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Uprated clutch


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9 hours ago, Z320 said:

Hi Andreas,

please, I don't understand what you want to tell us with this?

Ciao, Marco

If the bearing travels let us say always precise 5mm it will releases the clutch spring more the bigger the diameter of the bearings is.

This ist because the spring fingers are touched more close to their rotating point outside in the clutch cover.

So with a large bearing you can reduce diametre of master cylinder a bit more.

The release travel way of the clutch pressure plate ist defined by size of master and slave and diametre of release bearing.

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4 yeses for that, in theory, 

but allow me to tell you about my experience and calculation:

the influence of the diameter from the small "Sachs" to the standard "RHP" release bearing is +/- 3 % to max. 5%,

while the masters make steps of 15% (0.75" to 0.70"), 25% (0.70" to 0.625") and 44% (0.75" to 0.625"),

so I found no need to bother the diameter of the release bearing.

I have no chioce anyway when I want to use the Opel Omega unit.

Ciao, Marco

Edited by Z320
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57 minutes ago, Z320 said:

the influence of the diameter from the small "Sachs" to the standard "RHP" release bearing is +/- 3 % to max. 5%,

I did those measurements on a test bench using different clutch plates and bearings. The bearing is rather insignificant. 
 

Jochem

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Is there a reason not to use the outer hole on the clutch lever to reduce effort?

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4 hours ago, Z320 said:

4 yeses for that, in theory, 

but allow me to tell you about my experience and calculation:

the influence of the diameter from the small "Sachs" to the standard "RHP" release bearing is +/- 3 % to max. 5%,

while the masters make steps of 15% (0.75" to 0.70"), 25% (0.70" to 0.625") and 44% (0.75" to 0.625"),

so I found no need to bother the diameter of the release bearing.

I have no chioce anyway when I want to use the Opel Omega unit.

Ciao, Marco

Yes, that seems not make that difference but I preferred to test instead of measure and calculate.

At another forum the guys did not want to use this set because bearing ist wider and Toyota bearing ist even wider and I wanted to point out that there ist always a solution possible to achieve a perfect disengagement of the clutch and nice pedal forces with a matching choice of the master.

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Hi Andreas,

sorry me, this is no criticism about you!

What you point out is the gist of the matter: the master rules (and the slave, and the diaphragm spring of the cover).

I know the standard discussion about smaller and bigger release bearings and the expected benefit from a smaller one.

The story sounds true, but it's only a story about their hope and their testing is not with a scale but by their "feeling".

And "my feeling is" can be very subjectiv and can be the way it is to prevent you from disappointment.

If you want to know my calculation:

the fingers (levers) of diaphragm spring are about 50 mm long with the RHP bearing,

with the Sachs bearing the are max. about 3 mm longer.

53 mm / 50 mm is 1.06%,

6% longer levers is 1 / 1.06 = 0.9466 = 5.34% less force - but the contact point is "rolling" closer to the 50 mm on the fingers while pressing the diaphragm spring.

And this seems to be confirmed by Jochem's measurements.

Ciao, Marco

@ all the others: sorry me for this boring discussion 

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I'm always curious why there's so much debate about clutch setup. As far as I can see, there's precious little you can do to change the weight of the TR6 clutch unless you use a lighter/heavier cover plate or change the length of the clutch pedal arm itself. That's because the travel required to fully release the clutch is only just achieved with full pedal movement and everything standard. If you use a smaller master cylinder diameter you need less effort but move less fluid at full travel (and don't fully release the clutch). Similar (in reverse) if you change the size of the slave cylinder or release bearing, or use a different hole in the arm. Does that make sense?

Using a cover plate with weaker springs works (isn't the original Laycock cover lighter than aftermarket items we now use?) until you get clutch slip, e.g., with a supercharged engine! I've never heard of anyone doing it, but in theory you could mess with the pedal length. A longer lever there would give you more pedal movement (and less effort) for the same travel at the master cylinder.

Of course if everything is perfect (no wear) then you have a little movement to spare and may be able to play a bit.

I'd be interested to know if the annular clutch feels any different. Any observations?

John

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10 hours ago, Tim D. said:

Is there a reason not to use the outer hole on the clutch lever to reduce effort?

Hi Tim,

I don't know why there are 3 drillings in the lever, next is my opinion, maybe someone else has a different explanation.

 

Best you use the one which holds the push rod inline to the center of the piston.

Otherwise you have sideward forces on the piston and it will grind on the surface of the bore.

 

The resulting force and the "real lever" are always in 90 deg. to each other.

To use the outer hole only makes sense when you also move the master cylinder out the same distance.

