19 replies to this topic

[Nev]

Does anyone know the master cylinder bore in our cars please?

 

And is the master cylinder the same for a  VXT and NA ?

 

Has anyone swapped theirs out for the next size down? If so, how did they find the pedal travel increase? And did it noticeably increase braking/lock out point please?

Edited by Nev, 13 August 2013 - 04:31 PM.

[Nelly Vx]

Na Vxt are the same , I've just replaced mine before the national . Actually got it from Chris Neal as a lotus part so must be the same one across the range, Nev the old ones in the van , could check the bore for you :-)

[fezzasus]

I think it's 23mm

[Nev]

Confirmation would be great Nelly.

 

Fez thanks for that, 23mm probably means it's a 1" bore which is fairly standard I think.

 

I bet there is a like for like (ie same form factor) OEM part I can buy that would drop the bore to 3/4"... anyone know? I am tempted to do an experiment and increase the pressure down the lines by swapping this part out. Would also swap out the original OEM rubber flexi pipes at the same time too, as they may not like the extra pressure.

 

Edited by Nev, 13 August 2013 - 04:40 PM.

[fezzasus]

Na Vxt are the same , I've just replaced mine before the national . Actually got it from Chris Neal as a lotus part so must be the same one across the range, Nev the old ones in the van , could check the bore for you :-)

 

Can I ask why, and if you noticed any improvement? I've never had much faith in my brakes and i'm running out of things to change

[Nelly Vx]

I think it's 23mm

Confirmed it is 23 mm:-)

[Nelly Vx]

Na Vxt are the same , I've just replaced mine before the national . Actually got it from Chris Neal as a lotus part so must be the same one across the range, Nev the old ones in the van , could check the bore for you :-)

  Can I ask why, and if you noticed any improvement? I've never had much faith in my brakes and i'm running out of things to change

Brake pedal kept on sticking down after half a hour of driving , changed the spring , fluid discs pads and , checked the lines and cslipers and so on .... It was the last thing in the system to change . Cured the fault too :-) , £225 plus vat from the stealers , £ 95 plus vat from lotus ;-)

[JohnTurbo]

Defo 23mm

[JohnTurbo]

But....23mm is not an inch! That's 25.4mm.

 

Also it might be worth you stating what you hope to achieve. No worries on pressure, but 3/4" will be mega servo'd and mega spongy.

 

362 rather than 529

 

68% of the area.

 

 

Edited by JohnTurbo, 13 August 2013 - 08:06 PM.

[Nev]

But....23mm is not an inch! That's 25.4mm.

 

Also it might be worth you stating what you hope to achieve. No worries on pressure, but 3/4" will be mega servo'd and mega spongy.

 

362 rather than 529

 

68% of the area.

 

 

 

Am tentatively considering a brake upgrade to stop the car faster and the master cylinder is the key.

[LY_Scott]

Mk4 golf IIRC Edit......it's from.

Edited by LY_Scott, 14 August 2013 - 01:03 PM.

[Nev]

Mk4 golf IIRC Edit......it's from.

 

Thanks for that, what I really need to know is a part number for an identical form factor unit with approx. 20% to 40% less x-sectional area. Can anyone help point me... ?

[fezzasus]

Stick within the VW range to ensure compatibility, and look for smaller cars, maybe the Polo?

[ArticMonkey]

Didn't a chap on here change his servo for a Subaru unit? Very impressive set up indeed with boxster callipers all round.

[fezzasus]

Yes, but that took the diameter up to 29 mm from 23 mm to account for the larger piston area.

[Nev]

Why did he do that then, if one is putting more cicumferance pots on, you need greater pressure (ie lower master cylinder bore) ???

Edited by Nev, 14 August 2013 - 09:20 PM.

[slindborg]

To maintain the fluid flow for a decent pedal travel....

[JohnTurbo]

Nev its worth reading a little about hydraulics...hence my question. Firstly nothing will make the car stop quicker without you increasing grip or improving balance. If you want to stop faster, push the pedal harder. ..this increases system pressure! If you arent strong enough to lock the wheels id be surprised! If joshua hadnt increased his master size his pedal would have felt like a soft sponge whilst insta-locking the wheels. Broadly you should keep master to slave area ratio the same to give decent feel...small adjustments to change feel. If you want the car to slow more for less pedal force the nest bet is higher cof pads. What most people achieve by cocking around with brakes is a car that stops slower than standard. My first couple of efforts are included.

Edited by JohnTurbo, 14 August 2013 - 09:38 PM.

[JohnTurbo]

Fyi your statement at 10:17 is the opposite to the true situation.

[rob999]

Didn't a chap on here change his servo for a Subaru unit? Very impressive set up indeed with boxster callipers all round.

JoshuaUXB