Hydraulic clutch solid line diameter.

Kai

Well just thinking out aloud on this one.... It's still not back together yet.

I bought the Saco hydraulic clutch kit which turned out to be no good for my application, well bits of it.

So as it currently sits I've used the Saco reservoir and the pipe supplied in the kit is the same size as the copper tube I used for my brake lines. Great as I had loads of this copper tube left over.

So I have used copper brake pipe to supply the clutch master cylinder fluid from the reservoir.

I used the brake pipe to supply fluid to the slave cylinder from the master cylinder.

The brake pipe is maybe 4mm OD. I've bleed it once already and the pedal was mega stiff, felt like something was gonna go if I really pushed it (long story short I felt it would be good to change my clutch arm and make a new bracket for the slave cylinder).

So my question is....

Could I benefit by increasing my hydraulic lines from 4mm to a 6mm copper pipe? I was told it would decrease the effort required to move the pedal.

I've used thread adaptors which have I would say small holes through them, if I increase the main pipes to 6mm should I be contemplating fitting adaptors with bigger bored holes through them?

If it's any use from memory I have a 19mm diameter master cylinder and a 22mm slave. No idea on the cylinder depths.
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13 window deluxe · Posted: Sat Nov 06, 2010 9:38 am Post subject:

4mm seems to small to me never seen one that diameter with all factory hydro clutchs they usually use 1/4" or 6mm pipe
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1964 rat 13 window deluxe 1Z tdi,
1975 rhd twin slider tintop (TBA)
1991 golf 2 gti with tweaked AHU tdi,

previous tdi swaps: gone but not forgotten
1979 rhd twin slider tintop bay ahu 1.9tdi
1990 T25 1Z 1.9tdi
1993 suzuki samurai with 1Z 1.9tdi

P4UL · Padawan Joined: 13 Sep 2010 Posts: 83 Location: Derbyshire

The OD is a useless measurement, use the inside dia to measure as wall thickness will vary.
Personally I would have used the same size as the kit was designed to use, get it working then adjustment pipe sizes from there.

Kai · Posted: Sat Nov 06, 2010 11:20 am Post subject:

I'm gonna bite the bullet and install a 6mm hydraulic line then. I've spent ages and ages f*****g around with this set up and I've bleed it loads of times now and each time it's just disappointing to see the end result. Im gonna redesign the bracket I've created for the mastercylinder too as it flexes a little too much when the pedal is depressed.

So my next Q

By increasing the line size to 6mm should I be changing the internal bore sizes of my thread adaptors?? They've an internal bore of maybe 2-3mm?

I have a flexy line in the system, should I be increasing the size of this too.

Think I'll pu it apart and get some measurements of all the items, I don't want to create a restrictive bottle neck in the system.

Thanks for all the replys people

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Think......

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Kai · Posted: Sat Nov 06, 2010 12:18 pm Post subject:

My current line is 3mm ID.
_________________
Think......

Don't sleep and drive!!!

13 window deluxe · Posted: Sat Nov 06, 2010 10:19 pm Post subject:

13 window deluxe · Posted: Sat Nov 06, 2010 10:25 pm Post subject:

Kai · Posted: Thu Nov 11, 2010 11:21 pm Post subject:

Woowho... Feeling alittle euphoric tonight.

So I've kept the small brake line (after buying 25 meters of 1/4") and actually got round to bleeding it this evening.

Well it only bloody works. The pedal is fairly heavy... How ever from memory it feels exactly the same as the old cable with KEP stage 1 or 2 pressure plate I removed. It's usable as is with the smaller line.

I'll still look into installing the larger line but that'll probably wait for the time being as ive got plenty more to be getting on with.

Cheers for all you help

_________________
Think......

Don't sleep and drive!!!