on the pedal :p leaver is the new one, and the little brass colored thing, is the original clevis, which is not brass, the small plate bolted to it is to realign the mater cylinder actuator rod.

 

I see, so the little bolt and nut is where the clutch rod is supposed to go?

Probably helps if I could see it all in place. Dunno if I trust my self doing the mod, bit of a mong that way, lol

But looking at the RJM Performance disassembly guide it doesn't look to daunting. I'd prolly worry that the clutch rod would fall off or retreat out of sight and I'd be sat there with no way of getting it back :lol::lol::lol:

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Thats correct the upper hole on the pedal :p leaver is the new one, and the little brass colored thing, is the original clevis, which is not brass, the small plate bolted to it is to realign the mater cylinder actuator rod.

 

I see, so the little bolt and nut is where the clutch rod is supposed to go?

Probably helps if I could see it all in place. Dunno if I trust my self doing the mod, bit of a mong that way, lol

But looking at the RJM Performance disassembly guide it doesn't look to daunting. I'd prolly worry that the clutch rod would fall off or retreat out of sight and I'd be sat there with no way of getting it back :lol::lol::lol:

 

 

Yes thats it, unfortunately its impossible to take any pics of it all in situ, the rod is captive in the cylinder, so no chance of it falling off.

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My car had a stiff clutch pedal.

 

It was down to the release bearing pivot arm becoming seized. I had the clutch changed and the release arm pivot freed off, cleaned and greased.

 

The clutch is now nice and light.

 

This mod may well work but you may only be masking a problem else where.

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Yes i agree its a possible, my pivot is in need of some lube as it squeaks sometimes, but its not seized, and i do wonder if the clutch pressure plate springs become stiffer with wear of the friction material,

Does the 350Z have a clutch assister spring? the 350GT does and the US Infiniti, so it must be a known problem otherwise the spring wouldn't be needed.

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Do you have a link to the US forum page? This is interesting.

 

First step is to grease the pivot up which might make it a little lighter, but this will increase the distance over which engagement occurs.

 

 

This is the review of the device that he sells, but there is no RHD option, hence the DIY.http://g35driver.com/forums/interior/39 ... acket.html

I fail to see how greasing the pivot will increase the engagement window?? if it does i spent three hours for nothing LOL!

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I fail to see how greasing the pivot will increase the engagement window?? if it does i spent three hours for nothing LOL!

 

 

Sorry I worded that badly: I meant to say that rebuilding and greasing the pivot with lighten the pedal somewhat.

 

Then your suggested mod will increase the engagement window (and lighten further).

 

Whats your pedal like now? Is it possible to do really smooth shifts - mine are always a little jerky :teeth:

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I fail to see how greasing the pivot will increase the engagement window?? if it does i spent three hours for nothing LOL!

 

 

Sorry I worded that badly: I meant to say that rebuilding and greasing the pivot with lighten the pedal somewhat.

 

Then your suggested mod will increase the engagement window (and lighten further).

 

Whats your pedal like now? Is it possible to do really smooth shifts - mine are always a little jerky :teeth:

 

 

Ahh right i see now, yes basically it has made the pedal effort lighter, not lots but enough, but it has more impact on the feel when modulating the clutch like in slow moving traffic and maneuvering, and makes for smoother shifting, as i certainly found my shifts where a bit jerky, but have become used to it i guess, now it just feels like it should have done in the first place :)

Doe's the Z have the assister spring on the clutch pedal?

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Doe's the Z have the assister spring on the clutch pedal?

 

yes - did yours?

 

Also did the pedal assembly come out of your RHD car much like the instructions on the american site?

 

 

Thanks for confirming that, i wasn't sure, yes my 350GT has it too, which confirms to me that the overall master/slave cylinder combo is a bad mismatch,

As for the US instruction, TBH i didn't read them, however i am certain that the RHD and LHD pedals are completely different, to remove its just a case of removing the tray under the steering column, and disconnect the associated plugs etc, and then its just a case of removing two nuts and one bolt, disconnecting the clutch switch (if you have j spec, you can also bypass this if you want while you can get to it) and master cylinder rod, and thats it, a little fiddly but not hard.

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Just in case anyone is interested, i drove 40 odd miles yesterday, and the clutch is now an absolute pleasure to use, a bit lighter and so much more controllable, gear changes have gone from a rather numb feel, because of the very short engagement point, which made for a jerky change, with no real hope of a smooth down shift, to really controllable with feel, up shift are just as precise and easy, well worth all the effort.

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Ok so maybe the clutch on a Zed is heavy compared to say a ..Golf..whatever but against a MGB..its light or any 1920's cars is feather light ..come to that compared to any 1970's cars its light and 1980's come on its what it is. how about the steeing is that a bit heavy too....oh the door handle and the brakes they can be heavy as well. BTW I dont remember the Bentley Boys complaining about the clutch being a bit heavy!!!!

Corn flakes for breakfast maybe ...hey ho :clap:

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Well compared to some cars i have owned back in the 80s its dam heavy! more so than an Austin Healy 3000, and a Corvette, and that also includes some commercial vehicle's, so either my car has a faulty/particularly heavy clutch, or apparently i am getting feeble in my old age. :p

 

However if you had bothered to read the whole thread you would have noticed that it was just as much about pedal feel as it was pressure ;)

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Ok so maybe the clutch on a Zed is heavy compared to say a ..Golf..whatever but against a MGB..its light or any 1920's cars is feather light ..come to that compared to any 1970's cars its light and 1980's come on its what it is. how about the steeing is that a bit heavy too....oh the door handle and the brakes they can be heavy as well. BTW I dont remember the Bentley Boys complaining about the clutch being a bit heavy!!!!

Corn flakes for breakfast maybe ...hey ho :clap:

 

 

For me its not about how heavy the clutch is.... its about the really short engagement window on pre-facelift cars as tricky-ricky says - the heaviness only compounds the problem. Although it is pretty heavy, nowhere near as bad as some bangers I've had with knackered clutch cables :lol:

 

Some people get on with and some people just can't. I let a mate drive my Z and he jumped in and drove it away smoothly immediately and actually said he preferred it.

 

I go between the Z and an 06 Golf and every time I've been driving the golf and then go to the Z I'm jerking down the road till I get used to it again.

 

Perhaps my clutch is worn, but it never slips and the other similar age Zs I tried pre purchase were the same.

 

I've driven all kinds of cars and only the 350Zs have been like this.

 

I'm going to try this mod when the weather warms up a bit.

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