When you angle the pushrod out of 90 deg to get a longer lever (indeed this is not the case) you loose what you win at the same time (and get sideward forces).

 

Ciao, Marco

 

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1 hour ago, Z320 said:

To use the outer hole only makes sense when you also move the master cylinder out the same distance.

When you angle the pushrod out of 90 deg to get a longer lever (indeed this is not the case) you loose what you win at the same time (and get sideward forces).

Umm, I'm not sure that's 100% correct. If you draw the actual geometry you'll see that using the outer hole does give you a longer lever - the thrust line is roughly 90 degrees to the arm, and the distance between holes doesn't change this by enough to negate the lever increase. But your point about off-centre forces is still worth taking into account.

John

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Hi John,

this is what I remember, I can't check this on my TR because I don't use this mechanism anymore.

But all you need to know is to use the hole which holds the push rod in line with the piston of the slave.

Anything different is worse.

I'm not shure about:

does it make sense to explain why the 0.625 master works well to members of this forum who feel better by believing it doesn't work?

Am I a liar telling you this? 

Probably it's better you have your own close look, than you can see what is obvious to see.

Ciao, Marco

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2 hours ago, Z320 said:

Hi Andreas,

sorry me, this is no criticism about you!

Did not feel so, all okay. Like your opinion. Also measurements from Jochem are interesting because I can not do that.

Just wanted to point out that we approach in a different way. I had a slippery clutch and found as a remedy the turbo clutch. Expected heavier pedal forces and found the throwout bearing to reduce a little bit.

Found a friend to try that all out as we need the turbo clutch anyway.

So i used my energy to produce a nice setup and at the end pedal forces and feeling for the clutch ended perfect.

 

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12 hours ago, Mike C said:

Reduced throw due to reduced rotation?

Meaning, the maximum lever movement possible with the slave cylinder will move the thrust bearing less with the pin in the outer hole, just looking at rotation & moments around the release bearing shaft. 

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17 minutes ago, Z320 said:

I'm not shure about:

does it make sense to explain why the 0.625 master works well to members of this forum who feel better by believing it doesn't work?

Am I a liar telling you this?

There are things between heaven and earth we do not fully understand. I built a friends engine very similar to mine, Megasquirt ist the same, and fuel table must be very different. No reason found.

Clutch ist similar. I found TRs that need the 0.75" master to open the clutch, others work nice with 0.7".

Also pedal forces often differ very much with identical clutch. The same Gremlins that perform in the electric system also work in the clutch. That was one reason for me to get rid of all the mechanic with Help of the hydraulic throwout bearing. I expect the Gremlins there.

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My mate Wolfgang is down to 12 kg on the pedal on his TR6

with a 0.625" master on my recommendation and one of the Opel Omega hydraulic units I made.

That really surprised him and also me!

Edited by Z320
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Hi All,

At the mo I am not too worried by the clutch pedal pressure. Just feels different at the mo as I have swapped it with a standard B&B clutch. I suspect I will get used to  it once I drive the car a bit. Small price to pay for loosing the clutch slip. 

Tim

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23 hours ago, Z320 said:

@ all the others: sorry me for this boring discussion 

 

21 hours ago, Z320 said:

I don't know why there are 3 drillings in the lever,

Not boring.  Many (30ish) years ago I replaced my clutch with a bad combination of new parts.  

The only way that I could make it operate normally was to shim the slave and set the rod at the closest release lever hole(drilling).

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Not sure about all this discussion. I've used the bottom hole on the operating shaft lever on a TR2 for many years to take up some wear in the various linkages. It does give more leverage on the operating shaft so does give more movement at the thrust race. It didn't do any damage to the slave cylinder bore. I've since fixed the wear in the bits needing it so have reverted to the middle hole.

However, reading this discussion reminded me to go and bleed the TR6 clutch. I have had a bit of difficulty with 2nd occasionally and have been getting a bit more clutch shudder when the car is really hot than was there before. Someone on here said to bleed the clutch as air or water in the system can affect the clutch operation to contribute to shudder on take up.

I didn't test drive long enough to get the car really hot (it has been a cool summer downunder so far) to test for clutch shudder but the clutch is working much better with 2nd sliding in smoothly. A bleed is a good thing to do occasionally.

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21 hours ago, Z320 said:

Am I a liar telling you this? 

Not at all ! And I'm sorry if that's the impression I gave. As I said, if everything is perfect you have more excess movement to play with. If you can get enough movement at the release bearing with a small diameter mc then you have the best of both worlds. 

John

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Quote

Clutch ist similar. I found TRs that need the 0.75" master to open the clutch, others work nice with 0.7".

