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Z320

hydraulic clutch release bearing (for TR4A-TR6)

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Hi Marco, the pressure forces dropped a little bit

referring to the old but nice working clutch but not

that much we expected.

For a TR6 clutch it is easy to press but not more.

 

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You can see on my calculation sheet our piston's surface is 750 mm^2 large, what size is yours?

With the original 0.75" master I do also not expect a surprise.

My idea was always to use a 0.625", what I already do. I'm now already very pleased with that!

 

Perhaps the story we all have been told is only the "Kings new clothes".

Friend of mine is psychologist, he always calls this "kognitive dissonanz reduktion" 

Edited by Z320

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Never calculated, HOWE recommended a 0.75"

so we kept what we had.

 

The fun started after fitment. As you found out we will

also fit the 0.625" master because we have more travel than needed.

I think than all possible has been done in this area.

 

We will also have to examine the pressure plates. The MF215

Sachs for Volvo can be obtained in two versions for different

engines, one smaller, one bigger.

Maybe a stock carb TR6 will work properly with the softer pressure plate.

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Hi,

I made a tool last week to determine the force I have to step on the clutch pedal.

Today out on the raod with friend A and B we found this:

23 kg, my TR4A, Borg+Beck cluch, 0.625" master instead of 0,75", slave original 1"

21 kg, friend B's TR6, Sachs 3082 100 041 (Saab/Vauhall), 0.70" master instead of 0.75", slave original 1"

19 kg; friend A's TR6, Sachs 3082 100 041 (Saab/Vauhall), 0.75" master, "our" Sachs hydraulic release bearing.

Friend A ordered a 0.70" master.....

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Hi Marco,

a nice straight comparison.

From your measurements it appears the new hydraulic clutch requires 2kg or 10 % less force, with a larger MC. And you can expect another 10-15% reduction with the 0.7 bore MC. That would result in a final 20-25%.

Have you also measured a modern car for comparison?

Cheers,

Waldi

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Indeed a good idea that was not in my mind,

but my BMW I3 has no gear box and my wife's car is an automatic.

Have to ask neigbors.....

 

Edited by Z320

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12.5 - 13.0 kg

on a 2014 VW Polo TSI, petrol engine with about 100 hp

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Since the Sachs 041 clutch plate is used on a Saab 99 it would be very interesting to know the required pressure on that car. That would be an actual comparison. 

Jochem

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Hi Jochem,

is a Saab 99 the same as a Saab 900? I know someone with this such a car.

Ciao, Marco

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20 minutes ago, Z320 said:

 

Hi Jochem,

is a Saab 99 the same as a Saab 900? I know someone with this such a car.

 

Saab 900 —> from 78 to 1990

Jochem

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I had a 99 Turbo when I was 24. No heavy clutch then:)

Waldi

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The VW Polo clutch is a ladies thing, like a toy, you will not like it.

Pressing the pedal the first time I expected it is only 5 kg , indeed it is 12.5 - 13 kg.

For me anything from 15 - 20 kg would be OK.

Edited by Z320

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16 kg on my colleague's "new" FIAT Cinquecento, no problem at all for her

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Hi,

got this video from friend A, sorry for no sound, it is made with an inspection camera.

His TR6 run about 1,000 km with the new hydraulic release clutch without problems.

I'm so glad the release bearing is not wobbling (what I did not expect but could be the case).

Ciao, Marco

 

Edited by Z320

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Hi Marco,

    a nice video clip. It looks as though it functions beautifully.   Are you happy that the bearing is rotating continually.?

 

Roger

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Hi Roger,

that's what it's made for, this can't be wrong.

When I was allowed to drive the car last Saturday everything worked fine.

Marco

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Hi Marco,

         Indeed bearings are built to rotate. God quality will spin forever.

 

Roger

 

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It should not spin until pedal applied .You need to be bang on when setting one up and know how to do it,there after very good but expensive.

Edited by ntc

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7 hours ago, ntc said:

 

It should not spin until pedal applied .You need to be bang on when setting one up and know how to do it,there after very good but expensive.

 

These units are designed to spin! There is an internal spring pressing the bearing against the pressure plate. 

Jochem

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This is the common design of clutch release bearings - already for decades.

It seems to be better to have it always running instead of accelerate it every time you change the gear.

The load of the internal spring is 10 - 12 kg (did I already post that?)

 

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Hi,

the 0.70" master is in friends A's TR6,

I expected the force to press the clutch pedal drops from 19 kg to about 16.0 - 16.5 kg.

Yesterday he reported:

"Made a first test drive, first impression: sensational!!!

Pedal feels like falling down to the floor panel by itself, anyway the clutch works proper and is lovely to handle.

WAF (woman acceptance factor) is definitely 100% (3 woman smileys), car drives like a VW Polo 1.0 l.

For me it's so easy working that I have to get used to it".

I think its 16 kg :) indeed the difference is sensational, we will determine the force when we meet next time.

Ciao, Marco

 

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Very nice Marco, 

I can see a couple of happy TR-ers.

Cheers,

Waldi

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Hi,

I met the son of a friend of mine last weekend, his is 19 years old and

is learing to be a car mechanic and car restorer for vintage and classic cars, most BMW 328.

He told me he recently had to work on the clutch of a pre war Bugatti, which is very "special".

Indeed, see here.

 

Enjoy it

Marco

Edited by Z320

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