clutch biting point
Turbo Mini Forums

i have lengthened the push rod from the slave cyl to the clutch arm and that has moved the piston up in to the slave more but not given me any more travel at the plunger,
the clutch slips from about half pedal travel but is not fully disengaged untill the pedal is on the floor the problem is i get the slightest whiff of clutch drag and high rpm shifting is a little hit and miss
i have taken a slither of steel off the bottom of the clutch pedal and trimmed the u bolt from the steering rack managed to gain ~5mm more travel and its helped but i would like more

next step i think is changing the slave cylinder, any suggestion an what to try?

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what clutch are you running?

check the pin that connects the clutch pedal to the master rod for wear , in fact ,check all the pins .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

yeah,

pull all the pins and check the ball on the end of the clutch arm too. this is another reason I like the RTS, its essentially self adjusting.

Im running an AP-RTS with a 1275 and turbo spring. the 2 clutch arm pins have noticable wear the pedal to master pin is new. The clutch arm ball has very little wear on it i will try these 2 first

Yes i moved to the darkside

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its not the plate that the slave bolts to flexing is it?

i dont think so,

Yes i moved to the darkside

Instagram @jdm_brett

leaky master?,

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did you set the throwout stop for 6.5mm and does the throwout stop bottom out at full pedal travel? Any more than 6.5mm can cause the fingers of the spring to bind on clutch center boss.. If you did set the throwout at 6.5mm and the stop does bottom out at full pedal travel, your problem is nothing to do with the actuating mechanism

The problem with lengthening the pushrod on a Verto clutch is that as the frictionsurfaces wear, the slavecylinder piston is pushed further into the cylinder when the clutch is engaged. If there is no room for this to happen IE the push rod has been lengthened to push the piston further into the cylinder, the clutch might not fully engage as wear takes place.

one other thing, clutch bite with the verto moves as wear takes place. with a new well set up verto the bite is usually at the top of the pedal travel, and as the clutch wears it ends up at the bpttpm pf the pedal travel. standard clutches are designed to slip in normal operation when they are worn and need replacing, this being the indicator to the driver that it needs replacing before the rivets damage the friction faces. This cannot be applied to an RTS since there is a greater clamping capacity to begin with therfore, when its worn, it won't slip.

Edited by Brett on 28th Apr, 2012.

Yes i moved to the darkside

Instagram @jdm_brett

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

I've got a spare brand new pin for the arm - wok you can have if you want Brett. Benny is heading over in a bit, so I can give it to him to relay if you like.

yeah can do mate, want anything for it?

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a beer at some point

Ok Ok what I meant was that with a standard verto setup the bite point moves within the pedal travel. The RTS not exactly standard

On 29th Apr, 2012 robert said:

On 28th Apr, 2012 Sprocket said:
one other thing, clutch bite with the verto moves as wear takes place. with a new well set up verto the bite is usually at the top of the pedal travel, and as the clutch wears it ends up at the bpttpm pf the pedal travel. standard clutches are designed to slip in normal operation when they are worn and need replacing, this being the indicator to the driver that it needs replacing before the rivets damage the friction faces. This cannot be applied to an RTS since there is a greater clamping capacity to begin with therfore, when its worn, it won't slip.

so far in my experience i'll have to disagree colin

the plate wear has not caused a change in pedal bite position , also you can definately get a rts to slip.mine slipped so badly, before a redesign of the system, i thought the car had slipped into neutral .this was only above around 230 ft/lbs though .

Anyone know if Brett managed to cure this with just new pins?

I've got the same problem. RTS with 2 No. 998 springs. Barely disenaging at bottom of pedal, not even enough to get it in gear. There seems to be plenty of plunger travel :/

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I’m fighting this EXACT thing right now. If I’m driving along in gear, my clutch seems to be releasing about half way of the “heavy travel” at the pedal (by this, I mean ignoring the first 3/4” to 1” of pedal travel that has little to no resistance), but the FULL disengagement point, is right at the floor. It means I basically have to put the pedal mashed into the carpet and wait three seconds before I can get reverse. If I have a piece of 1/4” board under the pedal, it won’t disengage.

I’ve just lengthened my clutch master pushrod by the absolute max, such that when the pedal is not connected to master cylinder (clevis pin removed) the master cyl clevis eye lines up with the pedal clevis eye. Basically, as good as it can possibly be!