Well, that reminds me on my trip to Sweden to a race in Karlskoga around 15 years ago when the clutch collapsed. First what gave up was the master. A former swedish rally-champion nearby gave me that of his wonderful 123GT (he gave it to me for free. from his own note 1 car. what a guy!). And it was different to my TR´s one (I cannot even remember if the Volvo one was a 7.5 and my one 7 or vice versa). But I do remember that there was no difference (it was with a B&B clutch). later I changed to a Sachs. There was no difference between them still.

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On 12/29/2020 at 8:50 AM, JohnC said:

That's because the travel required to fully release the clutch is only just achieved with full pedal movement and everything standard. If you use a smaller master cylinder diameter you need less effort but move less fluid at full travel (and don't fully release the clutch).

Hi John, I tell you the story!

What you state I've been told agiain and again and again when I asked different mates and supliers for advice to use a 0.70" master instead the 0.75" master.

And I asked myself more and more and more: what they are talking about!?!?

Because the clutch of my TR4A released with VERY short pedal way, the rest of the way (about 80%) is "empty".

So I swoped some years ago to a 0,70" master and the clutch still released with short way of the pedal, so I swoped 3 years ago to a 0.625" master, still in use.

This is because the cluch cover is like a sea saw: when loaded (gap off, play off) you need only a minimum more of way to get a gap and release the clutch.

This is after only 5 - 6 mm of travel (most elastic bend of the fingers) at all of the release bearing.

So why do "some" guys have this bleeding and release problems:

in my impression this are mostly TR6 guys because the clutch mechanism went worse with the TR6.

It suffers from wrong installed slave cylinders, after market slaves with wrong positioned flange, too much play for the self adjustmend and misunderstanding.

A self made pushrod with individual length or an adjustable pushrod is not needed on the TR6 - but it can help to solve the problem (I made some).

Or a swop to a hydraulic concentric unit like Andreas' Howe or the Opel Omega unit I use to get rid from all that stuff.

This is why my mate Wolfgang's TR6 clutch works well with a 0.625" master and the Opel Omega unit.

He didn't trust me for that advice for a while but finally fitted one.

That's already all of the story....

Ciao, Marco

Edited by Z320
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It interesting what you say Marco. I noticed with the Saab clutch that there is indeed a fair bit of unused pedal movement beyond the release point. Could the pivot point in the pressure plate and hence effective lever length be different to the B&B clutch?

The saab clutch also seems to have a much more pronounced decrease in pedal pressure Once released. 

Tim

 

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5 hours ago, Z320 said:

after market slaves with wrong positioned flange

Hi Marco,

You may have just solved a mystery for me! I have an aftermarket slave which I need to install through the mounting plate *from the rear*, even though the machined face is on the other side of the flange. If I mount it “correctly”, the piston is very close to popping out of the cylinder when the pedal is depressed. I could also use a longer push rod but mounting from the back solved the problem.

Cheers,
John

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If you want to make a individual push rod for your TR6 use a "Gabelkopf M8" and a long bolt M8.

"Gabelkopf M8" you should get by browsing "fork head M8", you get them long and short, buy a long one.

The long bolt is a "Schlosserschraube M8", the thread is always 30 mm long, english you call this "carriage screw".

But please keep attention: with this let enough way for the piston for the self adjustage or further check the gap like on the 4 cylinders.

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Happy motoring in 2021

Ciao, Marco

Edited by Z320
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On 12/30/2020 at 7:06 AM, John McCormack said:

Not sure about all this discussion. I've used the bottom hole on the operating shaft lever on a TR2 for many years to take up some wear in the various linkages. It does give more leverage on the operating shaft so does give more movement at the thrust race. It didn't do any damage to the slave cylinder bore. I've since fixed the wear in the bits needing it so have reverted to the middle hole.

However, reading this discussion reminded me to go and bleed the TR6 clutch. I have had a bit of difficulty with 2nd occasionally and have been getting a bit more clutch shudder when the car is really hot than was there before. Someone on here said to bleed the clutch as air or water in the system can affect the clutch operation to contribute to shudder on take up.

I didn't test drive long enough to get the car really hot (it has been a cool summer downunder so far) to test for clutch shudder but the clutch is working much better with 2nd sliding in smoothly. A bleed is a good thing to do occasionally.

Hi John!

Clutch judder in my experience is usually caused by the m/s bearing carrier binding on the gearbox nose. Always noticeably on hot dry days in London traffic, some people call it ratcheting. It plagued me for 40 years and I only got rid of it by using a bronze bearing carrier from Revington as used by the original TRs. The difference in clutch operation is very different, its nice and smooth now. I am still looking for a Luke clutch trust bearing as I am told they are the DB!  as against the RHP type.

Bruce.

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