This gives me 3/4” more pedal travel, and hopefully just enough to release this clutch (with its brand new plate). As things bed in, it should get better of course!

Edited by TurboDave16V on 17th Jun, 2018.

As a reference, it looks like you can get almost 1” pushrod travel at the pedal (with the clevis arm of the pedal touching the crossmember box that it sits in) to full compression.

The master seems to have a travel of about 1.3” so there is no chance of bottoming out the master.

I made a little jig to measure the pin top of the pin position on the pedal to the gasket face under the master to get the exact distance I needed to lengthen my pushrod by.

Thanks Dave, good to know it's not just me.

I've got a new slave and arm on order. Turns out I'd fitted a pre-verto slave by mistake but I'm not convinced 9 thou smaller bore will make much difference.

I'll check the master pushrod length to see if I can extend it.

Have you measured how much movement you have at the plunger?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I’m literally working On this right now, I’ve just come inside to get myself a quick bite to eat, and get out this heat!
I’ll report back in an hour or so

Edited by TurboDave16V on 17th Jun, 2018.

The other thing I have noticed, is that seems to be something wrong with the stack up of parts installed on my system.

Obviously, a twin spring clutch should have the throwout bearing further away from the water pump than a standard clutch, all other things being equal.

What I am noticing, is that the centre of the hole in the clutch plunger is directly in line, with the pivot hole in the wok. Obviously, for optimal leverage, and ratio, the holes should be in line at mid travel - Or to put it another way, The hole in the plunger, should be about half travel further away from the arm pivot hole... Mine is definitely not like this. I’ll probably offset bore the Hole in the arm and put a bronze sleeve or similar in there to address this.

Edited by TurboDave16V on 17th Jun, 2018.

Alrighty then!

Success !!!!

My clutch now releases and re-engages the Idler rattle noise at approx 1” from the floor. Before it was right at the floor.

So, the trick clearly is that you want the MASTER CYLINDER pushrod to be sufficiently long that with the pedal in the maximum “up” position, your master should bolt in, and the clevis hole align, to maximise your pedal travel. Minis seem to have a lot of variance in Tolerances of the clutch pedal and master cylinder, So you just need to pay attention to this one time when putting your master cyl in. You will likely have to re-optimise, every time you change your master cylinder.

It should be noted, that I had already extended my pushrod many years ago, when I didn’t have enough travel to disengage a grey diaghram. I don’t even remember what I added all those years ago, but I’ve had to add approx .1” onto what I had before.

I’m in the garage on my own right now, So I’m unable to measure my plunger travel, but will report back later once my neighbor gets home!

Edited by TurboDave16V on 17th Jun, 2018.

It’s kind of hard to measure the required pedal travel, as it goes through an arc, but measuring between the same points (on the side of the pedal rubber, at the centre of the pedal) between pedal on the floor to pedal fully raised) is now 4.5” on my mini.

Edit - ignore the above 4.5” - it’s actually measuring right at 4”

Pedal up, measured from where the point that aligns with Centre of pedal when at the floor (next pic)
http://www.turbominis.co.uk/uploads/i/wh10...odave-4278.jpeg

Pedal down, measured from same place
http://www.turbominis.co.uk/uploads/i/wh10...odave-4279.jpeg

And as a reference, this distance is what my master cyl pushrod now measures. Note that this is not from the CL of the clevis hole, but the edge of the hole - to the mounting face.
http://www.turbominis.co.uk/uploads/i/wh10...odave-4280.jpeg

Edited by TurboDave16V on 17th Jun, 2018.

I will say this; the small (pre 74?) pedal rubbers are a pain to use with the twin spring clutch. It’s not my leg that hurts after continuous pushing; it’s the ball of my foot that is throbbing from the pressure point of the small pedal. Given my typical shoe is 3x wider than the pedal rubber means there is room for improvement - but I kind of like the factory look of the small pedal.
Then again, the VW accelerator pedal isn’t exactly standard 1970 fayre, so maybe I should machine a new large pedal (and paint or anodise it black) that looks like the square early pedals, and call it a day at that. I certainly don’t want any “Bad Boy Boost” bling pedals!

Edited by TurboDave16V on 17th Jun, 2018.